Results from the 2018 National Survey on Drug Use and Health:
Detailed Tables

This glossary is a resource to provide definitions for many of the commonly used measures and terms in tables and reports from the 2018 National Survey on Drug Use and Health (NSDUH). Where relevant, cross-references to details in the 2018 NSDUH methodological summary and definitions report also are provided.

For some key terms, specific question wording is provided for clarity. In some situations, information also is included about specific gate questions. In many instances, a gate question is the first question in a series of related questions. How a respondent answers the gate question affects whether the respondent is asked additional questions in that section of the interview or is routed to the next section of the interview. In some sections of the interview, respondents may be asked more than one gate question to determine whether they are asked additional questions in that section or are routed to the next section.¹

Because of changes to the 2015 questionnaire, estimates for several measures in 2015 onward are not comparable with those from 2014 or prior years, even if the basic definitions may be the same or similar to those from prior years. Definitions corresponding to measures affected by questionnaire changes due to the partial questionnaire redesign in 2015 or other questionnaire changes since 2015 are starred with an asterisk (*). Definitions completely new since 2015 because of the questionnaire changes are indicated by a dagger symbol (†). See Section C in the methodological summary and definitions report for the 2015 NSDUH for details about the questionnaire changes in 2015 and their effects on comparability of estimates between 2015 and prior years.²

Abbreviated WHODAS

SEE: "World Health Organization Disability Assessment Schedule (WHODAS)."

Abuse*

NSDUH questions about criteria for abuse of alcohol or illicit drugs ask about the following symptoms, consistent with the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV³): (1) problems at work, home, and school; (2) doing something physically dangerous; (3) repeated trouble with the law; and (4) problems with family or friends because of use of alcohol or illicit drugs in the past 12 months. Respondents meet criteria for abuse if they report one or more of these symptoms and if the criteria for dependence were not met for that substance. Respondents were asked the abuse questions for illicit drugs other than marijuana if they reported any use of these substances in the past 12 months. Respondents were asked the alcohol and marijuana abuse questions if they indicated use of these substances on 6 or more days in the past 12 months. These questions for measuring abuse for illicit drugs or alcohol have been included in the survey since 2000. Questions about abuse related to the use of methamphetamine in the past year were added to the survey in 2015 and were patterned after the questions for cocaine abuse. Data for abuse since 2015 are comparable with data prior to 2015 for alcohol, marijuana, cocaine, and heroin. Data for abuse since 2015 are not comparable with data prior to 2015 for the any illicit drug summary measure, hallucinogens, inhalants, and prescription psychotherapeutic drugs. Separate data for methamphetamine abuse did not exist prior to 2015. Data for abuse are not available for benzodiazepines because respondents could report symptoms of abuse that apply to tranquilizers or sedatives that are not benzodiazepines.

SEE: "Alcohol Use Disorder (AUD)," "Classified as Needing Substance Use Treatment," "Dependence," "Illicit Drugs," "Opioid Use Disorder," "Sedative Use or Misuse," "Substance Use Disorder (SUD)," "Tranquilizer or Sedative Use Disorder," and "Tranquilizer Use or Misuse."

ACASI

ACASI stands for audio computer-assisted self-interviewing. ACASI questions in NSDUH appear on a laptop computer screen while an audio recording of the questions plays on headphones. Respondents enter their answers directly into the computer without the interviewer knowing how they answered. ACASI is designed to provide the respondent with a highly private and confidential mode for responding to questions about illicit drug use and other sensitive behaviors. The audio also is helpful for respondents with limited reading skills. For information on interview sections administered using ACASI, see the list of the content of the 2018 NSDUH instrument.⁴

SEE: "CAPI."

Age

Age of the respondent was defined as "age at time of interview." The interview program calculated the respondent's age from the interview date and the date of birth reported to the interviewer. The interview program prompts the interviewer to confirm the respondent's age after it has been calculated.

AIAN

SEE: "American Indian or Alaska Native (AIAN)."

Alcohol Use

Measures of use of alcohol in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime and recency of use (e.g., "How long has it been since you last drank an alcoholic beverage?"). The question about recency of use was asked if respondents previously reported any use of alcohol in their lifetime.

The following definitional information preceded the question about lifetime alcohol use: "The next questions are about alcoholic beverages, such as beer, wine, brandy, and mixed drinks. Listed on the next screen are examples of the types of beverages we are interested in. Please review this list carefully before you answer these questions. These questions are about drinks of alcoholic beverages. Throughout these questions, by a 'drink,' we mean a can or bottle of beer, a glass of wine or a wine cooler, a shot of liquor, or a mixed drink with liquor in it. We are not asking about times when you only had a sip or two from a drink."

SEE: "Binge Use of Alcohol," "Current Use or Misuse," "Heavy Use of Alcohol," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," "Recency of Use or Misuse," and "Underage Alcohol Use."

Alcohol Use Disorder (AUD)

Alcohol use disorder was defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV⁵), for either dependence or abuse for alcohol. Respondents who used alcohol on 6 or more days in the past 12 months were defined as having dependence if they met three or more of the following seven criteria: (1) spent a lot of time engaging in activities related to alcohol use, (2) used alcohol in greater quantities or for a longer time than intended, (3) developed tolerance (i.e., needing to use alcohol more than before to get desired effects or noticing that the same amount of alcohol use had less effect than before), (4) made unsuccessful attempts to cut down on alcohol use, (5) continued use despite physical health or emotional problems associated with alcohol use, (6) reduced or eliminated participation in other activities because of alcohol use, and (7) experienced withdrawal symptoms when respondents cut back or stopped using alcohol. Respondents who used alcohol on 6 or more days in the past 12 months and did not meet criteria for alcohol dependence were defined as having abuse if they reported one or more of the following: (1) problems at work, home, and school because of alcohol use; (2) regularly using alcohol and then doing something physically dangerous; (3) repeated trouble with the law because of alcohol use; and (4) continued use of alcohol despite problems with family or friends.

SEE: "Abuse," "Alcohol Use," "Dependence," and "Substance Use Disorder (SUD)."

Alcohol Use in Combination with Illicit Drug Use*

Starting in 2015, respondents were defined as having alcohol use in combination with illicit drug use if they reported using one or more of six selected illicit drugs with their last alcohol use or within a couple of hours of drinking alcohol. The selected illicit drugs respondents were asked about using in combination with alcohol were marijuana, cocaine or crack, heroin, hallucinogens, inhalants, and methamphetamine. Respondents who used both alcohol and selected illicit drugs in the past month were asked about this behavior. Respondents could report the use of more than one selected illicit drug in combination with alcohol. The definition since 2015 has not included alcohol use in combination with prescription pain relievers, prescription tranquilizers, prescription stimulants, or prescription sedatives because respondents were asked about misuse of these prescription psychotherapeutic drugs in combination with alcohol at any point in the past 30 days (i.e., not just the last time they used alcohol).

SEE: "Alcohol Use," "Cocaine Use," "Crack Use," "Hallucinogen Use," "Heroin Use," "Illicit Drugs," "Inhalant Use," "Marijuana Use," and "Methamphetamine Use."

Alternative Service Professional

An alternative service professional was defined in the adult depression and adolescent depression sections as a (1) religious or spiritual advisor (e.g., minister, priest, or rabbi) or (2) herbalist, chiropractor, acupuncturist, or massage therapist seen because of sadness, discouragement, or lack of interest (for adults) or sadness, discouragement, or boredom (for adolescents). Respondents could report they received treatment from more than one of these categories of alternative service professionals.

SEE: "Health Professional," "Major Depressive Episode (MDE)," and "Treatment for Depression."

American Indian or Alaska Native (AIAN)

American Indian or Alaska Native only, not of Hispanic, Latino, or Spanish origin, including North American, Central American, or South American Indian. This does not include respondents reporting two or more races. Respondents reporting they were American Indians or Alaska Natives and of Hispanic, Latino, or Spanish origin were classified as Hispanic.

SEE: "Hispanic or Latino," "Race/Ethnicity," and "Two or More Races."

Any Excluding Serious Mental Illness

SEE: "Mental Illness."

Any Mental Illness (AMI)

SEE: "Mental Illness."

Any Use of Psychotherapeutics†

Any use of psychotherapeutics refers to use of prescription psychotherapeutic medication (pain relievers, tranquilizers, stimulants, or sedatives) for any reason. This could include use of prescriptions of one's own as directed by a doctor or misuse of these medications. Starting in 2015, respondents were asked whether they used a series of specific prescription psychotherapeutic drugs in the past 12 months. For pain relievers, stimulants, and sedatives, respondents were instructed not to include the use of over-the-counter (OTC) drugs (e.g., aspirin, Tylenol^®, Advil^®, Aleve^®, Dexatrim^®, No-Doz^®, Hydroxycut^®, 5-Hour Energy^®, Sominex^®, Unisom^®, Benadryl^®, Nytol^®). This instruction not to include OTC drugs was not included for tranquilizers because all tranquilizers in the United States currently require a prescription. The questions about any use in the past 12 months included electronic images of pills or other forms of the drugs (where applicable) to aid respondents in recalling whether they used a specific prescription drug in the past 12 months. Respondents who did not report use in the past 12 months of any specific prescription psychotherapeutic drug within a category (e.g., prescription pain relievers) were asked whether they ever, even once, used any prescription psychotherapeutic drug within that category (e.g., any prescription pain reliever). Respondents were not asked about any use of prescription psychotherapeutic drugs in the past 30 days.

SEE: "Benzodiazepine Use or Misuse," "Lifetime Use or Misuse," "Misuse of Psychotherapeutics," "Pain Reliever Use or Misuse," "Past Year Use or Misuse," "Psychotherapeutic Drugs," "Recency of Use or Misuse," "Sedative Use or Misuse," "Stimulant Use or Misuse," "Tranquilizer or Sedative Use or Misuse," and "Tranquilizer Use or Misuse."

Asian

Asian only, not of Hispanic, Latino, or Spanish origin, in accordance with federal standards for reporting race and ethnicity data.⁶ This does not include respondents reporting two or more races. Respondents reporting they were Asian and of Hispanic, Latino, or Spanish origin were classified as Hispanic. Specific Asian groups asked about were Asian Indian, Chinese, Filipino, Japanese, Korean, Vietnamese, and Other Asian.

SEE: "Hispanic or Latino," "Race/Ethnicity," and "Two or More Races."

At Risk for Initiation*

Individuals were defined as being at risk for initiation in the past 12 months if they did not use a given substance in their lifetime or if they used it for the first time in the past year. Individuals who first used the substance more than 12 months ago were no longer considered to be at risk for initiation. NSDUH can identify individuals at risk for initiation of use of marijuana, cocaine, crack, heroin, hallucinogens, lysergic acid diethylamide (LSD), phencyclidine (PCP), Ecstasy, inhalants, methamphetamine, cigarettes, smokeless tobacco, cigars, and alcohol and also those at risk for initiation of daily cigarette use.

NSDUH cannot identify individuals at risk for initiation of illicit drug use, misuse of prescription psychotherapeutic drugs (i.e., pain relievers, tranquilizers, stimulants, or sedatives), benzodiazepines, misuse of opioids, and use of illicit drugs other than marijuana. For these measures, the 2018 detailed tables do not show percentages for initiation among those at risk for initiation due to questionnaire changes starting with the 2015 NSDUH. Specifically, the focus for questions about the misuse of specific psychotherapeutic drugs changed in 2015 from the lifetime to the past year period. Because of this change, respondents who last misused any prescription psychotherapeutic drug in a category (e.g., pain relievers) more than 12 months ago may underreport misuse. These respondents who did not report misuse that occurred more than 12 months ago would be misclassified as still being at risk for initiation. This change also affected aggregate risk for initiation measures that include prescription psychotherapeutic drugs (i.e., opioids, any illicit drug, any illicit drug other than marijuana). See Section 3.4.2 in the 2018 NSDUH methodological summary and definitions report for additional details.

SEE: "Initiation of Substance Use or Misuse" and "Misuse of Psychotherapeutics."

Benzodiazepine Use or Misuse†

Measures of the use or misuse of benzodiazepines in the past year were derived from questions that asked respondents about any use (i.e., for any reason) in the past 12 months of specific prescription tranquilizers or sedatives classified as benzodiazepines (see below). Respondents who reported they used specific benzodiazepines were asked for each drug whether they used it in the past 12 months in any way not directed by a doctor. Examples of use in any way a doctor did not direct respondents to use prescription tranquilizers or sedatives (including benzodiazepines) were presented to respondents and included (1) use without a prescription of the respondent's own; (2) use in greater amounts, more often, or longer than told to take a drug; or (3) use in any other way a doctor did not direct the respondent to use a drug.

Questions about the past year use and misuse of benzodiazepines covered the following subcategories of benzodiazepines prescribed as tranquilizers: alprazolam products (Xanax^®, Xanax^® XR, generic alprazolam, or generic extended-release alprazolam), lorazepam products (Ativan^® or generic lorazepam), clonazepam products (Klonopin^® or generic clonazepam), or diazepam products (Valium^® or generic diazepam). Questions covered the following subcategories of benzodiazepines prescribed as sedatives: flurazepam (also known as Dalmane^®), temazepam products (Restoril^® or generic temazepam), or triazolam products (Halcion^® or generic triazolam).

Respondents were asked about their use and misuse of benzodiazepines only for the past year; therefore, there are no lifetime or past month measures for benzodiazepines. See Section 4.6 in the 2018 NSDUH methodological summary and definitions report for additional details.

SEE: "Any Use of Psychotherapeutics," "Misuse of Psychotherapeutics," "Past Year Use or Misuse," "Psychotherapeutic Drugs," "Sedative Use or Misuse," and "Tranquilizer Use or Misuse."

Binge Use of Alcohol*

Binge use of alcohol was defined since 2015 for females as drinking four or more drinks on the same occasion (i.e., at the same time or within a couple of hours of each other) and for males as drinking five or more drinks on the same occasion on at least 1 day in the past 30 days. Respondents were asked about the number of days they had five or more drinks (for males) or four or more drinks (for females) on the same occasion if they reported last using any alcohol in the past 30 days based on the following question: "How long has it been since you last drank an alcoholic beverage?" Prior to the 2015 NSDUH, binge alcohol use was defined for both males and females as drinking five or more drinks on the same occasion on at least 1 day in the past 30 days. For males, data for binge alcohol use since 2015 are comparable with data prior to 2015. For females and the total population of males and females combined, data for binge alcohol use since 2015 are not comparable with data prior to 2015.

SEE: "Alcohol Use" and "Heavy Use of Alcohol."

Black

Black/African American only, not of Hispanic, Latino, or Spanish origin. This does not include respondents reporting two or more races. Respondents reporting they were black or African American and of Hispanic, Latino, or Spanish origin were classified as Hispanic.

SEE: "Hispanic or Latino," "Race/Ethnicity," and "Two or More Races."

Blunts

Blunts were defined as cigars with marijuana in them. Measures of use of blunts in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime and recency of use (e.g., "How long has it been since you last smoked part or all of a cigar with marijuana in it?"). The question about recency of use was asked if respondents previously reported any use of cigars with marijuana in them in their lifetime.

The following definitional information preceded the question about lifetime use of cigars with marijuana in them: "Sometimes people take tobacco out of a cigar and replace it with marijuana. This is sometimes called a 'blunt.'"

SEE: "Cigar Use," "Current Use or Misuse," "Lifetime Use or Misuse," "Marijuana Use," "Past Month Use or Misuse," "Past Year Use or Misuse," "Recency of Use or Misuse," and "Tobacco Product Use."

CAPI

CAPI stands for computer-assisted personal interviewing. CAPI questions in NSDUH are interviewer administered. Interviewers read these questions to respondents, then enter the respondents' answers into a laptop computer. For information on interview sections administered using CAPI, see the list of the content of the 2018 NSDUH instrument.⁷

SEE: "ACASI."

Cigar Use

Measures of use of cigars, including big cigars, cigarillos, and little cigars that look like cigarettes, in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime cigar use, use in the past 30 days, and the recency of use (if not in the past 30 days) (e.g., "During the past 30 days, have you smoked part or all of any type of cigar?" and "How long has it been since you last smoked part or all of any type of cigar?"). Responses to questions in a later section about use of cigars with marijuana in them (blunts) were not included in these measures to maintain the comparability of estimates over time. Questions about use of cigars in the past 30 days or the most recent use of cigars (if not in the past 30 days) were asked if respondents previously reported any use of cigars in their lifetime.

SEE: "Blunts," "Cigarette Use," "Current Use or Misuse," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," "Recency of Use or Misuse," "Smokeless Tobacco Use," and "Tobacco Product Use."

Cigarette Use

Measures of use of cigarettes in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime cigarette use, use in the past 30 days, and the recency of use (if not in the past 30 days) (e.g., "During the past 30 days, have you smoked part or all of a cigarette?" and "How long has it been since you last smoked part or all of a cigarette?"). Questions about use of cigarettes in the past 30 days or the most recent use of cigarettes (if not in the past 30 days) were asked if respondents previously reported they smoked part or all of a cigarette in their lifetime.

SEE: "Cigar Use," "Current Use or Misuse," "Daily Cigarette Use," "Lifetime Use or Misuse," "Nicotine (Cigarette) Dependence," "Past Month Use or Misuse," "Past Year Use or Misuse," "Recency of Use or Misuse," "Smokeless Tobacco Use," and "Tobacco Product Use."

Classified as Needing Alcohol Use Treatment*

Respondents were classified as needing treatment for an alcohol use problem if they met the criteria for an alcohol use disorder as defined in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV⁸), or they received treatment for alcohol use at a specialty facility (i.e., drug and alcohol rehabilitation facility [inpatient or outpatient], hospital [inpatient only], or mental health center). Although the alcohol use questions did not change for 2015 for determining who would be asked questions about receipt of treatment at a specialty facility for alcohol use, other changes to questions for determining who was asked questions about receipt of treatment at a specialty facility for illicit drug use could have an unknown effect on the need for alcohol use treatment measure.

