Not to B-negative, but your blood type could offer a clue to your risk of having a stroke before 60.
Researchers at the University of Maryland (UMD) found that people with type A blood are more likely to experience an early-onset ischemic stroke — caused by a blockage of blood flow to the brain — while those with blood type O have a lower risk.
“The number of people with early strokes is rising,” said Dr. Steven J. Kittner, co-principal investigator of the study and neurologist with the UMD Medical Center. “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.”
In a 2022 analysis, Kittner and his colleagues sifted through data from 48 genetic studies, involving 17,000 stroke patients and nearly 600,000 healthy individuals who had never suffered a stroke. All participants were between 18 and 59 years old.
After reviewing their genetic profiles, researchers discovered a potential link between early strokes and the part of the chromosome that contains the gene determining whether your blood type is A, AB, B or O.
“The association of blood type with later-onset stroke was much weaker than what we found with early stroke,” said Dr. Braxton D. Mitchell, principal investigator and professor of medicine at UMD.
After adjusting for sex and other factors, the team found that people with blood type O — the most common blood type — had a 12% lower risk of suffering a stroke compared to other blood types.
Meanwhile, those with type A blood, which accounts for about 36% of Americans, had a 16% higher risk of suffering an early stroke.
But before you rush to make a doctors appointment, researchers stressed that those with blood type A shouldn’t panic or jump into unnecessary medical testing based on the findings.
“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,” Kittner explained.
Blood clots are a leading cause of ischemic strokes, as they block blood flow to the brain. Previous studies suggest that people with blood type A may be more prone to developing clots in the legs, a condition known as deep vein thrombosis.
“We clearly need more follow-up studies to clarify the mechanisms of increased stroke risk,” Kittner said.
Researchers also noted that their study had some limitations, including lack of diversity among participants.
While strokes are more common in adults aged 65 and older, the number of cases among younger adults is on the rise globally.
In the US, the rate of ischemic stroke among adults aged 20 to 44 surged from 17 per 100,000 adults in 1993 to 28 per 100,000 in 2015. The risk of stroke death among young adults is also on the rise.
For survivors, the physical toll can be severe, often leading to lasting cognitive deficits, vision impairment, coordination problems, weakness and paralysis. The mental impact is also heavy, as many stroke survivors also battle depression and anxiety.
Traditional stroke risk factors include high blood pressure, high cholesterol, diabetes, smoking and alcohol consumption. Obesity, an unhealthy diet, and a lack of exercise can also increase your chances.
“This study raises an important question that requires a deeper investigation into how our genetically predetermined blood type may play a role in early stroke risk,” said Dr. Mark T. Gladwin, executive vice president for medical affairs at UMD Baltimore. “It points to the urgent need to find new ways to prevent these potentially devastating events in younger adults.”
