Epidemiology of Autism

Autism spectrum disorder (ASD) refers to a range of conditions characterized by deficits in social and communication skills as well as restricted and repetitive behaviorsa and anarrow range of interests and activities. According to WHO, it is estimated that worldwide one in ۱۶۰ children suffer from ASD. This estimate represents an averagefigure, and reported prevalence varies substantially across nations. Some studies have, however, reported figures that are higher. The prevalence of ASD in many low andmiddle income countries is still unknown. In ۲۰۱۰, WHO estimated ۰.۷۶% of the world’s children had ASD, though this estimate was based on studies in countries representingonly ۱۶% of the global child population. A ۲۰۱۲ review of global prevalence estimates of autism spectrum disorders found a median of ۰.۶۲% (۶۲ cases per ۱۰,۰۰۰). Othersystematic reviews of prevalence studies internationally have produced similar summary estimates, of approximately ۰.۷%, Yet, summary estimates make considerable variability across geography, methodological approach, and time. In Iran, the prevalence rate of autism has been investigated in only few studies. A National Population-Based study reported the prevalence rate of ۰.۱% (۱۰/۱۰۰۰), with a ۲:۱ male to female ratio. Another study was conducted in Iran which was based on national screening of five-year-old children for ASD prior to school entry. Out of ۱.۳۲ million, the number of the children who subsequently were given a diagnosis of autistic disorder when formally assessed using the Persian translation of the Autism Diagnostic was around N = ۸۲۶ [۶.۲۶ per ۱۰,۰۰۰]. It was also found that the prevalence of children assessed as having ASD was twice as high in the more developed Provinces of Iran (۸.۸۱ per ۱۰,۰۰۰) than in the less developed Provinces (۳.۸۸ per ۱۰,۰۰۰). The overall Iranian prevalence of ۶.۲۶ per ۱۰,۰۰۰ for five year olds is similar to that previously reported for certain European countries. Nevertheless, the reported Iranian rates are much lower than those reported for some European and American countries. In this study, boys were almost ۴ times more suspected as having autism or were diagnosed with it than girls. Epidemiological studies, however, show that over the past ۵۰ years, the prevalence of ASD has increasing globally. However, this increase may be due to better methods of medical diagnosis, improved awareness and more accurate reports.

Keywords:

Autism , Epidemiology , Prevalence , Iran