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. Figuring out how many children have autism is extremely difficult because diagnosis is based on a child's behavior, said Dr. Susan 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.”
The new estimate would mean about 673,000 American children have autism. Previous estimates put the number at about 560,000.
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 that their preliminary findings also show about 1 in 100 children have the disorders.
The CDC uses an in-depth method for its estimate, said CDC researcher Catherine Rice. 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.
President Obama has made autism a priority for research, Insel said. Federal stimulus money has been earmarked for it and a 2006 law pumped millions of dollars of federal money into autism research, screening and treatment.
The published findings, which include state-level data, will help the government plan new services, said Michael Kogan, a researcher with the federal Health Resources and Services Administration, who led the new study.
The findings are based on results of a national telephone survey of more than 78,000 parents of children ages 3 to 17. The survey dealt with many health issues and included two questions on autism.
Parents were asked whether they'd ever been told by a health care provider that their child had autism, Asperger's syndrome, pervasive developmental disorder or other autism spectrum disorder.
If the parent said yes, they were asked if their child currently has autism or an autism spectrum disorder. “Yes” to both questions was counted as a child with an autism disorder.
Children with autism can have trouble communicating and interacting socially. They may have poor eye contact and engage in repetitive behavior such as rocking or hand-flapping.