Smoking increases bleeding into the brain, study finds

Past smokers show no increased stroke risk, suggesting new benefit for smoking cessation

Thursday, November 13, 2003

New research from Brigham and Women's Hospital (BWH) suggests that women who currently smoke are at a heightened risk for a severe and often fatal type of stroke caused by bleeding within the brain. The research team at BWH found that the stroke risk for women increased proportionately with the number of cigarettes smoked each day. In contrast, women who stopped smoking were at no additional risk. The findings appear in the November 13 online edition of the journal, Stroke, a publication of the American Heart Association.

"We already understood that smoking increases the risk of ischemic stroke and subarachnoid hemorrhage for women, but for the first time we documented that there is an important relationship between smoking and intracerebral hemorrhage, a bleeding into the brain tissue, that increased with the amount of cigarettes smoked," said Tobias Kurth, MD, ScD, BWH researcher. "This new information increases the importance of campaigns that encourage current smokers to not only reduce the number of cigarettes they smoke, but to stop smoking entirely."

It is estimated that approximately 21 percent of all women age 18 and older are current smokers and women account for three out of every five strokes deaths in the United States. According to the American Stroke Association, stroke is the nation’s leading cause of disability.

The study showed that women who smoked 15 cigarettes or more a day had a 229 percent increased risk of all strokes caused by bleeding, compared to women who never smoked, whereas women who smoked 15 cigarettes or less per day had 93 percent increase. When the researchers examined the link between smoking and type of stroke more specifically, they found that current smokers (15 or more cigarettes per day) had a 167 percent increased risk of intracerebral hemorrhage and a 302 percent increased risk of subarachnoid hemorrhage. However, women who reported to have smoked in the past had no increased risk of stroke. This finding led Kurth to suggest that smoking cessation may help curb the overwhelming stroke risk associated with smoking.

"It is one thing to tell smokers to stop smoking, but when we can support this claim with documented benefits, such as showing people that their risk of stroke will decrease, we have a much more powerful public health message to share," said Kurth, also of Harvard Medical School.

These findings were based on a study of more than 39,000 American women enrolled in the Women’s Health Study who were followed for nine years. During the study period, a total of 70 cases of hemorrhagic stroke were reported and confirmed. The data was categorized according to four classes of women: never, past and current smokers of less than 15 cigarettes a day, and current smokers of 15 cigarettes or more a day.

BWH is a 725-bed nonprofit teaching affiliate of Harvard Medical School and a founding member of Partners HealthCare System, an integrated health care delivery network. Internationally recognized as a leading academic health care institution, BWH is committed to excellence in patient care, medical research and the training and education of health care professionals. The hospital’s preeminence in all aspects of clinical care is coupled with its strength in medical research. A leading recipient of research grants from the National Institutes of Health, BWH conducts internationally acclaimed clinical, basic and epidemiological studies.

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