Study: Sibling Stroke Increases Risk

U.S. researchers said Wednesday that if you have a brother or sister who had a stroke, your risk of having a brain attack is markedly increased.

The risk increases depending on ethnicity, researchers said at the 59th annual meeting of the American Academy of Neurology in Boston.

Mexican-American men whose siblings have had a stroke are at particularly high risk, said Lewis Morgenstern, professor of neurology and epidemiology at the University of Michigan at Ann Arbor.

He said they are nearly three times as likely to have a stroke themselves. In the general population, the risk of having a stroke is nearly doubled if a sibling has been stricken.

Morgenstern said the increases pertain to both strokes and transient ischemic attacks, so-called ministrokes, caused when blockages in arteries leading to the brain become clogged. If the blockage is transient, a patient usually returns to normal function. With a stroke, blockage can result in permanent damage.

Researchers aren’t sure why the association exists. We don’t know whether it’s shared environmental factors such as diet and smoking habits or genetics at play, Morgenstern said. We think it’s a combination of both.

The study included 807 siblings, ages 45 to 64, of people who had strokes in Nueces County, Texas. Nearly 60 percent of the subjects in the study were Mexican-American and the rest were non-Hispanic whites. About half were women. Among the non-Hispanic whites, only siblings of women who have had strokes were at an increased risk.