Autism rates rise: Disorder affects 1 in 88 children, CDC study finds
Some experts questioned the validity of relying on records to estimate autism's prevalence.
Los Angeles Times
LOS ANGELES — Federal health authorities have significantly raised their estimate of the prevalence of autism in children, concluding in a new study of 8-year-olds that 1 in 88 has some form of the disorder.
For the analysis, released Thursday, researchers scoured tens of thousands of health and special-education records in 14 states, looking for an autism diagnosis or the symptoms that would add up to one.
It is the latest in a series of studies by the U.S. Centers for Disease Control and Prevention (CDC) showing autism rates climbing substantially in the past decade.
The previous estimate, from 2006, was 1 in 110.
The new figure, based on 2008 data, is sure to fuel debate over whether a growing environmental threat could be at work. But autism researchers around the country said the CDC data suggest that rising awareness of the disorder, better detection and improved access to services can explain much of the surge, and perhaps all of it.
Washington was not one of the states included in the study, and autism is not tracked by state health officials. But Dr. Bryan King, director of the Seattle Children's Autism Center, said the report of growing numbers of children with autism spectrum disorder wasn't news to those who work in the field. "We're up against a tidal wave of need," he said.
More than 1,000 families are on a waiting list for diagnostic and therapy services from Children's, he said. "Families are having to confront the difficulties in accessing services and providers are trying to keep up with the press of humanity at the door."
Nobody knows what causes autism, and there is no blood test or other biological marker. It is diagnosed by its symptoms — social and communication difficulties starting in early childhood and repetitive behaviors or abnormally intense interests — and has come to include a wide range of symptoms.
Milder forms are now recognized. One, Asperger syndrome, describes behavior that in the past might have been seen as peculiar and abnormal but not evidence of illness. Ultimately, a diagnosis comes down to clinical judgment.
Some experts questioned the validity of relying on records to estimate the disorder's true prevalence.
David Mandell, an autism expert at the University of Pennsylvania, said the CDC's numbers primarily reflect the degree to which the diagnosis and services have taken hold in different places and among different groups.
"As the diagnosis is associated with more and more services, this becomes a less and less rigorous way to determine the prevalence of autism," he said, referring to the CDC's methods.
The federal agency found that Utah, which has widespread screening programs, had the highest rate: 1 child in 47. The state was closely followed by New Jersey, which prides itself on its autism services, at 1 in 49.
At the bottom was Alabama, one of the poorest states. Its autism rate fell 20 percent between 2006 and 2008: from 1 in 167 to 1 in 208.
CDC officials acknowledged the limitations of their analysis. In surveillance areas where researchers had access only to health records, and not school records, prevalence estimates were generally lower.
"Our study really is more of a study of demographic differences and population differences," said Jon Baio, a CDC epidemiologist and principal investigator on the report.
The researchers hope, however, that the study will draw attention to the need for more vigorous screening early in children's lives. Research shows that early intervention offers autistic children the best long-term prospects
More than one-fifth of children identified as autistic by the CDC had no autism diagnosis in their records.
Dr. Coleen Boyle, director of the CDC's National Center on Birth Defects and Developmental Disabilities, said children "still aren't being identified enough."
In response to rising concern over the skyrocketing diagnosis rates in the 1990s, the CDC set up a network of surveillance sites nationwide. Researchers do not examine children but instead periodically review records of 8-year-olds.
In its first analysis, using data from 2000, the CDC estimated that 1 in 150 children had some form of the disorder. The latest estimate of 1 in 88 is already being touted as evidence that something in the environment is driving up cases.
"Autism is now officially becoming an epidemic in the United States," Mark Roithmayr, president of the advocacy group Autism Speaks, said at a news conference with CDC officials Thursday.
Others noted that as autism awareness has grown, health-care providers and school officials are more likely to label a child autistic or note autistic symptoms in the documentation that the CDC researchers rely on.
In all, the CDC identified 3,820 children with some form of autism, out of 337,093 in the surveillance areas.
As has been previously established, boys were much more heavily affected: The rate was 1 in 54, compared with 1 in 252 girls.
The rate for white children was 1 in 83, compared with 1 in 127 for Latinos and 1 in 98 for black people — but the data show those minorities have been closing the gap.
"What we're looking at is mostly due to practices and infrastructure and culture rather than some underlying biological phenomenon," said Dr. Daniel Geschwind, an autism expert at UCLA.
Autism often has devastating effects on families, and treatment requires time, skill and patience. Medical expenses for children with autism are six times higher than for children without the disorder. Behavioral therapy, often delivered one on one, can cost as much as $60,000 a year. The advocacy group Autism Speaks estimates autism spectrum disorders cost the United States $137 billion a year.
Seattle Times health reporter Carol M. Ostrom contributed to this report. Material from The Washington Post is included in this report.