Autism prevalence data remain scarce in low- and middle-income countries. In 2022, Brazil incorporated, for the first time, a specific question on prior medical diagnosis of autism in its national census. Results from the preliminary publication of the 2022 Census sample, released in 2025, indicated that 1.2% of the population, approximately 2.42 million individuals, reported a diagnosis of autism. Among boys aged 5 to 9 years, prevalence reached 2.6%, declining to 1.6% among adolescents and 0.3% among adults aged 30 years or older. Although based on self-reported diagnosis, these data provide the first nationwide population estimate of autism in Brazil. Comparisons with U.S. figures from the Autism and Developmental Disabilities Monitoring Network should be interpreted cautiously given methodological differences. The observed age gradient suggests potential historical under-identification in older cohorts. Regional variation further highlights differences in diagnostic patterns across the country. The inclusion of autism in Brazil's national census represents an important step toward strengthening surveillance, research, and policy planning in low- and middle-income settings.Lay AbstractIn 2022, Brazil included, for the first time, a specific question on medical diagnosis of autism in its national census, as mandated by federal law. Results from the 2025 preliminary publication of the Census sample showed that 1.2% of the population reported a prior medical diagnosis of autism, totaling about 2.42 million people. Among boys aged 5 to 9 years, prevalence reached 2.6%, while rates were lower among adolescents and adults. This age pattern may reflect historical differences in access to diagnosis. Regional variation was also observed across states. Including autism in Brazil's national census represents a major step forward for epidemiological monitoring and policy planning in Latin America.
Santos et al. (Tue,) studied this question.