In The Politics of Autism, I write:
While many people with autism received the tag of “mentally ill,” even more fell into the category of “mentally retarded.” Again, the reasons for the label are easy to grasp. Some people on the spectrum do have low IQs, though not as many as researchers once thought. More important, poor attention to task may cause intelligent people with autism to stumble on standardized tests. “Mental retardation” was a convenient catchall category for people with low scores and unusual behavior.At Left Brain/Right Brain, Matt Carey looks at data from the California Department of Developmental Services. He finds support for the idea that diagnostic substitution accounts for much of the apparent rise in autism prevalence:
You see I also graphed intellectual disability. I got autism counts, intellectual disability counts and “unduplicated” (total, each disabled person counted once) by birth year. I also got census data by birth year. And I graphed them. And anyone claiming CDDS data show an autism epidemic needs to do the same and to explain this graph, complete with the sharp peak for birth year 1993. (click to enlarge):
Intellectual disability has dropped. Off about 40% of the peak value.
If you think your idea for the rise in autism is correct, let’s take the failed vaccine idea as an example, you need to also explain how that resulted in far fewer people with intellectual disability. Plain and simple. And none of these claimed causes of an “epidemic” can explain the drop in ID.
Why bother challenging the people claiming an autism epidemic? Because it denies the existence of undiagnosed autistic adults. We have very little effort to identify those who were missed in past generations. And the likelihood is that these people–our people–are not being supported appropriately because of their misdiagnoses. And not only are we abandoning the misdiagnosed, we are failing to learn. What worked for past generations, the adults of today? What failed? What are the appropriate supports for the various needs of autistic adults? We don’t know today. And are unlikely to know by the time my kid is an adult, especially if we aren’t even looking at autistic adult needs today.
And then there’s the whole autism causation question. People spending their time trying to correlate CDDS data–data clearly confounded by numerous social influences–are unlikely to ever find a real answer.
But, for those who want to keep trying, include all the data. Give an explanation for this and you may be on to something.