Smoking Raises Multiple Sclerosis Risks

Oct. 27, 2003 -- As if increasing the risk of cancer, heart and lung disease, and stroke wasn't enough, a new study shows that smoking also raises the risk of the disabling disease multiple sclerosis (MS).

Researchers found smokers are nearly twice as likely to develop multiple sclerosis as people who have never smoked.

"This is one more reason for young people to avoid smoking," says researcher Trond Riise, PhD, of the University of Bergen in Norway, in a news release. "Hopefully, these results will help us learn more about what causes MS by looking at how smoking affects the onset of the disease."

The exact cause of MS is unknown. About 300,000 Americans suffer from the

neurological disorder, which is thought to be partially caused by the body's immune system attacking healthy nerves.

MS usually strikes young adults, and women are affected about twice as often as men.

Smoking May Play a Role in MS

In the study, researchers looked at smoking habits and MS prevalence among a group of 22,312 adults in Norway who ranged in age from 40 to 47. Of those, 87 had MS.

Researchers found that smokers were 1.81 times more likely to have MS than non-smokers. Most people started smoking about 15 years before they developed multiple sclerosis.

The smoking-related MS risks also varied among men and women. Men who smoked were 2.75 times more likely to have MS as men who never smoked, and women who smoked were 1.61 times more likely as women who never smoked.

In addition, the study showed that the risk of MS was higher among smokers compared with nonsmokers regardless of education level.

The results appear in the Oct. 28 issue of Neurology.

Researchers say smoking has also been linked to other diseases that affect the immune system, such as rheumatoid arthritis. By studying how smoking acts in the body to increase the risks of these diseases, they may also be able to learn more about the cause of MS and develop new treatments.

"Environmental factors, which could include infections or exposure to solvents, and lifestyle factors, such as smoking and diet, may cause the disease to develop in people who are genetically susceptible to it," says Gary Franklin, MD, MPH, of the University of Washington School of Public Health and Community Medicine in Seattle, in a news release.

"Neither having the susceptible genes by themselves, nor just being exposed to the environmental factors alone, is enough to cause the disease," says Franklin, who wrote an editorial that accompanies the study.