Friday, August 15, 2008
Two Packs Daily Can Increase Risk for Stroke Nine-fold
Researchers from the University of Maryland School of Medicine have found that the risk of stroke among young women increases the more they smoke. That is the key finding in a study to be published in the August 14 edition of Stroke: Journal of the American Heart Association.
"We studied the risk of stroke for women under age 50 and we found that the more cigarettes they smoked, the more likely they were to have a stroke," says John Cole, M.D., M.S., assistant professor of neurology at the University of Maryland School of Medicine. "Among women who smoked 40 or more cigarettes a day, the stroke risk increased more than nine times over that of a non-smoker. But we found that any smoking at all more than doubles the risk of stroke."
This study is one of the first to examine the relationship between higher rates of smoking and ischemic strokes, those caused by a blockage in the brain, in an ethnically-diverse group of young women. It is part of the University of Maryland’s on-going Stroke Prevention in Young Women initiative, in which researchers are looking at genetic and non-genetic risk factors for stoke.
"This new study shows how behavior can greatly influence a woman’s risk for stroke. It also emphasizes the importance of getting younger women to stop smoking or never to start," adds Dr. Cole, who is also a neurologist and stroke specialist at the University of Maryland Medical Center and a clinical research scientist at the Baltimore Veterans Affairs Medical Center.
In their analysis, the Maryland researchers obtained the smoking history of a group of more than 400 African-American and Caucasian women between the ages of 15 and 49 who had suffered an ischemic stroke. After face-to-face interviews, the researchers classified the women into three groups: current smokers, former smokers and never smokers, defined as women who had not smoked more than 100 cigarettes in their lifetime. Former smokers had smoked more than 100 cigarettes, or five packs, in their lifetime but had not smoked in the month prior to their stroke.
The team compared the smoking rates to a control group of women with similar age, race and ethnicity who had not suffered a stroke. Former smokers and “never” smokers showed no difference in their risk of stroke compared to each other; however, the number of cigarettes smoked by the current smokers revealed a significant dose-related increase in risk:
• 1 – 10 cigarettes per day = 2.2 times increased stroke risk
• 11 – 20 cigarettes per day = 2.5 times increased stroke risk
• 21-39 cigarettes per day = 4.3 times increased stroke risk
• 40 or more cigarettes per day = 9.1 times increased stroke risk
Almost 120,000 women and 105,000 men in the United States under the age of 45 have suffered a stroke, which is the nation’s leading cause of disability and third leading cause of death.
"While strokes in younger people are rare, they can have a significant effect on people’s lives and can leave them with difficulties with speech, vision, balance and thinking. So it’s very important that we find ways to reduce the risk of stroke, and, as our study shows, smoking cessation is an important step," says Dr. Cole.
Smoking causes the walls of the arteries to thicken and become less elastic, which can lead to plaque and fat accumulations inside the vessel. If this plaque breaks off, it can travel in the blood stream to the brain causing a clot, resulting in a stroke. Smoking also makes the blood more "sticky" and likely to clot.
According to previous research, stroke risk decreases significantly two years after smoking cessation and reaches the level of nonsmokers by five years after quitting. The benefits also appear to be greater the earlier in life a person quits, particularly for a person under age 35, although stopping smoking has health benefits at any age.
The Centers for Disease Control reports that more than 20 percent of young women between the ages of 18-44 described themselves as smokers. The Maryland team also found a large prevalence of smoking among African-Americans in both the stroke group and the control group.
The researchers plan to conduct a similar study for stroke and smoking in younger men.