Older men who slept in an oxygen-deprived state had higher level of microinfarcts....

Excerpt by Salynn Boyles, Contributing Writer, MedPage Today. Peer reviewed by MedPage Today® and Perelman School of Medicine at the University of Pennsylvania

Elderly people with sleep issues resulting in low nocturnal oxygenation and reduced time in deep sleep seemed to be at an elevated risk for cognitive decline and dementia, according to researchers. 

In a prospective study that followed older men from sleep assessment to autopsy, the men were divided into groups based on the amount of time spent with lower than normal blood oxygen levels during sleep. Those who spent the most time in an oxygen-deprived state were found to have more microinfarcts (mini-strokes) at later autopsy compared with men who spent the least sleep time in this state reported Rebecca P. Gelber, MD, MPH, of the VA Pacific Island Health Care System in Honolulu.

The most sleep-deprived men who spend less time in the slow-wave deep, restorative stage of sleep (important in processing new memories) also had more brain atrophy (cell loss).

Study Details

Sleep-disordered breathing (apnea), nocturnal hypoxia, and changes in sleep architecture have been shown in some studies to increase dementia risk in the elderly, and this relationship is supported by the finding that continuous positive airway pressure (CPAP) treatment in patients with obstructive sleep apnea (OSA) may improve cognitive performance, even after dementia has developed, Gelber noted.

"In this study, sleeping men with ~70% of their time at lower (<95%) oxygen levels were about four times more likely to have moderate to high levels of microinfarcts, as compared with men who spent <13% of their sleep with lower oxygen levels."

She added that men who spent at least 15% of their sleep in slow wave sleep are 66% less likely to have moderate or high levels of atrophy, compared with those who had less than 1.5% of their sleep in slow wave restful cycles.

"Many people diagnosed clinically with Alzheimer's disease have other brain lesions contributing to their dementia," she stated. "Two of the other major pathologic findings seen in persons with dementia are atrophy and microinfarcts.

Funded by the National Institute on Aging, the Alzheimer's Association, the Hawaii Community Foundation, and the Office of Research and Development, Department of Veterans Affairs Pacific Islands Health Care System.

Primary Source: Gelber RP, et al "Associations of brain lesions at autopsy with polysomnography features before death" Neurology 2015; 84: 1-8.