Study suggests low oxygen levels, less time in deep shut-eye may contribute to brain changes
WebMD News from HealthDay
By Amy Norton
HealthDay Reporter
WEDNESDAY, Dec. 10, 2014 (HealthDay News) -- Older men who have breathing difficulties or spend less time in deep sleep may be at greater risk of brain changes that can precede dementia, a new study suggests.
Experts said the findings don't prove that breathing disorders, including sleep apnea, lead to dementia. But they add to evidence that poor sleep may play a role in some older adults' mental decline.
Past studies have suggested that people with certain sleep disturbances may face a greater dementia risk, the researchers note. But the reasons remain unclear.
The new findings "help to explain how sleep disturbances may actually contribute to the development of cognitive impairment and dementia," said study leader Dr. Rebecca Gelber, of the VA Pacific Islands Health Care System in Honolulu.
Specifically, the researchers found that elderly men who had less oxygen circulating in their blood during sleep tended to show more "microinfarcts" in the brain. Microinfarcts are tiny abnormalities in brain tissue that can precede dementia.
Meanwhile, men who spent less time in slow-wave sleep -- the deep, restorative stage of sleep -- tended to show more atrophy in their brain tissue.
"Microinfarcts and atrophy are known to be much more common, and more severe, in people with dementia, than in people without memory problems," Gelber explained.
But this is the first study, she said, to show that certain sleep features are related to those brain changes.
However, an expert who reviewed the study urged caution in interpreting the results.
"All this shows is a linkage, not cause-and-effect," said Keith Fargo, director of scientific programs and outreach for the Alzheimer's Association in Chicago.
Fargo stressed that research into the role of sleep in dementia risk is "very important," but there are still many questions.
"What we can say is, people with sleep disturbances appear more likely to have brain changes associated with dementia," Fargo said. "There is some relationship, but researchers don't understand it yet."
The findings -- published online Dec. 10 in Neurology -- are based on brain autopsies from 167 elderly Japanese-American men who'd taken part in a long-term health study before their deaths. As part of that study, the men had their oxygen levels and brain activity monitored as they slept.
source : Sleep Apnea May Raise Risk for Dementia
