Research at Cambridge University's Autism Research Centre (ARC) has found that exposure to high levels of testosterone in the womb is related to the development of autistic traits.

We all have some autistic traits - these are a spectrum or a dimension of individual differences, like height.

Professor Baron-Cohen

The findings, published in yesterday's British Journal of Psychology (January 12), show that levels of testosterone in amniotic fluid were linked to children's autistic traits up to ten years later.

Dr Bonnie Auyeung, Professor Simon Baron-Cohen and their colleagues at the ARC measured the levels of foetal testosterone in the amniotic fluid of 235 women who underwent amniocentesis (a test of the amniotic fluid to determine genetic defects in the foetal DNA) during pregnancy. Years later these mothers completed questionnaires that measured their child's autistic traits. By this time, the 118 boys and 117 girls were aged between 6 and 10.

High levels of foetal testosterone were found to be associated with high scores on two separate measures of autistic traits (the Child Autism Spectrum Quotient (AQ-Child) and the Childhood Autistic Spectrum Test (CAST)) for both boys and girls. High scores on these measures of autistic traits reflected poorer social skills and imagination but good attention to, and memory for detail.

Professor Baron-Cohen said: "The study highlights for the first time the association between foetal testosterone and autistic traits. We all have some autistic traits - these are a spectrum or a dimension of individual differences, like height."

He added: "It is a shame that this research was inaccurately reported in some sections of the media that suggested the study demonstrated that elevated foetal testosterone is associated with a clinical diagnosis of autism or Asperger Syndrome. Our study has not yet shown that. To do that would need a sample size of thousands, not hundreds. Our ongoing collaboration with the Biobank in Denmark will enable us to test that link in the future.

"Reports also linked this research with prenatal screening for autism that was not the objective of this study. This study was not a screening study and was conducted purely to understand the basic neurobiological mechanisms underlying individual differences in autistic traits."

Dr Auyeung commented: "This research goes further than previous studies which have found that higher levels of foetal testosterone are associated with less eye contact in the child's first year, slower language development by their second birthday, more peer difficulties at four years old and more difficulties with empathy by the time they're six. This new study also links higher foetal testosterone to autistic traits such as excellent attention to detail, and a love of repetition, as well as social and communication difficulties".

This unique longitudinal project was funded by the Medical Research Council and the Boston-based Nancy Lurie Marks Family Foundation. The published paper as a pdf is available from the Autism Research Centre's website, follow the link on the right.

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