SEE: "Abuse," "Alcohol Use Disorder (AUD)," "Dependence," "Specialty Substance Use Treatment Facility," and "Substance Use Treatment."

Classified as Needing Illicit Drug Use Treatment*

Respondents were classified as needing treatment for an illicit drug use problem if they met the criteria for an illicit drug use disorder as defined in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV⁹), or they received treatment for illicit drug use at a specialty facility (i.e., drug and alcohol rehabilitation facility [inpatient or outpatient], hospital [inpatient only], or mental health center).

Starting in 2015, the measure of the need for illicit drug use treatment took into account changes to the computer-assisted interviewing logic in 2015 for determining who was asked questions about dependence or abuse or the receipt of treatment at a specialty facility based on the addition of the new section for methamphetamine and changes to the sections for hallucinogens, inhalants, and misuse of prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, and sedatives). See Section C in the methodological summary and definitions report for the 2015 NSDUH.¹⁰

SEE: "Abuse," "Dependence," "Illicit Drug Use Disorder (IDUD)," "Specialty Substance Use Treatment Facility," "Substance Use Disorder (SUD)," and "Substance Use Treatment."

Classified as Needing Substance Use Treatment*

Respondents were classified as needing substance use treatment (i.e., treatment for an illicit drug or alcohol use problem) if they met the criteria for a substance use disorder as defined in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV¹¹), or they received treatment for illicit drug or alcohol use at a specialty facility (i.e., drug and alcohol rehabilitation facility [inpatient or outpatient], hospital [inpatient only], or mental health center).

Starting in 2015, the measure of the need for substance use treatment took into account changes to the computer-assisted interviewing logic in 2015 for determining who was asked questions about dependence or abuse or the receipt of treatment at a specialty facility based on the addition of the new section for methamphetamine and changes to the sections for hallucinogens, inhalants, and misuse of prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, and sedatives). See Section C in the methodological summary and definitions report for the 2015 NSDUH.¹²

SEE: "Abuse," "Alcohol Use Disorder (AUD)," "Dependence," "Illicit Drug Use Disorder (IDUD)," "Specialty Substance Use Treatment Facility," "Substance Use Disorder (SUD)," and "Substance Use Treatment."

Cocaine Use

Measures of use of cocaine, including powder, crack, free base, and coca paste, in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime and recency of use (e.g., "How long has it been since you last used any form of cocaine?"). The question about recency of use was asked if respondents previously reported any use of cocaine in their lifetime.

SEE: "Crack Use," "Current Use or Misuse," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Cocaine Use Disorder

Cocaine use disorder was defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV¹³), for either dependence or abuse for cocaine. Respondents who used cocaine in the past 12 months (including those who reported using crack or cocaine with a needle in that period) were defined as having dependence if they met three or more of the following seven criteria: (1) spent a lot of time engaging in activities related to cocaine use, (2) used cocaine in greater quantities or for a longer time than intended, (3) developed tolerance (i.e., needing to use cocaine more than before to get desired effects or noticing that the same amount of cocaine use had less effect than before), (4) made unsuccessful attempts to cut down on cocaine use, (5) continued use despite physical health or emotional problems associated with cocaine use, (6) reduced or eliminated participation in other activities because of cocaine use, and (7) experienced withdrawal symptoms when respondents cut back or stopped using cocaine. Respondents who used cocaine in the past 12 months and did not meet criteria for cocaine dependence were defined as having abuse if they reported one or more of the following: (1) problems at work, home, and school because of cocaine use; (2) regularly using cocaine and then doing something physically dangerous; (3) repeated trouble with the law because of cocaine use; and (4) continued use of cocaine despite problems with family or friends.

SEE: "Abuse," "Cocaine Use," "Crack Use," "Dependence," "Illicit Drug Use Disorder (IDUD)," and "Substance Use Disorder (SUD)."

College Enrollment Status*

This measure was developed only for respondents aged 18 to 22 based on answers to questions about current or upcoming enrollment in school and (if applicable) about whether respondents were full- or part-time students and the year of school they were or will be attending. Respondents in this age group were classified either as full-time college students or as some other status, which included respondents not enrolled in school, enrolled in college part time, enrolled in other grades either full time or part time, or enrolled with no other information available. Respondents were classified as full-time college students if they reported they were attending or will be attending their first through fifth or higher year of college or university and they were or will be a full-time student. Respondents whose current enrollment status was unknown were excluded from this measure. Starting in 2015, these questions were self-administered using audio computer-assisted self-interviewing (ACASI) instead of being interviewer administered through computer-assisted personal interviewing (CAPI). Additional changes were made in 2016 to the question about being enrolled in school. However, these changes in 2016 did not affect the comparability of the college enrollment status measure between 2015 and 2016 or between 2016 and subsequent years.

SEE: "ACASI" and "CAPI."

County Type*

Starting in 2015, county type was based on the "Rural/Urban Continuum Codes" developed in 2013 by the U.S. Department of Agriculture (USDA).¹⁴ All U.S. counties and county equivalents were grouped based on revised definitions of metropolitan statistical areas (MSAs) and definitions of micropolitan statistical areas as defined by the Office of Management and Budget (OMB) as of February 2013.¹⁵ In order to compare estimates by county type since 2015 with estimates from prior years, a revised version of county type was created based on the 2013 "Rural/Urban Continuum Codes" for the years 2002-2014. Therefore, estimates for 2014 and prior years based on the 2013 county type definition will not be comparable with estimates by county type in previously published tables of NSDUH estimates.

Large MSAs (large metro) have a total population of 1 million or more. Small MSAs (small metro) have a total population of fewer than 1 million. Nonmetropolitan (nonmetro) areas include counties in micropolitan statistical areas as well as counties outside of both metropolitan and micropolitan statistical areas. Nonmetro counties with a population of 20,000 or more in urbanized areas are classified as "urbanized," nonmetro counties with a population of at least 2,500 but fewer than 20,000 in urbanized areas are classified as "less urbanized," and nonmetro counties with a population of fewer than 2,500 in urbanized areas are classified as "completely rural." The terms "urbanized," "less urbanized," and "completely rural" for counties are not based on the relative proportion of the county population in urbanized areas but rather on the absolute size of the population in urbanized areas. For example, some counties classified as "less urbanized" had over 50 percent of the county population residing in urbanized areas, but this represented fewer than 20,000 people in the county. Population counts used are from the 2010 census representing the resident population. Data from the 2006 to 2010 American Community Surveys were also used by OMB and USDA to define these areas. See Section 3.4.5 in the 2018 NSDUH methodological summary and definitions report for additional details.

Crack Use

Crack was defined as cocaine used in rock or chunk form. Measures of use of crack cocaine in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime and recency of use (e.g., "How long has it been since you last used crack?"). The question about recency of use was asked if respondents previously reported use of cocaine in any form and specifically any use of crack in their lifetime. Respondents who reported they never used any form of cocaine were logically defined as never having used crack.

SEE: "Cocaine Use," "Current Use or Misuse," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Current Use or Misuse*

For substances other than prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, or sedatives), current use refers to any reported use of a specific substance in the past 30 days (also referred to as "past month use"). For prescription psychotherapeutic drugs, current misuse refers to misuse of psychotherapeutics in the past 30 days. (Respondents were not asked about any use of psychotherapeutics in the past 30 days.)

SEE: "Lifetime Use or Misuse," "Misuse of Psychotherapeutics," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Daily Cigarette Use

Respondents who smoked cigarettes in the past 30 days were defined as being past month daily cigarette users if they smoked part or all of a cigarette on all 30 days in that period. Respondents were defined as being lifetime daily cigarette users if they reported daily cigarette use in the past month or they reported a period in their lifetime when they smoked cigarettes every day for at least 30 days.

SEE: "Cigarette Use."

Daily or Almost Daily Use*

Respondents who used or misused a substance other than cigarettes on 20 or more days in the past month were defined as daily or almost daily users in the past month. Respondents who used a substance on 300 or more days in the past year were defined as daily or almost daily users in the past year. Respondents were not asked about the number of days in the past year they used tobacco products or misused prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, or sedatives). Respondents who reported smoking cigarettes on each of the past 30 days were defined as daily smokers.

SEE: "Daily Cigarette Use."

Delinquent Behavior

Youths aged 12 to 17 were asked a series of six questions: "During the past 12 months, how many times have you… gotten into a serious fight at school or work?" "taken part in a fight where a group of your friends fought against another group?" "carried a handgun?" "sold illegal drugs?" "stolen or tried to steal anything worth more than $50?" and "attacked someone with the intent to seriously hurt them?" Response options were (1) 0 times, (2) 1 or 2 times, (3) 3 to 5 times, (4) 6 to 9 times, or (5) 10 or more times. Respondents were defined as having engaged in a specific delinquent behavior if they reported engaging in that behavior at least one time in the past 12 months. In addition, respondents were defined as having engaged in physical delinquent behaviors if they reported they got in a serious fight at school or work, took part in a fight against another group, or attacked someone with the intent to seriously hurt them at least one time in the past 12 months. Respondents were defined as having engaged in nonphysical delinquent behaviors if they reported they carried a handgun, sold illegal drugs, or stole or tried to steal anything worth more than $50 at least one time in the past 12 months.

Dependence*

NSDUH dependence questions for alcohol or illicit drugs ask about the following symptoms, consistent with the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV¹⁶): (1) spent a lot of time engaging in activities related to substance use, (2) used the substance in greater quantities or for a longer time than intended, (3) developed tolerance (i.e., needing to use the substance more than before to get desired effects or noticing that the same amount of substance use had less effect than before), (4) made unsuccessful attempts to cut down on substance use, (5) continued substance use despite physical health or emotional problems associated with substance use, (6) reduced or eliminated participation in other activities because of substance use, and (7) experienced withdrawal symptoms. For the specific illicit drugs (i.e., cocaine, heroin, methamphetamine, prescription pain relievers, prescription stimulants, and prescription sedatives) and alcohol that include a withdrawal criterion as one of the criteria that can be used to establish dependence, respondents were defined as meeting the criteria for dependence if they met three out of the seven criteria. For illicit drugs that do not include questions in NSDUH about a withdrawal criterion for establishing dependence (i.e., marijuana, hallucinogens, inhalants, and prescription tranquilizers), respondents were defined as meeting the criteria for dependence if they met three out of the six criteria for that substance. Respondents were asked the dependence questions for illicit drugs other than marijuana if they reported any use in the past 12 months. Respondents were asked the alcohol and marijuana dependence questions only if they indicated use of these substances on 6 or more days in the past 12 months. These criteria were not used to define nicotine (cigarette) dependence, which used a different series of items. Questions about dependence related to the use of methamphetamine in the past year were added to the survey in 2015 and were patterned after the questions for cocaine dependence. Data for dependence since 2015 are comparable with data prior to 2015 for alcohol, marijuana, cocaine, and heroin. Data for dependence since 2015 are not comparable with data prior to 2015 for the any illicit drug summary measure, hallucinogens, inhalants, and prescription psychotherapeutic drugs. Separate data for methamphetamine dependence did not exist prior to 2015. Data for dependence are not available for benzodiazepines because respondents could report symptoms of dependence that apply to tranquilizers or sedatives that are not benzodiazepines.

SEE: "Abuse," "Alcohol Use Disorder (AUD)," "Classified as Needing Alcohol Use Treatment," "Classified as Needing Illicit Drug Use Treatment," "Classified as Needing Substance Use Treatment," "Nicotine (Cigarette) Dependence," "Opioid Use Disorder," "Sedative Use or Misuse," "Substance Use Disorder (SUD)," "Tranquilizer or Sedative Use Disorder," and "Tranquilizer Use or Misuse."

Depression

SEE: "Major Depressive Episode (MDE)."

Distress

SEE: "Kessler-6 (K6) Scale" and "Serious Psychological Distress (SPD)."

DMT, AMT, or 5-MeO-DIPT ("Foxy") Use*

Starting in 2015, measures of the use of dimethyltryptamine (DMT), alpha-methyltryptamine (AMT), or N, N-diisopropyl-5-methoxytryptamine (5-MeO-DIPT or "Foxy") in the respondent's lifetime, the past year, and the past month were derived from responses to the hallucinogen questions about lifetime and recency of use (e.g., "How long has it been since you last used DMT, AMT, or Foxy?"). Estimates of DMT, AMT, or 5-MeO-DIPT use from 2006 to 2014 were not incorporated in estimates of use of hallucinogens, illicit drugs, or illicit drugs other than marijuana in those years.

SEE: "Current Use or Misuse," "Hallucinogen Use," "Illicit Drugs," "Illicit Drugs Other Than Marijuana," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Driving Under the Influence*

Starting in 2016, respondents who reported the use of alcohol or selected illicit drugs in the past 12 months were asked individual questions about driving a vehicle in the past 12 months while under the influence of alcohol, marijuana, cocaine or crack, heroin, hallucinogens, inhalants, or methamphetamine. Respondents who reported driving under the influence of alcohol and one or more of these illicit drugs were asked an additional question about driving under the influence of only alcohol. Prior to the 2015 NSDUH, respondents were asked three questions about driving under the influence of (a) alcohol and illegal drugs used together, (b) alcohol only, or (c) illegal drugs only.¹⁷

Respondents were defined as driving under the influence of one or more selected illicit drugs if they reported driving under the influence of marijuana, cocaine (including crack), heroin, hallucinogens, inhalants, or methamphetamine. Respondents were defined as driving under the influence of one or more selected illicit drugs other than marijuana if they reported driving under the influence of cocaine (including crack), heroin, hallucinogens, inhalants, or methamphetamine, regardless of whether they also reported driving under the influence of marijuana.

SEE: "Alcohol Use," "Cocaine Use," "Crack Use," "Hallucinogen Use," "Heroin Use," "Inhalant Use," "Marijuana Use," and "Methamphetamine Use."

Ecstasy Use*

Measures of use of Ecstasy or MDMA (methylenedioxy-methamphetamine) in the respondent's lifetime, the past year, and the past month were derived from responses to the hallucinogen questions about lifetime and recency of use (e.g., "How long has it been since you last used Ecstasy or 'Molly,' also known as MDMA?"). The question about recency of use was asked if respondents previously reported any use of Ecstasy or MDMA in their lifetime. Starting in 2015, the term "Molly" was included in questions about Ecstasy use.

SEE: "Current Use or Misuse," "Hallucinogen Use," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Education*

Starting in 2015, educational attainment among adult respondents aged 18 or older was based on respondents' reports of their highest grade or level of school they completed, including the highest degree they completed. Response options for respondents who completed the 11th grade or lower were presented in terms of single years of education, ranging from 0 if respondents never attended school up to the 11th grade. Response options for higher levels of education than the 11th grade indicated whether respondents received a high school diploma, completed the 12th grade without receiving a diploma, received a general educational development (GED) certificate, obtained some college credit but did not receive a degree, or received some kind of college degree (i.e., associate's, bachelor's, master's, doctoral, or professional).

Adult respondents were classified into four categories based on their answers: (1) less than high school, (2) high school graduate, (3) some college or associate's degree, and (4) college graduate. Starting in 2015, adults who indicated they completed the 12th grade but did not receive a high school diploma were classified as having less than a high school education. Adults who indicated they received a high school diploma or GED were classified as high school graduates. Adults who received an associate's degree were classified in the "some college" category, along with adults who received some college credit but had not obtained a degree. Adults who indicated they received a bachelor's degree or higher were defined as being college graduates.

Prior to 2015, respondents were asked to report the highest grade or year of school they completed. Adult respondents who reported completing the 12th grade were classified as high school graduates, and adults who reported completing 4 or more years of college or university were classified as being college graduates. However, these assumptions were not always true for such respondents. The question prior to 2015 also did not capture information on the receipt of an associate's degree. For these reasons, education data since 2015 are not comparable with data prior to 2015.

Employment*

Respondents were asked to report whether they worked in the week prior to the interview and, if not, whether they had a job despite not working in the past week. Respondents who worked in the past week or who reported having a job despite not working were asked whether they usually work 35 hours or more per week. Respondents who did not work in the past week but had a job were asked to report why they did not work in the past week despite having a job. Respondents who did not have a job in the past week were asked to report why they did not have a job in the past week. Starting in 2015, these questions were self-administered using audio computer-assisted self-interviewing (ACASI) instead of being interviewer administered through computer-assisted personal interviewing (CAPI). Therefore, employment data since 2015 are not comparable with data prior to 2015.

Full-time

"Full-time" includes respondents who usually work 35 or more hours per week and who worked in the past week or had a job despite not working in the past week.

Part-time

"Part-time" includes respondents who usually work fewer than 35 hours per week and who worked in the past week or had a job despite not working in the past week.

Unemployed

"Unemployed" refers to respondents who did not have a job and were looking for work or who were on layoff. For consistency with the Current Population Survey definition of unemployment, respondents who reported they did not have a job but were looking for work needed to report making specific efforts to find work in the past 30 days, such as sending out resumes or applications, placing ads, or answering ads.

Other

"Other" includes all responses defined as not being in the labor force, including being a student, keeping house or caring for children full time, retired, disabled, or other miscellaneous work statuses. Respondents who reported they did not have a job and did not want one also were classified as not being in the labor force. Similarly, respondents who reported not having a job and looking for work also were classified as not being in the labor force if they did not report making specific efforts to find work in the past 30 days. Those respondents who reported having no job and provided no additional information could not have their labor force status determined and were therefore assigned to the Other employment category.

SEE: "ACASI" and "CAPI."

Ethnicity

SEE: "Race/Ethnicity."

Ever Used

SEE: "Lifetime Use or Misuse."

Exposure to Drug Education and Prevention

The following measures were created for exposure to drug education and prevention among youths aged 12 to 17: (a) exposure to prevention messages in school, (b) participation in a prevention program outside of school, (c) seeing or hearing prevention messages from sources outside of school, and (d) conversations with parents about the dangers of substance use.

