NEUROLOGY 

Andersen O and Filippi M

Neurology May 2020, 94 (18) 771-772

DOI: https://doi.org/10.1212/WNL.0000000000009367

A number of risk factors established for multiple sclerosis (MS) may also be valid for the process of evolution from a clinically isolated syndrome; these factors include low levels of vitamin D, smoking, and Epstein-Barr virus (EBV) infection. They interact with genetic risk factors, mainly Class II human leukocyte antigen (HLA) alleles.1 Some combinations are strong risk indicators, reaching an odds ratio near a magnitude of 10. However, reverse causality is a caveat, e.g., the vitamin D association might depend on genetic enzymatic factors, and the Epstein-Barr association on individual disposition in cellular immunity. Notably, there are conflicting results whether risk factors for MS incidence are also predictors or modifiers of the course of the disease. Vitamin D treatment has no effect on relapses, disability, or MRI measures. However, this evidence was mainly from studies of 1- or 2-year duration,2 and prediction studies with longer follow-up from the established risk factors with sensitive outcome parameters are needed.