Lifetime exposure to smoking and substance abuse may be associated with late-onset multiple sclerosis: a population-based case-control study.

Background: Late-onset multiple sclerosis (LOMS), defined as the development of MS after the age of 50, has shown a substantial surge in incidence rates and is associated with more rapid progression of disability. Besides, studies have linked tobacco smoking to a higher chance of MS progression. However, the role of smoking on the risk of developing LOMS remains unclear.