Your blood type could predict your risk of having a stroke before age 60: study

By Melissa Lopez-Martinez

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    TORONTO (CTV Network) — Amid rising reports of strokes found in people under the age of 60, a new study suggests the risk of stroke in younger age groups could potentially be determined by their blood type.

Researchers at the University of Maryland’s School of Medicine compared the blood type of those who have had a stroke at a younger age versus those who were either older when they had one or never experienced one at all. Their findings suggest those with blood type A were more likely to have an early stroke and those with blood type O had the lowest risk.

The study published in the Neurology journal on Wednesday collected data from 48 studies that followed 17,000 stroke patients and nearly 600,000 healthy people who have never experienced one. Researchers analyzed the genetic profiles of the patients, specifically the gene in their chromosome that determines whether a person has a type A, AB, B or O blood type.

Those with blood type A had a 16 per cent higher risk for early stroke among all the other blood types, while those with blood type O had a 12 per cent lower risk. According to the Canadian Blood Services, 39 per cent of Canadians are O-positive, making it the most common blood type. A-positive is the second most common with 36 per cent of the population sharing this type.

While the study authors say they are not sure what the correlation between stroke risk and blood type is yet, they theorize it could potentially be related to the development of blood clots. A stroke, which is the loss of brain function after a brain blood vessel is blocked or ruptures, can happen for many reasons, including having heart problems, a clotting disorder or even inflammation in the blood vessels.

“We still don’t know why blood type A would confer a higher risk, but it likely has something to do with blood-clotting factors like platelets and cells that line the blood vessels as well as other circulating proteins, all of which play a role in the development of blood clots,” neurologist and co-author of the study Steven J. Kittner said in a press release.

Michael Hill, professor of neurology at the University of Calgary says people with blood type A shouldn’t be concerned since the findings are preliminary and the risk of stroke is most commonly related to other genetic conditions and a person’s lifestyle.

“The differences between blood group type A and someone who’s type B or O are so small that for an individual person, it wouldn’t change what you do or how you live your life,” Hill told CTVNews.ca in a phone interview on Thursday.

However, Hill says studies like this could potentially help pave the way for future treatments as more information is discovered relating to the pathology of strokes.

About 878,500 Canadians over the age of 20 have experienced a stroke and one quarter of those are under the age of 65, according to Health Canada. A report in 2017 from the Heart and Stroke foundation said 19 per cent of stroke hospitalizations were among patients aged 20 to 59. While the reason for stroke among younger people does include heart problems or their genetics, one third of strokes in those aged 18 to 45 are unknown.

Hill says strokes are the most common neurological illness among all age groups, however certain health factors that have changed over the years could explain why different demographics are affected and why risk factors have evolved.

“The causes of stroke are somewhat different in younger people compared to those who are in their 70s. Typically you think of high-blood pressure, smoking or diabetes as your key risk factors for stroke, but in younger people it’s other things like a congenital heart malformation,” he said.

“In our population overall in Canada, we’ve seen rapidly declining smoking rates, so we just don’t see the strokes related to smoking as much as we used to 15 years ago.”

Ultimately, Hill says Canadians of all ages can help reduce their risk of stroke by eating a healthy diet, staying physically active and above all else controlling their blood pressure.

“The biggest thing that people don’t pay attention to is high blood pressure, it’s by far the most important risk factor for stroke in all age groups. So getting people to pay attention to the fact that blood pressure is measurable and treatable and remediable; that is really important in their overall health,” he said.

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Sonja Puzic