Study Finds That Cognitive Decline is Key Factor in Determining Alzheimer’s Life Expectancy
When a person is diagnosed with Alzheimer’s, their life expectancy can vary. According to the Alzheimer’s Association, the average person will live four to eight years after diagnosis, but that can stretch as far as 20 years. Which factors play the biggest role in how long a patient lives? Researchers recently conducted a study to learn just that.
The research team, from the University of Texas Southwestern, looked at data on more than 750 Alzheimer’s patients to see which factors influenced their lifespans. Their findings, published in the Journal of Alzheimer’s Disease, uncovered seven such factors. The most significant was cognitive decline. Researchers are hopeful these results can help patients and families gauge how much time is left to them.
Dr. C. Munro Cullum, study author and neuropsychologist investigator in the Peter O’Donnell Jr. Brain Institute, explains, “Families are anxious to know what to expect and how to best plan for the time ahead in terms of finances, family caregiving, and how they want to live out their lives. We’re trying to get them better answers.”
To conduct the study, the team used data from the National Alzheimer’s Coordinating Center on 764 autopsy-confirmed cases of the disease. The patients involved had all died between 2005 and 2015, with a range of one month to 11 years of life after diagnosis. Researchers zeroed in on 14 possible lifespan predictors, learning that seven were significant.
The most significant was poor performance on a short cognitive screening test focused on orientation, which accounted for about 20% of the variation in life expectancy. Other important factors included sex, age, race/ethnicity, neuropsychiatric symptoms, abnormal neurological exam results, and functional impairment ratings.
Dr. Jeffrey Schaffert, first author and postdoctoral fellow in clinical neuropsychology, says, “We found that beyond global cognitive function, patients who were older, non-Hispanic, male, and who had more motor and psychiatric symptoms had a significantly shorter life expectancy.”
Dr. Schaffert also notes that there are 21 predictors of Alzheimer’s life expectancy, but most prior studies had only focused on a few. This work was a little more comprehensive. He says their access to autopsy-confirmed cases helped ensure that there wasn’t confounding data from other types of dementia that are not Alzheimer’s, as well.
The researchers note that life expectancy is complicated, and further study is needed to better understand how certain cognitive factors impact a patient’s timeline. They plan to follow up with more study on sensitive measures of memory and other cognitive abilities. Because this study sample was largely white and well-educated, they also hope to include a more diverse group in the future.
