This Blood Type May Put You at the Greatest Risk for Stroke

If you’ve not yet hit retirement age or are otherwise healthy, you might not consider yourself at risk of having a stroke. However, data shows that that stroke rates among adults under age 64 are increasing. While many factors may contribute to this increase, a recent study has drawn an unexpected connection between risk of early stroke and blood type.

Led by researchers from the University of Maryland, the 2022 study found that those with one specific blood type may have a 16% higher chance of early stroke compared to those with other blood types.

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The Blood Type That Increases Risk of Early Stroke

Published in Neurology, the study analyzed 48 different studies on genetics and ischemic stroke—which occurs when a blockage prevents blood from reaching part of the brain. The meta-analysis included genetic data from nearly 17,000 stroke patients and 600,000 individuals who had not experienced a stroke.

Researchers parsed through all collected chromosomes for genetic variants tied to stroke, and ultimately found a link between the early-onset stroke and the gene that determines blood type. They then analyzed genetic variants and different blood types in people who had late-onset stroke (older than 60).

Blood types refer to a classification of blood based on substances present on your red blood cells. The four basic blood types include A, AB, B, or O, with O being the most common.

The study found that people with blood type A had a 16% higher risk of having an ischemic stroke before the age of 60. Meanwhile, those with blood type O had a 12% lower risk of having a stroke at any age. People with blood type B had a greater risk of having a stroke regardless of age.

Related: How to Find Out Your Blood Type, Why It's Important to Know

Why Does Blood Type Play a Role in Stroke Risk?

Researchers aren’t sure yet, but in a press release on the findings, one of the study’s co-principal investigators said it might have something to do with how different blood types form blood clots.

Dr. Jason Hinman, MD, PhD., a vascular neurologist at UCLA Health, echoes that hypothesis. Blood types impact the surface protein characteristics of red blood cells, which can make them more or less sticky when they pass through blood vessels, potentially resulting in a blood clot, Dr. Hinman says.

“So in the right circumstance, having a particular blood type combined with another risk factor might increase the possibility of an arterial clot forming and causing a stroke,” Dr. Hinman adds.

Related: The Unexpected Stroke Sign Most People Miss

Does that sound scary? Yes. Should you panic? No. The researchers emphasized that the increased risk of early-onset stroke for people with type A blood is still low, so there’s no need to seek out extra medical testing or screenings.

Further, more data is needed to fully understand the relationship between blood type and stroke risk. While this study offers valuable information, the researchers acknowledged that diversity was a limitation in their findings. The original studies were conducted across North America, Europe, Japan, Pakistan, and Australia, with people of non-European ancestry making up about 35% of the pool.

Having reviewed the study, Dr. Hinman also questions what this data might look like if participants weren’t divided by early- and late-onset stroke.

“While we sometimes do that clinically,” Dr. Hinman notes. “For a study like this, it might have been more interesting to look at whether there was a continuous relationship between the genes that they identified and the age of onset of stroke for the individuals included in the analysis.”

Related: Why Some Women Face 78% Higher Stroke Risk—and What to Do About It

How to Lower Your Stroke Risk

Each year, just under 800,000 people in the U.S. experience a stroke, with approximately three-quarters of all strokes occurring in people 65 and older. While you can’t change your blood type, there’s still many precautions you can take to lower your risk.

Dr. Hinman recommends paying attention to traditional stroke risk factors, such as obesity, high blood pressure and diabetes. According to the U.S. Centers for Disease Control and Prevention (CDC), lifestyle changes can help mitigate those risks—that might include upping your fruit and vegetable intake or finding a consistent workout routine. You also will absolutely want to quit smoking and/or vaping (and if you don't smoke or vape, please never start).

Related: This Blood Type Is 82% More Likely to Develop Dementia

Additionally, since genes are associated with stroke, Dr. Hinman urges people to consult their doctors about their family medical history.

“While genetic risk is non-modifiable," Dr. Hinman says, "there are other risk factors that can be addressed and increased monitoring that can help in a preventive way.”

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Related: 5 Crucial and Surprising Secrets Your Blood Type Can Tell You About Your Health

Sources

• “Prevalence of Stroke — Behavioral Risk Factor Surveillance System, United States, 2011–2022.” Morbidity and Mortality Weekly Report (MMWR).

• “Contribution of Common Genetic Variants to Risk of Early-Onset Ischemic Stroke.” Neurology.

• “UM School of Medicine Researchers Find Blood Type Linked to Risk of Stroke Before Age 60.” University of Maryland School of Medicine.

• Dr. Jason Hinman, MD, PhD, a vascular neurologist at UCLA Health

• “Aging and ischemic stroke.” Aging.

• “Preventing Stroke.” US Centers for Disease Control and Prevention.