“…Other studies conducted in Iran and other parts of the world reported a higher prevalence for MS. The prevalence of this disorder among adults was 38.5% in the United States [9], 27.8% in Spain [32], 21.1% in France [10], 25.9% in Norway [33], 54.8% in Mexico [11], 35.73% in Morocco [2], 30% in Tanzania [34], 25% in Korea [35], 21.3 -39% in China [12,13], 40-50% in India [36], 21% in Saudi Arabia [14], 36.3% in Jordan [37], 33.5% in Turkey [15], and 21.9% -32% in different regions of Iran [16][17][18][19][20][21][22][23]. Possible reasons for this difference and lower prevalence of MS, are racial and regional differences, age differences between studies, and the use of different definitions for MS.…”