Youths who reported they attended any type of school at any time in the past 12 months were asked: "During the past 12 months… Have you had a special class about drugs or alcohol in school?" "Have you had films, lectures, discussions, or printed information about drugs or alcohol in one of your regular classes such as health or physical education?" "Have you had films, lectures, discussions, or printed information about drugs or alcohol outside of one of your regular classes such as in a special assembly?" Youths who reported having had any of these were defined as having seen or heard prevention messages in school.

Youths who reported they were home schooled in the past 12 months also were asked these questions. Youths who reported they were home schooled were instructed to think about their home schooling as "school."

Youths also were asked: "During the past 12 months… Have you participated in an alcohol, tobacco or drug prevention program outside of school, where you learn about the dangers of using, and how to resist using, alcohol, tobacco, or drugs?" "Have you seen or heard any alcohol or drug prevention messages from sources outside school such as posters, pamphlets, radio, or TV?" "Have you talked with at least one of your parents about the dangers of tobacco, alcohol, or drug use?" Youths who answered these questions as "yes" were defined as having been exposed to prevention messages from these sources outside of school.

Family Income*

Family income was estimated by asking respondents about their total personal income and total family income, based on the following questions: "Of these income groups, which category best represents [your/SAMPLE MEMBER's] total personal income during [the previous calendar year]?" and "Of these income groups, which category best represents [your/SAMPLE MEMBER's] total combined family income during [the previous calendar year]?" Family was defined as any related member in the household, including all foster relationships and unmarried partners (including same-sex partners). It excluded roommates, boarders, and other nonrelatives. Categories for family income since 2015 ranged from less than $1,000 to $150,000 or more. From 2004 to 2014, categories ranged from less than $1,000 to $100,000 or more. From 2002 to 2004, the highest level of income was $75,000 or more.

NOTE: If no other family members were living with the respondent, total family income was based on information about the respondent's total personal income. For youths aged 12 to 17 and those respondents who were unable to respond to the health insurance or income questions, proxy responses were accepted from a household member identified as being better able to give the correct information about health insurance and income.

Functional Impairment

Functional impairment refers to interference in a person's daily functioning or limitations in carrying out one or more major life activities. The Global Assessment of Functioning (GAF) allows mental health clinicians to assess a person's level of impairment because of a diagnosable mental, behavioral, or emotional disorder.¹⁸ In follow-up interviews conducted in 2008 to 2012 with a subset of adult NSDUH respondents, mental health clinicians used the GAF and rated respondents' worst period of functioning in the past 12 months because of a mental disorder. See Section 3.4.7 in the 2018 NSDUH methodological summary and definitions report for additional details about how functional impairment is assessed for adults in NSDUH.

SEE: "Global Assessment of Functioning (GAF)," "Mental Illness," "Sheehan Disability Scale (SDS)," and "World Health Organization Disability Assessment Schedule (WHODAS)."

Geographic Division

In the United States, nine geographic divisions are within four geographic regions based on classifications developed by the U.S. Census Bureau.¹⁹ Within the Northeast Region are the New England Division (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont) and the Middle Atlantic Division (New Jersey, New York, Pennsylvania). Within the Midwest Region are the East North Central Division (Illinois, Indiana, Michigan, Ohio, Wisconsin) and the West North Central Division (Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota). Within the South Region are the South Atlantic Division (Delaware, District of Columbia, Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, West Virginia), the East South Central Division (Alabama, Kentucky, Mississippi, Tennessee), and the West South Central Division (Arkansas, Louisiana, Oklahoma, Texas). Within the West Region are the Mountain Division (Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, Wyoming) and the Pacific Division (Alaska, California, Hawaii, Oregon, Washington).

SEE: "Region."

GHB Use

Measures of use of gamma hydroxybutyrate (GHB) in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime and recency of use (e.g., "How long has it been since you last used GHB?"). The questions about GHB were added to the interview in 2006 and were not incorporated in estimates of use of illicit drugs or illicit drugs other than marijuana for 2006 to 2014 because inclusion of these questions would affect the comparability of estimates over time. Questions about GHB also were not incorporated in estimates of use of illicit drugs or illicit drugs other than marijuana since 2015.

The following definitional information preceded the question about lifetime use of GHB: "The next question is about GHB, also called G, Georgia Home Boy, Grievous Bodily Harm, Liquid G, or gamma hydroxybutyrate."

SEE: "Current Use or Misuse," "Illicit Drugs," "Illicit Drugs Other Than Marijuana," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Global Assessment of Functioning (GAF)

As indicated in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV²⁰), mental health clinicians use the Global Assessment of Functioning (GAF) to consider a person's psychological, social, and occupational functioning on a hypothetical continuum. Clinicians do not include impairment in functioning due to physical or environmental limitations. When adequate information is available, numeric ratings for the GAF range from 1 to 100. Lower values on the rating scale indicate a greater extent of impairment due to the presence of a diagnosable mental, behavioral, or emotional disorder. In follow-up interviews conducted in 2008 to 2012 with a subset of adult NSDUH respondents, mental health clinicians used the GAF and rated respondents' worst period of functioning in the past 12 months because of a mental disorder. See Section 3.4.7 in the 2018 NSDUH methodological summary and definitions report for additional details.

SEE: "Mental Illness," "Sheehan Disability Scale (SDS)," and "World Health Organization Disability Assessment Schedule (WHODAS)."

Hallucinogen Use*

Measures of use of hallucinogens in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime and recency of use (e.g., "How long has it been since you last used any hallucinogen?"). The question about recency of use was asked if respondents previously reported any use of hallucinogens in their lifetime.

Respondents were asked a series of gate questions about any use of specific hallucinogens in their lifetime. These gate questions were preceded by the following definitional information about hallucinogens: "The next questions are about substances called hallucinogens. These drugs often cause people to see or experience things that are not real."

Since 2015, gate questions asked whether respondents ever used the following hallucinogens, even once: (a) LSD, also called "acid"; (b) PCP, also called "angel dust" or phencyclidine; (c) peyote; (d) mescaline; (e) psilocybin, found in mushrooms; (f) "Ecstasy" or "Molly," also called MDMA; (g) ketamine, also called "Special K" or "Super K"; (h) DMT, also called dimethyltryptamine, AMT, also called alpha-methyltryptamine, or Foxy, also called 5-MeO-DIPT; (i) Salvia divinorum; and (j) any other hallucinogen besides the ones that have been listed. Questions for ketamine, DMT, AMT, 5-MeO-DIPT, and Salvia divinorum were included in the hallucinogen section starting in 2015.

SEE: "Current Use or Misuse," "DMT, AMT, or 5-MeO-DIPT ("Foxy") Use," "Ecstasy Use," "Ketamine Use," "Lifetime Use or Misuse," "LSD Use," "Past Month Use or Misuse," "Past Year Use or Misuse," "PCP Use," "Recency of Use or Misuse," and "Salvia divinorum Use."

Hallucinogen Use Disorder*

Hallucinogen use disorder was defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV²¹), for either dependence or abuse for hallucinogens. Respondents who used hallucinogens in the past 12 months were defined as having dependence if they met three or more of the following six criteria: (1) spent a lot of time engaging in activities related to hallucinogen use, (2) used hallucinogens in greater quantities or for a longer time than intended, (3) developed tolerance (i.e., needing to use hallucinogens more than before to get desired effects or noticing that the same amount of hallucinogen use had less effect than before), (4) made unsuccessful attempts to cut down on hallucinogen use, (5) continued use despite physical health or emotional problems associated with hallucinogen use, and (6) reduced or eliminated participation in other activities because of hallucinogen use. Respondents who used hallucinogens in the past 12 months and did not meet criteria for hallucinogen dependence were defined as having abuse if they reported one or more of the following: (1) problems at work, home, and school because of hallucinogen use; (2) regularly using hallucinogens and then doing something physically dangerous; (3) repeated trouble with the law because of hallucinogen use; and (4) continued use of hallucinogens despite problems with family or friends.

SEE: "Abuse," "Dependence," "Hallucinogen Use," "Illicit Drug Use Disorder (IDUD)," and "Substance Use Disorder (SUD)."

Health Insurance Status

A series of questions was asked to identify whether respondents currently were covered by Medicare, Medicaid, the Children's Health Insurance Program (CHIP), military health care (such as TRICARE or CHAMPUS), private health insurance, or any kind of health insurance (if respondents reported not being covered by any of the above). If respondents did not currently have health insurance coverage, questions were asked to determine the length of time they were without coverage and the reasons for not being covered.

NOTE: For youths aged 12 to 17 and those respondents who were unable to respond to the health insurance or income questions, proxy responses were accepted from a household member identified as being better able to give the correct information about health insurance and income.

SEE: "Medicaid" and "Medicare."

Health Professional

A health professional was defined in the adult depression and adolescent depression sections as any of the following types of medical doctors or other professionals respondents saw because of sadness, discouragement, or lack of interest (for adults) or sadness, discouragement, or boredom (for adolescents): general practitioner or family doctor; other medical doctor (e.g., cardiologist, gynecologist, urologist, or other medical doctors that are not general practitioners or family doctors); psychologist; psychiatrist or psychotherapist; social worker; counselor; other mental health professional (e.g., mental health nurse or other therapist where type is not specified); and nurse, occupational therapist, or other health professional. Respondents could report they saw more than one type of health professional for these feelings.

SEE: "Alternative Service Professional," "Major Depressive Episode (MDE)," and "Treatment for Depression."

Heavy Use of Alcohol*

Starting in 2015, heavy use of alcohol was defined for males as drinking five or more drinks on the same occasion (i.e., at the same time or within a couple of hours of each other) and for females as drinking four or more drinks on the same occasion on each of 5 or more days in the past 30 days. Heavy alcohol users also were defined as binge users of alcohol. Respondents were asked about the number of days they had five or more drinks (for males) or four or more drinks (for females) on the same occasion if they reported last using any alcohol in the past 30 days based on the following question: "How long has it been since you last drank an alcoholic beverage?" Prior to the 2015 NSDUH, heavy alcohol use was defined for both males and females as drinking five or more drinks on the same occasion on each of 5 or more days in the past 30 days. For males, data for heavy alcohol use since 2015 are comparable with data prior to 2015. For females and the total population of males and females combined, data for heavy alcohol use since 2015 are not comparable with data prior to 2015.

SEE: "Alcohol Use" and "Binge Use of Alcohol."

Heroin Use

Measures of use of heroin in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime and recency of use (e.g., "How long has it been since you last used heroin?"). The question about recency of use was asked if respondents previously reported any use of heroin in their lifetime.

SEE: "Current Use or Misuse," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Heroin Use Disorder

Heroin use disorder was defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV²²), for either dependence or abuse for heroin. Respondents who used heroin in the past 12 months (including those who reported smoking, sniffing or using heroin with a needle in that period) were defined as having dependence if they met three or more of the following seven criteria: (1) spent a lot of time engaging in activities related to heroin use, (2) used heroin in greater quantities or for a longer time than intended, (3) developed tolerance (i.e., needing to use heroin more than before to get desired effects or noticing that the same amount of heroin use had less effect than before), (4) made unsuccessful attempts to cut down on heroin use, (5) continued use despite physical health or emotional problems associated with heroin use, (6) reduced or eliminated participation in other activities because of heroin use, and (7) experienced withdrawal symptoms when respondents cut back or stopped using heroin. Respondents who used heroin in the past 12 months and did not meet criteria for heroin dependence were defined as having abuse if they reported one or more of the following: (1) problems at work, home, and school because of heroin use; (2) regularly using heroin and then doing something physically dangerous; (3) repeated trouble with the law because of heroin use; and (4) continued use of heroin despite problems with family or friends.

SEE: "Abuse," "Dependence," "Heroin Use," "Illicit Drug Use Disorder (IDUD)," and "Substance Use Disorder (SUD)."

Hispanic or Latino

Hispanic or Latino was defined as anyone of Hispanic, Latino, or Spanish origin. Respondents were classified as Hispanic or Latino in the race/ethnicity measure regardless of race, in accordance with federal standards for reporting race and ethnicity data.²³

SEE: "American Indian or Alaska Native (AIAN)," "Asian," "Black," "Native Hawaiian or Other Pacific Islander (NHOPI)," "Race/Ethnicity," "Two or More Races," and "White."

Illicit Drug Use Disorder (IDUD)*

Illicit drug use disorder (IDUD) is defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV²⁴), for either dependence or abuse for one or more of the following illicit drugs: marijuana, cocaine, heroin, hallucinogens, inhalants, methamphetamine, or prescription psychotherapeutic drugs that were misused (i.e., pain relievers, tranquilizers, stimulants, and sedatives).

SEE: "Abuse," "Cocaine Use Disorder," "Dependence," "Hallucinogen Use Disorder," "Heroin Use Disorder," "Illicit Drugs," "Inhalant Use Disorder," "Marijuana Use Disorder," "Methamphetamine Use Disorder," "Pain Reliever Use Disorder," "Sedative Use Disorder," "Stimulant Use Disorder," "Substance Use Disorder (SUD)," and "Tranquilizer Use Disorder."

Illicit Drugs*

Illicit drugs include marijuana, cocaine (including crack), heroin, hallucinogens, inhalants, methamphetamine, or prescription psychotherapeutics that were misused, which include pain relievers, tranquilizers, stimulants, and sedatives. Illicit drug use refers to use of any of these drugs based on responses to questions for these substances only in the relevant sections of the interview. Responses to questions about the use of the following drugs, which have been included in the survey since 2006, were not included in these measures: GHB (gamma hydroxybutyrate) and nonprescription cough or cold medicines.

SEE: "Current Use or Misuse," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," "Psychotherapeutic Drugs," and "Recency of Use or Misuse."

Illicit Drugs Other Than Marijuana*

These drugs include cocaine (including crack), heroin, hallucinogens, inhalants, methamphetamine, or prescription psychotherapeutics that were misused, which include pain relievers, tranquilizers, stimulants, and sedatives. This measure includes marijuana users who used any of the above drugs in addition to using marijuana, as well as users of those drugs who have not used marijuana. This measure excludes respondents who used only marijuana. The measure for illicit drugs other than marijuana is defined based on responses to questions for these substances only in the relevant sections of the interview. Responses to questions about the use of the following drugs, which have been included in the survey since 2006, also were not included in these measures: GHB (gamma hydroxybutyrate) and nonprescription cough or cold medicines.

SEE: "Current Use or Misuse," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," "Psychotherapeutic Drugs," and "Recency of Use or Misuse."

Income

SEE: "Family Income."

Inhalant Use*

Measures of use of inhalants in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime and recency of use (e.g., "How long has it been since you last used any inhalant for kicks or to get high?"). The question about recency of use was asked if respondents previously reported any use of inhalants in their lifetime.

Respondents were asked a series of gate questions about any use of specific inhalants in their lifetime. These gate questions were preceded by the following definitional information about inhalants: "These next questions are about liquids, sprays, and gases that people sniff or inhale to get high or to make them feel good. We are not interested in times when you inhaled a substance accidentally—such as when painting, cleaning an oven, or filling a car with gasoline."

Gate questions asked whether respondents ever inhaled the following substances, even once, for kicks or to get high: (a) amyl nitrite, "poppers," locker room odorizers, or "rush"; (b) correction fluid, degreaser, or cleaning fluid; (c) gasoline or lighter fluid; (d) glue, shoe polish, or toluene; (e) halothane, ether, or other anesthetics; (f) lacquer thinner or other paint solvents; (g) lighter gases, such as butane or propane; (h) nitrous oxide or "whippits"; (i) felt-tip pens, felt-tip markers, or magic markers; (j) spray paints; (k) computer keyboard cleaner, also known as air duster; (l) some other aerosol spray; and (m) any other inhalant besides the ones that have been listed.

SEE: "Current Use or Misuse," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Inhalant Use Disorder*

Inhalant use disorder was defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV²⁵), for either dependence or abuse for inhalants. Respondents who used inhalants in the past 12 months were defined as having dependence if they met three or more of the following six criteria: (1) spent a lot of time engaging in activities related to inhalant use, (2) used inhalants in greater quantities or for a longer time than intended, (3) developed tolerance (i.e., needing to use inhalants more than before to get desired effects or noticing that the same amount of inhalant use had less effect than before), (4) made unsuccessful attempts to cut down on inhalant use, (5) continued use despite physical health or emotional problems associated with inhalant use, and (6) reduced or eliminated participation in other activities because of inhalant use. Respondents who used inhalants in the past 12 months and did not meet criteria for inhalant dependence were defined as having abuse if they reported one or more of the following: (1) problems at work, home, and school because of inhalant use; (2) regularly using inhalants and then doing something physically dangerous; (3) repeated trouble with the law because of inhalant use; and (4) continued use of inhalants despite problems with family or friends.

SEE: "Abuse," "Dependence," "Illicit Drug Use Disorder (IDUD)," "Inhalant Use," and "Substance Use Disorder (SUD)."

Initiation of Substance Use or Misuse*

For substances other than prescription psychotherapeutic drugs, substance use initiation refers to the use of a substance for the first time (new use). For prescription psychotherapeutic drugs, substance use initiation refers to misusing any drug in that category for the first time.²⁶ Initiation statistics in NSDUH reflect first use or misuse occurring within the 12 months prior to the interview. This is referred to as "past year initiation."

For substances other than prescription psychotherapeutic drugs, initiation estimates were based on retrospective questions asked of lifetime users about the age at first use of substances and the year and month of first use for recent initiates, along with the respondent's date of birth and the interview date. For prescription psychotherapeutic drugs starting in 2015, initiation estimates were based on similar retrospective questions. However, questions about first misuse of prescription psychotherapeutic drugs were asked only of respondents who reported they misused prescription psychotherapeutic drugs in the past 12 months. Respondents who misused prescription psychotherapeutic drugs in the past 12 months were defined as past year initiates if they reported only past year initiation of the drugs they misused in that period and they reported they did not misuse any prescription psychotherapeutic drug in that category prior to the past 12 months.

