News

21st April 2004

Testosterone link to autism

Researchers at Cambridge University have suggested that autism, a condition that affects social development and communication, may be related to high levels of the male sex hormone testosterone produced while a baby is developing in the womb.

Professor Simon Baron-Cohen, director of the Autism Research Centre at Cambridge University, and his team measured the levels of testosterone (produced naturally by foetuses) in the amniotic fluid of a group of women who underwent amniocentesis during pregnancy. The scientists have subsequently studied the development of communication skills in their children at different ages.

The team found that babies who produced higher testosterone levels before birth made less eye contact at 12 months than those who had lower levels. At 18 months old, the toddlers with higher antenatal testosterone levels tended to have slower language development and smaller vocabularies.

The most recent stage of the research, where the children were tested at 48 months, shows that the children who had high antenatal testosterone levels were also likely to have reduced communication skills at this stage. None of the children in the study have so far been diagnosed with autism, which often does not happen until around five or six, but as the children grow up, the researchers hope to be able to establish whether there is a link between elevated testosterone levels in the womb and autistic spectrum conditions.

Professor Baron-Cohen has suggested that autism, which is frequently characterised by unusually strong, obsessive interests as well as difficulty with social interaction, may be an extreme version of the typically systematic male brain (he says that men's brains are generally better at systemising, while women's brains are generally better at empathising). This is borne out by the finding that autistic-like traits may be linked to raised levels of male sex hormones in the foetus.

Up to 10 times more boys than girls have autistic spectrum conditions, which may also lend weight to the theory that it is an extreme form of male behaviour. However, in the study, both boys and girls who had raised levels of foetal testosterone exhibited similar traits to those found in autistic children, suggesting that hormones may have a powerful effect on foetal brain development. This adds to the growing evidence that autistic spectrum conditions could be caused by factors affecting the development and function of the brain.

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