Nature Medicine | Spoonful of Medicine

Autism reaches record high levels in the US

The US Centers for Disease Control and Prevention today reported that the number of children with autism spectrum disorders (ASD) has risen to an estimated 1 in 88 (1.1%), up from 1 in 110 (0.9%) according to agency estimates from two years previous. The prevalence figure is the highest since the CDC began its biennial nationwide survey of children ten years ago.

The survey released today assessed rates of autism in eight-year-olds at sites in fourteen states in 2008. The new US rate is on par with the 1% rate reported in the UK, and is significantly lower than the 2.6% prevalence observed in South Korea, according to reports from last September.

“Some of the increase is due to an increase in diagnosis, although how much is due to this is unknown,” Coleen Boyle, director of the CDC’s National Center on Birth Defects and Developmental Disabilities, said in a press telebriefing today. In the last decade, doctors, parents and teachers have gotten better at recognizing symptoms of ASD. But “a large portion of the increase, some 50%, remains unexplained,” said Mark Roithmayr, president of Autism Speaks, a New York-based advocacy group. “We need more research into potential environmental causes.”

Roithmayr is not alone in his concern that environmental factors may be partly to blame for the rise in autism. As Nature reported in November, the steady increase in ASD prevalence has led epidemiologists at the CDC and elsewhere to launch multiple studies in the past five years that have gathered environmental, developmental and genetic information from large numbers of children in the hopes of pinpointing the driving factors behind the disease. Yet, despite a slew of genetic markers have been correlated to high rates of autism, their actual importance and how and why those genes are expressed remains a mystery. The harrowing history of false alarms, such as the discredited link between vaccines and autism, raises the bar for such studies.

Regardless of the cause, all the experts at today’s press conference agreed that earlier detection of ASD is critical. Today’s report shows that the average age of diagnosis continues to hover near four years old, nearly unchanged from recent years, meaning that although detection is getting better overall, services are not getting to children any earlier. And, as the University of Rochester’s Susan Hyman, chairperson of the autism subcommittee of the American Academy of Pediatrics, pointed out, “To meet the need presented by increasing ASD diagnoses, federal autism resources will need to expand.”

Photo courtesy of the US Centers for Disease Control and Prevention


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