Dramatic Explosion of Autism Rates Does Not Fit the Genetic Model -- Environmental Causes Are Being Studied

The number of children who have been diagnosed with one of the autism spectrum disorders (ASDs) has climbed to a startling degree.

The most severe ASD is autistic disorder (which often is called simply “autism”); another form is Asperger syndrome. In the United States, the diagnosis of ASDs increased roughly 10-fold over the course of a decade, from 4–5 children per 10,000 in the 1980s to 30–60 children per 10,000 in the 1990s, according to a report in the August 2003 Journal of Autism and Developmental Disorders.

The prevalence of ASDs plays into the fundamental question of what causes these disorders. If the number of cases is truly on the rise, then it would seem likely that some change in the environment is driving up the total. That’s partly what has divided scientists into opposing camps—they cannot agree on the relative importance of genetic and environmental factors in the disorders’ etiology.

Despite the promise of new epidemiological studies indicating the importance of environmental factors, some researchers are still dismayed, as one scientist put it, that “geneticists are running the show, and ignoring the environmental aspects.” What would it take for things to change?

One researcher invokes the ideas of philosopher Thomas Kuhn, who suggested that scientific revolutions occur when an old paradigm is replaced by a new one. “I believe we’re in the middle of a paradigm shift,” the scientist said. “The dramatic explosion of autism rates does not fit the genetic model. It’s an anomaly that will kill the old paradigm.”