For all initiation estimates, respondents who are immigrants were included regardless of whether their first use or misuse occurred inside or outside the United States. See Section 3.4.2 in the 2018 NSDUH methodological summary and definitions report for additional details.

SEE: "At Risk for Initiation."

Inpatient Mental Health Service Use among Adults

SEE: "Mental Health Service Use among Adults."

Kessler-6 (K6) Scale

The Kessler-6 (K6) scale consists of six questions that gather information on how frequently adult respondents experienced symptoms of psychological distress during the past month or the 1 month in the past year when they were at their worst emotionally.²⁷ These questions ask about the frequency of feeling (1) nervous, (2) hopeless, (3) restless or fidgety, (4) sad or depressed, (5) that everything was an effort, and (6) no good or worthless. Since 2008, adult respondents have first been asked about these symptoms for the past 30 days. Adults are then asked if they had a period in the past 12 months when they felt more depressed, anxious, or emotionally stressed than they felt during the past 30 days. If so, they are asked the K6 questions for the 1 month in the past 12 months when they felt the worst. Responses to these six questions for the past 30 days and (if applicable) the past 12 months are coded and summed to produce a score ranging from 0 to 24; if respondents are asked the K6 questions for both the past 30 days and past 12 months, the higher of the two scores is chosen as the final score for the past year reference period. Higher K6 total scores indicate greater distress. The K6 scale provides a measure of psychological distress and does not directly measure the presence of a diagnosable mental, behavioral, or emotional disorder, nor does it capture information on functional impairment due to having psychological distress or a mental disorder. The K6 and scales for measuring functional impairment (the Sheehan Disability Scale [SDS]²⁸ only in 2008 and the World Health Organization Disability Assessment Schedule [WHODAS]^29,30 in 2008 to the present) are used in models that predict whether a respondent can be categorized as having serious mental illness (SMI). See Section 3.4.7 in the 2018 NSDUH methodological summary and definitions report for more information about the K6 and its scoring, as well as the development of SMI prediction models.

SEE: "Global Assessment of Functioning (GAF)," "Mental Illness," "Serious Psychological Distress (SPD)," "Sheehan Disability Scale (SDS)," and "World Health Organization Disability Assessment Schedule (WHODAS)."

Ketamine Use*

Starting in 2015, measures of the use of ketamine in the respondent's lifetime, the past year, and the past month were derived from responses to the hallucinogen questions about lifetime and recency of use (e.g., "How long has it been since you last used Ketamine?"). The question about lifetime use of ketamine noted that ketamine also is called "Special K" or "Super K." Estimates of ketamine use from 2006 to 2014 were not incorporated in estimates of use of hallucinogens, illicit drugs, or illicit drugs other than marijuana in those years.

SEE: "Current Use or Misuse," "Hallucinogen Use," "Illicit Drugs," "Illicit Drugs Other Than Marijuana," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Large Metro

SEE: "County Type."

Latino

SEE: "Hispanic or Latino."

Lifetime Use or Misuse*

These measures indicate use or misuse of a specific substance at least once in the respondent's lifetime and include respondents who also reported last using substances other than prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, or sedatives) or last misusing prescription psychotherapeutic drugs in the past 30 days or past 12 months. For prescription psychotherapeutic drugs, any lifetime use includes respondents who also reported any use in the past 12 months.

SEE: "Any Use of Psychotherapeutics," "Current Use or Misuse," "Misuse of Psychotherapeutics," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Location of Most Recent Underage Alcohol Use

Respondents aged 12 to 20 who reported drinking at least one alcoholic beverage within the past 30 days were asked to indicate where they drank alcoholic beverages the last time they drank. The possible locations were (1) in a car or other vehicle; (2) at the respondent's home; (3) at someone else's home; (4) at a park, on a beach, or in a parking lot; (5) in a restaurant, bar, or club; (6) at a concert or sports game; (7) at school; or (8) some other place. Those who reported "some other place" were asked to type in a response indicating the specific location. Estimates for commonly reported other locations are included in the 2018 detailed tables. Respondents could report more than one location.

SEE: "Alcohol Use" and "Underage Alcohol Use."

Location of Outpatient Mental Health Services among Adults

Respondents aged 18 or older who reported they received outpatient mental health services in the past year were asked where they received the mental health services. Response options for the location of outpatient mental health services were as follows: (1) an outpatient mental health clinic or center, (2) office of a private therapist, psychologist, psychiatrist, social worker, or counselor that was not part of a clinic; (3) a doctor's office that was not part of a clinic; (4) an outpatient medical clinic; (5) a partial day hospital or day treatment program; or (6) some other place. Respondents who reported "some other place" were asked to type in a response indicating the specific location. Estimates for commonly reported other locations are included in the 2018 detailed tables. Respondents could report more than one location for services.

SEE: "Mental Health Service Use among Adults" and "Source of Payment for Mental Health Services among Adults."

Low Precision

Estimates based on a relatively small number of respondents or with relatively large standard errors were not presented in reports and tables; they have been replaced with an asterisk (*) in the detailed tables and noted as "low precision." These estimates have been omitted because one cannot place a high degree of confidence in their accuracy. Table 3.2 in the 2018 NSDUH methodological summary and definitions report includes a complete list of the rules used to determine low precision.

SEE: "Suppression of Estimates."

LSD Use

Measures of use of lysergic acid diethylamide (LSD) in the respondent's lifetime, the past year, and the past month were derived from responses to the hallucinogen questions about lifetime and recency of use (e.g., "How long has it been since you last used LSD?"). The question about recency of use was asked if respondents previously reported any use of LSD in their lifetime.

SEE: "Current Use or Misuse," "Hallucinogen Use," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Major Depressive Episode (MDE)

Individuals were defined as having had a lifetime major depressive episode (MDE) if they reported at least five or more of the following nine symptoms nearly every day (except where noted) in the same 2-week period in his or her lifetime, in which at least one of the symptoms was a depressed mood or loss of interest or pleasure in daily activities: (1) depressed mood most of the day; (2) markedly diminished interest or pleasure in all or almost all activities most of the day; (3) significant weight loss when not dieting or weight gain or decrease or increase in appetite; (4) insomnia or hypersomnia; (5) psychomotor agitation or retardation; (6) fatigue or loss of energy; (7) feelings of worthlessness; (8) diminished ability to think or concentrate or indecisiveness; and (9) recurrent thoughts of death or recurrent suicide ideation. Unlike the other symptoms listed previously, recurrent thoughts of death or suicidal ideation did not need to have occurred nearly every day.

This definition is based on the definition found in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5³¹). Individuals were defined as having an MDE in the past year if they (a) had a lifetime MDE, (b) had a period of time in the past 12 months when they felt depressed or lost interest or pleasure in daily activities for 2 weeks or longer, and (c) reported during this period of 2 weeks or longer in the past 12 months they had "some of the other problems" they reported for a lifetime MDE. Consistent with the DSM-5 criteria, NSDUH does not exclude MDEs that occurred exclusively in the context of bereavement.

To make the questions developmentally appropriate for youths, some depression questions are worded differently for adults and youths. Therefore, the adult and youth measures for MDE should not be combined or compared.

Because of changes made in the 2008 NSDUH questionnaire, the comparability of MDE estimates over time, including severe impairment due to MDE, was affected for adults. Adjusted MDE variables have been developed to allow trends in adult MDE to be reported for 2005 onward.³² However, the estimate of severe impairment due to MDE among adults was not adjusted for 2008. More information on the comparability of MDE measures for adults can be found in Appendix G of the codebook for the 2017 NSDUH public use file.³³

SEE: "Kessler-6 (K6) Scale," "Severe Impairment Due to Major Depressive Episode," "Sheehan Disability Scale (SDS)," and "World Health Organization Disability Assessment Schedule (WHODAS)."

Marijuana Use

Measures of use of marijuana in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime and recency of use (e.g., "How long has it been since you last used marijuana or hashish?"). The question about recency of use was asked if respondents previously reported any use of marijuana or hashish in their lifetime. Responses to separate questions about use of cigars with marijuana in them (blunts) were not included in these measures. Creation of these measures did not take into account responses to questions included in the survey since 2013 about use of marijuana in the past 12 months that was recommended by a doctor or other health care professional.

The following definitional information preceded the question about lifetime use of marijuana: "The next questions are about marijuana and hashish. Marijuana is also called pot or grass. Marijuana is usually smoked, either in cigarettes called joints, or in a pipe. It is sometimes cooked in food. Hashish is a form of marijuana that is also called hash. It is usually smoked in a pipe. Another form of hashish is hash oil."

SEE: "Blunts," "Current Use or Misuse," "Illicit Drugs," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Marijuana Use Disorder

Marijuana use disorder was defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV³⁴), for either dependence or abuse for marijuana. Respondents who used marijuana on 6 or more days in the past 12 months were defined as having dependence if they met three or more of the following six criteria: (1) spent a lot of time engaging in activities related to marijuana use, (2) used marijuana in greater quantities or for a longer time than intended, (3) developed tolerance (i.e., needing to use marijuana more than before to get desired effects or noticing that the same amount of marijuana use had less effect than before), (4) made unsuccessful attempts to cut down on marijuana use, (5) continued use despite physical health or emotional problems associated with marijuana use, and (6) reduced or eliminated participation in other activities because of marijuana use. Respondents who used marijuana on 6 or more days in the past 12 months and did not meet criteria for marijuana dependence were defined as having abuse if they reported one or more of the following: (1) problems at work, home, and school because of marijuana use; (2) regularly using marijuana and then doing something physically dangerous; (3) repeated trouble with the law because of marijuana use; and (4) continued use of marijuana despite problems with family or friends.

SEE: "Abuse," "Dependence," "Illicit Drug Use Disorder (IDUD)," "Marijuana Use," and "Substance Use Disorder (SUD)."

Medicaid

Medicaid is a public assistance program that pays for medical care for low-income and disabled people. Respondents were asked specifically about the Medicaid program in the state where they lived. Respondents aged 12 to 19 were asked specifically about the Children's Health Insurance Program (CHIP) in their state. Respondents aged 12 to 19 who reported they were covered by the CHIP in their state also were classified as being covered by Medicaid. Respondents aged 65 or older who reported they were covered by Medicaid were asked to verify their answer was correct.

NOTE: For youths aged 12 to 17 and those respondents who were unable to respond to the health insurance or income questions, proxy responses were accepted from a household member identified as being better able to give the correct information about health insurance and income.

SEE: "Health Insurance Status" and "Medicare."

Medicare

Medicare is a health insurance program for people aged 65 or older and for certain disabled people. Respondents under the age of 65 who reported they were covered by Medicare were asked to verify their answer was correct.

NOTE: For youths aged 12 to 17 and those respondents who were unable to respond to the health insurance or income questions, proxy responses were accepted from a household member identified as being better able to give the correct information about health insurance and income.

SEE: "Health Insurance Status" and "Medicaid."

Mental Health Care

SEE: "Mental Health Service Settings among Youths," "Mental Health Service Use among Adults," and "Treatment for Depression."

Mental Health Service Settings for Youths

For youths aged 12 to 17, mental health service settings refer to locations or types of providers where youths received treatment or counseling for any emotional or behavioral problem (not caused by the use of alcohol or drugs) in the past 12 months.

Mental health services settings, differentiated by the type of setting, were defined as follows:

Specialty

Specialty mental health settings for youths include outpatient, inpatient, or residential mental health settings. The outpatient settings include (1) private therapists, psychologists, psychiatrist, social workers, or counselors; (2) mental health clinics or centers; (3) partial day hospitals or day treatment programs; and (4) in-home therapists, counselors, or family preservation workers. The inpatient settings include (1) hospitals and (2) residential treatment centers. Youths were defined as having received specialty mental health services if they reported receiving treatment or counseling in any of these settings for emotional or behavioral problems.

Nonspecialty

Nonspecialty mental health settings for youths include the education, general medical, juvenile justice, and child welfare settings. The education setting includes mental health services from (1) school social workers, school psychologists, or school counselors; (2) special schools or school programs (within a regular school) for students with emotional or behavioral problems. The general medical setting includes mental health services from pediatricians or other family doctors. The juvenile justice setting includes services in a juvenile detention center, prison, or jail provided by psychiatrists, psychologists, social workers, or counselors who work for the court system. The child welfare setting includes foster care or therapeutic foster care.

Youths could report the receipt of mental health services in both specialty and nonspecialty settings. Youths also were allowed to indicate receiving mental health services from more than one of the specialty settings and more than one of the nonspecialty settings if applicable.

These definitions differ from the definitions used in reports and tables prior to the 2013 survey. Starting with the 2013 NSDUH, the child welfare setting was defined as a separate nonspecialty service category instead of being included as an inpatient service under specialty services.

Measures of the receipt of mental health services for youths in these service settings include different service settings from those included in the measures for the receipt of adult mental health services. In addition to the differences in service settings included in the youth and adult mental health service measures, data on the use of prescription medication to treat any emotional or behavioral problem are not collected from youths. Therefore, the adult and youth mental health service measures should not be combined or compared.

Mental Health Service Use among Adults

For adults aged 18 or older, use of mental health services was defined as the receipt of treatment or counseling for any problem with emotions, nerves, or mental health in the 12 months prior to the interview in any inpatient or outpatient setting or the use of prescription medication to treat a mental or emotional condition. Respondents were asked not to report inpatient or outpatient treatment for the use of alcohol or drugs. Mental health services, differentiated by the type of service, were defined as follows:

Inpatient

Respondents were defined as having received mental health services as an inpatient in the past 12 months if they reported staying overnight or longer in any of the following locations to receive treatment or counseling for any problem they were having with their emotions, nerves, or mental health: (1) private or public psychiatric hospital; (2) psychiatric unit of a general hospital; (3) medical unit of a general hospital; (4) another type of hospital; (5) residential treatment center; and (6) some other facility.

Outpatient

Respondents were defined as having received mental health services as an outpatient in the past 12 months if they reported receiving outpatient treatment or counseling for any problem they were having with their emotions, nerves, or mental health at any of the following locations: (1) outpatient mental health clinic or center; (2) office of a private therapist, psychologist, psychiatrist, social worker, or counselor that was not part of a clinic; (3) doctor's office that was not part of a clinic; (4) outpatient medical clinic; (5) partial day hospital or day treatment program; and (6) some other place.

Prescription Medication

Respondents were defined as having used prescription medication as a mental health service if they reported taking prescription medications prescribed for them to treat a mental or emotional condition.

In 2017, adult outpatient mental health service use measures from the 2010 to 2016 NSDUHs were revised to be consistent with data collected prior to 2010 by excluding data on outpatient service locations respondents wrote in for other alternative sources of mental health services. This revision did not compromise comparability for this measure. Because of this revision, however, estimates in 2017 NSDUH reports and tables for the receipt of outpatient mental health services among adults in 2010 to 2016 may differ slightly from previously published estimates for 2010 to 2016.

Measures of mental health service use for adults are defined using different criteria from the measures for the receipt of youth mental health services. Therefore, the adult and youth mental health service measures should not be combined or compared.

SEE: "Location of Outpatient Mental Health Services among Adults," "Reasons for Not Receiving Mental Health Services among Adults," "Source of Payment for Mental Health Services among Adults," and "Unmet Need for Mental Health Services among Adults."

Mental Health Treatment

SEE: "Mental Health Service Settings among Youths," "Mental Health Service Use among Adults," "Reasons for Receiving Mental Health Services among Youths," and "Treatment for Depression."

Mental Illness

The definition of mental illness among adults aged 18 or older has two dimensions: (1) the presence of a diagnosable mental, behavioral, or emotional disorder in the past year (excluding developmental and substance use disorders) of sufficient duration to meet diagnostic criteria specified within the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV³⁵); and (2) the level of interference with or limitation of one or more major life activities resulting from a disorder (functional impairment). A statistical model predicting the likelihood of having mental illness was developed based on a subsample of adult NSDUH respondents from 2008 to 2012 who completed a clinical follow-up interview after the main NSDUH interview. The follow-up interviews consisted of detailed mental health assessments administered by trained mental health clinicians. The dependent variable for mental illness in the model was established through the clinical interviews using modules from the Structured Clinical Interview for DSM-IV-TR Axis I Disorders, Research Version, Non-patient Edition (SCID-I/NP)³⁶ for the following past year disorders or symptoms: major depressive disorder (including major depressive episode [MDE]), dysthymic disorder, bipolar I disorder (including manic episode), specific phobia, social phobia, generalized anxiety disorder, panic disorder (with and without agoraphobia), agoraphobia (without history of panic disorder), obsessive-compulsive disorder, posttraumatic stress disorder, anorexia nervosa, bulimia nervosa, adjustment disorder, and psychotic symptoms (i.e., hallucinations or delusions). The clinical interviews also included the Global Assessment of Functioning scale to measure functional impairment. This model was used to predict each adult NSDUH respondent's mental illness status based on his or her responses to questions in the main NSDUH interview on psychological distress (Kessler-6 scale), functional impairment (an abbreviated version of the World Health Organization Disability Assessment Schedule), past year MDE, past year suicidal thoughts, and age. See Section 3.4.7 in the 2018 NSDUH methodological summary and definitions report for additional details on the model and specifications.

Mental illness, differentiated by the level of functional impairment, was defined as follows for adults:

Any

Any mental illness (AMI) among adults was defined as adults aged 18 or older who currently or at any time in the past year have had a diagnosable mental, behavioral, or emotional disorder as defined above, regardless of the level of impairment in carrying out major life activities. AMI was estimated based on a statistical model of a clinical diagnosis and responses to questions in the main NSDUH interview on distress (Kessler-6 scale), impairment (truncated version of the World Health Organization Disability Assessment Schedule), past year major depressive episode, past year suicidal thoughts, and age.

