Study: Sleep quality linked to Alzheimer's

Poor-quality sleep may have worse effects than simple fatigue: A preliminary new study suggests it's linked to the buildup of brain plaques seen in people with Alzheimer's disease.

Researchers at Washington University School of Medicine in St. Louis monitored the sleep patterns of 100 mentally healthy people between the ages of 45 and 80 -- half of whom had a family history of Alzheimer's disease -- and found that those who awakened more than five times an hour were more likely to have amyloid plaque accumulations than those with fewer sleep disturbances.

Amyloid protein plaques are a trait of Alzheimer's, a condition affecting at least 5.4 million Americans that robs patients of memory and reasoning skills. These characteristics, detectable with brain scans and spinal fluid tests, can appear years before Alzheimer's symptoms begin.

"We were initially looking at duration of sleep, but it seems the quality of sleep is more important to this association," said study author Dr. Yo-El Ju, an assistant professor of neurology. "We don't know if early Alzheimer's is causing poor sleep, or vice-versa.

"It's possible that there's some change in brain activity going on during sleep that allows soluble amyloid to decrease overnight," Ju added, "but we need to study this much more closely."

Preliminary results from the study were released Feb. 14 in advance of their presentation at the American Academy of Neurology's annual meeting in April in New Orleans.

For two weeks, study participants wore a device on their wrists that determined whether they were awake or asleep depending on body movements.