hands clasping over chest. Heart attack and stroke theme
Sarah Biren
Sarah Biren
May 29, 2024 ·  3 min read

Your Blood Type Indicates Your Risk of Early Stroke, Scientists Find

An ischemic stroke is a medical emergency that occurs when the blood supply to the brain is blocked or reduced. The brain cells are then unable to get oxygen and nutrients and begin to die. A stroke can happen suddenly, without any warning. There are notable factors that increase people’s risk of stroke, such as age, high blood pressure, high cholesterol, and family history. But now, there is another genetic factor that is linked to a higher risk of stroke: blood type.

The Rise of Early Strokes

A meta-analysis recently published in the journal Neurology included 48 studies and over 600,000 subjects. This included all available data from genetic studies regarding ischemic strokes occurring in people aged 60 and younger. (This type of stroke is much more common than a hemorrhagic stroke.)

The number of people with early strokes is rising,” said Steven J. Kittner, MD, MPH, a professor of neurology at the University of Maryland School of Medicine, and senior author. “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.”

Read More: These Are The Most Up-to-date Blood Pressure Guidelines. Are They Right for Everyone?

Blood Type and Strokes

So the researchers analyzed the studies, which involved a total of 16,700 stroke patients and 599,237 participants who’ve never had a stroke. There they discovered a link between a stroke occurring before age 60 and the gene that determines blood type. Furthermore, they found that people who suffered an early-onset stroke were more likely to have blood type A (and less likely to have type O). People who had early and late strokes were more likely to have blood type B compared to the control group.

Overall, the researchers found that people with blood type A had a 16% higher risk of early stroke compared to other blood types. Plus, people with type O had a 12% lower risk of stroke compared to the others. 

Blood Type Screening?

However, the researchers emphasize that this additional risk is so small, people with blood type A don’t require any extra vigilance or screening. Additionally, this group of people don’t have a higher risk compared to other blood types after the age of 60.

We still don’t know why blood type A would confer a higher risk [for an early stroke],” said Kittner. “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.” 

Read More: New Study: Blood Test Can Predict Dementia 10 Years Before Official Diagnosis

Risk Factors and Blood Type

“Clinically, we shouldn’t be worried about our blood types putting us at high risk for stroke,” said the study’s co-principal investigator Braxton Mitchell. “There are other risk factors for stroke that are much more important, like hypertension and smoking, for example. So if we want to reduce our risk of stroke, those are really the factors that we should be paying attention to”.

However, does blood type A make those risk factors ever more dangerous? “We don’t know that yet,” said Mitchell. “But that’s one of the things that we’re looking at”.

Stroke Prevention

For now, the best way to prevent a stroke is to maintain a healthy lifestyle. This includes:

  • Keep healthy blood pressure levels
  • Avoid smoking
  • Limit alcohol consumption
  • Eat a diet rich in fruits, vegetables, whole grains, etc. and low in saturated, cholesterol, and trans fats.
  • Exercise regularly
  • Maintain healthy cholesterol levels
  • Manage diabetes
  • Maintain a health weight
  • Treat obstructive sleep apnea

Read More: Blood Tests Could One Day Replace Biopsies and MRIs for These Conditions


  1. “Can Blood Type Predict Risk of Early Stroke?Everyday Health. Becky Upham. September 6, 2022
  2. “Your Blood Type Affects Your Risk of Early Stroke, Scientists Discover.Science Alert. Felicity Nelson. January 3, 2024
  3. “Contribution of Common Genetic Variants to Risk of Early-Onset Ischemic Stroke.Neurology. Thomas Jaworek, MS. August 31, 2022
  4. “Your blood type may affect your risk of having a stroke before age 60, study finds.EurNews.health. Nicole Lin Chang. September 10, 2022
  5. “Stroke.” Mayo Clinic. April 30, 2024.