Research has uncovered a significant link between blood type and the risk of experiencing an early stroke, particularly for individuals with type A blood. This finding, published in the journal Neurology in 2022, suggests that people with this specific blood type face a higher likelihood of stroke before the age of 60.
According to Mark Gladwin, a physician-scientist at the University of Maryland, this research expands the understanding of non-modifiable risk factors for stroke, such as blood type. The study highlights that while some risks are beyond individual control, awareness can aid in prevention efforts.
The research team analyzed data from 48 genetic studies, which involved approximately 17,000 stroke patients and nearly 600,000 non-stroke controls. Participants ranged from ages 18 to 59. The results indicated a notable association between the A1 blood subgroup and an increased risk of early-onset stroke.
Steven Kittner, a senior author and vascular neurologist, noted that early strokes are rising, with affected individuals facing potentially life-altering disabilities. “These people are more likely to die from the life-threatening event, and survivors potentially face decades with disability,” he stated. Despite the concerning nature of these findings, the researchers emphasized that the additional risk for those with type A blood is relatively small, suggesting no immediate need for increased vigilance or screening.
The genome-wide search revealed two areas linked to an earlier risk of stroke. One of these regions aligns with the genes responsible for blood type. Further analysis showed that individuals with a genetic variant for blood type A had a 16 percent higher chance of experiencing a stroke before age 60, compared to individuals with other blood types. Conversely, those with a gene for group O1 exhibited a reduced risk of 12 percent.
While the implications of blood type on stroke risk may seem alarming, it is crucial to consider the broader context. In the United States alone, nearly 800,000 individuals experience a stroke each year, predominantly affecting those aged 65 and older. The risk of stroke doubles every decade after the age of 55.
The study participants were primarily from North America, Europe, Japan, Pakistan, and Australia, but only 35 percent were of non-European ancestry. Kittner underscored the necessity for future studies that include a more diverse demographic to better understand these findings.
In examining the differences between early-onset and late-onset strokes, researchers found that the increased risk for those with type A blood diminished significantly in individuals who experienced strokes after age 60. This suggests that the mechanisms behind early strokes diverge from those occurring later in life. Early strokes are less likely to result from atherosclerosis, or fatty deposits in arteries, and are more likely related to factors influencing blood clot formation.
The study also noted that individuals with type B blood were approximately 11 percent more likely to experience a stroke compared to non-stroke controls, regardless of age. Previous research has linked the ABO locus, which determines blood type, to conditions such as coronary artery calcification and venous thrombosis, both of which can increase the risk of cardiovascular events.
As the understanding of stroke risk factors evolves, Kittner emphasized the importance of conducting further studies to elucidate the mechanisms behind the increased risk associated with blood type. The findings of this research contribute to a growing body of evidence indicating that genetic factors can play a critical role in individual health outcomes.
