Autism may be more common worldwide than previously thought, according to researchers from the George Washington University (GW) and Yale University. The researchers conducted an autism prevalence study for the first time in South Korea and estimated that the prevalence of autism spectrum disorder is as high as 2.6 per cent of the population of school-age children, equivalent to 1 in 38 children.

The study, “Prevalence of Autism Spectrum Disorder in a Total Population Sample,” scheduled to be published online soon in the American Journal of Psychiatry, reports on autism among approximately 55,000 children ages 7 to 12 years in a South Korean community. These children include those enrolled in special education services and a disability registry, as well as children enrolled in general education schools.

All children were screened with surveys distributed to both parents and teachers, and then evaluated using comprehensive diagnostic assessments. Unlike the studies carried out by the CDC, which analysed records and registries, the researchers attempted to look at each child in every school, even those who did not have a record of any special education need. This method unmasked cases that could have gone unnoticed to epidemiologists relying on a records-based approach.

To date, researchers have not found a difference in the way ASD is expressed in children around the world, but certain cultural factors may affect diagnostic practices and prevalence estimates. Therefore, this study took a comprehensive and anthropological approach to mitigate potential cultural bias. Additionally, the diagnostic tools were also translated, back-translated and validated for Korean children and only best-estimate clinical diagnoses were reported.

The team considered that more Korean children with ASD may be found in mainstream education settings based on the design of the Korean educational system. In these settings, instruction is highly structured with significant behavioural regulation across a longer school day - often more than 12 hours long, with 5-6 days of instruction each week and extracurricular academic tutoring at off-site academic institutes.

The researchers emphasized that this study is further evidence that autism transcends cultural, geographic and ethnic boundaries and that autism is a global public health concern, not limited to the Western world.