Over on Kevin Leitch’s Left Brain/Right Brain, an author identified as Joseph has an entry worth reading. Under the title “Is the Prevalence of Low Functioning Autism Among the Amish Actually Lower Than Expected?” Mr. Joseph discusses data reflecting the hypothesis that prevalence of Autism in children in Amish families will be lower than it is in the general population, because Amish families do not use vaccinations.
The prevalence of low functioning autism among 2-9 year-old Amish children in Lancaster County, Pennsylvania, has a lower bound of 14.2 in 10,000. This is in line with the prevalence of reported autism with mental retardation in the California DDS system (at most 13.1 in 10,000) for the same age cohort. Additionally, it is not too far away from the prevalence of low functioning autism as ascertained by more methodologically rigorous epidemiological studies.
While no assertion can be made about the prevalence of high functioning autism among the Amish, the existence of an “Amish anomaly†is unsupported and appears increasingly unlikely.
I am wary of interpreting these data as providing strong evidence, because the samples appear open to doubt. The issue in these discussions is the prevalence of Autism and determining prevalence of a disorder requires samples in which every individual in the population has an equal chance of being included (at least in my simple understanding, that’s what “representative” means when it’s used as an adjective with the word “sample”). So, these data appear helpful in raising questions, but not in establishing facts.
That quibble, aside, it’s interesting to see the discussion.
Link to Mr. Joseph’s article.
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Thanks for the link. It is in fact difficult to make a comparison. The Amish of Pennsylvania have something called “The Clinic For Special Children” that specializes in genetic syndromes, where autistic children are apparently referred. The same is not true of California I think, but on the other hand, it would be reasonable to suppose there’s more awareness of autism in California and a lot more specialists able to diagnose autism.
Of course, what I reported was an absolute minimum prevalence. It is actually quite possible that the Amish have a much higher prevalence of low functioning autism (mostly syndromic) than the general population. I say that because of the following.
(source)