Sleep Disorder Linked to Stroke Risk

Sleep Apnea, Even its Milder Form, Puts Men at Increased Risk of Stroke

A large study shows that obstructive sleep apnea, a sleep disorder, is associated with an increased risk of stroke in middle-aged and older adults, especially men.

Results of the Sleep Heart Health Study (SHHS), which was supported by the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health, indicate that the risk of stroke appears in men with mild sleep apnea and rises with the severity of sleep apnea. The result of the study was published online March 25 in the American Journal of Respiratory and Critical Care Medicine.

The researchers noted that men with moderate to severe sleep apnea were nearly three times more likely to have a stroke than men without sleep apnea or with mild sleep apnea. "Men who had untreated sleep apnea were up to three times more likely to experience a stroke than men who did not have sleep apnea," says Dr. Michael Twery in an interview by the National Institutes of Health's NIH Radio. Twery is the Director of the NIH National Center on Sleep Disorders Research.

According to the NIH, obstructive sleep apnea is a common disorder in which the upper airway is occasionally narrowed or blocked, disrupting sleep and breathing during sleep. Experts believe that there are more than 12 million American adults who have sleep apnea, and most are not diagnosed or treated.

Stroke, on the other hand, is the second leading cause of death worldwide and the third leading cause of death in the United States. "Although scientists have uncovered several risk factors for stroke — such as age, high blood pressure and atrial fibrillation, and diabetes — there are still many cases in which the cause or contributing factors are unknown, " noted NHLBI Acting Director Susan B. Shurin, M.D. "This is the largest study to date to link sleep apnea with an increased risk of stroke. The time is right for researchers to study whether treating sleep apnea could prevent or delay stroke in some individuals. "

There were 5,422 participants aged 40 years and older without a history of stroke in the study. The study began with the participants performing a standard at-home sleep test that determined whether they had sleep apnea and, if so, the severity of the condition. The researchers then followed the participants for a period of 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).

The researchers suggest that the differences between men and women might be because men are more likely to develop sleep apnea at younger ages. Therefore, they tend to have untreated sleep apnea for longer periods of time than women.

"What the Sleep Heart Health Study has revealed in this study is that people have apnea and then later develop cardiovascular disease risk—whether it be stroke or high blood pressure or heart attack and so forth—the development of apnea preceded the development of the cardiovascular disease," Twery said. He further added, "And this gives us an important clue as to whether treating the sleep apnea maybe a potential important way to reduce these cardiovascular risks."

Source:
National Institutes of Health (NIH). "Sleep Apnea Tied to Increased Risk of Stroke (Even Mild Sleep Apnea Puts Men in Danger)." Available at . Accessed on September 8, 2010.

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