Any Excluding Serious

Any mental illness (AMI) excluding serious mental illness (SMI) was defined to include adults aged 18 or older who currently or at any time in the past year have had a diagnosable mental, behavioral, or emotional disorder as defined above and resulting in less than substantial impairment in carrying out major life activities, based on clinical interview Global Assessment of Functioning scores of greater than 50. AMI excluding SMI was estimated based on a statistical model of a clinical diagnosis and responses to questions in the main NSDUH interview on distress (Kessler-6 scale), impairment (truncated version of the World Health Organization Disability Assessment Schedule), past year major depressive episode, past year suicidal thoughts, and age.

Serious

Serious mental illness (SMI) among adults was defined in Public Law 102-321 as adults aged 18 or older who currently or at any time in the past year have had a diagnosable mental, behavioral, or emotional disorder and resulting in substantial impairment in carrying out major life activities.³⁷ In NSDUH, a diagnosable mental, behavioral, or emotional disorder was defined as for the other mental illness categories described previously (i.e., based on the Diagnostic and Statistical Manual of Mental Disorders, 4th edition [DSM-IV³⁸] and excluding developmental and substance use disorders); substantial impairment was defined based on clinical interview Global Assessment of Functioning scores of 50 or less. SMI was estimated based on a statistical model of a clinical diagnosis and responses to questions in the main NSDUH interview on distress (Kessler-6 scale), impairment (truncated version of the World Health Organization Disability Assessment Schedule), past year major depressive episode, past year suicidal thoughts, and age. All adults with SMI were also defined as having AMI.

SEE: "Global Assessment of Functioning (GAF)," "Kessler-6 (K6) Scale," "Major Depressive Episode (MDE)," "Suicide," and "World Health Organization Disability Assessment Schedule (WHODAS)."

Methamphetamine Use*

Measures of use of methamphetamine in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime and recency of use (e.g., "How long has it been since you last used methamphetamine?"). The question about recency of use was asked if respondents previously reported any use of methamphetamine in their lifetime. Starting in 2015, respondents were asked about their use of methamphetamine separate from questions about their misuse of prescription stimulants.

The following definitional information preceded the question about lifetime use of methamphetamine: "Methamphetamine, also known as crank, ice, crystal meth, speed, glass, and many other names, is a stimulant that usually comes in crystal or powder forms. It can be smoked, 'snorted,' swallowed or injected."

SEE: "Current Use or Misuse," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," "Recency of Use or Misuse," and "Stimulant Use or Misuse."

Methamphetamine Use Disorder*

Methamphetamine use disorder was defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV³⁹), for either dependence or abuse for methamphetamine. Respondents who used methamphetamine in the past 12 months (including those who reported using methamphetamine with a needle in that period) were defined as having dependence if they met three or more of the following seven criteria: (1) spent a lot of time engaging in activities related to methamphetamine use, (2) used methamphetamine in greater quantities or for a longer time than intended, (3) developed tolerance (i.e., needing to use methamphetamine more than before to get desired effects or noticing that the same amount of methamphetamine use had less effect than before), (4) made unsuccessful attempts to cut down on methamphetamine use, (5) continued use despite physical health or emotional problems associated with methamphetamine use, (6) reduced or eliminated participation in other activities because of methamphetamine use, and (7) experienced withdrawal symptoms when respondents cut back or stopped using methamphetamine. Respondents who used methamphetamine in the past 12 months and did not meet criteria for methamphetamine dependence were defined as having abuse if they reported one or more of the following: (1) problems at work, home, and school because of methamphetamine use; (2) regularly using methamphetamine and then doing something physically dangerous; (3) repeated trouble with the law because of methamphetamine use; and (4) continued use of methamphetamine despite problems with family or friends.

SEE: "Abuse," "Dependence," "Illicit Drug Use Disorder (IDUD)," "Methamphetamine Use," and "Substance Use Disorder (SUD)."

Midwest Region

The states included are those in the East North Central Division (Illinois, Indiana, Michigan, Ohio, and Wisconsin) and the West North Central Division (Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, and South Dakota).

SEE: "Geographic Division" and "Region."

Misuse of Psychotherapeutics*

Starting in 2015, misuse of psychotherapeutics (prescription pain relievers, prescription tranquilizers, prescription stimulants, or prescription sedatives) was defined as use "in any way a doctor did not direct you to use [it or them]" and focused on behaviors that constitute misuse of prescription drugs. Examples of misuse were presented to respondents and included (1) use without a prescription of the respondent's own; (2) use in greater amounts, more often, or longer than told to take a drug; or (3) use in any other way a doctor did not direct the respondent to use a drug. Prior to 2015, misuse (which was referred to as "nonmedical use") was defined as (1) use of at least one of these medications without a prescription belonging to the respondent or (2) use that occurred simply for the experience or feeling the drug caused.

Starting in 2015, respondents who reported they used specific prescription psychotherapeutic drugs in the past 12 months were shown a list of the drugs they used in the past 12 months and were asked for each drug whether they used it (or them) in the past 12 months in any way not directed by a doctor. Beginning in 2017, respondents were reminded not to include over-the-counter drugs when they were asked if they used any other prescription pain reliever, stimulant, or sedative in the past 12 months in any way not directed by a doctor. This reminder was not added for prescription tranquilizers because no tranquilizers were available over the counter.

If respondents reported misuse of one or more specific drugs within a category in the past 12 months, they were asked whether they used any drug in that category (e.g., prescription pain relievers) in the past 30 days in any way a doctor did not direct the respondent to use it or them. Respondents who reported any use of prescription psychotherapeutics in the past 12 months but did not report misuse in the past 12 months or who reported any use in their lifetime but not in the past 12 months were asked whether they ever, even once, used any prescription psychotherapeutic drug within that category (e.g., any prescription pain reliever) in a way a doctor did not direct them to use it. Consequently, estimates of misuse in the lifetime or past month periods were available only for an overall prescription psychotherapeutic drug category (e.g., pain relievers) and not for specific prescription drugs within that category.

SEE: "Any Use of Psychotherapeutics," "Benzodiazepine Use or Misuse," "Current Use or Misuse," "Lifetime Use or Misuse," "Pain Reliever Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," "Psychotherapeutic Drugs," "Recency of Use or Misuse," "Sedative Use or Misuse," "Source of Psychotherapeutic Drugs," "Stimulant Use or Misuse," "Tranquilizer or Sedative Use or Misuse," and "Tranquilizer Use or Misuse."

Module

In some NSDUH publications, modules in the NSDUH questionnaire refer to sections of the interview that are organized together by mode of administration (i.e., computer-assisted personal interviewing [CAPI] or audio computer-assisted self-interviewing [ACASI]), content, and computer-assisted interviewing logic for determining which questions respondents were asked. Several modules include an initial question or series of initial questions, sometimes referred to as "gate questions," that ask whether the behavior or characteristic of interest was applicable to respondents. If so, respondents are asked further questions about that topic. If the behavior or characteristic of interest is not applicable, then respondents are routed to the next module in the interview.

SEE: "ACASI" and "CAPI."

Native Hawaiian or Other Pacific Islander (NHOPI)

Native Hawaiian, Guamanian or Chamorro, Samoan, or Other Pacific Islander, not of Hispanic, Latino, or Spanish origin, in accordance with federal standards for reporting race and ethnicity data.⁴⁰ This does not include respondents reporting two or more races. Respondents reporting they were Native Hawaiian, Guamanian or Chamorro, Samoan, or Other Pacific Islander and of Hispanic, Latino, or Spanish origin were classified as Hispanic. The categories "Guamanian or Chamorro" and "Samoan" have been included in the NSDUH questionnaire since 2013.

SEE: "Hispanic or Latino," "Race/Ethnicity," and "Two or More Races."

Need for Alcohol Use Treatment

SEE: "Classified as Needing Alcohol Use Treatment."

Need for Illicit Drug Use Treatment

SEE: "Classified as Needing Illicit Drug Use Treatment."

Need for Substance Use Treatment

SEE: "Classified as Needing Substance Use Treatment."

NHOPI

SEE: "Native Hawaiian or Other Pacific Islander (NHOPI)."

Nicotine (Cigarette) Dependence

Respondents who reported they smoked cigarettes in the past month were defined as having nicotine (cigarette) dependence if they met either the dependence criteria derived from the Nicotine Dependence Syndrome Scale (NDSS)^41,42 or the Fagerstrom Test of Nicotine Dependence (FTND).^43,44 Nicotine (cigarette) dependence is based only on the use of cigarettes. See Section 3.4.3 in the 2018 NSDUH methodological summary and definitions report for additional details.

SEE: "Cigarette Use" and "Dependence."

Nonmetro

SEE: "County Type."

Nonphysical Delinquent Behavior

SEE: "Delinquent Behavior."

Nonprescription Cough or Cold Medicine Use

Measures of use of nonprescription cough or cold medicine to get high in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime and recency of use (e.g., "How long has it been since you last took one of these cough or cold medicines to get high?"). The questions about nonprescription cough or cold medicine use were added to the interview in 2006 and are not incorporated in estimates of use of illicit drugs or illicit drugs other than marijuana.

SEE: "Current Use or Misuse," "Illicit Drugs," "Illicit Drugs Other Than Marijuana," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Nonspecialty Mental Health Service Settings for Youths

SEE: "Mental Health Service Settings for Youths."

Northeast Region

The states included are those in the New England Division (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont) and the Middle Atlantic Division (New Jersey, New York, and Pennsylvania).

SEE: "Geographic Division" and "Region."

Opioid Misuse*

Respondents were defined as having past year or past month opioid misuse if they reported using heroin, misusing prescription pain relievers, or both using heroin and misusing prescription pain relievers in these periods. See Section 4.4 in the 2018 NSDUH methodological summary and definitions report for additional details.

SEE: "Current Use or Misuse," "Heroin Use," "Misuse of Psychotherapeutics," "Pain Reliever Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Opioid Use Disorder*

Respondents were classified as having an opioid use disorder if they met criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV⁴⁵), for heroin use disorder, prescription pain reliever use disorder, or both in the past year. Respondents were not counted as having opioid use disorder if they did not meet the full dependence or abuse criteria individually for either heroin or prescription pain relievers. For example, respondents who met fewer than three criteria for heroin dependence and met fewer than three criteria for pain reliever dependence were not defined as having opioid dependence, regardless of whether the number of symptoms across the heroin and pain reliever dependence criteria summed to three or more.

SEE: "Abuse," "Dependence," "Heroin Use," "Heroin Use Disorder," "Pain Reliever Use Disorder," "Pain Reliever Use or Misuse," and "Substance Use Disorder (SUD)."

Outpatient Mental Health Service Use among Adults

SEE: "Mental Health Service Use among Adults."

OxyContin^® Use or Misuse*

Information about any use or misuse of the prescription pain reliever OxyContin^® was obtained only for the past year. Measures of use or misuse of OxyContin^® were derived from reports of any use and misuse of this specific pain reliever in the past 12 months. If respondents reported any use of OxyContin^® in the past 12 months, they were asked the following question: "In the past 12 months, did you use OxyContin in any way a doctor did not direct you to use it?"

SEE: "Any Use of Psychotherapeutics," "Misuse of Psychotherapeutics," "Pain Reliever Use or Misuse," and "Past Year Use or Misuse."

Pain Reliever Use Disorder*

Pain reliever use disorder was defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV⁴⁶), for either dependence or abuse for prescription pain relievers. Respondents who misused prescription pain relievers in the past 12 months were defined as having dependence if they met three or more of the following seven criteria: (1) spent a lot of time engaging in activities related to prescription pain reliever use, (2) used prescription pain relievers in greater quantities or for a longer time than intended, (3) developed tolerance (i.e., needing to use prescription pain relievers more than before to get desired effects or noticing that the same amount of prescription pain reliever use had less effect than before), (4) made unsuccessful attempts to cut down on prescription pain reliever use, (5) continued use despite physical health or emotional problems associated with prescription pain reliever use, (6) reduced or eliminated participation in other activities because of prescription pain reliever use, and (7) experienced withdrawal symptoms when respondents cut back or stopped using prescription pain relievers. Respondents who misused prescription pain relievers in the past 12 months and did not meet criteria for pain reliever dependence were defined as having abuse if they reported one or more of the following: (1) problems at work, home, and school because of prescription pain reliever use; (2) regularly using prescription pain relievers and then doing something physically dangerous; (3) repeated trouble with the law because of pain reliever use; and (4) continued use of prescription pain relievers despite problems with family or friends.

Respondents who reported use but not misuse of prescription pain relievers in the past 12 months were not asked questions about prescription pain reliever use disorder.

SEE: "Abuse," "Dependence," "Opioid Use Disorder," "Pain Reliever Use or Misuse," "Psychotherapeutic Drug Use Disorder," and "Substance Use Disorder (SUD)."

Pain Reliever Use or Misuse*

Measures of use or misuse of prescription pain relievers in the respondent's lifetime and past year were derived from a series of questions that first asked respondents about any use (i.e., for any reason) of specific prescription pain relievers in the past 12 months. Respondents were instructed not to include the use of over-the-counter (OTC) pain relievers, such as aspirin, Tylenol^®, Advil^®, or Aleve^®. Respondents who did not report use of any pain reliever in the past 12 months were asked whether they ever, even once, used prescription pain relievers.

Respondents who reported they used specific prescription pain relievers in the past 12 months for any reason were shown a list reminding them of the drugs they used in the past 12 months. For each of these drugs, respondents were asked whether they misused it (or them) in the past 12 months (i.e., use in any way a doctor did not direct them to use it). Examples of misuse were presented to respondents and included (1) use without a prescription of the respondent's own; (2) use in greater amounts, more often, or longer than told to take a drug; or (3) use in any other way a doctor did not direct the respondent to use a drug. Beginning in 2017, respondents were reminded not to include OTC drugs when they were asked if they misused any other prescription pain reliever in the past 12 months. If respondents reported misuse of one or more specific prescription pain relievers in the past 12 months, they were asked whether they misused prescription pain relievers in the past 30 days. Respondents who reported any use of prescription pain relievers in the past 12 months but did not report misuse in the past 12 months or who reported any use in their lifetime but not in the past 12 months were asked whether they ever, even once, misused any prescription pain reliever. Consequently, estimates of the misuse of prescription pain relievers in the lifetime or past month periods are available only for the overall pain reliever category and not for specific pain relievers.

Questions about past year use and misuse in the 2018 NSDUH covered the following subcategories of pain relievers: hydrocodone products (Vicodin^®, Lortab^®, Norco^®, Zohydro^® ER, or generic hydrocodone); oxycodone products (OxyContin^®, Percocet^®, Percodan^®, Roxicodone^®, or generic oxycodone); tramadol products (Ultram^®, Ultram^® ER, Ultracet^®, generic tramadol, or generic extended-release tramadol); codeine products (Tylenol^® with codeine 3 or 4, or generic codeine pills); morphine products (Avinza^®, Kadian^®, MS Contin^®, generic morphine, or generic extended-release morphine); fentanyl products (Duragesic^®, Fentora^®, or generic fentanyl); buprenorphine products (Suboxone^®, generic buprenorphine, or generic buprenorphine plus naloxone); oxymorphone products (Opana^®, Opana^® ER, generic oxymorphone, or generic extended-release oxymorphone); Demerol^®; hydromorphone products (Dilaudid^® or generic hydromorphone, or Exalgo^® or generic extended-release hydromorphone); methadone; or any other prescription pain reliever. Other prescription pain relievers could include products similar to the specific pain relievers listed previously. Questions were not asked about past month pain reliever use or misuse for the specific subtype categories.

Although the specific pain relievers listed above are classified as opioids, use or misuse of any other pain reliever could include prescription pain relievers that are not opioids. For misuse in the past year or past month, estimates could include small numbers of respondents whose only misuse involved other drugs that are not opioids. See Section 4.4 in the 2018 NSDUH methodological summary and definitions report for additional details.

SEE: "Any Use of Psychotherapeutics," "Lifetime Use or Misuse," "Misuse of Psychotherapeutics," "Opioid Misuse," "OxyContin^® Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," "Psychotherapeutic Drugs," "Recency of Use or Misuse," and "Source of Psychotherapeutic Drugs."

Past Month Use or Misuse*

These measures indicate use of a substance other than prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, or sedatives) or misuse of prescription psychotherapeutic drugs in the 30 days prior to the interview. Respondents were not asked about any use of prescription psychotherapeutic drugs in the past 30 days. Respondents who indicated past month use or misuse of a specific substance also were classified as lifetime and past year users or misusers.

SEE: "Current Use or Misuse," "Lifetime Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Past Year Use or Misuse*

These measures indicate use or misuse of a specific substance in the 12 months prior to the interview. For prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, or sedatives), measures include any use or misuse in the past 12 months. Measures for prescription psychotherapeutic drugs are determined from respondents' answers to questions about any use or misuse in the past 12 months. For tobacco products, past year use measures were determined from respondents' answers to questions about use in the past 30 days or most recent use. For all other substances (alcohol through methamphetamine), past year use measures were determined from questions about respondents' most recent use of that substance. Respondents who indicated past year use or misuse of a specific substance also were classified as lifetime users or misusers.

SEE: "Any Use of Psychotherapeutics," "Current Use or Misuse," "Lifetime Use or Misuse," "Misuse of Psychotherapeutics," "Past Month Use or Misuse," and "Recency of Use or Misuse."

PCP Use

Measures of use of phencyclidine (PCP) in the respondent's lifetime, the past year, and the past month were derived from responses to the hallucinogen questions about lifetime and recency of use (e.g., "How long has it been since you last used PCP?"). The question about recency of use was asked if respondents previously reported any use of PCP in their lifetime.

