Testosterone Levels Linked To Autistic Traits

Exposure to high levels of testosterone in the womb is related to the development of autistic traits.

This is the conclusion of groundbreaking research published in the British Journal of Psychology on 12th January 2009, which found that levels of testosterone in amniotic fluid were linked to children's autistic traits up to ten years later.

Psychologists Dr Bonnie Auyeung, Professor Simon Baron-Cohen and their team at the Autism Research Centre at the University of Cambridge measured the levels of foetal testosterone in the amniotic fluid of 235 women who underwent amniocentesis during pregnancy.

Years later these mothers completed questionnaires that measured their children'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, imagination and mind reading but good attention to, and memory for detail. The team followed the children from before birth during the unique longitudinal project, which was funded by the Medical Research Council (UK) and the Boston-based Nancy Lurie Marks Family Foundation.

This research goes further than previous studies which have found that higher levels of foetal testosterone are associated with less eye contact at children's first birthday, slower language development at their second birthday, more peer difficulties at their fourth birthday, and more difficulties with empathy at their sixth birthday.

What is novel in this new study is that as it 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.

Professor Baron-Cohen said: "The study highlights for the first time the association between foetal testosterone and autistic traits, and indicates that foetal testosterone not only masculinises the body, it masculinises the mind and therefore the brain. "We all have some autistic traits - these are a spectrum or a dimension of individual differences, like height. It is important to note that this research does not demonstrate that elevated foetal testosterone is associated with a clinical diagnosis of autism or Asperger Syndrome; 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. Dr Auyeung added: "Since the male foetus produces on average twice as much testosterone as the female foetus, the present research may be relevant to the theory that autistic spectrum conditions autism is reflect an 'extreme male brain' - that autism is an extreme manifestation in terms of the structure and function of the male brain. This theory may also explain the higher incidence of these conditions in boys than in girls." Notes The British Journal of Psychology Part 1 2009 also contains a commentary on this paper by Dr Ami Klin of Yale University School of Medicine.

The Autism Research Centre at Cambridge University comprises a group of scientists and clinicians conducting research into the psychology and biomedical aspects of autism and Asperger Syndrome, and pioneers the development and evaluation of special educational methods.