From The Guardian
A prenatal screening test for autism comes closer today as new research is published that links high levels of the male hormone testosterone
in the womb of pregnant women to autistic traits in their children.
The ground-breaking study, published in the British Journal of Psychology by some of Britain's leading autism researchers, was prompted by the fact that autism is four times more common in boys than in girls. It is linked with other traits that are found more commonly in boys, such as left-handedness.
For more than eight years, a team at Cambridge University's autism research centre has been observing and testing the development of a group of 235 children whose mothers had an amniocentesis during pregnancy.
Dr Bonnie Auyeung, Professor Simon Baron-Cohen and colleagues, who publish their findings today, say they have consistently found a link between higher testosterone levels in the womb and autistic traits, such as a lack of sociability and verbal skills, in the children.
These are not autistic children, but many have traits that are more pronounced in those who have a medical diagnosis. Autism has been described as a consequence of an extreme male brain.
In the early years of the study, the scientists could not measure autistic traits in the children, but they noticed some very early indicators. Male babies with higher testosterone levels were less likely to make eye contact at 12 months, their vocabulary was more limited between 12 months and 18 months, and at the age of four they were less sociable and had narrower interests.
Today's paper is a significant step forward because the children, now between eight and 10, are old enough to be psychologically assessed using two separate autism rating tests. Scientists found a clear link, in both tests, between higher testosterone levels when the child was in the womb and autistic traits.
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, said Baron-Cohen.
The children will continue to be followed for some years, but Baron-Cohen and his team have at the same time expanded their research to look at the relationship between testosterone levels in the womb and children with a diagnosis of autism.
The work opens the way for a screening test for pregnant women, which could potentially involve amniocentesis to draw off fluid from the womb to measure testosterone levels.
A prenatal test would have the advantage of giving parents advance warning, so that they would be able to do everything possible to help their child from birth.
Even if a testosterone test is not developed (scientists may still find that it is not completely reliable), genetic screening will one day be on the cards. Scientists know that autism is partly genetic, because it runs in families, although environmental factors must play a part because there have been occasions where one identical twin was autistic and the other was not. More than 100 genes have been associated with autism, but it is not yet clear which are most important.