SEE: "Current Use or Misuse," "Hallucinogen Use," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Perceived Availability*

Respondents were asked to assess how difficult or easy it would be for them to get various illicit drugs if they wanted these drugs. These drugs include marijuana, lysergic acid diethylamide (LSD), cocaine, crack, and heroin. Response options were (1) probably impossible, (2) very difficult, (3) fairly difficult, (4) fairly easy, and (5) very easy. Although these questions on the perceived availability of various substances did not change for 2015, other changes to the 2015 questionnaire appeared to affect the comparability of several of these measures between 2015 and prior years. See Section C in the methodological summary and definitions report for the 2015 NSDUH.⁴⁷

SEE: "Cocaine Use," "Crack Use," "Heroin Use," "LSD Use," and "Marijuana Use."

Perceived Need for Alcohol Use Treatment*

Respondents were defined as perceiving a need for alcohol use treatment if they reported feeling a need for alcohol use treatment when asked, "During the past 12 months, did you need treatment or counseling for your use of alcohol?" or if they indicated feeling a need for additional treatment specifically for alcohol use when asked, "During the past 12 months, for which of the following drugs did you need additional treatment or counseling?" Although the alcohol use questions did not change for 2015 for determining who would be asked questions about their perceived need for alcohol use treatment, other changes to the illicit drug use questions for determining who was asked questions about receipt of substance use treatment could have an unknown effect on the perceived need for alcohol use treatment measure.

SEE: "Substance Use Treatment."

Perceived Need for Illicit Drug Use Treatment*

Respondents were defined as perceiving a need for illicit drug use treatment if they reported feeling a need for treatment for the use of one or more drugs when asked specifically about each of the individual drugs they had indicated using: "During the past 12 months, did you need treatment or counseling for your use of [drug]?" They also were defined as perceiving a need for illicit drug use treatment if they indicated feeling a need for additional treatment specifically for the use of one or more drugs when asked, "During the past 12 months, for which of the following drugs did you need additional treatment or counseling?" The response list of drugs included marijuana or hashish, cocaine or crack, heroin, hallucinogens, inhalants, prescription pain relievers, prescription tranquilizers, prescription stimulants, prescription sedatives, or some other drug.

Starting in 2015, the measure of the perceived need for illicit drug use treatment took into account changes to the computer-assisted interviewing logic in 2015 to determine the respondents who were asked questions about whether they felt they needed treatment or counseling (or additional treatment). The computer-assisted interviewing logic in 2015 changed because of the addition of the new section for methamphetamine and changes to the sections for hallucinogens, inhalants, and misuse of prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, and sedatives). See Section C in the methodological summary and definitions report for the 2015 NSDUH.⁴⁸

SEE: "Substance Use Treatment."

Perceived Need for Substance Use Treatment*

Respondents were defined as perceiving (or feeling) a need for substance use treatment if they perceived a need for illicit drug use treatment or alcohol use treatment.

Starting in 2015, the measure of the perceived need for substance use treatment took into account changes to the computer-assisted interviewing logic to determine the respondents who were asked questions about whether they felt they needed treatment or counseling (or additional treatment). The computer-assisted interviewing logic for 2015 changed because of the addition of the new section for methamphetamine and changes to the sections for hallucinogens, inhalants, and misuse of prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, and sedatives). See Section C in the methodological summary and definitions report for the 2015 NSDUH.⁴⁹

SEE: "Perceived Need for Alcohol Use Treatment" and "Perceived Need for Illicit Drug Use Treatment."

Perceived Recovery from Mental Health Issues

Respondents aged 18 or older were defined as perceiving themselves to be in recovery or to have recovered from mental health issues at the time of the interview if they (a) reported they ever had a problem with their mental health, and (b) considered themselves to be in recovery or recovered from their problem.

Perceived Recovery from Substance Use Problems

Respondents aged 18 or older were defined as perceiving themselves to be in recovery or to have recovered from substance use problems at the time of the interview if they (a) reported they ever had a problem with their drug or alcohol use, and (b) considered themselves to be in recovery or recovered from their problem.

Perceived Risk/Harmfulness*

Respondents were asked to assess the extent to which people risk harming themselves physically and in other ways when they use various illicit drugs, alcohol, and cigarettes, with various levels of frequency. Response options were (1) no risk, (2) slight risk, (3) moderate risk, and (4) great risk. Although these questions on the perceived risk of harm from using various substances did not change for 2015, other changes to the 2015 questionnaire appeared to affect the comparability of several of these measures between 2015 and prior years. See Section C in the methodological summary and definitions report for the 2015 NSDUH.⁵⁰

Perceived Unmet Need for Mental Health Services among Adults

Perceived unmet need for mental health services among adults was defined as a perceived need for mental health treatment or counseling in the past 12 months that was not received. Perceived unmet need for mental health services was defined based on responses to the following question asked of all adults aged 18 or older: "During the past 12 months, was there any time when you needed mental health treatment or counseling for yourself but didn't get it?" This measure of perceived unmet need for mental health services also could include adults who received some type of mental health services in the past 12 months but could have felt an unmet need for services before or after they received services. An unmet need for services after adults had received some services would indicate a perceived need for additional services they did not receive. See Section 3.4.4 in the 2018 NSDUH methodological summary and definitions report for additional details.

SEE: "Mental Health Service Use among Adults" and "Reasons for Not Receiving Mental Health Services among Adults."

Percentages

Estimated percentages presented in NSDUH reports and tables are based on weighted data. Analysis weights are created so that estimates are representative of the target population. See Section 2.3.4 in the 2018 NSDUH methodological summary and definitions report for additional details about the development of analysis weights in NSDUH.

SEE: "Rounding."

Physical Delinquent Behavior

SEE: "Delinquent Behavior."

Poverty Level

Poverty level was defined by comparing a respondent's total family income with the U.S. Census Bureau's poverty thresholds (both measured in dollar amounts) in order to determine the poverty status of the respondent and the respondent's family. Information on family income, size, and composition (i.e., number of children) was used to determine the respondent's poverty level. The poverty level was calculated as a percentage of the poverty threshold by dividing a respondent's reported total family income by the appropriate poverty threshold amount. Three categories for poverty level were defined relative to the poverty threshold: (1) less than 100 percent (i.e., total family income was less than the poverty threshold); (2) 100 to 199 percent (i.e., total family income was at or above the poverty threshold but less than twice the poverty threshold); and (3) 200 percent or more (i.e., total family income was twice the poverty threshold or greater). In addition, the measure for poverty level excluded respondents aged 18 to 22 who were living in a college dormitory. Starting in 2015, the poverty level measures took into account the addition of new categories in 2015 for incomes of $100,000 to $149,999 and of $150,000 or more; in 2014, the highest income category was $100,000 or more.

SEE: "Family Income."

Prescription Medication Use as a Mental Health Service among Adults

SEE: "Mental Health Service Use among Adults."

Probation/Parole

Respondents were asked if they were on probation at any time during the past 12 months or if they were on parole, supervised release, or other conditional release from prison at any time during the past 12 months. Respondents could indicate being on both probation and parole during the past 12 months; therefore, these questions are not mutually exclusive.

Psychotherapeutic Drug Use Disorder*

Psychotherapeutic drug use disorder is defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV⁵¹), for either dependence or abuse for one or more of the following prescription psychotherapeutic drugs misused in the past year: pain relievers, tranquilizers, stimulants, or sedatives.

SEE: "Abuse," "Dependence," "Pain Reliever Use Disorder," "Psychotherapeutic Drugs," "Sedative Use Disorder," "Stimulant Use Disorder," "Substance Use Disorder (SUD)," "Tranquilizer or Sedative Use Disorder," and "Tranquilizer Use Disorder."

Psychotherapeutic Drugs*

Psychotherapeutic drugs are prescription medications with legitimate medical uses as pain relievers, tranquilizers, stimulants, and sedatives. The respondent is asked to report any use and misuse of these drugs. Misuse is defined as use in any way a doctor did not direct a respondent to use the drugs, including (1) use without a prescription of the respondent's own; (2) use in greater amounts, more often, or longer than told to take a drug; or (3) use in any other way a doctor did not direct the respondent to use a drug. Starting in 2015, methamphetamine was not included as a prescription stimulant.

SEE: "Any Use of Psychotherapeutics," "Benzodiazepine Use or Misuse," "Lifetime Use or Misuse," "Misuse of Psychotherapeutics," "Pain Reliever Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," "Recency of Use or Misuse," "Sedative Use or Misuse," "Source of Psychotherapeutic Drugs," "Stimulant Use or Misuse," "Tranquilizer or Sedative Use or Misuse," and "Tranquilizer Use or Misuse."

Race/Ethnicity

Race/ethnicity was used to refer to the respondent's self-classification of racial and ethnic origin and identification, in accordance with federal standards for reporting race and ethnicity data.⁵² For Hispanic origin, respondents were asked, "Are you of Hispanic, Latino, or Spanish origin or descent?" For race, respondents were asked, "Which of these groups describes you?" Response options for race were (1) white, (2) black or African American, (3) American Indian or Alaska Native, (4) Native Hawaiian, (5) Guamanian or Chamorro, (6) Samoan, (7) Other Pacific Islander, (8) Asian, and (9) Other. The categories for Guamanian or Chamorro and for Samoan have been included in the NSDUH questionnaire since 2013.

Respondents were allowed to choose more than one of these groups. Categories for a combined race/ethnicity variable included Hispanic (regardless of race); non-Hispanic groups where respondents indicated only one race (white; black or African American; American Indian or Alaska Native; Native Hawaiian, Guamanian or Chamorro, Samoan, or Other Pacific Islander; Asian); and non-Hispanic groups where respondents reported two or more races. However, respondents choosing more than one category from among Native Hawaiian, Guamanian or Chamorro, Samoan, or Other Pacific Islander but no other categories were classified as being in the "Native Hawaiian or Other Pacific Islander" category instead of the "two or more races" category. These categories were based on classifications developed by the U.S. Census Bureau.

SEE: "American Indian or Alaska Native (AIAN)," "Asian," "Black," "Hispanic or Latino," "Native Hawaiian or Other Pacific Islander (NHOPI)," "Two or More Races," and "White."

Reasons for Misusing Psychotherapeutics†

Respondents who reported misuse of prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, and sedatives) in the past year were asked to report the last drug they misused in the past year and the reasons why they misused it. Response options varied by psychotherapeutic category. Response options for the misuse of pain relievers were (1) to relieve physical pain, (2) to relax or relieve tension, (3) to experiment or to see what the drug is like, (4) to feel good or get high, (5) to help with sleep, (6) to help with feelings or emotions, (7) to increase or decrease the effect(s) of some other drug, (8) because the respondent is "hooked" or has to have the drug(s), or (9) for some other reason. The same response options were presented for tranquilizer misuse and sedative misuse, except that "to relieve physical pain" was not presented as an option; the first response option for both of these psychotherapeutic categories was "to relax or relieve tension." Response options for the misuse of stimulants were (1) to help lose weight, (2) to help concentrate, (3) to help be alert or stay awake, (4) to help study, (5) to experiment or to see what the drug(s) is (or are) like, (6) to feel good or get high, (7) to increase or decrease the effect(s) of some other drug, (8) because the respondent is "hooked" or has to have the drug(s), or (9) for some other reason.

For each of the four psychotherapeutic drug categories, respondents could report more than one reason for their last misuse. Respondents who reported more than one reason were asked to report the main reason for their last misuse. If respondents reported only one reason for their last misuse, they were not asked to report their main reason; therefore, this reason was considered to be their main one.

SEE: "Misuse of Psychotherapeutics," "Pain Reliever Use or Misuse," "Sedative Use or Misuse," "Stimulant Use or Misuse," and "Tranquilizer Use or Misuse."

Reasons for Not Receiving Mental Health Services among Adults

Respondents aged 18 or older who reported there was a time in the past year when they needed mental health treatment or counseling but did not get it were asked up to two questions to report why they did not get the treatment or counseling they thought they needed. Reasons in the first question were (1) could not afford the cost; (2) concerned that getting mental health treatment or counseling might cause their neighbors or community to have a negative opinion of them; (3) concerned that getting mental health treatment or counseling might have a negative effect on their jobs; (4) health insurance does not cover any mental health treatment or counseling; (5) health insurance does not pay enough for mental health treatment or counseling; (6) did not know where to go to get services; (7) concerned that the information they gave the counselor might not be kept confidential; (8) concerned that they might be committed to a psychiatric hospital or might have to take medicine; or (9) some other reason. Respondents who reported some other reason in the first question were asked a follow-up question listing additional reasons. Reasons in the second question included (1) did not think they needed treatment at the time; (2) thought they could handle the problem without treatment; (3) did not think treatment would help; (4) did not have time (because of job, childcare, or other commitments); (5) did not want others to find out that they needed treatment; (6) had no transportation, or treatment was too far away, or the hours were not convenient; or (7) some other reason. Respondents who reported "some other reason" in this second question were asked to type in a response indicating the most important other reason. Respondents could report more than one reason in either question.

SEE: "Mental Health Service Use among Adults" and "Unmet Need for Mental Health Services among Adults."

Reasons for Receiving Mental Health Services among Youths

Youths aged 12 to 17 who received treatment or counseling for emotional or behavioral problems (not caused by drug or alcohol use) in different mental health service settings in the past year were asked about their reasons for receiving the services in these settings. For each relevant setting, respondents were asked up to two questions to report why they received services in that setting. Reasons in the first question included (1) thought about killing self or tried to kill self, (2) felt depressed, (3) felt very afraid and tense, (4) was breaking rules and "acting out," (5) had eating problems, or (6) some other reason. Respondents who reported some other reason in the first question were asked a follow-up question listing additional reasons. Reasons in the second question included (1) trouble controlling anger, (2) getting into physical fights, (3) problems at home or in family, (4) problems with friends, (5) problems with people other than family or friends, (6) problems at school, or (7) some other reason. Respondents who reported "some other reason" in the second question were asked to type in a response indicating the most important other reason. Estimates for commonly reported other reasons are included in the 2018 detailed tables. Respondents could report more than one reason in either question. Respondents were not asked to report reasons for receiving services in the following settings: a school for students with emotional or behavioral problems, a school program for students with emotional or behavioral problems, or the juvenile justice setting.

SEE: "Mental Health Service Settings for Youths."

Receipt of Treatment for Specific Substances*

This is based on reports of specific substances for which respondents received substance use treatment during their last or current treatment in the past year. Respondents who received substance use treatment in the past year but were not currently receiving treatment were asked to report the specific substances for which they received treatment during their most recent substance use treatment in the past year. Respondents who reported they were currently receiving treatment or counseling for their alcohol or illicit drug use were asked to report the specific substances for which they were currently receiving treatment. The specific substances included in these questions were alcohol, marijuana, cocaine or crack, heroin, hallucinogens, inhalants, methamphetamine, prescription pain relievers, prescription tranquilizers, prescription stimulants, prescription sedatives, and some other drug; however, respondents were not asked about a specific substance if they had not used it in their lifetime.⁵³ The wording of the questions for these substances differed according to whether respondents were no longer receiving treatment or they were currently receiving treatment. For example, lifetime alcohol users who were no longer receiving treatment were asked, "The last time you entered treatment, did you receive treatment or counseling for your use of alcohol?" Lifetime alcohol users who were currently receiving treatment were asked, "Are you currently receiving treatment or counseling for your use of alcohol?"

Asking these questions based on the most recent treatment episode (either last or current) was done to increase the accuracy of reporting, especially among respondents who entered treatment for their use of multiple substances or who had more than one episode of treatment in the past year. Because some individuals could have had more than one episode of treatment in the past year, the estimate of the number of people who received treatment for a specific substance during their most recent treatment in the past year is not the same as the total number of people who received treatment for that substance at any time in the past year.

SEE: "Alcohol Use," "Illicit Drugs," "Misuse of Psychotherapeutics," and "Substance Use Treatment."

Recency of Use or Misuse*

Respondents who previously reported any use of tobacco, alcohol, or illicit drugs other than prescription psychotherapeutic drugs in their lifetime were asked about their most recent use of that substance. This information was the source for the lifetime, past year, and past month estimates of substance use or misuse. The question "How long has it been since you last used [substance name]?" was essentially the same for all substances other than tobacco and prescription psychotherapeutic drugs.

For tobacco products (cigarettes, smokeless tobacco, or cigars), a question first was asked about use in the past 30 days if respondents indicated ever using that tobacco product in their lifetime. If the respondents did not use the product in the past 30 days, the recency question was asked as above, with the response options (1) more than 30 days ago but within the past 12 months, (2) more than 12 months ago but within the past 3 years, and (3) more than 3 years ago. For the remaining substances, the response options were (1) within the past 30 days, (2) more than 30 days ago but within the past 12 months, and (3) more than 12 months ago.

For prescription psychotherapeutic drugs, respondents were not asked a single question about their most recent use or misuse. Most recent use of psychotherapeutic drugs for any reason was determined first from respondents' reports of any use of specific psychotherapeutic drugs within a category (e.g., prescription pain relievers) in the past 12 months. Any use more than 12 months ago was established from follow-up questions about lifetime use that were asked if respondents did not report use in the past 12 months of any specific prescription psychotherapeutic drug within a category. Similarly, most recent misuse of psychotherapeutic drugs (i.e., use in any way not directed by a doctor) was determined first from respondents' reports of misuse in the past 12 months of specific psychotherapeutic drugs within a category respondents reported using in that period. If respondents reported misuse of any psychotherapeutic drug in the past 12 months, misuse within the past 30 days was determined in one of two ways: (1) if respondents initiated misuse of a specific drug in the past 30 days or (2) otherwise, from a follow-up question about misuse of any drug in that category in the past 30 days. Misuse of prescription psychotherapeutic drugs more than 12 months ago was established from follow-up questions about lifetime use asked if respondents reported (a) any use of specific prescription psychotherapeutics in the past 12 months, but they did not report misuse in the past 12 months; or (b) any use of prescription psychotherapeutic drugs in an overall category in their lifetime but not in the past 12 months.

SEE: "Any Use of Psychotherapeutics," "Current Use or Misuse," "Lifetime Use or Misuse," "Misuse of Psychotherapeutics," "Past Month Use or Misuse," and "Past Year Use or Misuse."

