Disorder linked to high levels of testosterone in womb

Prenatal screening tests could follow ground-breaking research into 235 children

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. The procedure involves drawing off fluid surrounding the baby in the womb using a fine needle and is offered by hospitals to pregnant women over 35 or 37 to test for Down's syndrome. The age and circumstances of the women have been taken into account in the research.

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 of us 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. Those affected do not empathise easily with other people (as girls tend to do more readily than boys). They cannot guess what other people are thinking or feeling. They have a much stronger drive towards analysis and constructing systems and can have a great ability to focus on something that absorbs them. People with autism include some brilliant, albeit eccentric and reclusive, mathematicians and musicians, as well as children who are never able to communicate and may end up in an institution.

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. They have turned to Denmark, where a biobank has been freezing and storing many thousands of samples of amniotic fluid from pregnant women since 1990. A new, collaborative study, which will include autistic children, will be published this year.

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.

The work is published on the day the General Medical Council hearing into Dr Andrew Wakefield and colleagues at the Royal Free hospital resumes. The three doctors face allegations of serious professional misconduct over their study, published in the Lancet journal in 1998, which suggested a link between autism and MMR vaccination.

Their paper came at a time of intense anxiety over soaring autism levels, which doctors have ascribed partly to better diagnosis but have not completely explained. More than half a million people are diagnosed with an autistic spectrum disorder, including Asperger's syndrome, in Britain. One of the reasons it sparked such a furore is that parents with an autistic child have no idea what has caused the condition and are left in a state of bewilderment and worry, wondering if they themselves could somehow be responsible. Diagnosis is usually delayed and often followed the MMR vaccinations, given at around 13 months and three to four years.

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.

In numbers: Autism facts

• Autism is a complex developmental disability involving a biological abnormality in the functioning of the brain. It is not a learning disability or a mental health problem, although people with autism may also be affected by those conditions.

• The first detailed description of a child with autism was written in 1799 by the French doctor Jean-Marc Gaspard Itard in his account of the "wild boy of Aveyron".

• People with autism who have an extraordinary talent are known as "autistic savants". They are extremely rare, with at most one or two in 200 people with an autistic spectrum disorder thought to be savants.

• It is likely that more than half of those with an autistic spectrum disorder have an average to high IQ.

• Asperger's syndrome is a form of autism that affects how a person makes sense of the world, processes information and relates to other people. They may like a fixed daily routine because the world can seem confusing and uncomfortable. People with Asperger's are less affected by the syndrome and usually able to lead a normal life. 
David Batty