The October International Psychogeriatrics Article of the Month is entitled ‘The association of traumatic brain injury with rate of progression of cognitive and functional impairment in a population-based cohort of Alzheimer’s disease: the Cache County Dementia Progression Study’ by Mac Gilbert, Christine Snyder, Chris Corcoran, Maria C. Norton, Constantine G. Lyketsos and JoAnn T. Tschanz

With a diagnosis of Alzheimer’s dementia comes an understanding that the affected individual will suffer an inevitable and progressive decline in their cognitive and functional abilities. However, what is not known is how fast the decline will occur. Will the person need 24 hour supervision and care shortly after diagnosis or five to ten years in the future?

We have studied this question in our population-based sample of persons with Alzheimer’s dementia and found tremendous variability in the course of decline. It seems that about half of those in our sample declined slowly and a small but significant percentage declined quite rapidly. Is there anything in person’s background that will predict whether they will become a slow or a fast decliner?

We set out to study this issue by examining a person’s medical history, specifically, whether they had a history of concussion or traumatic brain injury (TBI). Several studies have found that those who have had a history of TBI in their lifetimes show an increased risk for Alzheimer’s dementia later in life. However, it was not known whether TBI also predicts the rate of decline after the onset of dementia.

As published in this month’s issue of the journal, we obtained the medical history of persons with Alzheimer’s dementia before onset, and characterized them as either positive or negative for a history of TBI and its severity. We also examined number of TBI (0, 1, 2 or more) and timing of TBI relative to the onset of dementia (none, within 10 years of onset, or greater than 10 years of onset). We repeatedly tested those with Alzheimer’s dementia about every 6 to 18 months, checking their memory, attention, concentration, language and visuospatial abilities. We also rated their functional decline from their caregiver’s report.

We found that a history of TBI predicted more rapid functional decline, but only among those who had experienced a TBI within 10 years of dementia onset. This finding adds to our previous work where a history of TBI was associated with disinhibited behavior after the onset of Alzheimer’s dementia, and persons in better overall health tended to function at higher levels after the onset of dementia.

What is the take home message of this research? While we can’t change the past, we can be proactive by taking steps to prevent TBI and other health problems from occurring. Preventing falls (a major cause of TBI in late life) by ensuring proper foot ware, installing safety bars, and ensuring safe walkways may help prevent new instances of TBI in older adults. Following up with one’s health care provider for any health problems is also suggested. Although there is currently no cure for Alzheimer’s dementia, adopting preventive measures may be one way to slow the progression of decline and optimize one’s level of functioning over the course of the illness.

The full paper “The association of traumatic brain injury with rate of progression of cognitive and functional impairment in a population-based cohort of Alzheimer’s disease: the Cache County Dementia Progression Study” is available free of charge for a limited time here.

The commentary on the paper, “The association of traumatic brain injury with rate of progression of cognitive and functional impairment in a population-based cohort of Alzheimer’s disease: the Cache County dementia progression study by Gilbert et al. Late effects of traumatic brain injury on dementia progression” is also available free of charge for a limited time here.