What to make of the surprising new data.
Correction (published Oct. 8, 2009): In the original article, the description of a study of autism in California misstated the percentage of new cases in that state that could be attributed to changing criteria for diagnoses. In the original, we said that 56 percent of the increase in autism cases could be explained by doctors diagnosing milder cases than they would have before, and that 24 percent came from doctors diagnosing cases in younger children, which meant that 20 percent of the new autism rate was unexplained. In actuality, 29 percent of the increase came from relaxed or changed diagnosis criteria and 4 percent came from cases being diagnosed in younger children, leaving 67 percent of the increase unexplained. The text has been updated to reflect this correction. NEWSWEEK regrets the error.
For years the autism community’s most powerful public-relations weapon has been a striking statistic: an estimated 1 in 150 children have the diagnosis. Now it appears that estimate is actually too small. According to two new studies, the number of kids diagnosed with autism or a related disorder in the U.S. is closer to 1 in 100.
The new data has everyone who cares about autism abuzz. But, as with so many issues connected to the disorder, no one can quite agree on what it means.
One of the new studies, published in Pediatrics, is based on a survey of more than 78,000 parents. Researchers asked them if doctors had ever diagnosed any of their children with autism or a related disorder on the autism spectrum, such as Asperger syndrome. More than 1,400 of the parents said yes. If those numbers represent the population at large, that means 673,000 American kids likely have a form of autism.