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.
Research by Hertz-Picciotto and others suggests that air pollution, nutrition, medications and toxic chemicals might all be contributing to the rise in autism rates. “While we're not completely sure of what is driving the rise in autism cases, it is certainly striking enough to warrant exploring in detail the possibility that environmental exposures contribute to this,” said Marc Weisskopf, an epidemiologist and associate professor at the Harvard School of Public Health, who is studying a possible link between air pollution and autism. “There are plenty of other reasons to avoid chemical toxicants, but we can't yet pinpoint whether one of these is a culprit in this rise.”
“What we do know for certain is autism is common and needs to be effectively served,” says CDC Director Thomas Frieden. “We need to continue to increase the number of kids who are detected, detected early and enrolled in services early.”
Autism Speaks, an advocacy and research funding agency, says the figures mean that the U.S. needs to take fast action to help families and children on the spectrum, and invest in the kind of research that will help better explain why the numbers are rising so rapidly. “Clearly, we have a national emergency and clearly, we need a national plan,” said Mark Roithmayr, the group's president. “It's time for us as a nation to see these numbers for what they truly are, and for us as a nation to commit to doing much more than we've done for date.”
The CDC plans to use its autism surveillance network to examine rates of cerebral palsy, intellectual disabilities and vision problems, according to Susan Levy, a developmental pediatrician at the Children's Hospital of Philadelphia, who is involved in the research. Knowing the rates of other conditions will help put the autism in a broader context, Levy said. “If everything is increasing, it gives you perspective.”
Autism-spectrum disorders include three major categories, autism, Asperger's and Pervasive Developmental Disorder-Not Otherwise Specified, or PDD-NOS. To be diagnosed with autism, a child must have deficits in three areas: communication, social skills and in the ability to shift focus — children tend to perform repetitive behaviors such as hand flapping. Those diagnosed with Asperger's learned to speak at the appropriate time but communicate awkwardly.