Dramatic changes in multiple sclerosis incidence in Iran may be related to the “Will Rogers phenomenon”

Abstract

In recent years, studies have shown that multiple sclerosis (MS) incidence has greatly increased in different geographical areas of Iran (Pakdel et al., 2020; Hosseinzadeh et al., 2021). The increases in MS incidence in Iran are usually attributed to obesity and overweight childhood, cigarette and waterpipe smoking, vitamin D deficiency, urbanization, industrialization, and air pollution (Amiri, 2021; Hosseinzadeh et al., 2019; Asmarian et al., 2021). However, one of the most important factors that may be related to the increase of MS incidence in Iran and has been neglected is the “Will Rogers phenomenon