Why No Increase?

With such clear data, why would anyone think there is no increase in autism?

Critic of the "autism epidemic" point of view centers around several issues. At the basis of these issues lies diagnosis substitution. An autistic person would not have been diagnosed with autism in the 17th century because Kanner first described autism in 1943. If there were autistic people prior to 1943 they would have been diagnosed differently. Most likely they would be considered developmentally delayed or mentally retarded. Maybe Kanner just described as a separate condition what was earlier considered a subset of mental retardation and/or developmental delays. As his definition became better known and accepted by other physicians and psychiatrists an increasing number of people were diagnosed as autistic.

Diagnosis substitution has been driven to a large degree by broadening of diagnostic criteria. Over the years there have been several revisions of the autism definition, each time broadening the criteria to include more cases. One could actually view Kanner's paper as the first broadening of the autism definition. Every time the autism definition is expanded diagnosis substitution increases.

Another frequently raised point is that in recent years the societal stigma of having autism has been significantly reduced and many services have been offered to autistic individuals. This has provided incentives for doctors to give autism diagnosis to their patients, thus making them eligible for services. Again, this results in wider diagnosis substitution.

Besides diagnosis substritution, it is possible that, as criteria and awareness of autism have expanded, many high-functioning autistics who would not have been diagnosed with any disability in times past are now receiving an autism diagnosis.

All these trends are undeniable. But are the effects sufficient to fully explain the increase in autism diagnosis? This issue is controversial and very important. If there is an actual significant increase in autism, then there is likely an environmental cause. Research efforts should be focused on finding this cause or causes. A significant increase in recent years would point to some assault that has been introduced and/or significantly increased recently, such as pesticides, immunizations, environmental polution, etc. If, on the other hand, there isn't a real increase in autism there would be little reason to focus significant research efforts on recent environmental changes.

With this in mind, it is well worth it to examine the available studies on autism prevalence.