Cigarette smokers are two to three times more likely to suffer strokes than non-smokers, but nicotine users can reduce that risk by more than half if they kick the habit, government researchers said Wednesday.
"The message is: First of all, don't start smoking," said Robert D. Abbott of the National Heart, Lung and Blood Institute in Bethesda, Md. "The second message is: If you do smoke, stop, because it is not too late. If you quit there are real benefits."
In the largest study of its kind and the first to examine the relationship of quitting smoking to the risk of suffering a stroke, researchers followed 7,872 men of Japanese ancestry in Hawaii for 12 years. The group included 3,435 smokers and 4,437 men who were non-smokers when the study began.
While 117--or 2.5%--of the non-smokers suffered a stroke, 171--or 5.2%--of the smokers had strokes. The smokers who had quit six years after the study began had reduced their risk by more than half.
'Real, Real Benefits'
"A lot of people say, 'I've been smoking for a long time, and if I quit it won't help,' " Abbott said. "Here is evidence that says if you actually stop, there are real, real benefits."
Researchers are unsure how a cigarette habit increases the risk of having a stroke, but Abbott said that nicotine may cause arteries in the brain to become narrowed or weakened so that they are vulnerable to blockage or bursting.
A spokeswoman for the Tobacco Institute in Washington refused to comment on the study, which was published in the New England Journal of Medicine.
After adjusting the data for a variety of risk factors, including the possibility that heart disease caused by smoking was the direct cause of the strokes, the researchers found also that a smoking habit seemed to influence the type of stroke suffered.
Brain Hemorrhages Counted
Smokers were four to six times more likely than non-smokers to have a hemorrhagic stroke, an uncommon but most lethal type of stroke in which a blood vessel in the brain bursts.
Quitting smoking, however, cut the risk of having a hemorrhagic stroke by two-thirds, Abbott said.
Smokers were two to three times more likely than non-smokers to have a thromboembolic stroke, the most common form, in which a blood clot travels to the brain and lodges in a blood vessel.
Although the study involved only men of Japanese descent, Abbott said the findings could be applied to men and women in the general population.