A Blood Type May Elevate Risk of Early-Onset Stroke, New Research Finds
A meta-analysis of 48 genetic studies (about 17,000 stroke patients and 600,000 controls aged 18–59) found that people with the A1 blood subgroup (blood type A) have about a 16% higher risk of stroke before age 60, while O1 carriers have about 12% lower risk; type B blood shows roughly 11% higher risk regardless of age. The increased risk for early stroke is small and does not warrant extra screening, and the association weakens for strokes after age 60, suggesting different mechanisms and underscoring the need for more diverse follow-up studies.