Testosterone in Womb Linked to Autism

Science Daily — Foetuses that produce high levels of testosterone have more autistic traits during development, said Professor Baron-Cohen from the University of Cambridge at the BA Festival of Science on September 11, 2007.

Current research by Baron-Cohen and Bonnie Auyeung at the same university shows a significant link between amniotic testosterone levels and the number of autistic traits in children. Baron-Cohen is following the development of children from 235 mothers, whose prenatal levels of testosterone were determined by amniocentesis.

So far, the children have been observed at 4 stages in their development: 12, 18, 46 and 96 months.

A difference between the children was observed as early as one year old.

The typical autistic traits observed in the children with high amniotic testosterone levels included poor empathy and social skills, and good pattern recognition and numerical reasoning.
The babies with higher testosterone levels were less likely to look at their mother’s face during playtime. Once they reached eighteen months, high-testosterone babies performed badly in vocabulary tests and were able to recognise fewer words.

At 8 years old, the children with high testosterone levels performed well in pattern recognition tests and badly in empathy tests.

The causes of elevated foetal testosterone levels are not known. There is not thought to be a link between foetal and maternal testosterone levels. Smoking and alcohol have been discounted as possible causes.

A genetic and/or environmental factor may be to blame. Twin studies have shown similar testosterone levels in identical twins, giving weight to the genetic argument.

In cases of non-identical twins, with one male and one female twin, which share the same amniotic sac, the female twin has higher testosterone levels than normal.

The Medical Research Council is funding an expansion of Professor Baron-Cohen’s study to include diagnosed autistic children. Baron-Cohen will collaborate with Denmark to match their register of autistic patients against its biobank of amniotic samples.

In future, it may be possible to select foetuses based on testosterone levels. This would raise the question of whether it is right to select children on the basis of extreme ‘maleness’ characteristics.

It is well known that men have higher foetal testosterone levels than women. Testosterone has been linked to the typical male characteristic of good problem solving.