Smoking, high blood pressure, drug use and family history all contribute towards stroke caused by a burst blood vessel.
Sub-arachnoid hemorrhage (SAH) accounts for just three per cent of all strokes, but is probably the most deadly form. It arises when a blood vessel on the surface of the brain ruptures and starts to bleed. SAH is fatal in up to half of all cases, and is more likely among younger people.

Researchers at the University of Cincinnati, Ohio, have studied cases of SAH and compared these people with a group of healthy young adults. This reveals that two thirds of those with SAH are current smokers. What is more, three per cent reported cocaine use, compared to none in the control group.

High blood pressure was another important risk factor for SAH, highlighting the importance of monitoring blood pressure and keeping it under control. Meanwhile, those with SAH were nearly four times more likely to report a family history of the condition than those who were healthy.