New figures from the National Survey of Children's Health, a telephone survey conducted by the Centers for Disease Control, show an updated autism spectrum prevalence of 1-in-50 U.S. children.
Parents reported that 2 percent of 6- to 17-year-olds had a diagnosis for an autism spectrum disorder, which is higher than the 2007 estimate of 1.16 percent. Overall, the increase was greater for boys and among 14- to 17-year-olds than for girls or younger children.
The report's authors attribute the change to doctors identifying the disorder more often now. "Much of the prevalence increase from 2007 to 2011 [to] 2012 for school-aged children was the result of diagnoses of children with previously unrecognized ASD," they wrote.
Tristam Smith, a professor of neurodevelopmental and behavioral pediatrics at the University of Rochester Medical Center, said she believed increased detection would be a major contributing factor. "But," she asked, "is it the only thing? It's hard to say."
Of the 95,000 parents contacted for the survey, however, only about a quarter answered questions, and CDC officials admit parents of children with autism could be more likely to participate in a health survey. A more thorough analysis of school records will be needed to corroborate the findings.
The CDC believes its previous 1-in-88 estimate of the prevalence of autism spectrum is too low. That number comes from 2008 data gathered in only 14 states, and only for 8-year-olds. The official CDC estimate is widely used by health care providers, public health officials and policy-makers when quantifying the prevalence of autism in the U.S.
Autism spectrum covers a group of developmental disorders characterized by language and social impairment, and unusual communication and behaviors. There is no biological test for autism and there is no known cause, although growing scientific research suggests it is a combination of genetic and environmental factors.