Blood Type A Linked to Higher Early Stroke Risk, New Study Reveals

A new study has revealed a potential connection between blood type and the likelihood of experiencing a stroke before the age of 60. The research suggests that individuals with blood type A may face a slightly elevated risk, while those with blood type O may have a reduced risk.

Each year, approximately 15 million people worldwide suffer a stroke, according to the World Health Organization (WHO). Of these, 5 million are fatal, and another 5 million result in permanent disability. This groundbreaking study indicates that the risk of early-onset stroke may be predetermined by blood type.

The meta-analysis, conducted by researchers at the University of Maryland School of Medicine (UMSOM), suggests that blood type could serve as a predictor of stroke risk in individuals under 60. The findings, published in the journal Neurology, may pave the way for new strategies to predict and prevent strokes in younger adults.

Understanding Stroke

A stroke occurs when blood flow to the brain is interrupted, either by a blockage or sudden bleeding. There are two primary types of stroke:

• Ischemic stroke
• Hemorrhagic stroke

An ischemic stroke happens when a blood clot obstructs an artery, preventing blood from reaching the brain. Hemorrhagic strokes, on the other hand, occur when a blood vessel ruptures, causing bleeding into the brain. Ischemic stroke is the more prevalent type, accounting for about 87% of all strokes.

Blood Type and Stroke: The Connection

The recent study uncovered a potential link between an individual's blood type and their susceptibility to early stroke. The meta-analysis encompassed data from various genetic studies focusing on ischemic strokes in adults under the age of 60.

Steven J. Kittner, MD, MPH, Professor of Neurology at UMSOM, emphasized the rising incidence of early strokes, highlighting the increased risk of mortality and long-term disability faced by survivors. He noted the limited research dedicated to understanding the causes of early strokes.

Kittner's team analyzed 48 studies on genetics and ischemic stroke, involving 17,000 stroke patients and nearly 600,000 healthy individuals without a history of stroke. The research aimed to identify genetic factors associated with early strokes and determine variations that could explain increased risks in certain individuals.

The findings revealed that individuals with early stroke were more likely to have blood type A and less likely to have blood type O, the most common blood type. People with blood type A had a 16% higher risk of experiencing an early stroke compared to those with other blood types, while those with blood type O had a 12% lower risk.

Expert Perspectives

Braxton D. Mitchell, PhD, MPH, Professor of Medicine at UMSOM, explained that the meta-analysis identified associations between blood type and the risk of early-onset stroke based on individuals' genetic profiles. He noted that the link between blood type and later-onset stroke was considerably weaker.

The researchers emphasized that the elevated risk was modest and cautioned individuals with blood type A against unnecessary worry or additional screening based solely on this study.

Dr. Kittner stated that the underlying reasons for the higher risk associated with blood type A remain unclear but may involve blood-clotting factors, cells lining blood vessels, and circulating proteins. He stressed the need for further research to clarify the mechanisms responsible for the increased stroke risk. Previous studies have also suggested a slightly higher risk of developing blood clots in the legs, known as deep vein thrombosis, in individuals with blood type A.

The researchers concluded that the study highlights the importance of investigating the role of genetically predetermined blood type in early stroke risk and underscores the urgent need for new prevention strategies in younger adults.