By Maxine Frith
Scientists claim that dramatic new evidence shows that autism may be just an extreme version of the male brain - suggesting the condition may be entirely genetic rather than environmental.
The research, led by a team at Cambridge University, links autism to higher levels of the male hormone testosterone in babies in the womb.
The theory holds out the possibility that in the future pregnant mothers could be screened for autism in the same way that tests are conducted for Down's Syndrome.
It also throws further doubt on the controversial claims that the MMR vaccine is to blame for a huge rise in autism in children.
Autism is a developmental disorder characterised by a lack of empathy, poor communication skills and a highly systematic view of the world. The latest research, presented earlier this year at the annual conference of the British Psychological Society by the internationally respected autism expert Professor Simon Baron-Cohen, director of the Autism Research Centre at Cambridge University, is based on studies of babies in the womb to the current point where they are four years old.
Amniotic fluid was taken from their mother's wombs and tested for levels of the hormone testosterone. At one year old, babies with higher levels of foetal testosterone were found to have much less eye contact than those with lower rates.
At 18 months, they were also found to have slower language development. The most recent research, not yet published, was conducted when they reached four. Children with higher levels of testosterone in the womb found it harder to make friends and were more obsessional. There were no differences between the girls and the boys.
Professor Baron-Cohen said: "All our research is suggesting that hormones are having an effect on development. Your chromosomes can make you female but you may have a male brain because of the levels of testosterone. This research was conducted on children who do not have autism and are developing normally but the traits we were seeing in children with higher foetal testosterone are similar to those we see with autism."