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Published online 13 January 2009 | Nature | doi:10.1038/news.2009.21
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What is the link between autism and testosterone?
Controversial theory of autism makes headlines, but leaves scientific community unconvinced.
Children who are exposed to high levels of testosterone in the womb show similar results in psychological tests to people with autism. The findings provide support for a contentious theory of the condition's cause, researchers say.
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Dr Kate Plaisted-Grant says that our 2009 study in the British J. Psychology has not established a link between foetal testosterone (FT) and the cognitive profile of autism. However, this study did not set out to test that link, as it does NOT study children with autism. This is a common misunderstanding. The study focuses on typically developing children. To test for a link between FT and autism per se would require a sample size of thousands, not hundreds, as autism is only 1% of the population. We are pleased to see that she acknowledges that FT creates a 'special brain', though she refrains from using the term 'male brain'. For us, this special brain is, as your journalist describes, one that has a stronger drive to systemize but a weaker drive to empathize. Prof Laurent Mottron also makes a common error, namely, saying that males and people with autism score the SAME on autism questionnaires. In fact, there are no studies that show this, but there are many that show that people with autism show an extreme of the male score on autism questionnaires. And nor do male and autistic brains weigh the same, if we take Mottron's comment literally. The average male brain weighs more than the average female brain, and the average autistic brain weighs even more than the average male brain. The citations supporting the above statements can be found in Baron-Cohen, S, Knickmeyer, R, & Belmonte, M (2005) Sex differences in the brain: implications for explaining autism. Science, 310, 819-823. The extreme male brain theory of autism remains to be tested using MRI, and the FT theory of autism also remains to be tested in large enough samples. Finally, I too would oppose prenatal screening for autism (which the Guardian (January 12th 2009) confused with our study) with a view to prevention or termination, on moral grounds. Though if such a test existed (which it does not yet), parents are of course free to exercise their legal right to choose. Simon Baron-Cohen, Cambridge
Even if it is ?a moral, rather than a scientific, question?, surely the science is still crucial to the consideration of that question? The media reporting included statements along the lines of, ?A prenatal test for autism would [potentially] deprive the world of future geniuses? [Guardian]. Would this be valid reasoning in the case of autism and a prenatal test for it or would it be an example of the ?Beethoven fallacy??
Why do people keep referring to autism and aspergers as if they were single disorders? There are clearly many different disorders being lumped together as autism and there are at least two or three disorders being lumped together as aspergers. You can tell some of these disorders appart by their appearance. Sebat et al' paper in Science showed that some people with ASD were hemizygous for oxytocin explaining their symptoms.
paul hayes makes a good point. a foetus does not have to prove their right to life by having a potential talent. there is a discussion of this at http://www.communitycare.co.uk/Articles/2009/01/14/110412/professor-simon-baron-cohen-autism-is-not-cancer.html
Although I agree that a foetus has no obligation to prove its 'worth', that is not the point I was trying to make. What concerned me about what I'd read in the media reports and the responses to them was a) the failure to distinguish between reproductive choice and discrimination between or against existing persons and b) the failure to consider whether or not there does actually exist evidence concerning the nature of autism and any likely prenatal test for it which would suffice to render the "Beethoven fallacy" moot. I realise that autism is not the same as cancer, and the question is far more complicated, but does the autism science really imply that a prospective parent, told the results of a prenatal test indicating e.g. a high probability of disabling autism, should also take into consideration that their decision might have negative 'eugenic' consequences as far as the number of Diracs provided to society is concerned? http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1733465