Older adults who were excessively sleepy during the day showed signs of brain changes typical of Alzheimer’s disease. The findings add to a growing body of evidence linking at least some types of sleep troubles with an increased risk for dementia.
For the study, researchers analyzed 283 men and women 70 and older who were part of the large and ongoing Mayo Clinic Study of Aging. All were free of obvious Alzheimer’s or other forms of dementia.
All volunteered to have at least two brain scans between 2009 and 2016 to look for changes that might signal impending Alzheimer’s. They also underwent assessments of their sleep and wakefulness levels; 63 of the participants, or 22 percent, were considered to have excessive daytime sleepiness.
The researchers found that those who were excessively tired during the day were much more likely to have high levels of a toxic protein called beta-amyloid in their brains. Beta-amyloid buildup is a hallmark of Alzheimer’s disease, forming plaques that can damage healthy brain cells, and levels of the toxic protein tend to build up for years before memory loss and thinking problems become evident.
Other studies have shown that sound sleep at night may help to clear beta-amyloid from the brain. Poor sleep, on the other hand, may promote its accumulation.
“Elderly individuals with excessive daytime sleepiness may be more vulnerable to Alzheimer’s disease-related changes,” said study author Prashanthi Vemuri, an associate professor of radiology at the Mayo Clinic in Rochester, Minn.
“Sleep has been proposed to be important for clearance of brain amyloid,” she said. “This study affirms that disrupted sleep may be a risk factor for Alzheimer’s disease via increased amyloid.” The findings appeared in JAMA Neurology.
In an editorial accompanying the study, Bryce Mander, an assistant professor of psychiatry and human behavior at the University of California, Irvine School of Medicine, noted that persistent and untreated sleep troubles appear to promote the progression of Alzheimer’s disease.
“These findings further support the idea that chronically disturbed sleep may facilitate the development of Alzheimer’s disease or accelerate its progression,” he said. He urged patients to talk to their doctors about sleep troubles, because many can be treated, though it is still unknown whether treating poor sleep can reduce the buildup of plaques in the brain.
Excessive daytime sleepiness may also be an early warning sign to doctors of impending Alzheimer’s disease, even if memory and thinking problems are not readily apparent.
Poor night sleep is common in the elderly, and an estimated 20 percent to 30 percent of older men and women end up feeling sleepy during the day. So excessive daytime sleepiness in no way means that Alzheimer’s is imminent. Many older people with insomnia and other sleep troubles will not go on to develop dementia.
But, as this study shows, sleep troubles are linked to an increased risk of beta-amyloid buildup in the brain. If you are having sleep troubles — excessive sleepiness during the day or poor night sleep — speak with your doctor. A sound night’s sleep may be a critical component of a healthy lifestyle – and might even help to keep Alzheimer’s at bay.
By www.ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Sources: Diego Z. Carvalho, M.D., Erik K. St. Louis, M.D., Kavid S. Knopman, M.D., et al: “Association of Excessive Daytime Sleepiness With Longitudinal Beta-Amyloid Accumulation in Elderly Persons Without Dementia.” JAMA Neurology, March 12, 2018
“Waking Up to the Importance of Sleep in the Pathogenesits of Alzheimer Disease,”by Joseph R. Winer, M.A., of the University of California, Berkeley, and Bryce A. Mander, Ph.D., of the University of California, Irvine. JAMA Neurology March 12, 2018