Autism Cases on the Rise; Reason for Increase a Mystery
Scientists are scouring genetic and evironmental data to find a cause for the rise in autism.
Autism: A True Increase or Semantics? continued...
Another study conducted by the CDC in 14 states found an overall prevalence of one in 152, which Milunsky and others say is the generally accepted figure today.
Other experts say autism is on the increase but that factors other than more children being diagnosed play a role. Some of the increase in reported cases is because of "diagnostic substitution," says Paul Shattuck, PhD, assistant professor of social work at Washington University in St. Louis and an autism researcher.
"A kid labeled autistic today could have been labeled mentally retarded 10 years ago in the same school system," Shattuck says. It wasn't until 1992 that schools began to include autism as a special education classification.
Today, children diagnosed as having autism spectrum disorder are often more mildly affected than the classic "Rain Man" stereotype some people associate with the disorder, Shattuck says. After autism was first identified in 1943, some of the first studies found most of the children mentally retarded. "Today the minority of kids [with ASD] are mentally retarded,'' Shattuck tells WebMD.
The debate about whether the reported increase in autism is affected by factors such as more awareness misses the point, says Isaac Pessah, PhD, a professor of toxicology, director of the Center for Children's Environmental Health Sciences, and a member of the MIND Institute at the University of California Davis. Rather than argue about whether the increase is because of some children being reclassified or other factors, he says, "We need to understand why it's one in 150."
Focusing on the actual numbers -- rather than the debate -- is wise, says Craig Newschaffer, PhD, chairman and professor of the department of epidemiology and biostatistics at Drexel University School of Public Health in Philadelphia. "We thought autism was a very rare occurrence, and it's clear that it's not."
Getting to the Causes of Autism
Getting to the cause -- or, more accurately, causes -- of autism will be more difficult than unraveling the causes of cancer, says Gary Goldstein, MD, president and CEO of Kennedy Krieger Institute in Baltimore, a facility that helps children with autism and other developmental disorders.