The study involved 87 people with MS who were among more than 30,000 people in a larger study. The people with MS were divided into three groups: non-smokers, early smokers (smokers who began before age 17), and late smokers (those who started smoking at 17 or older), and matched by age, gender, and race to 435 people without MS.

Early smokers were 2.7 times more likely to develop MS than nonsmokers. Late smokers did not have an increased risk for the disease. More than 32 percent of the MS patients were early smokers, compared to 19 percent of the people without MS.
The cause of MS is unknown. But experts believe that a combination of genetic and environmental factors is responsible. 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.  Early smoking is an environmental factor that can be avoided.

MS is an autoimmune disease, which means that the person’s own immune system attacks the central nervous system. Smoking has been linked with other diseases that operate through the immune system, such as rheumatoid arthritis.
The study results will be presented at the American Academy of Neurology’s 61st Annual Meeting April 25th to May 2nd.