Sex Hormones Associated with Autism

Autism Spectrum Disorders are more common in males than in females. A new study suggests that the brain's estrogen signalling might be linked to higher rates of this developmental disorder in male children.

Autism Spectrum Disorder or ASD is a range of neurodevelopmental disorders characterized by problems in communication, inability to form social connections and restricted, repetitive patterns of behavior.

The researchers analyzed brains of patients that had autism and compared them to the controls. The team found that key estrogen receptors are far too few in brains of autistic brains than others.

"Our study is the first indicator that estrogen receptors in the brain of Autism Spectrum Disorder patients may be different to controls. Though this suggests a possible reason for the gender bias, we still need to determine what causes the reduced production of estrogen-related proteins," Anilkumar Pillai, lead author, said in a news release.

The sample size was small - just 13 people with autism and another 13 from controls. The researchers say that the small sample size is because the brains of autistic individuals are too scarce. The team assessed levels of ERβ - an estrogen receptor molecule - as well as aromatase, an enzyme that converts testosterone to estradiol.

The researchers found 35 percent less ERβ mRNA and 38 percent less aromatase mRNA in the brains of the test subjects than controls. Also, mRNA of estrogen receptor co-factors SRC1, CBP and P/CAF were less in brains of autistic people than others. The lower levels of estrogen receptors and aromatase can lead to decrease in the rate at which testosterone is converted to estradiol. This could in turn, increase levels of testosterone.

"It is worth looking at whether drugs which modulate estrogen reception, but do not cause feminization, could allow for the long-term treatment of male patients with Autism Spectrum Disorders. Current treatment involves the use of antipsychotics, which has long been a major concern as these patients are typically still in a stage of life where brain development is very rapid. However, additional studies are needed to test the estrogen mechanism," Anilkumar Pillai said in a news release.

The study is published in the journal Molecular Autism.