Autism spectrum disorders affect one in 111 children

Efforts to identify risk factors continue.

Rates of autism spectrum disorder increased anywhere from 27% to 95%, at 10 U.S. sites between 2002 and 2006, with about 1% of the nation’s 8 year olds affected by the disorder, data released today indicated.

“We know that more children are identified with ASD than in the past. These new numbers are concerning and indicate that even more individuals, families and communities are struggling to find answers,” CDC researcher Catherine Rice, PhD, said during a press briefing.

Boys remain four-to-five times more likely to receive an autism spectrum diagnosis than girls — 1 in 70 boys vs. 1 in 315 girls. But increases were prevalent across all subgroups regardless of gender, race/ethnicity and cognitive function.

On average, Hispanic children experienced the greatest increase at 90%, compared with a 55% increase among white children, and a 41% increase among black children.

A similar proportion of children among the two study years had some other documented intellectual disability, about 43%, and a similar proportion received their first ever ASD diagnosis, about 45%.

Findings also suggested a disparity between parental concerns and actual diagnosis. Medical records indicate parents are often concerned about their child’s condition before age 2 years, yet average age at first diagnosis is much later, at 4.5 years.

The data come from a retrospective analysis of school and health records among children aged 8 years old who were part of the Autism and Developmental Disabilities Monitoring Network, a surveillance system comprised of about 300,000 children that account for about 8% of the population.

Rice said the overall rates observed in this study were consistent with those reported earlier this year.

Better detection accounts for some of the increases in prevalence, she said, but added that a true increase in risk cannot be ruled out. “We know there are multiple and complex genetic and environmental factors which result in multiple forms of autism, and we have much to learn about the causes.”

CDC is currently enrolling children to participate in the Study to Explore Early Development (SEED), to help identify risk and protective factors for ASDs and other developmental disabilities. The study will explore potential risk factors that may be related to genes, health conditions and other factors that may have affected the mother’s pregnancy and the child’s first few year of life, according to Rice. – by Nicole Blazek

CDC. MMWR Surveill Summ. 2009;58:SS-10.