New Delhi: People with blood group A may be more susceptible to getting a stroke early in life while for those with type O, the risk may be the lowest among all blood groups, a US study has found.
Researchers from the University of Maryland School of Medicine (UMSOM), Baltimore, have linked blood groups to the risk of early stroke in an article published Thursday in the peer-reviewed medical journal Neurology.
The researchers found that people with blood group A were at an 18 per cent higher risk of suffering an early stroke than those with other blood groups. Meanwhile, those with blood type O had a 12 per cent lower risk of early stroke than people with other blood groups.
A stroke occurs when blood supply to a part of the brain is cut off. It could either happen because of a ruptured blood vessel resulting in bleeding, or when a small clot gets stuck in the fine blood vessels supplying to the brain. The extent of functional loss caused by a stroke depends on many factors, such as which part of the brain has been affected, and how quickly the patient gets medical care.
“The number of people with early strokes is rising. These people are more likely to die from the life-threatening event, and the survivors potentially face decades of disability. Despite this, there is little research on the causes of early strokes,” said the study’s co-principal investigator Steven J. Kittner, MD, MPH, professor of neurology at UMSOM and neurologist with the University of Maryland Medical Centre, in a press statement.
For the purpose of the study, early onset stroke was defined as the stroke occurring in a person aged less than 60 years.
“We still don’t know why blood type A would confer a higher risk, 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. We clearly need more follow-up studies to clarify the mechanisms of an increased stroke risk,” the statement quoted Kittner as saying.
The study, which listed co-authors from over 50 institutions, was supported by the National Institutes of Health and the US Department of Veterans Affairs.
The blood group link in other diseases
The link between blood group and disease risk is known to exist in many other ailments too. Earlier studies have shown that, compared with blood group O, people with blood groups A and B have a higher risk of developing deep vein thrombosis — a condition in which blood clots develop in the vessels of the legs. These clots can travel up to precipitate a stroke or a cardiac arrest.
Other conditions that can have differential risks depending on the blood group of the individual include risk of kidney stones, chances of developing gestational hypertension, and some bleeding conditions.
A 2017 study in PLOS One, a scientific journal, had also claimed a similar link in cancer. “Compared with blood type A, blood type B was associated with statistically significant reduced risk of all cancers. Both blood types B and AB were associated with significantly lower risk of gastrointestinal cancer and colorectal cancer, respectively,” wrote researchers from the University of Pittsburgh Cancer Institute.
(Edited by Siddarth Muralidharan)