Scientists are lauding a new breakthrough in understanding autism and how it develops. In a new study published in Molecular Psychiatry, researchers from the University of Cambridge and the State Serum Institute in Denmark found a link between levels of estrogen and autism in male fetuses.
Autism is a spectrum disorder that has symptoms that include repetitive behaviors, difficulties with speech and nonverbal communication, and impaired social skills, per the American Psychiatric Association. According to the CDC, the number of children diagnosed with autism has grown exponentially in recent years, from 1 in 166 in 2004 to 1 in 59 in 2018 (via Autism Speaks). Though many doctors believe that the increase is partially due to better education and identification of the disability, others are looking for a scientific reason for the surge.
According to this new study, that scientific reason may be the levels of estrogen in the amniotic sac during fetal development. Researchers tested amniotic fluid samples from 275 male fetuses and found that levels of the four major types of estrogen were elevated in the 98 that later developed autism. Meanwhile, the other 177 that did not have elevated levels of the hormone did not show any signs of autistic symptoms.
This builds off of previous research from the team, which found in 2015 that males who had high levels of androgens in the amniotic sac were more likely to develop autism. Androgens are often converted into estrogen, linking the two studies together. Moreover, androgen levels in the womb are higher for males, which might explain why autism tends to affect more boys than girls.
Though estrogen may have a reputation for being linked with femininity, in fetal development, the hormone is vital for brain development and actually serves to "masculinize" the brain in many mammals, according to The University of Cambridge.
Researchers are optimistic that this new breakthrough can lead to a better understanding of the disorder and help with its treatment.
"This finding is exciting because the role of estrogens in autism has hardly been studied, and we hope that we can learn more about how they contribute to fetal brain development in further experiments. We still need to see whether the same result holds true in autistic females," said Dr Alexa Pohl, part of the Cambridge team.
Alex Tsompanidis, a PhD student in Cambridge who also worked with the team, added that the research also gives scientists a new blueprint for new studies.
"These elevated hormones could be coming from the mother, the baby or the placenta. Our next step should be to study all these possible sources and how they interact during pregnancy."