Tuesday, September 20, 2005

Reviewing the Autism Prevalence (The Use of the IDEA Data: Part 1)

The Individuals with Disabilities Education Act (IDEA, 1990) was a renaming and a revision of earlier law special education law. The IDEA has since gone through several revisions of its own which can be traced on the US Department of Education website (http://www.ed.gov/policy/speced/guid/idea/idea2004.html).

A yearly accounting of various things including the number of children served in the IDEA service categories are issued by the US department of Special Education to the US Congress every year. It is from these reports that some have begun to track Autism prevalence (The Autism AutoImmunity Project, 2004)

IDEA (1990) created Autism, as a service category in U.S. special education. The IDEA definition is characterized as an assessment of need, not a diagnosis by eligibility alone (Autism Watch, September 15, 2004). This is further complicated by the fact that the States have some freedom to make their diagnostic criteria for Autism more permissive. This seems to be exactly what the States of Oregon and Minnesota have done (Autism Watch, September 15, 2004). These two states have the most students receiving services under the Autism category. In Oregon and Minnesota the diagnostic criteria is permissive when compared to other States. Oregon requires a general agreement from multidisciplinary team that a child meets criteria for Autism, as opposed to an additional separate diagnosis from a professional certified to use the DSM-IV (Autism Watch, September 15, 2004).

The education based data from the IDEA reports to Congress also require some critical thinking. The diagnostic differs from the ICD-10 and the DSM-IV. The US mental health professionals use the DSM-IV. International mental health professionals may use the DSM-IV or the ICD-10. School IEP teams use the IDEA definitions. This is important because, there are discrepancies between the diagnostic systems. A person receiving services under the Autism category of the IDEA may simultaneously be diagnosed with Pervasive Developmental Disorder-Not Otherwise Specified, according to the DSM-IV.

There are other differences as well. In the mental health diagnostic systems, roughly the same percent of persons are diagnosed from their respective racial populations (Fombonne, 2003). So if 1 in 166 White children are diagnosed, 1 in 166 Hispanic children are also going to be diagnosed. This not what we observe in the IDEA data sets.

Figure 4, is created from data provided from IDEAdata.org. The overall population comes from the 2000 census projections. I have added in the Mental Retardation data to give an additional comparison group. The data indicate slightly more White students receiving services for Autism than their overall racial percentage. This is a difference of roughly 5 percentage points. This seems only very moderately discrepant from the (Fombonne, 2003) observation.

This is more pronounced in individual States. Figure 6, represents the data from California. In California, (11%) more White students receive services than their overall racial percentage. At the same time (17%) fewer Hispanic students receive services compared to their overall racial percentage. The differences in racial categories, concerning receiving Autism category services, seems significant in California and discrepant with the (Fombonne, 2003) observation. Due to this discrepancy it is useful to review the mental health numbers supplied by California’s Department of Disability Services and compare it to the census projections for California in 2003. We can look at this in Figure 7. This is extremely interesting because, the Hispanic discrepancy noted in the education numbers are not noted in the DDS numbers.

So what the heck is going on in California and in whole US to some extent? The disappointing part is, it is not possible to know for sure. We can make some statements that are completely valid however, such as “The IDEA data for autism is different from the epidemiology in several important ways.”

When we go on to consider that IDEA definitions and the DSM-IV-TR serve different tasks and utilize different definitions, is this really so surprising?


American Psychiatric Association. (1994). Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. Washington, DC: American Psychiatric Association; 1994.

Autism AutoImmunity Project. (2004).
Accessed September 16, 2005

Autism Watch. Laidler, J. September 15, 2004.
http://www.autism-watch.org/general/edu.shtml.Accessed September 16, 2005.

Day, J. C. (1996). Population projections of the United States by age, sex, race, and Hispanic origin: 1995 to 2050. US Bureau of the Census, Current Population Reports, P25-1130, U.S. Government Printing Office, Washington, DC.

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.

Individuals with Disabilities Education Act. (1990). Public Law 101-476, U.S.C.

World Health Organization. (1992). International Classification of Diseases, 10th Revision (ICD-10). Geneva, Switzerland: World Health Organization; 1992.

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 (IDEAdata.org; 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.

Welcome to My Blog

The point of this blog is to look at statements and research relating to the Autism Spectrum. I am a student researcher and my primary interest is "research design in the autism spectrum". I have no conflict of interests or vested interests, I do not recieve funding or favors from private/public companies. As a graduate student I do recieve finnacial support from my university, but also the freedom to dictate my research based on my interests.

This blog will focus on topics that seem deservingly debatable, as opposed to more obvious quackery in the field of autism. I understand and appreciate that these subjects are personal and important to many people. I plan to focus only on the arguments and not upon charatcter or motive. I would ask for anyone who chooses to post here to follow this as well.