Sleep-disordered breathing is a risk factor for dementia in women

Adding to the damage list associated with sleep-disordered breathing, a study just published in JAMA (The Journal of the American Medical Association) offers evidence that sleep apneas and hypopneas can contribute to serious cognitive impairment. This is not surprising considering the importance of oxygen for brain health. The authors state:

"Sleep-disordered breathing (characterized by recurrent arousals from sleep and intermittent hypoxemia) is common among older adults. Cross-sectional studies have linked sleep-disordered breathing to poor cognition..."

So they designed their study to...

"...determine the prospective relationship between sleep-disordered breathing and cognitive impairment and to investigate potential mechanisms of this association."

Defining sleep-disordered breathing as an apnea-hypopnea index of 15 or more events per hour of sleep, they examined polysomnography ('sleep study') data for 298 women without dementia collected between January 2002 and April 2004. They then used data collected  between November 2006 and September 2008 to correlate hypoxia, sleep fragmentation, and sleep duration with cognitive status (normal, dementia, or mild cognitive impairment). What did the data reveal?

"Compared with the 193 women without sleep-disordered breathing, the 105 women (35.2%) with sleep-disordered breathing were more likely to develop mild cognitive impairment or dementia (31.1% vs 44.8%). Elevated oxygen desaturation index (≥15 events/hour) and high percentage of sleep time (>7%) in apnea or hypopnea (both measures of disordered breathing) were associated with risk of developing mild cognitive impairment or dementia (AOR, 1.71 and AOR, 2.04, respectively)."

In other words, the higher strata of sleep-disordered breathing doubled the risk for dementia. Interestingly...

"Measures of sleep fragmentation (arousal index and wake after sleep onset) or sleep duration (total sleep time) were not associated with risk of cognitive impairment."

Clinicians need to bear in mind the serious metabolic, cardiovascular and cognitive penalties of sleep-disordered breathing and question patients about tell-tale signs such has heavy snoring and daytime somnolence. The authors conclude:

"Among older women, those with sleep-disordered breathing compared with those without sleep-disordered breathing had an increased risk of developing cognitive impairment."

This study cohort was all female subjects, but I can think of no reason why the same consideration does not apply to male patients.