Region

Four regions, Northeast, Midwest, South, and West, are based on classifications developed by the U.S. Census Bureau.

SEE: "Geographic Division," "Midwest Region," "Northeast Region," "South Region," and "West Region."

Religious Service Attendance

Respondents were asked about the number of times they attended religious services in the past year. Respondents were asked not to include special occasions, such as weddings, funerals, or other special events. Response categories included (1) 0 times, (2) 1 to 2 times, (3) 3 to 5 times, (4) 6 to 24 times, (5) 25 to 52 times, or (6) more than 52 times. Although these questions were asked of both adults aged 18 or older and youths aged 12 to 17, only data for youths are presented in the 2018 detailed tables.

Rounding

The decision rules for the rounding of percentages are as follows:

1. If the second number to the right of the decimal point is greater than or equal to 5, the first number to the right of the decimal point is rounded up to the next higher number.
2. If the second number to the right of the decimal point is less than 5, the first number to the right of the decimal point remains the same.

Thus, an estimate of 16.55 percent will have been rounded to 16.6 percent, while an estimate of 16.44 percent will have been rounded to 16.4 percent. Although the percentages in the tables generally total 100 percent, the use of rounding sometimes produces a total of slightly less than or more than 100 percent. Rounding of estimates also needs to be taken into account when interpreting the results of tests for statistical significance because testing is done using unrounded estimates. Therefore, estimates for different years rounded to the same value may not show the same results for statistical testing.

SEE: "Percentages" and "Significance."

Salvia divinorum Use*

Starting in 2015, measures of the use of Salvia divinorum in the respondent's lifetime, the past year, and the past month were derived from responses to the hallucinogen questions about lifetime and recency of use (e.g., "How long has it been since you last used Salvia divinorum?"). Estimates of Salvia divinorum use from 2006 to 2014 were not incorporated in estimates of use of hallucinogens, illicit drugs, or illicit drugs other than marijuana in those years.

SEE: "Current Use or Misuse," "Hallucinogen Use," "Illicit Drugs," "Illicit Drugs Other Than Marijuana," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," and "Recency of Use or Misuse."

Sedative Use Disorder*

Sedative use disorder was defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV⁵⁴), for either dependence or abuse for prescription sedatives. Respondents who misused prescription sedatives in the past 12 months were defined as having dependence if they met three or more of the following seven criteria: (1) spent a lot of time engaging in activities related to prescription sedative use, (2) used prescription sedatives in greater quantities or for a longer time than intended, (3) developed tolerance (i.e., needing to use prescription sedatives more than before to get desired effects or noticing that the same amount of prescription sedative use had less effect than before), (4) made unsuccessful attempts to cut down on prescription sedative use, (5) continued use despite physical health or emotional problems associated with prescription sedative use, (6) reduced or eliminated participation in other activities because of prescription sedative use, and (7) experienced withdrawal symptoms when respondents cut back or stopped using prescription sedatives. Respondents who misused prescription sedatives in the past 12 months and did not meet criteria for sedative dependence were defined as having abuse if they reported one or more of the following: (1) problems at work, home, and school because of prescription sedative use; (2) regularly using prescription sedatives and then doing something physically dangerous; (3) repeated trouble with the law because of sedative use; and (4) continued use of prescription sedatives despite problems with family or friends.

Respondents who reported use but not misuse of prescription sedatives in the past 12 months were not asked questions about prescription sedative use disorder.

SEE: "Abuse," "Dependence," "Psychotherapeutic Drug Use Disorder," "Sedative Use or Misuse," "Substance Use Disorder (SUD)," and "Tranquilizer or Sedative Use Disorder."

Sedative Use or Misuse*

Measures of use or misuse of prescription sedatives in the respondent's lifetime and past year were derived from a series of questions that first asked respondents about any use (i.e., for any reason) of specific prescription sedatives in the past 12 months. Respondents were instructed not to include the use of over-the-counter (OTC) sedatives, such as Sominex^®, Unisom^®, Benadryl^®, or Nytol^®. Respondents who did not report use of any sedative in the past 12 months were asked whether they ever, even once, used prescription sedatives.

Respondents who reported they used specific prescription sedatives in the past 12 months for any reason were shown a list reminding them of the drugs they used in the past 12 months. For each of these drugs, respondents were asked whether they misused it (or them) in the past 12 months (i.e., use in any way a doctor did not direct them to use it). Examples of misuse were presented to respondents and included (1) use without a prescription of the respondent's own; (2) use in greater amounts, more often, or longer than told to take a drug; or (3) use in any other way a doctor did not direct the respondent to use a drug. Beginning in 2017, respondents were reminded not to include OTC drugs when they were asked if they misused any other prescription sedative in the past 12 months. If respondents reported misuse of one or more specific prescription sedatives in the past 12 months, they were asked whether they misused prescription sedatives in the past 30 days. Respondents who reported any use of prescription sedatives in the past 12 months but did not report misuse in the past 12 months or who reported any use in their lifetime but not in the past 12 months were asked whether they ever, even once, misused any prescription sedative. Consequently, estimates of the misuse of prescription sedatives in the lifetime or past month periods are available only for the overall prescription sedative category and not for specific sedatives.

Questions about past year use and misuse in the 2018 NSDUH covered the following subcategories of sedatives: zolpidem products (Ambien^®, Ambien^® CR, generic zolpidem, or generic extended-release zolpidem); eszopiclone products (Lunesta^® or generic eszopiclone); zaleplon products (Sonata^® or generic zaleplon); benzodiazepine sedatives (flurazepam [also known as Dalmane^®], temazepam products [Restoril^®, or generic temazepam], or triazolam products [Halcion^® or generic triazolam]); barbiturates (Butisol^®, Seconal^®, or phenobarbital); or any other prescription sedative. Other prescription sedatives could include products similar to the specific sedatives listed previously. Questions were not asked about past month sedative use or misuse for the subtype categories.

SEE: "Any Use of Psychotherapeutics," "Benzodiazepine Use or Misuse," "Lifetime Use or Misuse," "Misuse of Psychotherapeutics," "Past Month Use or Misuse," "Past Year Use or Misuse," "Psychotherapeutic Drugs," "Recency of Use or Misuse," "Source of Psychotherapeutic Drugs," and "Tranquilizer or Sedative Use or Misuse."

Self-Help Group*

Respondents who reported they received treatment for their use of alcohol or drugs in the past 12 months were asked whether they received treatment in a self-help group, such as Alcoholics Anonymous or Narcotics Anonymous. Treatment received in self-help groups was not considered specialty substance use treatment. Beginning with the 2006 survey, respondents also were asked in a different question whether they attended self-help groups in the past 12 months to receive help for their alcohol or drug use, regardless of whether they previously reported receiving any treatment in the past 12 months.

Starting in 2015, the measure of the receipt of substance use treatment in a self-help group took into account changes to the computer-assisted interviewing logic in 2015 for determining who was asked questions about their receipt of substance use treatment in the past year based on the addition of the new section for methamphetamine and changes to the sections for hallucinogens, inhalants, and misuse of prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, and sedatives). See Section C in the methodological summary and definitions report for the 2015 NSDUH.⁵⁵

SEE: "Specialty Substance Use Treatment Facility" and "Substance Use Treatment."

Serious Mental Illness (SMI)

SEE: "Mental Illness."

Serious Psychological Distress (SPD)

Serious psychological distress (SPD) for adults is defined as having a score of 13 or higher on the Kessler-6 (K6) scale. This scale consists of six questions that gather information on how frequently adult respondents experienced symptoms of psychological distress during the past month or the 1 month in the past year when they were at their worst emotionally. These questions ask about the frequency of feeling (1) nervous, (2) hopeless, (3) restless or fidgety, (4) sad or depressed, (5) that everything was an effort, and (6) no good or worthless.⁵⁶

Past month SPD estimates are presented from 2009 onward. Estimates of past year SPD are presented from 2005 onward. From 2005 to 2007, the K6 questions asked only about the 1 month in the past year when adult respondents were at their worst emotionally, and past year SPD was defined from the resulting scores. Starting in 2008, however, the K6 questions were asked both for the past 30 days and (if applicable) the 1 month in the past year when adult respondents were at their worst emotionally.

The maximum score of the two periods (i.e., past month and past year) was used to create the total past year score, and this score was used to define past year SPD for 2008 onward. Past year SPD estimates for 2005 through 2007 were statistically adjusted to make them comparable with those since 2008.⁵⁷ More information on the comparability of mental health measures for adults can be found in Appendix E of the 2017 NSDUH public use file codebook,⁵⁸ which was the most currently available public use file at the time this report was published.

SEE: "Kessler-6 (K6) Scale" and "Mental Illness."

Severe Impairment Due to Major Depressive Episode

Severe impairment was defined by the level of role interference for adults or the level of problems for youths that were reported to be caused by a major depressive episode (MDE) in the past 12 months. Impairment was defined based on the role domains for adults and for youths aged 12 to 17 in the Sheehan Disability Scale (SDS). Ratings of 7 or greater for interference (for adults) or problems (for youths) in one or more role domains were classified as severe impairment. The severe impairment measures are defined using different role domains for adults and youths; therefore, the adult and youth measures should not be combined or compared.

Because of changes made in the 2008 NSDUH questionnaire, the comparability of MDE estimates and severe impairment due to MDE was affected for adults. Adjusted MDE variables were developed to allow trends in adult MDE to be reported for 2005 onward.⁵⁹ However, the estimate of severe impairment due to MDE among adults was not adjusted for 2008 and therefore was not comparable with estimates of severe impairment due to MDE among adults for 2009 onward. See Section 3.4.8 in the 2018 NSDUH methodological summary and definitions report for additional details.

SEE: "Major Depressive Episode (MDE)" and "Sheehan Disability Scale (SDS)."

Sheehan Disability Scale (SDS)

The Sheehan Disability Scale (SDS)⁶⁰ consists of a series of four questions used in NSDUH to measure interference or problems in a person's daily functioning caused by major depressive episode. The SDS role domains are assessed on a 0 to 10 visual analog scale with impairment categories of "none" (0), "mild" (1-3), "moderate" (4-6), "severe" (7-9), and "very severe" (10). For adults aged 18 or older, the SDS role domains are (1) home management, (2) work, (3) close relationships with others, and (4) social life. For youths aged 12 to 17, the SDS role domains are (1) chores at home, (2) school or work, (3) close relationships with family, and (4) social life. Because the SDS asks about different role domains for adults and youths, the adult and youth SDS data should not be combined or compared.

SEE: "Severe Impairment Due to Major Depressive Episode" and "World Health Organization Disability Assessment Schedule (WHODAS)."

Significance

Two types of statistical comparisons are presented in NSDUH reports and tables: (1) between two different time points, and (2) between members of demographic subgroups. When reports compare estimates between two points in time (e.g., 2017 and 2018) or between demographic subgroups (e.g., males and females), a significance level of .05 generally is used to determine whether these estimates are statistically different. If differences do not meet the criteria for statistical significance, the values of these estimates are not considered to be different from one another. Low precision estimates are not included in statistical tests. Also, testing can indicate significant differences involving seemingly identical percentages that have been rounded to the nearest tenth of a percent. See Section 3.2.3 in the 2018 NSDUH methodological summary and definitions report for additional details.

In addition, testing for linear trends is conducted for some estimates for reporting purposes; these tests allow interpretation of whether estimates have decreased, increased, or remained steady over the entire span of the years of interest. These linear test results may be used indirectly in the descriptions of the data but are not published in NSDUH reports and tables.

SEE: "Low Precision" and "Rounding."

Small Metro

SEE: "County Type."

Smokeless Tobacco Use*

Starting in 2015, measures of the use of smokeless tobacco in the respondent's lifetime, the past year, and the past month were derived from responses to the questions about lifetime smokeless tobacco use, use in the past 30 days, and the recency of use (if not in the past 30 days) (e.g., "During the past 30 days, have you used 'smokeless' tobacco, even once?" "How long has it been since you last used 'smokeless' tobacco?"). Questions about use of smokeless tobacco in the past 30 days or the most recent use of smokeless tobacco (if not in the past 30 days) were asked if respondents previously reported any use of smokeless tobacco in their lifetime.

The following information preceded the question about lifetime use of smokeless tobacco: "The next questions are about your use of 'smokeless' tobacco such as snuff, dip, chewing tobacco, or snus."

SEE: "Cigar Use," "Cigarette Use," "Current Use or Misuse," "Lifetime Use or Misuse," "Past Month Use or Misuse," "Past Year Use or Misuse," "Recency of Use or Misuse," and "Tobacco Product Use."

Social Context of Most Recent Underage Alcohol Use

Respondents aged 12 to 20 who reported drinking at least one alcoholic beverage within the past 30 days were asked if they were alone, with one other person, or with more than one person the last time they drank.

SEE: "Alcohol Use" and "Underage Alcohol Use."

Source of Alcohol for Most Recent Underage Alcohol Use

Respondents aged 12 to 20 who reported drinking at least one alcoholic beverage within the past 30 days were asked questions pertaining to the source of the alcohol for their most recent alcohol use. The sources were (1) respondent purchased it, (2) someone else purchased it, (3) received it from a parent or guardian, (4) received it from another family member aged 21 or older, (5) received it from an unrelated person aged 21 or older, (6) received it from someone under age 21, (7) took it from own home, (8) took it from someone else's home, or (9) got it some other way. Respondents who reported "some other way" were asked to type in a response indicating the specific source. Estimates for commonly reported other sources are included in the detailed tables. Respondents could report more than one source.

The questions on the source of last alcohol use were presented in two categories: (a) respondents paid (they purchased the alcohol or gave someone else money to purchase the alcohol), and (b) respondents did not pay (they received the alcohol for free from someone or took the alcohol from their own or someone else's home).

SEE: "Alcohol Use" and "Underage Alcohol Use."

Source of Payment for Mental Health Services among Adults

Respondents aged 18 or older who reported receiving mental health services in the past year as an inpatient or an outpatient were asked who paid or will pay for the mental health services they received in that period. Response options for the source of payment were as follows: (1) self or a family member living in household, (2) a family member not living in the household, (3) private health insurance, (4) Medicare, (5) Medicaid, (6) a rehabilitation program, (7) employer, (8) VA or other military program, (9) other public source, (10) other private source, or (11) no payment because treatment was free. Respondents could report more than one source of payment. Respondents who reported taking prescription medicine in the past 12 months that was prescribed for a mental or emotional condition were not asked to report the source of payment for the prescription medication. Although these questions were asked of both adults who received mental health services as an inpatient and those who received mental health services as an outpatient, only data for the source of payment among adults who received services as an outpatient are presented in the 2018 detailed tables.

SEE: "Location of Outpatient Mental Health Services among Adults" and "Mental Health Service Use among Adults."

Source of Psychotherapeutic Drugs*

Respondents who reported misuse of prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, and sedatives) in the past year were asked how they obtained the last drug in a given category they misused. Response options for the source of the medications were as follows: (a) got a prescription from just one doctor; (b) got prescriptions from more than one doctor; (c) stole from a doctor's office, clinic, hospital, or pharmacy; (d) got from a friend or relative for free; (e) bought from a friend or relative; (f) took from a friend or relative without asking; (g) bought from a drug dealer or other stranger; and (h) got in some other way (includes other sources specified by respondents). Respondents who reported they obtained these drugs from a friend or relative for free were asked how the friend or relative obtained them, using the same response options (a) through (h) as the respondents' source questions. Starting in 2015, because most of the methamphetamine used in the United States is illegally manufactured and obtained, respondents were not asked how they obtained methamphetamine.

Respondents who reported misuse of psychotherapeutic drugs in the past 12 months were asked to report the last psychotherapeutic drug they misused in a given category and were asked the following question: "Now think again about the last time you used [fill in the name of the last prescription pain reliever, prescription tranquilizer, prescription stimulant, or prescription sedative that was misused] in any way a doctor did not direct you to use [it/them]. How did you get the [fill in the relevant drug name]? If you got the [fill in the relevant drug name] in more than one way, please choose one of these ways as your best answer."

SEE: "Misuse of Psychotherapeutics," "Pain Reliever Use or Misuse," "Psychotherapeutic Drugs," "Sedative Use or Misuse," "Stimulant Use or Misuse," and "Tranquilizer Use or Misuse."

South Region

The states included are those in the South Atlantic Division (Delaware, District of Columbia, Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, and West Virginia); the East South Central Division (Alabama, Kentucky, Mississippi, and Tennessee); and the West South Central Division (Arkansas, Louisiana, Oklahoma, and Texas).

SEE: "Geographic Division" and "Region."

Specialty Mental Health Service Settings for Youths

SEE: "Mental Health Service Settings for Youths."

Specialty Substance Use Treatment Facility*

A specialty substance use treatment facility was defined as a drug or alcohol rehabilitation facility (inpatient or outpatient), a hospital (inpatient only), or a mental health center. Starting in 2015, the measure of the receipt of treatment at a specialty facility took into account changes to the computer-assisted interviewing logic in 2015 for determining who was asked questions about the receipt of treatment for a substance use problem based on the addition of the new section for methamphetamine and changes to the sections for hallucinogens, inhalants, and misuse of prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, and sedatives). See Section C in the methodological summary and definitions report for the 2015 NSDUH.⁶¹

SEE: "Classified as Needing Substance Use Treatment," "Self-Help Group," and "Substance Use Treatment."

