MONDAY, Oct. 21 (HealthDay News) -- Older people who get less
sleep or poor sleep may have more of the plaque that is suggestive
of Alzheimer's disease in their brains, a new study indicates.
"There is a link between sleep and the amount of [beta] amyloid in the brain," said lead researcher Adam Spira, an assistant professor in the department of mental health at the Johns Hopkins Bloomberg School of Public Health.
The unanswered question is whether poor sleep is a result of
plaque build-up or if poor sleep leads to more plaque and
eventually Alzheimer's disease. Also, although the study showed an
association between the two, it did not prove any cause-and-effect
"We can't say that sleep disturbance preceded the amyloid deposits," Spira said. "One possibility is that changes in the brain are leading to disturbed sleep."
It is known that people with Alzheimer's disease have disturbed
sleep, Spira said. "But that we found this in people without
Alzheimer's disease leads us to think that there might be a
connection between sleep disturbance and developing amyloid plaque
and Alzheimer's disease, but we can't tell that yet," he said.
Still, Spira suggested it might be possible that improving sleep
could help prevent Alzheimer's disease. "We live in a
sleep-deprived society," he said. "It may be that changing sleep
habits has significant implications for mental health and
specifically the prevention of Alzheimer's disease, but that
remains to be seen."
The report was published online Oct. 21 in the journal
Spira said a study published Oct. 17 in the journal
Scienceshowed that during sleep there are changes in the
brains of mice that help flush out toxins such as beta amyloid.
The lead researcher of the
Sciencestudy, Dr. Maiken Nedergaard, co-director of the
University of Rochester Medical Center for Translational
Neuromedicine, said this latest study "fits perfectly with our
Another expert agreed that sleeping well might help prevent
"Since researchers know that more amyloid protein is produced by neurons in active circuits, the results could mean that quieting them down and getting a good night's sleep might help to prevent Alzheimer's," said Greg Cole, a neuroscientist at the Greater Los Angeles VA Healthcare System.
Or it might just mean that Alzheimer's disease causes sleep
disturbances, he added.
"So far, there is no evidence that sleeping pills reduce Alzheimer's disease risk," said Cole, who also is associate director of the Alzheimer's Disease Research Center at the University of California, Los Angeles, David Geffen School of Medicine. "Like problems with sleep, people treating the sleep loss with sleeping pills still have increased Alzheimer's disease risk. You wouldn't want to lose too much sleep worrying about sleep loss as a cause or consequence of Alzheimer's disease until we learn more."
Dr. Sam Gandy, director of the Mount Sinai Center for Cognitive
Health, in New York City, said sleep appears to be necessary to
clear the brain of toxins like beta amyloid.
"There is accumulating evidence that beta amyloid and other metabolites are cleared during sleep, so there is probably at least an effect of sleep dysfunction on beta amyloid accumulation," Gandy said.
"That does not exclude the possibility that amyloid regulates sleep," he said. "That should be testable, by transferring cerebrospinal fluid from sleep-deprived animals into non-sleep-deprived animals to see whether that causes sleep dysfunction in the recipient."
For this study, Spira's team used data from 70 adults who took
part in the Baltimore Longitudinal Study of Aging. Those in the
study, who had an average age of 76, reported how well they slept,
while the amount of beta amyloid in their brains was measured with
The researchers found that those who said they slept less --
around five hours a night -- and those whose quality of sleep was
poor had more plaque build-up than those who slept longer and
Alzheimer's Associationfor more on this
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