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Researchers say different blood types have different risk levels for stroke. SeventyFour/Getty Images
  • Researchers are reporting that people with type A blood have the highest risk of stroke before age 60 while people with type O have the lowest.
  • Experts say there are lifestyle changes people can make to lower their overall risk of stroke. These include stopping smoking, eating a Mediterranean-style diet, and exercising regularly.
  • They note there are other factors such as age and genetics that can’t be mitigated.

Your blood type might increase your risk for a stroke before age 60.

Researchers are reporting, in fact, that a person with blood type A may be more likely to have an early-onse stroke while a person with blood type O is less likely to have one.

In their study published today, researchers did a meta-analysis of 48 studies involving almost 17,000 people with a stroke and more than 570,000 people with no history of stroke.

The scientists examined the possible correlation between blood type and ischemic stroke risk. They report that people with blood type A had the highest risk for early-onset stroke, which occurs before age 60.

The researchers divided participants by blood type and compared this with stroke status: early stroke, late stroke, and no stroke. Some of the results included:

  • People with early stroke were more likely to have blood type A and less likely to have type O when compared to people who had a stroke at a later age or people who had not had a stroke.
  • People with both early and late stroke were more likely to have type B when compared to a control group.

After adjusting for sex and other factors, the researchers reported:

  • People with type A had an 18 percent higher risk of early stroke than those with different blood types
  • People with type O had a 12 percent lower chance of having an early stroke than those with other blood types

A direct link between blood type and stroke hasn’t been established yet. In addition, only 35% of the study participants were not of European ancestry, so the findings may not be consistent across racial and ethnic groups.

The study included the blood types A, AB, B, and O.

The four main blood groups are determined by the presence or absence of antigens, proteins that can trigger an immune reaction on the surface of red blood cells, according to the American Red Cross.

  • Type A – The A antigen is on red blood cells, and the B antibody is in the plasma
  • Type B – The B antigen is on red blood cells, and the A antigen is in the plasma
  • Type AB – Both antigen types are on red blood cells, and neither is in the plasma
  • Type O – Neither antigen type is on red blood cells, and both are in the plasma

Knowing a person’s blood type is crucial during a blood transfusion because the body could reject the blood if the immune system is activated.

Braxton Mitchell, Ph.D., MPH, the lead study author and a professor of medicine at the University of Maryland School of Medicine, says that people with the A blood type might be more likely to develop blood clots, which can lead to a stroke.

An ischemic stroke is the most common type of stroke. It occurs when blood flow to the brain is blocked.

In 2020, nearly 3.5 million people worldwide died from an ischemic stroke, according to the American Heart Association.

“Strokes occur suddenly,” Dr. Basit Rahim, a vascular neuro-critical care neurologist and Medical Director of Stroke at Providence Mission Hospital, told Healthline. “They can happen at any time and they don’t discriminate. Symptoms involving balance issues, vision problems (such as double or blurred vision), facial droop, arm weakness, or speech difficulty, should be evaluated immediately. There is a narrow window of time to which healthcare professionals can stop a stroke.”

Women might also experience:

  • Face, arm, or leg pain
  • Hiccups
  • Nausea
  • Chest pain
  • Palpitations
  • Shortness of breath

The most common cause of an ischemic stroke is a blood clot that cuts off the blood flow to the brain.

Some risk factors can be mitigated while others, including age, gender, or genetics, can’t be mitigated.

“Age plays a major role in stroke,” said Rahim. “The chance of a stroke nearly doubles every 10 years after age 55. This article presents valuable information regarding expanding medicine and science to explore genetic risk factors for stroke.”

“Your blood type is a nonmodifiable risk factor for cerebrovascular disease, including stroke,” said Dr. Sandra Narayanan, a vascular neurologist and neuro-interventional surgeon at Pacific Stroke & Neurovascular Center at Pacific Neuroscience Institute in California.

Strokes are uncommon in younger adults, but they can still happen. In fact, according to an article published in the journal Stroke, about 10 percent to 15 percent of strokes happen in adults between the ages of 18 and 50.

“Traditional stroke risk factors, such as hypertension, high cholesterol, diabetes, tobacco use, and obesity, are also common among younger acute stroke patients,” said Dr. Deepak Kumar Gulati, a vascular surgeon affiliated with The Ohio State University Wexner Medical Center.

“In addition to traditional stroke risk factors, more specific causes for early-onset stroke include blood clots, vasculitis, heart problems, and IV drug use,” he told Healthline. “There is a substantial genetic component for stroke patients under 60, when compared to those over 60.”

Although ischemic strokes typically occur suddenly, some people do have some warning signs.

“Ischemic strokes can be preceded by a transient ischemic attack (TIA), a ‘warning stroke,’ or ‘mini-stroke’ that shows similar symptoms of a stroke and typically lasts less than 5 minutes,” explained Gulati. “A TIA itself does not cause permanent injury to the brain but timely recognition of the TIA provides an opportunity to initial effective treatment to prevent a major stroke.”

“Up to 80 percent of strokes are preventable with lifestyle changes,” Narayanan told Healthline.

She says some lifestyle changes that can help reduce the risk include:

  • Quitting smoking.
  • Keeping a blood pressure machine at home if you have high blood pressure and take measurements daily. Write these down and bring the log to your doctor’s appointments.
  • Eating a Mediterranean-style diet rich in fruits, vegetables, whole grains, fish, and nuts.
  • Exercise – in any form, even if it’s just 10 minutes a day at first.
  • Know your cholesterol levels

“Consistency is key to maintaining healthy lifestyle habits,” Narayanan said.