Smoking and Disease Progression in Multiple Sclerosis

Abstract

Cigarette smokers are at higher risk of developing multiple sclerosis (MS) compared with never-smokers.¹ In smokers with clinically isolated syndromes, the disease may progress to clinically definite MS sooner than in nonsmokers²; however, whether smoking has adverse effects on the progression of MS remains uncertain. In a study relying on prospectively collected smoking information in 179 patients with relapsing-remitting MS (RRMS), Hernán et al³ found that in ever-smokers, RRMS converted to secondary progressive MS (SPMS) faster than in never-smokers. In contrast, Koch et al,⁴ in a retrospective study including 364 patients (164 of whom had RRMS), found that cigarette smoking was not significantly associated with the development of SPMS or progression of clinical disability as measured using the Expanded Disability Status Scale (EDSS). Neither study reported whether smoking was associated with magnetic resonance imaging (MRI) markers of disease severity.