Protective and Risk Factors in Multiple Sclerosis

Document Type : Narrative Review


1 Isfahan Neurosciences Research Center, Alzahra Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran

2 Department of Neurosurgery, Isfahan University of Medical Sciences, Isfahan, Iran


Several factors are involved in susceptibility to multiple sclerosis (MS)and alterations in disease activity. A full understanding regarding the mechanism which causes the disease is still lacking. Several factors have been considered to be associated, positively or negatively, with the onset, course, progression, and relapse rates of MS. However, the level of consensus on each factor is different. These factors are either genetic (including polymorphisms in human leukocyte antigen, microRNAs genes, etc) or environmental (such as serum levels of circulating vitamin D, helicobacter pylori, Epstein-Barr virus, human cytomegalovirus, human herpes virus type 6, human endogenous retrovirus infections, and latitude). Vitamin D sufficiency is a major protective factor on which there is a decisive consensus and has known interactions with many factors affecting MS onset/severity. Vitamin D therapy is speculated to exert beneficial effects on patients, the efficacy of which, along with the etiology of MS, is reviewed in this article.