A new CDC analysis of autism prevalence shows a nearly 30 percent jump in cases between 2008 and 2010: that means 1 out of every 68 eight-year-olds in the U.S. is diagnosed with the disorder.
But health officials still don't agree on what's driving the increase. Debate continues to rage over whether the increase in cases is due to changing definitions and greater awareness of autism spectrum disorders, or if it's due to some environmental or other factor.
Karen Weintraub reports for USA Today:
...virtually every grade in every elementary school has at least one child with autism – a seemingly astonishing rise for a condition that was nearly unheard of a generation ago.
What's still unknown is the driver of that increase. Many experts believe the rise is largely due to better awareness and diagnosis rather than a true increase in the number of children with the condition.
"We don't know the extent those factors explain in terms of the increase, but we clearly know they do play a role," said Coleen Boyle, director of the National Center on Birth Defects and Developmental Disabilities at the CDC. "Our system tells us what's going on. It (only) gives us clues as to the why."
The aging of parents is also known to be a factor; the chances of autism increase with the age of parents at conception.
"But that's not the whole story is it?" said Robert Ring, chief science officer for Autism Speaks, a research and advocacy group. Whether something in the environment could be causing the uptick remains "the million-dollar question," Ring said.
Despite their concern, experts said they were not surprised by the increase, because other data had suggested the numbers would continue to climb. In New Jersey, for instance, autism rates were 50% higher than in the rest of the nation in 2000, and they remained that much higher in 2010 – suggesting the national rates will continue to rise to catch up, said Walter Zahorodny, a psychologist who directs the New Jersey Autism Study. "To me it seems like autism prevalence can only get higher," he said.
The American Academy of Pediatrics released the following statement on the CDC numbers:
“The prevalence data makes even more important the Academy’s focus on early screening, identification and referral for intervention for allchildren, and our work to support collaborative medical homes for children, youth and adults with autism spectrum disorder,” said Susan Hyman, MD, FAAP, chair of the AAP autism subcommittee...
The AAP urges Congress to reauthorize the Combatting Autism Act, which has led to significant advances in early intervention, behavioral treatments, and understanding of the causes of autism. Today’s numbers highlight the need to immediately reauthorize this legislation before funding expires.
At the same time, researchers exploring the genetic underpinnings of autism report that differences in the brains of autistic children suggest that the spectrum of disorders likely begins in the womb. NPR reports:
Brain tissue taken from children who died and also happened to have autism revealed patches of disorganization in the cortex, a thin sheet of cells that's critical for learning and memory, researchers report in the New England Journal of Medicine. Tissue samples from children without autism didn't have those characteristic patches.
Organization of the cortex begins in the second trimester of pregnancy. "So something must have gone wrong at or before that time," says Eric Courchesne, an author of the paper and director of the Autism Center of Excellence at the University of California, San Diego.
The finding should bolster efforts to understand how genes control brain development and lead to autism. It also suggests that treatment should start early in childhood, when the brain is capable of rewiring to work around damaged areas.