Smoking leads to rapid progression of multiple sclerosis

Patients with multiple sclerosis who smoke appear to experience a more rapid progression of their disease, revealed by researchers in the Archives of Neurology.

Cigarette smokers are at higher risk of developing multiple sclerosis (MS). However, the effect of smoking on the progression of MS remains uncertain.

Brian C. Healy, Ph.D., of Brigham and Women’s Hospital, Harvard Medical School and Massachusetts General Hospital, Boston, and colleagues studied 1,465 patients with MS who visited a referral center between February 2006 and August 2007. Participants had an average age of 42 and had MS for an average of 9.4 years. Their progression was assessed by clinical characteristics as well as by magnetic resonance imaging (MRI) over an average of 3.29 years.

An adverse effect of smoking on the progression of MS would be consistent with previous research, the authors note.

Components of cigarette smoke are known to have toxic effects on brain and neural tissue; for example, cyanides, which have been associated with the destruction of nerve cells’ myelin coating (a characteristic feature of MS) in animals.

“Other chemicals in smoke (e.g., nicotine) can compromise the blood-brain barrier or have immunomodulatory effects,” the authors write. “Cigarette smoke increases the frequency and duration of respiratory infections, which have been linked to risk of MS and to the occurrence of MS relapses.”

“In conclusion, the results of this large and in part prospective investigation support the hypothesis that cigarette smoking has an adverse effect on progression of MS as measured by clinical and MRI outcomes,” they conclude. “Although causality remains to be proved, these findings suggest that patients with MS who quit smoking may not only reduce their risk of smoking-related diseases but also delay the progression of MS.”

Source: Archives of Neurology, USA

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