Approach to autism may increase autism spectrum disorder prevalence estimates in children worldwide

May 10, 2011

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 percent 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 on May 9 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.

“While this study does not suggest that Korean have more than other populations or that a more accurate rate for the U.S. is closer to 2.64 percent, it does suggest that autism may be more common than previously thought,” said Roy Richard Grinker, GW professor of anthropology and international affairs and member of the study’s research team. “This research powerfully demonstrates that the methods one uses to study prevalence will profoundly influence the estimate,” said Professor Grinker, author of Unstrange Minds: Remapping the World of Autism.

Under the leadership of Yale psychiatrist and epidemiologist Young-Shin Kim, 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 Centers for Disease Control and Prevention (CDC), which analyzed records and registries, the researchers attempted to look at each child in every school, even those who did not have a record of any 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. Parent and teacher focus groups were conducted to identify local beliefs that might influence symptom reporting and other misunderstandings. Additionally, the diagnostic tools were also translated, back-translated and validated for Korean children and only best-estimate clinical diagnoses were reported. Furthermore, each diagnostic team was composed of Korean diagnosticians with extensive clinical and research experience in both the U.S. and Korea and a random sample of diagnoses was validated by North American experts.

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 behavioral 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. This structure may help children with ASD to function at various levels in the Korean general while not receiving special education services.

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. Additionally, they highlighted that appropriate translation and adaptation of the gold-standard assessment methods used in the U.S. and other English-speaking countries can reliably diagnose autism in other languages and cultures.

Explore further: Study estimates rate of autism spectrum disorder in adults in England

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