The Cleveland Clinic....CLICK TO READ ARTICLE

Cigarette smoking has already been identified as a risk factor for multiple sclerosis (MS). Now new research for the first time also implicates smoking in the progression of the degenerative disease.

Researchers from the Harvard School of Public Health reported that current and past smokers with multiple sclerosis were more than three times as likely as patients who had never smoked to have more rapid progression of their disease.

"If indeed smoking does contribute to the progression of MS then that is something else for scientists to look at to better understand the disease and its progression," says Nicholas LaRocca, PhD, who is director of health care delivery and policy research for the National Multiple Sclerosis Society.

Smoking Hastens MS Progression

Between 300,000 and 500,000 Americans have multiple sclerosis, with about twice as many women afflicted as men.

Early in the course of the disease most patients have what is known as relapsing-remitting MS, meaning that their symptoms may come and go at random. This can last for many years. As the disease advances patients may develop secondary progressive MS, in which symptoms occur with increasing frequency due to steady deterioration of the brain and spinal cord.

In the newly published Harvard study, researcher Miguel A. Hernan, MD, and colleagues were able to follow a group of MS patients from the time of their first symptoms, sometimes years before multiple sclerosis was confirmed.

They did this by accessing a national health database from the U.K. to identify 179 patients originally diagnosed with relapsing-remitting MS. Medical records for the patients for the years prior to diagnosis were then examined, and information on smoking status was obtained from computer records.

The researchers found that the risk of progressing from relapsing-remitting MS to secondary progressive disease during roughly five years of follow-up was 3.6 times higher for current and past smokers than for patients who never smoked.

In an extension of the study comparing multiple sclerosis patients to people without the disease, cigarette smoking was associated with a 30% increase in the likelihood of getting MS. However, the finding was not significant and the researchers could not rule out the possibility of this being a chance finding.