Mild Cognitive Impairment: What Can We Do in Primary Care?

Hi, everyone. I'm Dr Kenny Lin. I am a family physician and associate director of the Lancaster General Hospital Family Medicine Residency, and I blog at Common Sense Family Doctor.

Kenneth W. Lin, MD, MPH

One of the challenges I frequently encounter in the office is caring for older patients with mild cognitive impairment (MCI). In addition to discussing practical issues such as driving safety and the need for assistance with activities such as meal preparation and paying bills, patients want to know whether and how quickly they will progress to Alzheimer's disease (AD) dementia. Will they eventually forget who they are, require around-the-clock care, and become a burden to their spouse and children? And is there anything their doctors can do to help them delay or prevent this outcome?

AD dementia affects 6 million Americans, a number that is projected to grow to 13 million by 2050. Outside of research studies, differentiating dementia from MCI is based on a clinical evaluation, including standardized cognitive tests. However, a study in China recently reported that changes in cerebrospinal fluid biomarkers could be detected as early as 18 years prior to the diagnosis of AD. The development of monoclonal antibody therapies that target beta-amyloid plaques in the brain has led the nonprofit Alzheimer's Association to propose expanding the definition of early AD to include cognitively normal patients with biomarker abnormalities. The prospect of diagnosing tens of millions of cognitively normal Americans with Stage 1 AD prompted a critical response to the proposal from the American Geriatrics Society and the withdrawal of the National Institute of Aging, which had partnered with the Alzheimer's Association on prior guidance, from formal sponsorship of the diagnostic criteria.

In a previous Medscape commentary, I discussed the controversial approval of aducanumab (Aduhelm). Rather than becoming a blockbuster, the drug's disappointing sales led the manufacturer to pull it from the market earlier this year. Attention of patients and caregivers has now turned to lecanemab (Leqembi) and donanemab, two similar therapies that showed statistically significant slowing of clinical progression in early AD over 18 months in randomized trials. However, a systematic review and meta-analysis concluded that cognitive and functional benefits demonstrated for each of these drugs are considerably smaller than what would be clinically meaningful.

Family physicians can and should weigh in on proposed changes to the definition of AD that would affect many of our patients today and in the future. Widening disease definitions increased overdiagnosis and overtreatment in hypertension and breast cancer. Similarly, only a minority of patients with abnormal amyloid levels will develop MCI or AD. Although learning about one's risk for future memory problems could change health-related behaviors and assist with financial and medical planning, it could also cause patients to worry about dementia every time they misplace their keys or have trouble retrieving a word in conversation.

Regardless of what happens, we will be having more discussions in primary care about the pros and cons of lecanemab (approved by the US Food and Drug Administration [FDA] in July 2023) and donanemab (FDA application pending). Two academic general internists developed a decision aid on the basis of the benefits and risks of lecanemab observed in clinical trials. This decision aid highlights that a person with a cognitive score of 82% at baseline who receives 36 lecanemab infusions over 18 months will end up at 76% compared with 73% if they did not take the drug. For every 1000 patients receiving lecanemab, 109 more will develop brain swelling and 83 more will develop brain bleeding. Most patients who experience these adverse effects will not feel them, but about 3% will have symptoms that require urgent management. Finally, though not included in the decision aid, the person who takes lecanemab will be $40,000 poorer if insurance doesn't pick up part of the cost.

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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.

Cite this: Mild Cognitive Impairment: What Can We Do in Primary Care? - Medscape - Mar 08, 2024.