Researchers studied 101 cognitively normal people, average age 63, who completed well-validated sleep questionnaires. They analyzed their spinal fluid for the presence of indicators of the plaques and tangles that are characteristic of Alzheimer’s. The study is in Neurology.
The reason for the association is unclear, but at least one animal study found that during sleep the brain’s capacity to clear toxins like beta amyloid, the toxic protein that forms plaques in the brains of those with Alzheimer’s, improves. It may be that poor sleep interferes with this process in people, too.
“Not everyone with sleep problems is destined to develop Alzheimer’s disease,” said the senior author, Barbara B. Bendlin, an associate professor of medicine at the University of Wisconsin School of Medicine and Public Health.
“We’re looking at groups of people, and over the whole group we find the association of poor sleep with the markers of Alzheimer’s. But when you look at individuals, not everyone shows that pattern.”