Autism in young boys is linked to high levels of hormones in the womb, new research shows
- Children who go on to develop autism are exposed to high levels of the hormones testosterone, progesterone and cortisol before birth
- Some of the hormones are produced in higher quantities in boys than girls
- Researchers say findings could explain why autism is more common in males
By EMMA INNES
PUBLISHED: 09:44 EST, 4 June 2014 | UPDATED: 12:37 EST, 4 June 2014
Children who develop autism were exposed to high levels of certain hormones when they were in the womb
Exposure to high levels of 'male' hormones in the womb increases the chance a baby boy will develop autism, new research has revealed.
The study showed children who develop the developmental disability are subjected to elevated levels of the hormones testosterone, progesterone and cortisol before birth.
The researchers, from the University of Cambridge and the Statens Serum Institute in Copenhagen, say the finding could help to explain why autism is more common in boys than in girls.
However, they say it cannot be used as a way of screening for the condition.
The team, led by Professor Simon Baron-Cohen and Dr Michael Lombardo in Cambridge and Professor Bent Nørgaard-Pedersen in Denmark, used 19,500 amniotic fluid samples stored in a Danish biobank from individuals born between 1993 and 1999.
Amniotic fluid surrounds the baby in the womb during pregnancy and is collected when some women choose to have an amniocentesis tests at 15 to 16 weeks of pregnancy.
This coincides with a critical period for early brain development and sexual differentiation, and therefore allows scientists access into this important window in foetal development.
The researchers identified amniotic fluid samples from 128 boys later diagnosed with an autism spectrum condition and matched these up with information from a central register of all psychiatric diagnoses in Denmark.
They found that levels of all steroid hormones were highly associated with each other and most importantly, that the autism group on average had higher levels of all steroid hormones, compared to a typically developing male comparison group.
Professor Baron-Cohen said: ‘This is one of the earliest non-genetic biomarkers that has been identified in children who go on to develop autism.
‘We previously knew that elevated prenatal testosterone is associated with slower social and language development, better attention to detail, and more autistic traits.
‘Now, for the first time, we have also shown that these steroid hormones are elevated in children clinically diagnosed with autism.
‘Because some of these hormones are produced in much higher quantities in males than in females, this may help us explain why autism is more common in males.’
Children who develop autism were subjected to high levels of testosterone, progesterone and cortisol. Levels of some of these hormones are higher in boys which could explain why autism is more common in boys
He added: ‘These new results are particularly striking because they are found across all the subgroups on the autism spectrum, for the first time uniting those with Asperger Syndrome, classic autism, or Pervasive Developmental Disorder Not-Otherwise-Specified. We now want to test if the same finding is found in females with autism.’
Dr Michael Lombardo said: ‘This result potentially has very important implications about the early biological mechanisms that alter brain development in autism and also pinpoints an important window in foetal development when such mechanisms exert their effects.’
Steroid hormones are particularly important because they exert influence on the process of how instructions in the genetic code are translated into building proteins.
The researchers believe that altering this process during periods when the building blocks for the brain are being laid down may be particularly important in explaining why autism develops.
Professor Baron-Cohen said: ‘These results should not be taken as a reason to jump to steroid hormone blockers as a treatment as this could have unwanted side effects and may have little to no effect in changing the potentially permanent effects that foetal steroid hormones exert during the early foundational stages of brain development.’