After adjusting for factors such as high blood pressure, diabetes and heart disease, which are known risk factors for stroke, the researchers found that people who had given up smoking between two and 10 years earlier still had an increased risk of stroke. There was no raised risk among ex-smokers who had quit for longer periods. Bonita, who is now the director of non-communicable disease surveillance at the World Health Organisation in Geneva, Switzerland, and her team also found that the risk of stroke increased with the number of cigarettes a person smoked. Strokes are caused by a blood clot or rupture of blood vessels in the brain. They vary in severity but generally cause some permanent damage such as slurred speech and confusion.
Severe cases can cause paralysis and death.
Half of stroke victims are over 75 years old.