SAN DIEGO – Not long ago, autism was among the rarest of disorders, afflicting only one child in every 2,000-5,000. This changed dramatically with the publication in 1994 of DSM IV (the manual of psychiatric diagnosis widely used around the world). Soon, rates exploded to about 1 per 100. And a large study in South Korea recently reported a further jump to 1 in 38 – an astounding 3% of the general population was labeled autistic. What is causing this epidemic and where are we headed?
The natural reaction to any plague is panic. Parents are now fearful that every delay in speech or socialization presages autism. Childless couples decide to avoid having kids. Parents with autistic children are desolate and desperate to determine its cause.
The British physician Andrew Wakefield’s vaccine theory became wildly popular among parents, many of whom began to withhold vaccination (thus subjecting their own and other children to the risk of entirely preventable, and sometimes serious, illnesses). Vaccination seemed a plausible cause because of the fortuitous correlation between getting shots and the onset of symptoms. Wakefield’s work has now been thoroughly discredited as incorrect and dishonest science. But fear of autism is so great, and the reactions to it so irrational, that in some circles Wakefield continues to be revered as a false prophet.
Other factors must be behind the sharp rise in the diagnosis. Before DSM IV, autism was among the most narrowly and clearly defined of disorders. Symptoms had to begin before age three and comprised a striking and unmistakable combination of severe language deficits, inability to form social relationships, and a preoccupation with a very narrow set of stereotyped behaviors. In preparing DSM IV, we decided to add a new category describing a milder (and therefore much more difficult to define and distinguish) form of autism, called Asperger's Disorder. This seemed necessary because some (still quite rare) children presented with more or less normal language development, but with grave social and behavioral difficulties. We knew that Asperger’s would likely triple the rate of autistic disorders to about 1 per 500-1,000, but this doesn't explain the new rate of 1 per 38.