CHICAGO -- Two new government studies indicate about 1 in 100 children have autism disorders -- higher than a previous U.S. estimate of 1 in 150.
Greater awareness, broader definitions and spotting autism in younger children may explain some of the increase, federal health officials said.
"The concern here is that buried in these numbers is a true increase," said Dr. Thomas Insel, director of the National Institute of Mental Health. "We're going to have to think very hard about what we're going to do for the 1 in 100."
Figuring out how many children have autism is extremely difficult because diagnosis is based on a child's behavior, said Dr. Susan E. Levy of the Children's Hospital of Philadelphia and a member of the American Academy of Pediatrics subcommittee on autism.
"With diabetes, you can get a blood test," said Levy. "As of yet, there's no consistent biologic marker we can use to make the diagnosis of autism."
One of the studies stems from the 2007 National Survey of Children's Health. The results were released today and published in October's Pediatrics.
In that study, based on telephone surveys, parents reported about 1 in 91 children, ages 3 to 17, had autism, including milder forms such as Asperger's syndrome.
The other government estimate has not been formally released yet.
But because of the new published findings, officials from the Centers for Disease Control and Prevention decided to announce Friday during an embargoed press briefing that their preliminary findings also show about 1 in 100 children have the disorders.
The CDC uses an in-depth method for its estimate, CDC researcher Catherine Rice said. An agency network reviews the education and health records of 8-year-old children in selected cities and determines whether the children meet the diagnosis. Autism experts generally consider this method more rigorous than a telephone survey.
One of the new study's authors was supported in part by a grant from Autism Speaks. The others work for federal agencies.
"Autism is a highly prevalent disorder," said Geraldine Dawson, chief science officer of the advocacy group Autism Speaks. "We're looking at a major public health challenge."
