Mapping Autism in Armenia Among Children and Adolescents Aged 0–18 Years: Population-Based Insights into Prevalence and Its Geographical Differences

<b>Background/Objectives:</b> This study aimed to estimate the prevalence of autism spectrum disorder (ASD) among children and adolescents aged 0-18 years in the Republic of Armenia (RA), characterize geographic and sex-specific variations, and determine the mean age at diagnosis. These data are essential for informing health system planning, evaluating potential disparities in access to diagnostic services, and generating hypotheses regarding the biological and healthcare-related factors underlying geographic variation in ASD prevalence. <b>Methods:</b> A cross-sectional study was conducted using administrative records from outpatient medical facilities serving children and adolescents across all ten marzes of RA and the city of Yerevan in 2021. ASD prevalence was estimated at the national and regional levels and stratified by urban and rural residence. The male-to-female prevalence ratio and the mean age at ASD diagnosis were also calculated. <b>Results:</b> The overall prevalence of ASD in RA was 2.3 per 1000 children (95% CI: 2.1-2.4). The highest prevalence was observed in Yerevan (3.7 per 1000). The mean age at diagnosis was 4.5 ± 2.5 years. Males exhibited a 5.1-fold higher prevalence compared to females. ASD prevalence was significantly higher in urban areas than in rural settings. <b>Conclusions:</b> ASD prevalence in RA demonstrates marked geographic and sex disparities, with significantly higher rates in urban regions and among males. These findings underscore the importance of continued ASD prevalence monitoring in RA to identify trends, explore potential biological and healthcare-related contributors to geographic variation, and improve healthcare system planning and management. In turn, improved understanding of regional differences in ASD prevalence may help inform more targeted and personalized approaches to care. The results may also support national and regional policymakers in health, education, and related sectors in developing and strengthening services for children and adolescents with ASD and their families.