Seniors who don't sleep well are more likely to have high levels of beta-amyloid, a biomarker for Alzheimer's, in their brains. Previous studies had linked disturbed sleep to cognitive impairment in older people. The new findings, published in JAMA Neurology, suggest that sleep problems may contribute to its development.
Alzheimer's disease is a progressive, irreversible brain disease that slowly destroys memory and thinking skills. According to the National Institutes of Health, as many as 5.1 million Americans may have the disease, with first symptoms appearing after age 60.
Brains of Alzheimer's patients have high levels of amyloid plaque, deposits of a substance consisting largely of beta-amyloid. According to the National Institute on Aging, it is not yet known whether amyloid plaque causes the disease or is a byproduct of it.
In a cross-sectional study of adults with an average age of 76, a team led by Adam Spira of the Johns Hopkins Bloomberg School of Public Health examined sleep as reported by research participants. Their duration of sleep ranged from more than seven hours a night to no more than five hours. Beta-amyloid in their brains was measured by positron emission tomography, or PET scans.
The results: Shorter sleep duration and lower sleep quality were both associated with greater beta-amyloid buildup.
Spira says that his study doesn't prove a causal link between poor sleep and Alzheimer's disease. Longitudinal studies with objective sleep measures are needed to further examine whether poor sleep actually can contribute to or accelerate Alzheimer's disease, he says.
"These findings are important in part because sleep disturbances can be treated in older people," Spira says. "To the degree that poor sleep promotes the development of Alzheimer's disease, treatments for poor sleep or efforts to maintain healthy sleep patterns may help prevent or slow the progression of Alzheimer's disease."