Children exposed to high levels of testosterone in the womb showed more autism-related traits later in life, according to findings that suggest the male hormone may play a key role in the complex brain disorder.
The results support a hypothesis that higher levels of testosterone may contribute to autism and reinforce findings from tests on animals, said Simon Baron-Cohen, director of the Autism Research Centre at Britain’s Cambridge University, who worked on the study.
He called the findings of the ongoing research promising but cautioned that they did not show a direct link between autism and testosterone and said other factors could be involved. None of the 235 children in the study had autism.
“It is a significant correlation and remains significant after you control for other factors,” he said on Tuesday at a meeting sponsored by the British Association for the Advancement of Science.
What is causing the spike in testosterone was not clear, though Baron-Cohen said environmental factors could be at play.
Autism symptoms range from mild awkwardness seen in Asperger’s syndrome, to severe disability and mental retardation. A recent survey found that 1 in every 150 U.S. children has autism or an autism spectrum disorder, a less severe condition related to autism, such as Asperger’s.
The rate is slightly lower in Britain.
Numerous genetic causes
No one knows what causes autism, a complex developmental disorder that includes problems with social interaction and communication.
But earlier this year, scientists published a large study indicating that autism has numerous genetic causes.
Experts agree that autism, a spectrum of disorders, is likely caused by environmental factors working on a child with a genetic predisposition. Testosterone in the womb might be one such factor.
In Baron-Cohen’s ongoing study, the researchers measured fetal testosterone levels from pregnant women who had amniotic fluid taken for other reasons.
When the children were eight years old, the researchers used questionnaires to see whether they preferred social to solitary activities and how empathetic they were.
This allowed them to measure traits, that in an extreme form, are indicative of autism. In the study children with higher levels of fetal testosterone were better at things such as remembering patterns but not as interested in socializing.
The next step is collaborating with Danish researchers to tap a biological bank that has about 90,000 amniotic fluid samples to test whether there is a direct link between fetal testosterone and autism.
“This may provide us with a marker to help tell us who might be at risk,” Baron-Cohen said.