Saturday, June 14, 2008

1 in 150? Really? Part 1.1?

Jonathan, of the Autism's Gadfly blog, pointed out in a response to my previous entry1, that the 1 in 150 prevalence rate for Autism in the US came from an ongoing study by the Centers for Disease Control.

Here is their information about Autism prevalence. Their report is here2,3,4. As a layman5 in the public health field, I will need to go over these papers a bit more closely in order to produce an analysis.

The only thing that I find to be consistent in all of these studies is how divergent their conclusions are, running the gamut from 2 in 10,000 to 62.6 per 10,000. Changes in the definition of Autism over the years accounts for a lot of the differences. Diagnoses can vary as well, because clinicians will often have to make a judgment call when faced with borderline cases.

Footnotes:

  1. Needless to say, I am thrilled that my blog is getting responses. I do not really care if you disagree with me, as long as you keep it civil. B^)

  2. Centers for Disease Control and Prevention. "Prevalence of Autism Spectrum Disorders — Autism and Developmental Disabilities Monitoring Network, Six Sites, United States, 2000" Surveillance Summaries, 2007-02-09 Morbidity and Mortality Weekly Report (2007) 56:SS-1

  3. Centers for Disease Control and Prevention. " Prevalence of Autism Spectrum Disorders — Autism and Developmental Disabilities Monitoring Network, 14 Sites, United States, 2002" Surveillance Summaries, 2007-02-09 Morbidity and Mortality Weekly Report (2007) 56:SS-1

  4. Centers for Disease Control and Prevention. " Evaluation of a Methodology for a Collaborative Multiple Source Surveillance Network for Autism Spectrum Disorders —Autism and Developmental Disabilities Monitoring Network, 14 Sites, United States, 2002" Surveillance Summaries, 2007-02-09 Morbidity and Mortality Weekly Report (2007) 56:SS-1

  5. Although I make my living writing computer software, my background is actually in physics.

3 comments:

jonathan said...

As a former special education student, I believe that one of the main reasons for the huge reported increases in autism prevalence is because diagnoses follow the dollar. There is a temporal relationship between including autism as a diagnostic category in 1991 under IDEA and increased prevalence. John Gurney an epidemiologist in Minnesota notes this relationship in one of his studies, though i don't have the link or reference handy. Also court decisions such as the Shannon Carter case which stated that noncredentialed teachers could be funded by the state which lead to persons without credential being able to practice Lovaas ABA.

So far there has been no evidence of a correlation of anything in the environment triggering autism increases. Vaccines and thimerosal the most popular whipping boys have been studied ad nauseum with no evidence that they are the culprits. However, no one will study the effects of special ed legislation and the pie in the sky promises of special education. The truth shall set us free but sometimes it can piss us off. You might want to include something about special education legislation and court decisions in your analysis and study of causes of autism increases.

R. Gerald Lovejoy said...

Thanks for your comments, jonathan.

One thing that I would like to explore further would be the distribution of ASDs. Parents of children on the severe end of the spectrum often accuse those of us who are Aspergers or high-functioning, either of not being "really" autistic, or of not being "representative" of the autistic population. Has there been any real, peer-reviewed research on the distribution of people on the Spectrum?

My suspicion is that those people on the low-functioning end of the spectrum are decidedly in the minority. This hypothesis is solely based on how a Gaussian distribution works: I have no actual proof one way or the other.

The work I am being paid for is getting in the way of blogging, but I hope to start something on this on Wednesday.

jonathan said...

Well, not sure of all of the research, but one thing that has been established time and time again in various studies including the recent one by the CDC is a prevalence among autistic males that is four times higher than autistic females. I think there have been also some studies that have found that generally, as a group, female autistics are generally lower functioning though i can't cite the specific references. For that reason, I think the persons who say that certain types of autistics, those who seem to post publically on the internet and are involved in neurodiversity are not representative of autistics as a whole have a valid point. Whether or not these people are really autistics is another issue.

You can see that the majority of these internet autistics are females who are very high functioning. I have written about this on my website www.jonathans-stories.com/non-fiction/neurodiv.html in my article "neurodiversity: just say no". They sometimes imply to be representative of autistics as a whole in saying "we don't want a cure" and things like that when this would not appear to be the case. At one time it was thought that 75% of autistic people were mentally retarded or at least functioned at a mentally retarded level because lack of speech would prevent them showing their true intellectual level. That figure is probably obsolete, but i doubt extremely mild autistics are in the minority as you imply and very few, myself included, function at a level anywhere near the one which you do.