People with type A blood are almost a fifth more likely to suffer a stroke before their 60th birthday.
A team from the University of Maryland combined the results of 48 studies of genetics and ischaemic strokes, the most common type of stroke.
The research, published in the journal Neurology, found that people who had an early stroke — defined as happening before the age of 60 — were more likely to have type A blood. This was after accounting for sex and other factors known to affect risk.
People with blood type A had an 18 per cent higher risk of early stroke. The risk for people with type B was slightly elevated and the risk for type O was lower. The researchers