Stimulant Use Disorder*

Stimulant use disorder was defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV⁶²), for either dependence or abuse for prescription stimulants. Respondents who misused prescription stimulants in the past 12 months were defined as having dependence if they met three or more of the following seven criteria: (1) spent a lot of time engaging in activities related to prescription stimulant use, (2) used prescription stimulants in greater quantities or for a longer time than intended, (3) developed tolerance (i.e., needing to use prescription stimulants more than before to get desired effects or noticing that the same amount of prescription stimulant use had less effect than before), (4) made unsuccessful attempts to cut down on prescription stimulant use, (5) continued use despite physical health or emotional problems associated with prescription stimulant use, (6) reduced or eliminated participation in other activities because of prescription stimulant use, and (7) experienced withdrawal symptoms when respondents cut back or stopped using prescription stimulants. Respondents who misused prescription stimulants in the past 12 months and did not meet criteria for stimulant dependence were defined as having abuse if they reported one or more of the following: (1) problems at work, home, and school because of prescription stimulant use; (2) regularly using prescription stimulants and then doing something physically dangerous; (3) repeated trouble with the law because of stimulant use; and (4) continued use of prescription stimulants despite problems with family or friends.

Since 2015, methamphetamine use disorder was asked about separately from prescription stimulant use disorder. Therefore, responses to methamphetamine use disorder questions were not considered in determining whether a respondent had a stimulant use disorder. Respondents who reported use but not misuse of prescription stimulants in the past 12 months were not asked questions about prescription stimulant use disorder.

SEE: "Abuse," "Dependence," "Psychotherapeutic Drug Use Disorder," "Stimulant Use or Misuse," and "Substance Use Disorder (SUD)."

Stimulant Use or Misuse*

Measures of use or misuse of prescription stimulants in the respondent's lifetime and past year were derived from a series of questions that first asked respondents about any use (i.e., for any reason) of specific prescription stimulants in the past 12 months. Respondents were instructed not to include the use of over-the-counter (OTC) stimulants, such as Dexatrim^®, No-Doz^®, Hydroxycut^®, or 5-Hour Energy^®. Respondents who did not report use of any prescription stimulant in the past 12 months were asked whether they ever, even once, used prescription stimulants.

Respondents who reported they used specific prescription stimulants in the past 12 months for any reason were shown a list reminding them of the drugs they used in the past 12 months. For each of these drugs, respondents were asked whether they misused it (or them) in the past 12 months (i.e., use in any way a doctor did not direct them to use it). Examples of misuse were presented to respondents and included (1) use without a prescription of the respondent's own; (2) use in greater amounts, more often, or longer than told to take a drug; or (3) use in any other way a doctor did not direct the respondent to use a drug. Beginning in 2017, respondents were reminded not to include OTC drugs when they were asked if they misused any other prescription stimulant in the past 12 months. If respondents reported misuse of one or more specific prescription stimulants in the past 12 months, they were asked whether they misused prescription stimulants in the past 30 days. Respondents who reported any use of prescription stimulants in the past 12 months but did not report misuse in the past 12 months or who reported any use in their lifetime but not in the past 12 months were asked whether they ever, even once, misused any prescription stimulant. Consequently, estimates of the misuse of prescription stimulants in the lifetime or past month periods are available only for the overall prescription stimulant category and not for specific stimulants.

Questions about past year use and misuse in the 2018 NSDUH covered the following subcategories of stimulants: amphetamine products (Adderall^®, Adderall^® XR, Dexedrine^®, Vyvanse^®, generic dextroamphetamine, generic amphetamine-dextroamphetamine combinations, or generic extended-release amphetamine-dextroamphetamine combinations); methylphenidate products (Ritalin^®, Ritalin^® LA, Concerta^®, Daytrana^®, Metadate^® CD, Metadate^® ER, Focalin^®, Focalin^® XR, generic methylphenidate, generic extended-release methylphenidate, generic dexmethylphenidate, or generic extended-release dexmethylphenidate); anorectic (weight-loss) stimulants (Didrex^®, benzphetamine, Tenuate^®, diethylpropion, phendimetrazine, or phentermine); Provigil^®; or any other prescription stimulant. Other prescription stimulants could include products similar to the specific stimulants listed previously. Since 2015, methamphetamine has not been included as a prescription stimulant. Questions were not asked about past month stimulant use or misuse for the subtype categories.

SEE: "Any Use of Psychotherapeutics," "Lifetime Use or Misuse," "Methamphetamine Use," "Misuse of Psychotherapeutics," "Past Month Use or Misuse," "Past Year Use or Misuse," "Psychotherapeutic Drugs," "Recency of Use or Misuse," and "Source of Psychotherapeutic Drugs."

Substance Use Disorder (SUD)*

Substance use disorder (SUD) was defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV⁶³), for either dependence or abuse for one or more illicit drugs or alcohol.

SEE: "Abuse," "Alcohol Use Disorder (AUD)," "Cocaine Use Disorder," "Dependence," "Hallucinogen Use Disorder," "Heroin Use Disorder," "Illicit Drug Use Disorder (IDUD)," "Inhalant Use Disorder," "Marijuana Use Disorder," "Methamphetamine Use Disorder," "Pain Reliever Use Disorder," "Sedative Use Disorder," "Stimulant Use Disorder," "Tranquilizer or Sedative Use Disorder," and "Tranquilizer Use Disorder."

Substance Use Treatment*

Respondents were defined as having received substance use treatment if they reported receiving treatment in any of the following locations in the past 12 months for their use of illicit drugs, alcohol use, or both illicit drug and alcohol use or if they received treatment for medical problems associated with illicit drug or alcohol use: (1) a hospital overnight as an inpatient, (2) a residential drug or alcohol rehabilitation facility where they stayed overnight, (3) a drug or alcohol rehabilitation facility as an outpatient, (4) a mental health center or facility as an outpatient, (5) an emergency room, (6) a private doctor's office, (7) a prison or jail, (8) a self-help group (e.g., Alcoholics Anonymous or Narcotics Anonymous), or (9) some other place. Of these locations, drug or alcohol rehabilitation facilities (inpatient or outpatient), hospitals (inpatient only), or mental health centers are considered specialty substance use treatment facilities. Thus, substance use treatment received at a specialty facility is included in estimates of substance use treatment received at any location.

Starting in 2015, the measure of the receipt of substance use treatment took into account changes for determining who was asked questions about the receipt of treatment based on the addition of the new section for methamphetamine and changes to the sections for hallucinogens, inhalants, and misuse of prescription psychotherapeutic drugs (pain relievers, tranquilizers, stimulants, and sedatives). See Section C in the methodological summary and definitions report for the 2015 NSDUH.⁶⁴

SEE: "Alcohol Use," "Illicit Drugs," "Classified as Needing Substance Use Treatment," "Receipt of Treatment for Specific Substances," "Self-Help Group," and "Specialty Substance Use Treatment Facility."

Suicide

Adults aged 18 or older were asked whether they had seriously thought about killing themselves at any time during the past 12 months. Respondents who reported seriously thinking about killing themselves were then asked if they made any plans to kill themselves or if they tried to kill themselves (regardless of whether they made a plan to kill themselves). Respondents who attempted suicide were asked whether they had received medical attention from a health professional, including whether they stayed overnight in a hospital in the past 12 months because of a suicide attempt.

Suppression of Estimates

Estimates presented in NSDUH reports and tables are run through a suppression rule that determines the suitability of the estimates for publication according to the standard errors of the estimates and the sample sizes on which the estimates are based. Estimates that do not meet the established precision criteria are suppressed (i.e., not published) in NSDUH reports and tables. Table 3.2 in the 2018 NSDUH methodological summary and definitions report includes a complete list of the rules used to determine low precision.

SEE: "Low Precision."

Tobacco Product Use

This measure indicates use of any of the following tobacco products: cigarettes, smokeless tobacco, cigars, or pipe tobacco. Tobacco product use in the past year includes past month pipe tobacco use; however, it does not include use of pipe tobacco more than 30 days ago but within 12 months of the interview because the survey did not capture this information. Measures of tobacco product use in the respondent's lifetime, the past year, or the past month also do not include reports from separate questions about use of cigars with marijuana in them (blunts). Although the smokeless tobacco questions changed for 2015, this change did not appear to affect the comparability of estimates for use of any tobacco product between 2015 and prior years. NSDUH does not currently ask separate questions about the use of electronic vaporizing devices ("vaping") for delivering nicotine.

SEE: "Blunts," "Cigar Use," "Cigarette Use," "Current Use or Misuse," "Daily Cigarette Use," "Lifetime Use or Misuse," "Nicotine (Cigarette) Dependence," "Past Month Use or Misuse," "Past Year Use or Misuse," "Recency of Use or Misuse," and "Smokeless Tobacco Use."

Total Family Income

SEE: "Family Income."

Tranquilizer or Sedative Use Disorder*

Respondents were classified as having a tranquilizer or sedative use disorder if they met criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV⁶⁵), for prescription tranquilizer use disorder, prescription sedative use disorder, or both in the past year. Respondents were not counted as having tranquilizer or sedative use disorder if they did not meet the dependence or abuse criteria for either prescription tranquilizers or prescription sedatives individually. For example, respondents who met fewer than three criteria for tranquilizer dependence and met fewer than three criteria for sedative dependence were not defined as having tranquilizer or sedative dependence, regardless of whether the number of symptoms across the tranquilizer and sedative dependence criteria summed to three or more.

SEE: "Abuse," "Dependence," "Sedative Use Disorder," "Sedative Use or Misuse," "Substance Use Disorder (SUD)," "Tranquilizer Use Disorder," and "Tranquilizer Use or Misuse."

Tranquilizer or Sedative Use or Misuse*

Respondents were defined as having past year or past month prescription tranquilizer or sedative use or misuse if they reported using or misusing prescription tranquilizers, prescription sedatives, or both in these periods.

SEE: "Current Use or Misuse," "Misuse of Psychotherapeutics," "Past Month Use or Misuse," "Past Year Use or Misuse," "Recency of Use or Misuse," "Sedative Use or Misuse," and "Tranquilizer Use or Misuse."

Tranquilizer Use Disorder*

Tranquilizer use disorder was defined as meeting criteria in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV⁶⁶), for either dependence or abuse for prescription tranquilizers. Respondents who misused prescription tranquilizers in the past 12 months were defined as having dependence if they met three or more of the following six criteria: (1) spent a lot of time engaging in activities related to prescription tranquilizer use, (2) used prescription tranquilizers in greater quantities or for a longer time than intended, (3) developed tolerance (i.e., needing to use prescription tranquilizers more than before to get desired effects or noticing that the same amount of prescription tranquilizer use had less effect than before), (4) made unsuccessful attempts to cut down on prescription tranquilizer use, (5) continued use despite physical health or emotional problems associated with prescription tranquilizer use, and (6) reduced or eliminated participation in other activities because of prescription tranquilizer use. Respondents who misused prescription tranquilizers in the past 12 months and did not meet criteria for tranquilizer dependence were defined as having abuse if they reported one or more of the following: (1) problems at work, home, and school because of prescription tranquilizer use; (2) regularly using prescription tranquilizers and then doing something physically dangerous; (3) repeated trouble with the law because of tranquilizer use; and (4) continued use of prescription tranquilizers despite problems with family or friends.

Respondents who reported use but not misuse of prescription tranquilizers in the past 12 months were not asked questions about prescription tranquilizer use disorder.

SEE: "Abuse," "Dependence," "Psychotherapeutic Drug Use Disorder," "Substance Use Disorder (SUD)," "Tranquilizer or Sedative Use Disorder," and "Tranquilizer Use or Misuse."

Tranquilizer Use or Misuse*

Measures of use or misuse of prescription tranquilizers in the respondent's lifetime and past year were derived from a series of questions that first asked respondents about any use (i.e., for any reason) of specific prescription tranquilizers in the past 12 months. Respondents who did not report use of any tranquilizer in the past 12 months were asked whether they ever, even once, used prescription tranquilizers.

Respondents who reported they used specific prescription tranquilizers in the past 12 months for any reason were shown a list reminding them of the drugs they used in the past 12 months. For each of these drugs, respondents were asked whether they misused it (or them) in the past 12 months (i.e., in any way a doctor did not direct them to use it). Examples of misuse were presented to respondents and included (1) use without a prescription of the respondent's own; (2) use in greater amounts, more often, or longer than told to take a drug; or (3) use in any other way a doctor did not direct the respondent to use a drug. If respondents reported misuse of one or more specific prescription tranquilizers in the past 12 months, they were asked whether they misused prescription tranquilizers in the past 30 days. Respondents who reported any use of prescription tranquilizers in the past 12 months but did not report misuse in the past 12 months or who reported any use in their lifetime but not in the past 12 months were asked whether they ever, even once, misused any prescription tranquilizer. Consequently, estimates of the misuse of prescription tranquilizers in the lifetime or past month periods are available only for the overall prescription tranquilizer category and not for specific tranquilizers.

Questions about past year use and misuse in the 2018 NSDUH covered the following subcategories of tranquilizers: benzodiazepine tranquilizers (including alprazolam products [Xanax^®, Xanax^® XR, generic alprazolam, or generic extended-release alprazolam], lorazepam products [Ativan^® or generic lorazepam], clonazepam products [Klonopin^® or generic clonazepam], or diazepam products [Valium^® or generic diazepam]); muscle relaxants (cyclobenzaprine [also known as Flexeril^®] or Soma^®); or any other prescription tranquilizer. Other prescription tranquilizers could include products similar to the specific tranquilizers listed previously. Questions were not asked about past month tranquilizer use or misuse for the subtype categories.

SEE: "Any Use of Psychotherapeutics," "Benzodiazepine Use or Misuse," "Lifetime Use or Misuse," "Misuse of Psychotherapeutics," "Past Month Use or Misuse," "Past Year Use or Misuse," "Psychotherapeutic Drugs," "Recency of Use or Misuse," "Source of Psychotherapeutic Drugs," and "Tranquilizer or Sedative Use or Misuse."

Treatment for a Mental Disorder

SEE: "Mental Health Service Settings for Youths," "Mental Health Service Use among Adults," and "Treatment for Depression."

Treatment for a Substance Use Problem

SEE: "Substance Use Treatment."

Treatment for Depression

Treatment for depression was defined as seeing or talking to a professional or using prescription medication in the past year for depression.⁶⁷ Starting in 2011, treatment professionals were subdivided into "Alternative Service Professional," "Health Professional," and "Other."

SEE: "Alternative Service Professional," "Health Professional," and "Major Depressive Episode (MDE)."

Two or More Races

Respondents were asked to report which racial group describes them. Response options were (1) white, (2) black or African American, (3) American Indian or Alaska Native, (4) Native Hawaiian, (5) Guamanian or Chamorro, (6) Samoan, (7) Other Pacific Islander, (8) Asian, and (9) Other. Starting in 2013, the categories for Guamanian or Chamorro and for Samoan were included in the NSDUH questionnaire.

Respondents were allowed to choose more than one of these groups. Respondents who chose more than one category from among Native Hawaiian, Guamanian or Chamorro, Samoan, and Other Pacific Islander (and no additional categories) were classified in a single category: Native Hawaiian or Other Pacific Islander. Otherwise, respondents reporting two or more of the above groups and that they were not of Hispanic, Latino, or Spanish origin were included in a "Two or More Races" category. People reporting two or more races do not include respondents who reported more than one Asian subgroup but who reported "Asian" as their only race. Respondents reporting two or more races and reporting that they were of Hispanic, Latino, or Spanish origin were classified as Hispanic.

SEE: "Hispanic or Latino" and "Race/Ethnicity."

Type of Mental Health Service Use among Adults

SEE: "Mental Health Service Use among Adults."

Underage Alcohol Use

Underage alcohol use was defined as any use of alcohol by people aged 12 to 20 in the respondent's lifetime, past year, or past month.

SEE: "Alcohol Use," "Binge Use of Alcohol," "Current Use or Misuse," "Heavy Use of Alcohol," "Lifetime Use or Misuse," "Location of Most Recent Underage Alcohol Use," "Past Month Use or Misuse," "Past Year Use or Misuse," "Recency of Use or Misuse," "Social Context of Most Recent Underage Alcohol Use," and "Source of Alcohol for Most Recent Underage Alcohol Use."

Unmet Need for Mental Health Services among Adults

SEE: "Perceived Unmet Need for Mental Health Services among Adults."

West Region

The states included are those in the Mountain Division (Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, and Wyoming) and the Pacific Division (Alaska, California, Hawaii, Oregon, and Washington).

SEE: "Geographic Division" and "Region."

White

White only, not of Hispanic, Latino, or Spanish origin. This does not include respondents reporting two or more races. Respondents reporting they were white and of Hispanic, Latino, or Spanish origin were classified as Hispanic.

SEE: "Hispanic or Latino," "Race/Ethnicity," and "Two or More Races."

World Health Organization Disability Assessment Schedule (WHODAS)

The World Health Organization Disability Assessment Schedule (WHODAS) consists of a series of questions used for assessing disturbances in social adjustment and behavior (i.e., functional impairment). A reduced set of WHODAS items was used in NSDUH.⁶⁸ Respondents were asked if they had difficulty doing any of the following eight activities during the 1 month when their emotions, nerves, or mental health interfered most with their daily activities: (1) remembering to do things they needed to do, (2) concentrating on doing something important when other things were going on around them, (3) going out of the house and getting around on their own, (4) dealing with people they did not know well, (5) participating in social activities, (6) taking care of household responsibilities, (7) taking care of daily responsibilities at work or school, and (8) getting daily work done as quickly as needed. These eight items were assessed on a 0 to 3 scale with categories of "no difficulty," "don't know," and "refuse" (0); "mild difficulty" (1); "moderate difficulty" (2); and "severe difficulty" (3). Some items had an additional category for respondents who did not engage in a particular activity (e.g., they did not leave the house on their own). Respondents who reported they did not engage in an activity were asked a follow-up question to determine if they did not do so because of emotions, nerves, or mental health. Those who answered "yes" to this follow-up question were subsequently assigned to the "severe difficulty" category; otherwise (i.e., for responses of "no," "don't know," or "refused"), they were assigned to the "no difficulty" category. Summing across the eight responses resulted in a total score with a range from 0 to 24.

SEE: "Mental Illness," "Severe Impairment Due to Major Depressive Episode," and "Sheehan Disability Scale (SDS)."