Your blood type may raise, lower your stroke risk, study says

Blood type might affect how likely one is to suffer a stroke, according to new research presented last week at an American Heart Association conference.

Using data from two large studies conducted over 20 years that included more than 90,000 men and women, Harvard researchers found that blood type AB was associated with a 28-percent increased risk in women and 32-percent increased risk in men compared to those with type O blood. Type B was linked to a 17 percent increased risk of stroke in women, but men with the blood type did not have that increased risk.

The increased risk for stroke with type AB blood was for ischemic stroke, the research abstract noted.

There are two types of stroke, hemorrhagic and ischemic, according to the American Stroke Association. Ischemic stroke results from blood clots, while the hemorrhagic involves, as its name suggests, bleeding in the brain.

The study said while the susceptibility to stroke was higher with certain AB blood types, it was still moderate. And there are other risk factors that are more certain, including smoking and high blood pressure. But "people with the higher-risk blood type should check their other risk factors and it may be recommended that they follow a more intensive, healthy lifestyle," the researchers said.

What type you are hinges on proteins called antigens on the red blood cell surface: either A or B. If you have A antigen, you're type A. If you have B, you're type B. People with AB blood have both types, and those with O have no antigens.

In conjunction with its coverage of the new research, CBS News noted 10 myths about strokes, including the idea that strokes only occur among the elderly — they absolutely happen at much younger ages, as well — that they occur in the heart when the direct damage is actually to the brain, and other misconceptions.

One of the study's leaders, Dr. JoAnn Manson, chief of preventive medicine at Harvard's Brigham and Women's Hospital, told the Associated Press' Marilynn Marchione that the research builds on other indications that blood type might "influence risk" of chronic disease.

"It's not at the level where we want to alarm people and we want to make that clear," she said. "But it's one more element of risk that people would want to know about," and another reason to control blood pressure and cholesterol levels.

As for age, a Utah County neurologist, Dr. Kevin Call, recently told the Deseret News that over the last decade, strokes have been striking "at younger ages overall," perhaps because of lifestyle issues like an increase in the number of people who are overweight. He also noted that some people may be ignoring nonsymptomatic disease processes when paying attention and using preventive steps could make a difference.

EMAIL: lois@desnews.com, Twitter: loisco