Older adults who report feeling sleepy during the day might be at higher risk of developing Alzheimer's, according to a study published earlier this month in SLEEP.
For the study, researchers used data from 123 adult volunteers who participated in the Baltimore Longitudinal Study of Aging, a long-term National Institute on Aging study that recorded the health of participants as they aged.
Researchers analyzed the data of men and women, average age 60, who reported their daytime drowsiness and sleeping habits between 1991 and 2000, and who had PET and M.R.I. scans about 16 years later to detect the development of beta-amyloid plaques—an indicator of Alzheimer's disease.
Sign of Alzheimer's disease more common among adults with daytime sleepiness
The researchers found that the adults who in earlier years reported feeling drowsy during the day were about three times more likely to have beta-amyloid plaques than those who did not report daytime sleepiness. When researchers adjusted for variables that could influence sleepiness—such as age, body-mass index, education, and sex—the researchers found adults who reported sleepiness were 2.75 times more likely to have beta-amyloid plaques.
Sleep disturbance is a symptom of Alzheimer's disease, but researchers are not quite sure how, or whether, inadequate sleep is related to the development of the disease.
But according to Adam Spira, an author of the study and professor at the Johns Hopkins Bloomberg School of Public Health, the study results "provid[e]... more evidence for the link between disturbed sleep and the development of" beta-amyloid plaques, suggesting that insufficient sleep might be a risk factor for Alzheimer's. He added, "Factors like diet, exercise, and cognitive activity have been widely recognized as important potential targets for Alzheimer's disease prevention, but sleep hasn't quite risen to that status—although that may well be changing."
Spira cautioned that the study is observational and does not demonstrate cause and effect. However, he noted, "If disturbed sleep contributes to Alzheimer's disease, we may be able to treat patients with sleep issues to avoid these negative outcomes." He added, "Prioritizing sleep may be one way to help prevent or perhaps slow this condition" (Bakalar, New York Times, 9/20; Scullin, "Hub," Johns Hopkins University, 9/6).
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