This is the first time that a modifiable risk factor for MS progression has been identified, providing a new strategy for patients hoping to control neurological damage from the disease.
Analyzing over 2,000 medical records in the General Practice Research Database (GPRD), researchers identified 179 British patients who were originally diagnosed with relapsing-remitting MS, a form of the disease in which symptoms fade and recur in unpredictable patterns. Patients who were current or past smokers were 3.6 times as likely as patients who had never smoked to develop secondary progressive MS, a later stage of the disease marked by steady deterioration of the central nervous system.
This disease progression also occurred more quickly in patients who were identified as current or past smokers. The study also supported earlier research showing that smoking may increase the risk of initial MS diagnosis. Current and past smokers were 30% more likely to be diagnosed with MS than those who had never smoked.
While more research is needed to understand the mechanisms behind these findings, the researchers speculate that nitrous oxide, a chemical present in cigarette smoke, may play a role in hastening the degeneration of nerve fibers. Alternatively, chemicals in cigarette smoke could damage the cells that create myelin, a protective coating for neurons, or may predispose smokers to autoimmune responses.