Brain testosterone theory:

Simon Baron-Cohen proposes a model for autism based in his empathising-systemising (E-S) theory. His team at the Autism Research Centre in Cambridge, UK, measured testosterone levels in the amniotic fluid of mothers while pregnant. This is presumed to reflect levels in the babies themselves. The team found that the babies with higher fetal testosterone levels had a smaller vocabulary and made eye contact less often when they were a year old.

His group has looked at the original 58 children again, at age four. The researchers found that the children with higher testosterone in the womb are less developed socially, and the interests of boys are more restricted than girls. The results will be published in the Journal of Child Psychology and Psychiatry (2004).

Baron-Cohen theorizes that high fetal testosterone levels push brain development towards an improved ability to see patterns and analyse systems. Males supposedly tend to be better at these tasks than females. But the high levels are thought to inhibit the development of communication and empathy, which are allegedly typical female skills. (New Scientist, 24 May 2003). There is still no demonstrable evidence that testosterone levels affect brain development at all, let alone autism. Gender or bio-determinism is a fashionable explanation for many human behaviours, but has been challenged by other professionals.

Vaccine theory:

The Wakefield Study: Controversial research by Andrew Wakefield in the UK, published in The Lancet in February 1998 suggested a possible link between autism and the MMR vaccine. The original research has come under criticism, Read more...

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