The environmental risk factors in multiple sclerosis susceptibility: A case-control study

Background: Multiple sclerosis (MS) is a demyelinating and degenerating disease which involves central nervous system. Environmental risk factors have a key role in MS susceptibility. Here we aim to investigate different risk factors effect on MS susceptibility in a large population of MS patients in Isfahan, Iran. Materials and Methods: This study is a cross-sectional hospital-based study, which was conducted on a large group of MS patients registered in Kashani hospital and a control group from normal healthy population. Demographic data, age at onset of the disease, history of viral infections, vaccination, history of trauma to head, recent stressful events, alimentation, familial history, method of delivery (caesarean section, normal vaginal delivery), disability score and history of smoking were gathered using a designed questionnaire. Results: Totally 536 MS patient with the mean age of 34.37 ± 9.22 and 399 individuals from healthy population with the mean age of 32.53 ± 9.91 were recruited. Significant difference in history of measles infection (control = 15.5%, case = 22.4%, P = 0.009), consumption of dairy products (case = 56.6%, control = 67.5%, P = 0.01) and major stressful life events (case = 62.2%, control = 52.7%, P < 0.05) between these two groups were demonstrated. Conclusion: A significant relation between stress, history of infection and milk consumption was reached that highlights the importance of environmental risk factors in MS pathogenesis