A new analysis has found a link between certain blood types and the likelihood of a stroke before age 60.

A person’s blood type may be linked to how likely they are to have an early stroke, according to a new meta-analysis of more than 600,000 patients in 48 studies. The findings, published August 31 in the journal Neurology, included all available data from genetic studies on ischemic strokes, which are caused by a blockage of blood flow to the brain, occurring in adults younger than 60. In the overall population, this type of stroke accounts for 87 percent of all strokes, according to the Centers for Disease Control and Prevention (CDC).

“The number of people with early strokes is rising,” said the study's co-principal investigator Steven J. Kittner, MD, MPH, in a press release. Dr. Kittner is a professor of neurology at the University of Maryland School of Medicine (UMSOM) in Baltimore. “These people are more likely to die from the life-threatening event, and survivors potentially face decades with disability. Despite this, there is little research on the causes of early strokes.”

It’s estimated 10 to 15 percent of strokes occur in people under age 50, according to a paper published in the February 2020 issue of the journal Stroke.

To investigate how genetic factors could influence the risk of stroke, researchers analyzed 48 studies on genetics and ischemic stroke, which included 16,700 stroke patients and 599,237 healthy controls who had never experienced a stroke.

They found a link between early-onset stroke — occurring before age 60 — and the area of the chromosome that includes the gene that determines whether a blood type is A, AB, B, or O.

The study found that people who experienced an early stroke were more likely to have blood type A and less likely to have blood type O than people with late stroke and people who never had a stroke.

Those who had both early and late stroke were also more likely to have blood type B than the healthy control group. After adjusting for sex and other factors, researchers found that those with blood type A had a 16 percent higher risk of early stroke than people with other blood types, and those who had blood type O had a 12 percent lower risk of stroke than people with other blood types.

The association of blood type with later-onset stroke was much weaker than blood type's association with early stroke, according to the authors.

This an interesting study, says Brandon Giglio, MD, the director of vascular neurology at NYU Langone Hospital in Brooklyn, New York, who was not involved in the study. “There’s been research to suggest there was also an association between blood type and other clotting disorders, like clots in the legs such as a deep vein thrombosis and of the pulmonary artery — a pulmonary embolism,” he says.

A study published in January 2020 in the American Heart Association journal Arteriosclerosis, Thrombosis, and Vascular Biology compared people with type O blood and those with type A or B blood and found the latter were 51 percent more likely to develop deep vein thrombosis and 47 percent more likely to develop a pulmonary embolism.

“It’s interesting that this association extends to these types of clots, which are in arteries as opposed to those other clots which are in veins, though different mechanisms and processes cause strokes than those other types of clots,” says Dr. Giglio. The findings suggest there’s probably a connection between the patient’s blood type and the way their body promotes the formation of a clot, he adds.

Blood types are determined by the presence or absence of certain antigens, which are substances that can trigger an immune response to foreign “invaders.”

The researchers emphasized that the increased risk was very modest and that people with type A blood should not worry about having an early-onset stroke or engage in extra screening or medical testing based on this finding.

Giglio agrees, saying, “With the information we have at present, I don’t think we have any interventions to modify risk based on the blood type,” he says.

No matter what blood type you have, there is clear evidence for ways to reduce your risk of stroke, says Giglio.

The CDC recommends the following healthy lifestyle choices.

“We clearly need more follow-up studies to clarify the mechanisms of increased stroke risk,” says Kittner.

The authors also acknowledge that the current study is limited by a “relative lack of diversity among participants.”

“Future research may look to see if there are associations between blood types and risk factors for strokes,” says Giglio. It could be that having a certain blood type puts people at risk for a disease that in turn puts them at higher risk of stroke, such as diabetes or obesity, he adds.

By subscribing you agree to the Terms of Use and Privacy Policy.

A stroke can be very scary, but there are many different treatments and rehabilitation methods available.

There are several easy, common-sense ways to prevent a stroke and improve your overall health.

Being able to quickly identify the signs of stroke can save lives, including your own.

People with post-stroke aphasia are more likely to experience depression and anxiety than adults without aphasia. Experts say a part of moving forward...

The American Heart Association and the American Stroke Association issued a joint statement on the necessity of better care for this historically underserved...

Some famous faces have experienced a sudden loss in language ability. Learn how these celebrities worked their way through aphasia.

Hailey Bieber's recent stroke scare shines a light on an often overlooked health condition that can affect young people.

By subscribing you agree to the Terms of Use and Privacy Policy.