Environmental Risk Factors in Multiple Sclerosis: A Narrative Review

Background Multiple sclerosis (MS) is one of the chronic autoimmune diseases and a progressive disease of the central nervous system that have unknown causes. Objective This study aims to review the environmental risk factors of MS. Methods In this review study, a search was conducted in databases such as PubMed, Scopus, ScienceDirect, Google Scholar and MagIran on related studies published in Persian and English from 2000 to 2021 using the keywords: Multiple Sclerosis, MS, Environmental risk factors, and Epidemiology. Results The studies showed that MS is an autoimmune disease with unknown genetic backgrounds. The age of 20-40 years, female gender, distance from the equator, migration, Epstein-Barr virus infection, smoking, air pollution, vitamin D deficiency, alcohol and coffee consumption, circadian disruption, and psychological factors are the environmental risk factors of MS. Conclusion Given the environmental risk factors of MS, their control is potentially helpful in preventing the disease and its rapid progression. It is necessary for health care providers to pay attention to these risk factors.