One of my queries with the notion that changes in diagnostic criteria have resulted in the increased diagnoses is that the changes to the criteria occur only once every few years. So for instance, one would expect the diagnostic changes in the early 1990s to produce a noticeable increase in diagnoses over the next few years, but that the rate of increase would level off over time. Instead, we are seeing a year-on-year increase over time with no levelling off. So that does not seem to fit?
This from wikipedia entry on autism epidemiology:
Quote:
A 2009 study of California data found that the reported incidence of autism rose 7- to 8-fold from the early 1990s to 2007, and that changes in diagnostic criteria, inclusion of milder cases, and earlier age of diagnosis probably explain only a 4.25-fold increase; the study did not quantify the effects of wider awareness of autism, increased funding, and expanding support options resulting in parents' greater motivation to seek services.[36]