The idea that autism may be the manifestation of an "extreme male brain" has received support from a study showing that higher levels of fetal exposure to testosterone are associated with the later presence of autistic traits in childhood.
Bonnie Auyeung and colleagues found that among 235 mothers, those who had higher levels of testosterone in their amniotic fluid during pregnancy, subsequently rated their children, when aged between six and ten years, as showing more autistic traits, such as avoiding eye contact. This was true whether the children were studied as a group, or if the analysis was done on just girls or just boys.
It's not yet known for sure whether fetal exposure to testosterone causes the presence of these autistic traits or whether a third unknown factor affects both testosterone levels and the presence of the traits. It is also worth remembering that the children in this study were not actually diagnosed with autism. Fetal exposure to testosterone has only been linked by this study with the presence of autistic-like traits. However, the researchers are planning to test the significance of fetal testosterone exposure among children with an actual diagnosis of autism.
"If, according to the extreme male brain theory, autistic spectrum conditions are an extreme of male-typical behaviour, exposure to elevated levels of fetal testosterone could be one important factor that is involved with the development of the condition," the researchers said.
The findings from this study led to discussion in the media about the prospects of a fetal test for autism. For example, co-author Simon Baron-Cohen wrote this piece for BBC News online.
Bonnie Auyeung, Simon Baron-Cohen, Emma Ashwin, Rebecca Knickmeyer, Kevin Taylor, Gerald Hackett (2009). Fetal testosterone and autistic traits. British Journal of Psychology, 100 (1), 1-22 DOI: 10.1348/000712608X311731
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.