Prevalence of autism spectrum disorder and autistic symptoms in a school-based cohort of children in Kolkata, India.
Kolkata schools show only 0.23 percent autism, but wider traits and sex gaps signal under-counting, not absence.
01Research in Context
What this study did
Workers visited 12 Kolkata schools. They screened the kids .
Teachers filled out a short checklist. Kids who scored high got a full autism exam.
What they found
the kids out of 11,849 had autism. That is 0.23 percent.
Another 3.5 percent showed some traits but did not meet full criteria.
How this fits with other research
Whalon et al. (2019) found 1.5 percent autism in UK schools. The gap shows India may miss many cases.
Hodge et al. (2025) found girls get spotted six months later than boys. Kolkata only found 4 girls vs 19 boys, so girls likely hide in the 3.5 percent traits group.
Amore et al. (2011) warn that PDD-NOS labels often change. Kolkata counted these kids as non-autistic, so true numbers could rise if followed longer.
Why it matters
Low numbers do not mean low need. They mean low detection. Use wide nets: screen adaptive skills, watch quiet girls, and plan re-checks every year. Share these local stats with teachers so they know autism is present even when it looks rare.
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02At a glance
03Original abstract
Despite housing ∼18% of the world's population, India does not yet have an estimate of prevalence of autism. This study was carried out to estimate the prevalence of autism in a selected population of school-children in India. N = 11,849 children (mean age = 5.9 [SD = 1.3], 39.5% females) were selected from various school types from three boroughs in Kolkata, India. Parents/caregivers and teachers filled in the social and communication disorders checklist (SCDC). Children meeting cutoff on parent-reported SCDC were followed up with the social communication questionnaire (SCQ). SCQ-positive children were administered the autism diagnostic observation schedule (ADOS). Teacher report on SCDC was available on all 11,849 children. Parent-report SCDC scores were obtained for 5,947 children. Mean scores on teacher SCDC were significantly lower than parent SCDC. Out of 1,247 SCDC-positive children, 882 answered the SCQ, of whom 124 met the cutoff score of 15. Six of these children met criteria for autism, autism spectrum disorder (ASD), or broader autism spectrum on the ADOS. The weighted estimate of supra-threshold SCQ scores was 3.54% (CI: 2.88-4.3%). The weighted prevalence estimate of positive scores (for broader autism spectrum + ASD + autism) was 0.23% (0.07-0.46%). As ∼20% children in this state are known to be out of the school system, and ASD prevalence is likely to be higher in this group, this estimate is likely to represent the lower-bound of the true prevalence. This study provides preliminary data on the prevalence of broader-spectrum autism and supra-threshold autistic traits in a population sample of school children in Eastern India. Autism Res 2017, 10: 1597-1605. ©2017 The Authors Autism Research published by Wiley Periodicals, Inc. on behalf of International Society for Autism Research.
Autism research : official journal of the International Society for Autism Research, 2017 · doi:10.1002/aur.1812