Smoking: effects on multiple sclerosis susceptibility and disease progression

Abstract

Multiple sclerosis (MS) is associated with both genetic and environmental factors that influence disease susceptibility. Exposure to cigarette smoke is emerging as a viable environmental risk factor for MS that contributes to both increased disease susceptibility and more rapid disease advancement. The relative risk for MS development is approximately 1.5 for smokers compared with nonsmokers. Furthermore, there may be important interactions between smoking, an individual's genetic background, and other environmental risk exposures. This review summarizes the current evidence supporting the association of smoking with MS risk and disease course, with additional comments on causation.

Keywords: causality; disease progression; multiple sclerosis; risk factors; smoking.

Figure 1.

Forest plot of 10 studies included in conservative model meta-analysis of smoking and multiple sclerosis risk [Handel et al. 2011].

Figure 2.

Forest plot of four studies included in a meta-analysis of smoking and the risk of secondary progressive multiple sclerosis [Handel et al. 2011].