Tuesday, June 7, 2011

How common is autism?

Earlier this month, a press release from Yale University announced: "Prevalence of Autism in South Korea Estimated at 1 in 38 Children". This estimate was considerably higher than recent UK studies (Baird et al, and Baron-Cohen et al). There are three possibilities: either children in South Korea are at unusually high risk of autism; previous studies have dramatically underestimated the prevalence of autism; or this new study gives an overestimate. The authors reject the first option and plump for the second. Their estimate, they maintain, is so high because they looked for children in mainstream schools, doing their own assessments of children detected on an initial screening questionnaire, rather than relying on existing diagnoses. Around two thirds of their cases of autism had not previously been diagnosed. This, they argue, is because an autism diagnosis is unpopular in South Korea since it is more likely to bring shame on the family than additional resources for the child (see my review of the senior author's book, Isabel's World). There is a problem, though. Asking how many children have autism is like asking how many children are intelligent. Everything hinges on definition, and the definition of autism is far from straightforward. Over the years, it has become increasingly clear that autism is not the all-or-none condition that Kanner had assumed.

Click here for full article.

A follow-up article on the flaws in the initial Korea study design.