Can daytime sleepiness predict Alzheimer's?
In a recently published study, scientists conclude that excessive daytime sleepiness could predict the onset of Alzheimer's in later life.
Alzheimer's disease is the most common form of dementia.
It affects around 5.7 million people in the United States — and this number is predicted to rise.
Some estimate that, by 2050, 13.8 million U.S. adults might be affected.
Despite its growing prevalence, treatment options are lacking and there is no cure.
The exact causes are not yet known, so a great deal of research goes into understanding what factors increase the risk of developing Alzheimer's. By recognizing the risk factors, it may be possible to significantly reduce the chances of getting Alzheimer's.
To date, a number of these risk factors have been discovered. The most well-known is age; most people who develop Alzheimer's are 65 or older. After the age of 85, the risk of developing Alzheimer's is almost one third.
Genetic factors also play a role; a person's risk increases if a family member has had the disease, and certain genes have been identified that are strongly linked to Alzheimer's risk.
Diet may also play a role, as might mental and physical activity. According to the latest research, sleep might soon be added to the list, too.
Sleep as a risk factor
Published in the journal SLEEP, the new study was led by Adam P. Spira, Ph.D., who is an associate professor at the Johns Hopkins Bloomberg School of Public Health in Baltimore, MD.
"Factors like diet, exercise, and cognitive activity," he states, "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."
Specifically, the researchers looked for a relationship between excessive daytime sleepiness and napping and the buildup of beta-amyloid plaques in the brain, which is a hallmark of Alzheimer's disease.
Understanding the links between sleepiness and Alzheimer's here could be important. "If disturbed sleep contributes to Alzheimer's disease," Spira explains, "we may be able to treat patients with sleep issues to avoid these negative outcomes."
To investigate, they took data from the Baltimore Longitudinal Study of Aging, which has followed the health of thousands of participants since 1958. Of particular interest was a questionnaire that was completed in 1991–2000. Two questions were relevant to this study:
- "Do you often become drowsy or fall asleep during the daytime when you wish to be awake?" This was a simple yes or no question.
- "Do you nap?" The multiple choice answers were: "daily," "one to two times each week," "three to five times each week," and "rarely or never."
Also, as part of the Baltimore study, some participants received brain scans that could detect beta-amyloid plaques in the brain.