People with type A blood may be at higher risk of having a stroke before age 60 compared to other blood types, researchers have found.
In contrast, people with blood type O are less likely to have an early stroke, according to the new meta-analysis.
The research was carried out by a team led by scientists from the University of Maryland School of Medicine in the United States, who looked at the relationship between genetic characteristics such as blood type and their relationship to strokes. .
To do this, they looked at data from 48 genetic studies of ischemic stroke in adults aged 18 to 59. Ischemic strokes are caused by a blockage of blood flow to the brain.
In total, the studies included around 17,000 stroke patients and nearly 600,000 healthy controls who had never had a stroke.
“We were interested in trying to identify the genetic determinants of stroke,” Braxton Mitchell, co-lead researcher of the study, told Euronews Next.
“For stroke, we’ve known for a long time that there’s a big environmental component, but there’s also a genetic component,” said Mitchell, who is a professor of medicine at the University of Maryland.
To dig deeper into this question, he and his colleagues looked at people’s genetic profiles and eventually found a link between early stroke and the area of the chromosome that includes the gene that determines a person’s blood type.
Humans have four main blood types, A, B, AB and O, and a person’s blood type is determined by the genes they inherit from their parents. Blood type O is the most common.
Researchers found that people who had an early stroke were more likely to have blood type A and less likely to have blood type O, compared to people who had a late stroke and people who never had a stroke. of stroke.
“Having blood type A increases your risk by about 16 percent for an early stroke, but only about 5 percent for a later stroke,” Mitchell said.
“If you are blood type O, you are 12% less likely to have an early stroke, compared to only 4% less likely to have a later stroke.”
Very modest increased risk of stroke
But although the researchers found associations between blood type A and early stroke risk, they pointed out that the increased risk was very modest.
They emphasize that people with type A blood should not worry about having an early stroke, or engage in additional screening or medical tests based on this finding.
“Clinically, we shouldn’t be concerned that our blood types put us at high risk for stroke,” Mitchell said.
“There are other, much bigger risk factors for stroke, like high blood pressure and smoking, for example. So if we want to reduce our risk of stroke, those are really the factors we need to pay attention to” .
He added: “Having said that, what we’re wondering is if you have those risk factors, and you also have blood type A, does that make those risk factors even more powerful? We don’t don’t know yet. But it’s one of the things we’re looking at.”
It’s still unclear why blood type A confers this higher risk, but researchers believe it may have something to do with blood clotting factors.
Other studies have suggested that people with blood type A have a slightly higher risk of developing blood clots in the legs – known as deep vein thrombosis.
“That kind of pro-clotting background of having blood type A probably puts you at higher risk for clotting-related diseases, of which stroke is one of them,” Mitchell said.
One of the limitations of the analysis was the relative lack of diversity among the participants, the majority of whom were of European ancestry, with the researchers welcoming further follow-up studies on a more diverse population.
“We all have different genetic variants, and genetic variants often tend to cluster within different ancestry groups,” Mitchell said.
“So we may be missing some important variants by only looking at a small representation of ancestry groups.”
Blood type linked to risk of other conditions
It’s not just about stroke risk – other research has suggested links between blood type and the risk of developing other health problems.
For example, a study by scientists from the Harvard School of Public Health found that people with blood type A, B, or AB have a higher risk of coronary heart disease than people with blood type O.
Those with the rarest blood type, AB, had the greatest risk.
Other studies have suggested that people with type A blood have a higher risk of stomach cancercompared to those of other blood groups.
It should be kept in mind that although studies have shown a relationship between blood type and certain health problems, we still don’t know what causes these relationships.
So if you have type A blood, how worried should you be?
A person can’t really change their blood type, Mitchell points out. And there are other stroke risk factors that are more within a person’s control, such as nicotine drinking habits, blood pressure, alcohol consumption, and amount of exercise.
“I would say, don’t worry at all,” Mitchell said. “I would think about these other modifiable risk factors and focus on those, because they’re not just risk factors for stroke, but they’re risk factors for heart disease and cancer, etc.” .
“Big step” towards reducing the risk of stroke
Commenting on the findings, Clare Jonas from the UK charity Stroke Association said the results were a “big step” towards better monitoring of risk factors for early stroke.
“The majority of strokes occur in older people, for reasons we know well, such as high blood pressure, thickening of the arteries or atrial fibrillation,” said Jonas, head of communications and commitment to research at the Stroke Association, which provides support for those who have suffered a stroke.
“The causes of strokes in young adults are not as well understood, making them harder to prevent,” she said in a statement.
“We don’t yet know why people with blood group A might be at increased risk of early stroke. This means we can’t yet develop targeted preventions for early stroke.”
“However, this research is a big step forward in helping healthcare professionals determine who would benefit most from monitoring other risk factors and from interventions offered to help reduce risk,” she said. added.