WASHINGTON—A population-wide study of South Korean children has shown autism rates much higher than in the United States, suggesting more people worldwide may have the disorder than previously thought.
By examining 55,000 children age 7-12, even those not enrolled in special education programs, researchers found that one in 38 children had some form of autism, including the more mild social disorder known as Asperger’s Syndrome.
In the United States, the autism prevalence rate is believed to be one in 110.
However, US studies have tended to focus on children in special education programs, and have not screened entire populations in the regular school system where high-functioning autistic children may be enrolled.
“These findings suggest that ASD (autism spectrum disorder) is under-diagnosed and under-reported and that rigorous screening and comprehensive population studies may be necessary to produce accurate ASD prevalence estimates,” said Geraldine Dawson, chief scientific officer at the research and advocacy group Autism Speaks.
The five-year study, published Monday in the American Journal of Psychiatry, was funded in part by Autism Speaks and led by the Yale Child Study Center’s Young-Shin Kim, who said the reasons for the apparent spike in South Korean cases remain unclear.
“Recent research reveals that part of the increase in reported ASD prevalence appears attributable to factors such as increased public awareness and broadening of diagnostic criteria,” said Kim.
“This study suggests that better case finding may actually account for an even larger increase.”
The study did not look at potential risk factors that may be unique to the South Korean population, but “does set the stage for ongoing work to examine genetic and environmental factors contributing to the risk of ASD,” Kim said.
Researchers stressed that the findings do not suggest that autism is more prevalent in South Korea but that it is often missed worldwide, and said many steps were taken to avoid potential cultural bias in diagnosis.
“Parent and teacher focus groups were conducted to identify local beliefs that might influence symptom reporting and to address stigma and misunderstandings related to ASD,” said co-author Roy Richard Grinker.
“Further, clinical diagnoses were established by Korean diagnosticians with extensive clinical and research experience in both the US and Korea and were validated by North American experts,” said Grinker, a cultural anthropologist at George Washington University.
Autism Speaks is funding further research on children in India, South Africa, Mexico, and Taiwan.
“Goyang City, host of the Korea study, has courageously responded to these study findings by providing comprehensive assessment and intervention services for all first graders entering their school system,” said Kim.
“We hope that others will follow Goyang City’s example so that any population based identification of children with ASD is accompanied by intervention services for those children and their families.”
Autism is a developmental disability that can interfere with social and communication skills. There is no cure, and its causes are unknown, though genetics are believed to play a role.
The US Centers for Disease Control and Prevention describes ASD as an “urgent public health concern” that affects about 1 in 80 boys and 1 in 240 girls in the United States.