1. current prevalence of autism in the US is 1 in 150;
2. 10 years ago, prevalence was 1 in 1500 (as stated on all of Autism Speaks' press releases);
3. the "rate of autism is rising 10-17 percent annually. Unfortunately, the numbers appear to be continuing their upward climb";
4. there is an "epidemic" of autism, and this is a "recent epidemic";
5. because the autism epidemic is recent, older autistics do not exist; and
6. there are 1.5 million autistic people, total, in the US.
Given this array of information, the question remains as to how Autism Speaks calculated their 1.5 million figure. This figure is inconsistent with existing data. Autism Speaks' Chief Science Officer, Geraldine Dawson, was kind enough to provide more information:
1. Autism Speaks is using the 2000 census figure of ~280 million for current total US population;
2. Autism Speaks is using not the 1 in 150 prevalence figure Autism Speaks widely promotes, but a prevalence of 1 in 166;
3. the source for the 1 in 166 figure is Bertrand et al. (2001);
4. applying a prevalence of 1 in 166 across the total US population of 280 million yields 1.68 million autistics (it is actually 1.69 million);
5. this figure is rounded down to the nearest half million, to the Autism Speaks 1.5 million.
I can spot some problems. Autism Speaks states that the prevalence reported in Bertrand et al. (2001) is 1 in 166. But even a cursory reading of this paper's abstract shows that this is false. Here's a quote:
"The prevalence of all autism spectrum disorders combined was 6.7 cases per 1000 children."Prevalence of 6.7 per 1000 comes out to 1 in 149--or about 1 in 150, the prevalence figure Autism Speaks widely promotes. Applying a prevalence of 1 in 150 across the 2000 US census figure of 280 million equals 1.87 million autistics. Following Autism Speaks' apparent policy of rounding to the nearest half million, that would be 2 million autistics in the US.
Then where does the 1 in 166 prevalence figure came from? The source Autism Speaks provided, Bertrand et al. (2001), does not report this figure. Autism Speaks' epidemiological expert, Michael Rosanoff, helpfully informed me that Autism Speaks was using figures from the US only, in calculating the Autism Speaks 1.5 million.
In fact the 1 in 166 figure first appeared in the literature in Chakrabarti and Fombonne (2001), as an estimate based on the results of three epidemiological studies. Two are UK studies (Baird et al., 2000; Chakrabarti & Fombonne, 2001); the other is the US study, Bertrand et al. (2001) which reported a prevalence of ~1 in 150. No published US epidemiological study reports a prevalence of 1 in 166.
Another problem is that Autism Speaks' Chief Science Officer is stating that there is a high, stable rate of autism. This is a scientifically sound position but, as enumerated above, one thoroughly rejected by Autism Speaks.
Instead, Autism Speaks widely disseminates the information that the prevalence of autism "has increased tenfold in the last decade." That is, 10 years ago, the prevalence of autism was 1 in 1500. If this is accurate, then the total number of autistics in the US would be less than 500,000. How much less would depend on what happened prior to 10 years ago, and how suddenly the leap from 1 in 1500 to 1 in 150 occurred.
At the same time, Autism Speaks is basing its epidemiology on three US studies. In Bertrand et al. (2001), the children were born between 1988 and 1995. Virtually all would be diagnosable as autistic by ten years ago, and the prevalence in this population was found to be ~1 in 150.
The more recently published CDC studies (ADDMN, 2007a, b) highlighted by Autism Speaks feature children born in 1992 and 1994. Again, virtually all would have been diagnosable as autistic by 10 years ago, and prevalence in this population was reported as ~1 in 150.
So Autism Speaks' array of information about autism prevalence is distant from what is reported in the scientific literature. Overall, Autism Speaks is claiming there are fewer autistics in the US than there actually are. How many fewer varies enormously, depending on which of Autism Speaks' contradictory figures is chosen.
And the upshot is primarily the denial of the lives and existence of older autistics. In an international "They Don't Exist" campaign, Autism Speaks is denying older autistics--around the world--recognition, rights, a voice, the kind of basic services nonautistics can take for granted, etc. This anti-scientific and unethical practice is a hallmark of autism advocacy. Autism Speaks is denying the existence of most autistic adults and of large numbers of autistic children.
In order to accomplish this amazing feat, this disappearing of autistics in the US and around the world, Autism Speaks is widely disseminating false, anti-scientific information about autistic people. This false information is deployed to raise money and to alter public policy according to Autism Speaks' goals. There is no thought as to the consequences for autistics. Autism Speaks is sending a powerful message that scientific findings--which Autism Speaks raises money to fund--should be dishonestly misrepresented and discarded, when these findings inconveniently get in the way of autism advocacy leaders such as themselves. And according to Autism Speaks, so should autistic lives be discarded, if they are in the way.
References:
Autism and Developmental Disabilities Monitoring Network Surveillance Year 2000 Principal Investigators; Centers for Disease Control and Prevention. (2007a). Prevalence of autism spectrum disorders--autism and developmental disabilities monitoring network, six sites, United States, 2000. MMWR Surveillance Summaries, 56, 1-11.
Autism and Developmental Disabilities Monitoring Network Surveillance Year 2002 Principal Investigators; Centers for Disease Control and Prevention. (2007b). Prevalence of autism spectrum disorders--autism and developmental disabilities monitoring network, 14 sites, United States, 2002. MMWR Surveillance summaries, 56, 12-28.
Baird, G., Charman, T., Baron-Cohen, S., Cox, A., Swettenham, J., Wheelwright, S., & Drew, A. (2000). A screening instrument for autism at 18 months of age: a 6-year follow-up study. Journal of the American Academy of Child and Adolescent Psychiatry, 39, 694-702.
Bertrand, J., Mars, A., Boyle, C., Bove, F., Yeargin-Allsopp, M., & Decoufle P. (2001). Prevalence of autism in a United States population: the Brick Township, New Jersey, investigation. Pediatrics, 108, 1155-61.
Chakrabarti, S., & Fombonne, E. (2001). Pervasive developmental disorders in preschool children. JAMA, 285, 3093-9.
[Conflict of interest declaration: I'm affiliated with a research group which receives funding from Autism Speaks, among other funding sources.]