Environmental risk factors of multiple sclerosis in the Middle East and North Africa region: A systematic review

The environmental factors play a role as risk factors of multiple sclerosis (MS). This study aimed at gathering environmental risk factors of MS in the Middle East and North Africa (MENA).

We used MEDLINE and EMBASE databases by a systematic review method. Out of a total of 123 studies, 16 studies met the eligibility criteria.

Totally, 47 risk factors were assessed as follows: six studies found sunlight exposure as a protective factor with the odds ratio (OR) ranging from 0.06 to 0.57. Six studies evaluated smoking as a risk factor with the OR ranging from 1.69 in all patients to 6.48 in female patients. Four studies supported measles infection as a risk factor with the OR ranging from 1.60 to 3.77, and in 3 studies, stressful events had a significant association with the OR of 1.80, 1.90, and 32.57.

Among 47 assessed risk factors, sunlight exposure, cigarette smoking, measles infection, Epstein-Barr virus (EBV) infection, and stressful events had a significant association with MS.