Researchers have determined that the already well-documented link between smoking and stroke risk appears even more potent at higher levels of smoking, HealthDay News reported Aug. 14.

John Cole, M.D., assistant professor of neurology at the University of Maryland School of Medicine, and colleagues interviewed a group of 1,070 women ages 15 to 49. Comparing data on smoking and stroke occurrence in this group, they found that any smoking doubles the risk of stroke. At high levels of smoking, the risk increases dramatically: It is 4.3 times greater for women who smoke 21 to 39 cigarettes a day, and 9.1 times greater for those who smoke 40 or more cigarettes a day.

Cole said the findings should lead to this conclusion about mitigating stroke risk: "Stopping [smoking] is the best thing to do, but cutting back will also reduce the risk."

The study offers new insight into the risks of smoking, in that there has been a lack of data on the actual dose response related to particular levels of tobacco use. David A. Meyerson, M.D., director of cardiology consultative services at Johns Hopkins University Bayview Medical Center, added that for young women not compelled by the stroke data, they also should be informed that smoking causes premature aging.

While this study looked at female smokers, a separate analysis of male smokers is now in the planning stages.

Study findings are published in the Aug. 15 issue of Stroke.