WEDNESDAY, Feb. 1 (HealthDay News) -- Sleep apnea, the disorder marked by abnormal pauses in breathing during sleep, is already known to boost the risk of stroke. Now, a new study links sleep apnea to so-called silent strokes, in which there is tissue death in the brain without symptoms.
In another new study, researchers found that rapid memory loss before a stroke boosts the risk of the stroke being fatal.
Both studies are slated for presentation Wednesday at the American Stroke Association's International Stroke Conference in New Orleans.
Stroke affects 795,000 Americans annually, according to the association.
In one study, Dr. Jessica Kepplinger, a fellow at the University of Technology in Dresden, Germany, and her colleagues evaluated 56 patients who had a stroke. They knew that silent strokes had been linked to an increased risk of strokes. However, "there are barely any studies that have investigated the relationship between sleep apnea and the so-called clinically silent strokes," she said.
To look at the relationship, they first gave patients in-hospital testing for apnea. "We found an overall high frequency of sleep apnea, 91 percent, in our study population of acute stroke patients, which underlines the importance of this stroke risk factor," Kepplinger said.
The team also performed brain-imaging studies. Those with sleep apnea were more likely to have the silent strokes, as evidenced on the brain scans, the researchers found. Having more than five episodes a night was linked with having silent strokes. The higher the severity of the apnea, the more likely these silent strokes were found on brain imaging.
The more severe the apnea, the less favorable the outcome when the patient was discharged.
The patients were on average 67 years old, and just over half of them were women, the study authors noted.
While the study found an
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