Study: Autism May Be More Common Than Thought

May 9, 2011 - A "startling" one in 38 children has autism, South Korean and U.S. researcher find.

The estimate is far higher than CDC's estimate of one in 110 children, as the study found many school kids have mild, undiagnosed autism.

The elaborate study searched for 7- to 12-year-old children with autism spectrum disorder (ASD) among 55,000 children in a community outside Seoul, South Korea. Largely funded by the advocacy organization Autism Speaks, the study was led by Young Shin Kim, MD, PhD, MPH, of Yale University.

"They came up with the startling number that one in 38 children has an autism spectrum disorder," Geraldine Dawson, PhD, chief science officer for Autism Speaks, tells WebMD. "This raises an important question for the U.S.: How many kids in the general education classroom actually have an ASD but not a diagnosis? These children may have gone under the radar."

"This means that about two-thirds of children with ASD are in the community, unrecognized and untreated. Their lives can be improved significantly with early identification and intervention," Kim said at a news conference.

The new findings do not mean that more children have suddenly come down with autism.

"It seems they have been there all along but were not counted in previous studies," Kim says.

It's the first time a large study has screened a general population for autism. Autism expert Rebecca Landa, PhD, director of the autism center at Baltimore's Kennedy Krieger Institute, tells WebMD in an email that the study methods will have to be validated by future studies. Landa was not involved in the Kim study.

Kim agrees that further studies will have to confirm the current findings. Such studies are underway in India, South Africa, Mexico, and Taiwan.

Study researcher Bennett L. Leventhal, MD, of the NYU Child Study Center, thinks the same study methods would yield similar results in the U.S.

"If researchers went into the grade schools in their communities and looked there, we think they would come up with numbers similar to those we are reporting," Leventhal said at the news conference. "This means there are uncounted children who are not in the services system."

School Kids With Undetected Autism

Who are these uncounted children? When they looked at kids already identified as special-needs children, Kim and colleagues found pretty much the same autism prevalence and the same levels of disability as seen in U.S. and European studies.

The surprise came from the undiagnosed children in the general school population. Some two-thirds of the kids diagnosed with autistic disorder, and 90% of those with other ASDs (such as pervasive developmental disorders) had average or superior intelligence.

"Historically, we thought children with autism were pretty disabled. But intellectual disability isn't the core feature of autism," Gary W. Goldstein, MD, president and CEO of the Kennedy Krieger Institute and professor of neurology and pediatrics at Johns Hopkins University, School of Medicine. Goldstein was not involved in the Kim study but does serve on the board of Autism Speaks.