"We found that if people had a lot of awakenings during the night, more than five awakenings in an hour, they are more likely to have preclinical Alzheimer's disease," says researcher Yo-El Ju, MD, assistant professor of neurology at Washington University School of Medicine in St. Louis.
Preclinical Alzheimer's disease is the term given to people who have normal mental skills but show brain changes associated with the degenerative disorder.
Ju is due to present her findings on sleep problems and Alzheimer's disease in April at the American Academy of Neurology's annual meeting in New Orleans.
The study is preliminary. It finds an association, but not a cause and effect.
"We don't know which is the cart and which is the horse," says Gary Small, MD, Parlow-Solomon professor on aging at the University of California Los Angeles and director of its Longevity Center. Are brain changes driving the sleep problems or vice-versa? More study is needed, says Small, who reviewed the findings for WebMD. Ju agrees.
Sleep Problems and Alzheimer's Disease
Ju and her colleagues evaluated 100 men and women aged 45-80. All were free of dementia at the study start. Half of them have a family history of Alzheimer's disease.
Ju is in the process of enrolling or evaluating another 100 people. She expects to have those results by the meeting.
For 14 days, the men and women wore a device that measures sleep. They also completed sleep diaries and questionnaires.
The researchers analyzed spinal fluid. They looked at brain scans. They were looking for indicators of “amyloid plaques.” These are deposits found in the brains of people with Alzheimer's. Experts believe the deposits can begin forming 10 to 15 years before the symptoms appear, Ju says.
People slept an average of six-and-a-half hours, although they spent about eight hours a night in bed.
Sleep Problems and Alzheimer's: Study Results
About 25% of the 100 people had evidence of pre-clinical Alzheimer's disease due to abnormal indicators reflecting amyloid plaques. Those who woke up most frequently, more than five times an hour, were more likely than the others to have these abnormal biomarkers.