By Dr Ananya Mandal, MD
According to latest figures, nearly one in 88 U.S. children have autism spectrum disorders. The report further urges national attention on the need for earlier diagnosis and treatment, especially in rural and minority communities.
Figures released Thursday by the Centers for Disease Control and Prevention (CDC) show a 23% increase in autism spectrum cases from 2006 to 2008, and 78% increase since 2002. The largest increases in autism prevalence were found among black and Hispanic children, who have lagged behind whites in previous counts. Numbers are higher for boys, with one in 54 8-year-olds now considered to have autism, Asperger's or a related condition, though no one knows why the condition is five times more likely to affect boys than girls. The CDC has a surveillance network around the country that has counted 8-year-olds on the autism spectrum every two years. The new numbers are based on tallies from 14 sites.
The report added that more children are being diagnosed at younger ages and the average age at diagnosis has dropped from 4½ to 4. However Coleen Boyle, director of the CDC's National Center on Birth Defects and Developmental Disabilities feels it should be diagnosed even earlier. “We heard from many parents that they were concerned long before their child was diagnosed. We are working hard to change that,” she said.
Although the CDC's 14 surveillance sites are not statistically representative of the nation, with some in large urban districts and others in rural areas, the agency is confident in the accuracy of its autism figures, Boyle says. The numbers are collected by looking through medical and educational records, she adds, which is why it took the CDC four years to prepare them. The rates also match up with autism figures derived in other ways, she says.
The exact cause of the rise is unknown. Researchers are examining air pollution, nutrition, medications, environmental toxins and other factors as possible contributors. At least some of the increase is due to better awareness and diagnosis, however, “I don't believe the whole thing is diagnostic,” says Peter Bearman, a Columbia University sociologist who studies autism rates in California. He says his data are consistent with the CDC's.
Roy Richard Grinker, an anthropology professor at The George Washington University in Washington, D.C., said he thinks the numbers still underestimate the problem. He conducted a study last year in South Korea that found an autism rate of one in 38 children there. States including Alabama, for instance, have long lagged behind others in autism diagnoses, Grinker said, because it is a large, rural state without many services for children with autism. Rising rates may actually be a good thing, he said, because it means more children who need help are being identified. “It doesn't mean that there's a true increase in cases,” says Grinker.
Irva Hertz-Picciotto, a professor at the University of California-Davis' M.I.N.D. Institute, said she thinks the government and private groups haven't spent enough money researching possible environmental contributors to autism. “So much of the funding has gone toward genetics that the environment has hardly been looked at and yet we already have several clues,” she says. “We also need to think about prevention and that's where the environmental concerns are so, so critical.”
In a study last year, Hertz-Picciotto found that mothers who did not take prenatal vitamins before and in the early months of pregnancy were more likely to have children on the spectrum. Anti-depressant use has also been linked to autism, as have immune problems in the mother and aging parents.