Smoking May Boost Risk for Multiple Sclerosis

Thomas S. May MA

BOSTON—In addition to its numerous other deleterious effects on health, cigarette smoking may also increase the risk of developing multiple sclerosis (MS), results of a new study suggest.

The research, presented at the 2007 annual meeting of the American Academy of Neurology, found that patients with MS are significantly more likely to be current or former smokers than people in the general population.

The study involved an analysis of data from the North American Research Committee on Multiple Sclerosis registry, which contains various demographic and clinical information on more than 31,000 registrants with MS. Smoking status was assessed with the help of a questionnaire from the Centers for Disease Control and Prevention’s Behavioral Risk Factor Surveillance Survey.

Of the 8,719 participants who returned the questionnaire, 25.6% reported they were current smokers, and 35.8% indicated they were former smokers. After age standardization to the 2000 U.S. census population, 30.6% (95% confidence interval [CI], 27.8-33.4) were current smokers, compared with 20.9% (95% CI, 20.3-21.5) of the U.S. population, and 35.9% (95% CI, 33.3-38.4) were former smokers, compared with 21.4% (95% CI, 20.9-22.0) of the U.S. population.

Although these data cannot prove that smoking increases the risk of developing MS, they add to the weight of evidence suggesting that cigarette smoking may in fact be causally related to MS. Several previous studies suggest that cigarette smoking is a risk factor, and there is some evidence that smoking may influence disease progression, said lead investigator Ruth Ann Marrie, MD, MS, associate researcher, Mellen Center for Multiple Sclerosis Treatment and Research at the Cleveland Clinic in Ohio.

It is also likely that high smoking frequencies could increase the risk of comorbidities and contribute to poor MS outcomes, according to Dr. Marrie. “Smoking is an important risk factor for many chronic diseases, including heart disease, stroke and cancer, and patients with multiple sclerosis who smoke are at risk for developing chronic diseases related to smoking,” she said.

“Clinicians caring for MS patients may focus their attention on the complexities of managing multiple sclerosis,” Dr. Marrie concluded. “However, attention also needs to be directed toward health behaviors such as smoking, if the overall health of MS patients is to be optimized.”