Zeidan and colleagues provide a large-scale synthesis of autism prevalence studies worldwide. By pooling results from multiple surveillance systems, population surveys, and registry data, this systematic review shows that reported prevalence varies substantially across countries and within regions, reflecting not only true differences but also diagnostic criteria, surveillance intensity, and cultural awareness. While older estimates placed prevalence around 1 in 150, more recent aggregated figures suggest prevalence estimates closer to ~1% (variable by location and methodology) — some high-income regions report higher rates due to active screening and services.
The review carefully dissects methodological sources of variation: study design (administrative registry vs community sample), age group studied, diagnostic criteria used (DSM-IV vs DSM-5), and whether co-occurring intellectual disability was accounted for. It also highlights disparities in low- and middle-income countries (LMICs), where under-recognition and limited surveillance likely lead to underestimates. The authors recommend harmonizing surveillance methods and improving capacity for epidemiological studies in LMICs.
Suggested citation: Global Prevalence of Autism: A Systematic Review Update.