Findings from a large, multicenter study released today show that sleep apnea - a disorder in which people repeatedly stop breathing when sleeping - more than doubles the risk of stroke among men and also poses a risk for women. The NIH explains more in a release:
In the latest report, researchers studied stroke risk in 5,422 participants aged 40 years and older without a history of stroke. At the start of the study, participants performed a standard at-home sleep test, which determined whether they had sleep apnea and, if so, the severity of the sleep apnea.
Researchers followed the participants for an average of about nine years. They report that during the study, 193 participants had a stroke - 85 men (of 2,462 men enrolled) and 108 women (out of 2,960 enrolled).
After adjusting for several cardiovascular risk factors, the researchers found that the effect of sleep apnea on stroke risk was stronger in men than in women. In men, a progressive increase in stroke risk was observed as sleep apnea severity increased from mild levels to moderate to severe levels. In women, however, the increased risk of stroke was significant only with severe levels of sleep apnea.
Previous research has shown an association between the disorder and stroke among men, but two things make this work especially significant. This is first time the link has been shown in women, and the study, which involved nine research institutions, was a major one. "The Sleep Heart Health Study is one of the largest studies funded by NIH in sleep medicine," Stanford sleep expert Clete Kushida, MD, PhD, told me today. "The number of patients and the long-term follow-up is what sets it apart."
Twelve million Americans are believed to have this sleep disorder, and untreated apnea has already been linked to high blood pressure, a decline in cognitive functions, and other health problems. These latest findings, Kushida said, just strengthen the case for the importance of early diagnosis and treatment.