TUESDAY, Aug. 9 (HealthDay News) -- Elderly women who experience sleep apnea have a higher risk of developing mild cognitive impairment or dementia, new research finds.
The study found that elderly women who began the study without dementia had 85 percent higher odds of developing mild cognitive impairment or dementia over the next five years if they had 15 or more sleep apnea events per hour of sleep.
"This was a prospective study of elderly women followed over time to understand the relationship of sleep apnea and cognitive impairment or dementia," explained study co-author Dr. Susan Redline, a researcher in the division of sleep medicine at Brigham and Women's Hospital in Boston.
"We found a very high prevalence of untreated sleep apnea -- about one third of the women had sleep apnea, and those women had about an 80 percent increased risk of developing cognitive impairment or dementia during the study," said Redline.
Although this study wasn't designed to uncover the mechanism by which repeated oxygen deprivation might cause dementia, Redline noted that it may harm brain health by affecting the way the brain constantly replenishes its cells. More research needs to be done to find the exact mechanism, she added.
The findings are published in the Aug. 10 issue of the Journal of the American Medical Association.
The study included 298 women who did not have dementia at the start of the study. The average age of the women was approximately 82. All of the women underwent an overnight sleep study using sensors and computerized monitoring (polysomnography) between 2002 and 2004.
One hundred and five women were diagnosed with sleep-disordered breathing. That meant they had 15 or more sleep apnea episodes per hour of sleep. During those episodes, the brain was temporarily deprived of oxygen.
Five years after the sleep study, women were given cogn
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