Blood Type Linked to Increased Stroke Risk Before Age 60, Study Finds

A significant stroke risk may be subtly linked to blood type A, particularly for individuals under 60, according to a comprehensive study published in 2022. Researchers identified a genetic variant associated with blood type A1 that appears to elevate the likelihood of experiencing a stroke before the age of 60.

The study analyzed genetic data from nearly 17,000 stroke patients and almost 600,000 individuals without a history of stroke, all aged between 18 and 59. The findings indicated that people with a genome variant linked to blood type A faced a 16% higher risk of stroke before 60 compared to those with different blood types. Conversely, individuals with a gene variant associated with blood type O1 showed a roughly 12% lower risk.

However, the researchers emphasize that this increased risk is marginal. They advise against additional medical investigations solely based on blood type A. "We still don't know why blood type A would confer a higher risk," explained Steven Kittner, a neurologist and study co-author. He suggested potential explanations might involve factors related to blood coagulation, such as platelets or proteins that contribute to clot formation.

Further analysis revealed that the association between blood type A and increased stroke risk was not significant for individuals over 60. This suggests that strokes occurring at younger ages might stem from different mechanisms than those in older populations, potentially being less related to atherosclerosis and more to blood clot formation. The study also noted an approximately 11% higher stroke risk for individuals with blood type B compared to those without, irrespective of age.

Despite these findings, the study authors urge caution in interpretation. The participant pool was predominantly from North America, Europe, Japan, Pakistan, and Australia, with non-European origins representing only about 35%. Consequently, the researchers call for additional studies involving more diverse populations to validate and expand upon these results.

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We still don't know why blood type A would confer a higher risk.