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Autism Hits 1 in 88 U.S. Kids, 1 in 54 Boys

CDC: Autism Up 23% From 2006 to 2008 as Rates Continue to Rise

Why Is Autism on the Rise? continued...

One hint comes from data showing that autism prevalence is higher in areas where doctors are better at diagnosing autism in kids with relatively high intellectual ability.

The CDC's huge multi-year Study to Explore Early Development (SEED), begun in 2008, is exploring various autism risk factors. The very first results should start coming out later this year. But since SEED follows kids from the time of their mother's pregnancy, it will take time for the study to mature.

It's known that autism results from a complex interaction between genetic and environmental influences. But it's not known which types of autism are most closely linked to which factors.

Autism Prevalence Varies Across States

The CDC study -- the Autism and Developmental Disabilities Monitoring (ADDM) study -- is based on data from over 337,000 8-year-olds in 14 states. That's 8.4% of all U.S. 8-year-olds. The study first used health and education records to identify kids with possible autism. Then all of the records were analyzed by autism professionals to identify kids who fit the current autism diagnosis.

Autism rates varied widely across states. Autism prevalence was one in 47 kids in Utah, but only one in 210 children in Alabama. Study sites that relied only on health records to identify kids with autism had significantly lower autism rates than sites that had both health and education records.

For example, in Colorado there was a single county with access to both education and health records. The autism rate there was twice as high as the rate in six Colorado counties with health records only.

Despite the different autism rates across sites, the overall autism prevalence detected is similar to that estimated by other national health surveys.

"This method is really the gold standard for tracking autism," Boyle says. "One thing we do know is we don't overestimate autism prevalence."

High Autism Rate a Call to Action

While it's important to understand why so many kids have autism, it's even more important to do something about it, says Rebecca Landa, PhD, director of the Center for Autism and Related Disorders at Baltimore's Kennedy Krieger Institute. Landa led one of the 14 sites in the ADDM study.

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