Impact of tobacco and alcohol consumption on disease progression and MRI in people with multiple sclerosis: results of the prospective cohort study NationMS.

Background: Lifestyle factors, such as smoking cigarettes and alcohol consumption, can influence disease progression in Multiple Sclerosis (MS). Objective: This study aimed to investigate the associations of smoking cigarettes and alcohol consumption with clinical parameters in people with MS (pwMS). Design: This is a prospective cohort study, analysing data from the German NationMS cohort. Methods: We analysed data of 1374 patients recruited between 2010 and 2017. Main outcomes were Expanded Disability Status Scale (EDSS), Timed 25-Foot Walk (T25FW) and Paced Auditory Serial Addition Test (PASAT). Secondary outcomes were number of T2 and GD+ lesions. We conducted logistic and linear mixed model regression, adjusted for age, sex, educational level, MS subtype. Results: Smoking cigarettes was associated with increased odds of reaching pre-defined cut-off values for EDSS and T25FW, as well as with increased mean differences across follow-ups. Alcohol consumption was associated with decreased odds of reaching the cut-off for EDSS and T25FW. Findings for PASAT were less consistent. We found no significant associations for T2 and GD+ lesions. Conclusion: This study provides further evidence that smoking cigarettes accelerates MS progression and that pwMS should be advised to quit smoking. However, this negative impact could not be demonstrated for alcohol consumption. Reverse causation cannot be ruled out and further research in this area is warranted. Trial registration: Instead of registration in a primary trial registry, a comprehensive study protocol was published a priori and is available online: https://osf.io/3xscy.