Triggers in MSThursday, October 03, 2013, 15:07 - 15:19
Smoking and multiple sclerosis susceptibilityA.K. Hedström, J. Hillert, T. Olsson, L. Alfredsson (Stockholm, SE)
Background: Smoking is one of the most established risk factors for multiple sclerosis (MS). The aim of this study was to investigate how age at smoking debut, duration, intensity and cumulative dose of smoking, and smoking cessation influence the association between smoking and MS risk.
Methods: In two Swedish population-based case-control studies (7883 cases, 9264 controls), subjects with different smoking habits were compared regarding multiple sclerosis risk, by calculating odds ratios with 95% confidence intervals.
Results: We observed a clear dose response association between cumulative dose of smoking and multiple sclerosis risk (p value for trend 5*10-36). Both duration and intensity of smoking contributed independently to the increased risk of multiple sclerosis. However, the detrimental effect of smoking abates a decade after smoking cessation regardless of the cumulative dose of smoking. Age at smoking debut did not affect the association between smoking and MS.
Conclusions: Smoking increases the risk of MS in a dose response manner. However, in contrary to several other risk factors for multiple sclerosis that seem to affect the risk only if the exposure takes place during a specific period in life, smoking affects MS risk regardless of age at exposure, and the detrimental effect slowly abates after smoking cessation.
Dr. Hedström receives research support from the Swedish Association for Persons with Neurological Disabilities. Dr. Hillert received honoraria for serving on advisory boards for BiogenIdec, Merck-Serono and Novartis and for speaker’s fees from BiogenIdec, Merck-Serono, Bayer-Schering, Teva and Sanofi-Aventis. He has served as P.I. for and received projects supported by BiogenIdec, Merck-Serono, and Bayer-Schering. His MS research is funded by the Swedish Research Council, Bibbi and Nils Jensens Foundation and the European Commission. Dr. Olsson served on scientific advisory boards for Merck-Serono, Biogen Idec, and SanofiAventis; served as Co-editor of Current Opinion in Immunology; received speaker honoraria from Novartis and Biogen; and receives research support from Bayer Schering, Sanofi-Aventis, Biogen Idec, the Swedish Research Council, EU fp6 Neuropromise, EURATools, the Söderberg Foundation, Bibbi and Nils Jensens Foundation, the Montel Williams Foundation, and the Swedish Brain Foundation. Dr. Alfredsson receives research support from the Swedish Medical Research Council and Swedish Council for Working life and Social Research. The work was supported by grants from the Swedish Medical Research Council; from the Swedish Council for Working Life and Social Research, the fp6 EU program Neuropromise, Bibbi and Niels Jensens foundation, Knut and Alice Wallenbergs Foundation, the Söderberg foundation, and the Swedish Association for Persons with Neurological Disabilities.