People with Alzheimer’s disease often sleep poorly. Now, a new study shows that sleep problems may signal the early onset of Alzheimer’s disease.
The findings, from researchers at Washington University School of Medicine in St. Louis, are consistent with earlier research in animals showing that sleep loss may be linked to the buildup of plaque-forming beta amyloid, a hallmark of Alzheimer’s, in the brain. Some evidence suggests that the buildup of plaque disrupts sleep, and that loss of sleep, in turn, promotes Alzheimer’s plaques.
"This link may provide us with an easily detectable sign of Alzheimer's pathology," said senior author Dr. David M. Holtzman, head of Washington University's Department of Neurology. "As we start to treat people who have markers of early Alzheimer's, changes in sleep in response to treatments may serve as an indicator of whether the new treatments are succeeding."
For the study, published in the Journal of the American Medical Association (JAMA) Neurology, researchers recruited 145 men and women, aged 45 to 75, who were enrolled in ongoing Alzheimer’s research at the University. All were free of serious memory problems at the start of the study, though 32 had abnormalities in the spinal fluid that suggested they might have high levels of plaque buildup in the brain, suggesting they may be in the earliest stages of Alzheimer’s disease.
The study participants kept daily sleep diaries for two weeks, noting the time they went to bed and got up, the number of naps taken on the previous day, and other sleep-related information. They also wore special sensors on their wrists that recorded their activity levels to help confirm when they were sleeping and when they were awake and moving about.
The researchers found that those men and women who slept the worst were more than five times as likely to have signs of preclinical Alzheimer’s, as measured by buildup of beta amyloid plaque, than those who slept soundly. Those with plaque buildup stayed in bed as long as other participants, but they spent less time asleep than the good sleepers. They also napped more often.
The researchers are following up with studies in younger participants who have sleep disorders to see how sleep may affect the brain and its susceptibility to dementia.
"We think this may help us get a better feel for the way this connection flows — does sleep loss drive Alzheimer's, does Alzheimer's lead to sleep loss, or is it a combination?" said Dr. Yo-El S. Ju, one of the study authors. "That will help us determine whether we can change the course of disease with pharmaceuticals or other treatments."
Areas of the brain important for sleep and wakefulness are affected early in the course of Alzheimer’s. As the disease progresses, sleep-wake problems like “sundowning,” in which patients grow increasingly restless and confused as daylight wanes, and nighttime wandering become apparent. Increased napping and insomnia affect from a quarter to half of people with mild to moderate Alzheimer’s.
This study is among the first to look at beta amyloid buildup and sleep problems in the earliest stages of Alzheimer’s before memory loss and thinking problems become apparent. Growing research shows that abnormalities may appear in Alzheimer’s 10 to 20 years before the disease is diagnosed. Sleep problems may be among the earliest signs.
Source: Yo-El S. Ju, MD, Jennifer S. McLeland, MSW, MA, Cristina D. Toedebusch, BS, et al: “Sleep Quality and Preclinical Alzheimer Disease.” JAMA Neurology. Published online March 11, 2013.