Friday, September 16, 2005

Reviewing the Autism Prevalence (Introduction)

I intend this to be the introductory post in a series on Autism Prevalence. This will be a little longer than most posts and much more general, but this should be a meaningful way of introducing a debated and sometimes emotional topic.

Various data sets show an increase in autism. These data can be reviewed and/or accessed (; Fombonne, 2004). Some individuals have determined partly based on those data, that an epidemic of Autism exists (MSNBC, Autism: The Hidden Epidemic, March 3, 2005). The Autism Society of America was alarmed enough to send out a email to their list subscribers (Gernsbacher, Dawson, Goldsmith, 2005).

However, the issue of an epidemic is contested, it is “in play” so to speak. Other blogs and sites attest to the disagreement (Autism Watch, September 15, 2004). This issue has repeatedly been shown to be emotionally charged (search the term “autism epidemic” and the sites and quotes speak for themselves).

Two questions emerge: Is there really an increase; and why is there an increase? It is not possible at this time to determine the answer for either of these, as causation can not be shown. We are left to logical inference and to questioning techniques.

We should then ask: Is there an increase in the actual prevalence of Autism or in the number of cases we identify? Why is there a change in the actual prevalence of autism? Why is there a change in the number of cases we identify? Why is there such bitter disagreement in an answer that should be clear?

First it is worth noting that correlation is not causation. Anecdote or even research that shows a correlation between the advent of any event and Autism is not demonstration of causation and is therefore not credible proof to the broader scientific community. We do not have proof then, of any cause of autism, but more limited evidence or educated guesses. I should note that others, even certain researchers would not agree.

Maybe we can ask next “Why is there a change in the actual prevalence of autism?” This could only be answered by proof of causation, this is unavailable. For various theories,
simply search “Autism causes”.

Some of the reason bitter disagreement exists is due to the lack of strong proof and also because of a lack of agreements in other areas of the autism field. It also may be related to the deeply personal aspects of Autism. To list and explain these are well beyond the scope of this post.

The questions “Is there an increase in the actual prevalence of Autism” and “Why is there a change in the number of cases we identify” might be inter-related and could have the same starting point for an answer. This involves an exploration of the data being used to show an increase. These include epidemiology, the Individuals with disabilities Education Act yearly reports to Congress, and California Department of Disabilities Services statistics.


Autism: The Hidden Epidemic. MSNBC. March 3, 2005.
Accessed September 16, 2005

Autism Watch. Laidler, J. September 15, 2004.
Accessed September 16, 2005.

Individuals with Disabilities Education Act Amendments
of 1997, P.L. 105-17, 20 U.S.C.

Gernsbacher MA, Dawson M, & Goldsmith HH. (2005).
Three reasons not to believe in an autism epidemic.
Current directions in psychological science, 14 (2), 55-58.


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