Hormones And Autism

Scientists have been studying autism for a long time, but they still don't understand why the brains of people with autism develop differently. Some scientists think that testosterone levels in the womb might be the reason, but they don't have enough proof yet.

Scientists used to think that a certain hormone called androgen was linked to autism, but now they think it might actually be estrogen. Even though autism is more common in boys, the link to estrogen makes sense because girls with autism usually have fewer autistic traits than boys. Some people think that autism is what happens when the brain has more traits that are usually found in boys. This doesn't mean that autistic people are more masculine overall, just that they have some traits that are more common or pronounced in boys. Studies show that men and women are more similar than different, but there are some traits that are more common in men's brains and seem to be amplified in people with autism. Researchers think that the biological pathways involved in the development of typically masculine traits might be connected to autism, which traces back to fetal sex differentiation. Researchers are now looking for clues to autism in fetal development and the conditions fetuses experience in-utero.

While that did include testosterone and another androgen, it also included progesterone—which got the researchers wondering maybe they needed to widen their scope. Which brings us to estrogen. Estrogen actually refers to a group of hormones which includes estriol, estradiol, estrone, and estetrol—none of which were tested in the 2015 study. And these so-called “female” hormones are very important for fetal development regardless of sex. Estradiol, in particular, contributes a lot to brain development. It helps to form and prune neurons and synapses, and it regulates the activity of the neurotransmitter GABA. In the brains of people with autism, synapse and neuron formation are all atypical. So it might make sense that estrogen levels in utero could play a role in the development of autism, too. To find out, those same researchers returned to the amniotic fluid samples they used in their 2015 study. These initially came from The Danish Historic Birth Cohort: a set of biological samples from more than a hundred thousand pregnant people collected between 1980 and 2004 who were followed up with to monitor the children’s health over time including whether they were diagnosed with autism. The researchers ended up with amniotic fluid samples from 98 males with autism and 177 neurotypical males.

They examined the samples to identify different types of estrogen and discovered that increased levels of estradiol, estriol, and estrone were all linked to a diagnosis of autism. Estradiol had the most significant impact, with a nearly 50% increase in the chances of autism with a rise in this hormone from the 25th to the 75th percentile. That's a lot more of an effect than has ever been seen with androgens. Now that we know what estrogen does to developing fetuses, we want to further determine why it might lead to "a so-called 'extreme male brain.'" We don't know yet what triggers high estrogen levels at 15 weeks gestation, but the researchers suggest that the placenta may play a role. Plus, placental issues and autism risk often go hand in hand. But as always there is much we don't understand about hormones and their relationship to babies and mothers.

That's probably because both genes and hormones are at play: like, high levels of estrogen might interact with particular gene variants to affect the way the brain forms. Also, the researchers have made it clear they're not interested in making some kind of 'screening test' for autism - as the lead researcher said, they want to understand autism, not prevent it.% One major drawback to this study is that %it was only in male fetuses; so it's unclear whether the findings hold true for everyone. At the time, the team simply didn't have enough samples to do these tests for female fetuses because the prevalence of autism is so much lower in them, but they hope to get those samples in the future. And the findings are still correlational - there may be some as yet unidentified factor that impacts amniotic hormone levels and the likelihood of an autism diagnosis. Still, it suggests that researchers may have overlooked key components in the development of autism by focusing on typically 'male' things like testosterone. And they're going to have to look at everything if they want to get to the bottom of this century-old mystery.’

Autism has puzzled scientists for years, and even though they have made progress in understanding it, there is still a lot that they do not know. One theory that has been suggested is that testosterone levels in the womb may play a role, but there is not enough evidence to support this yet. In fact, researchers now believe that estrogen might be the hormone linked to autism. This is surprising since autism is more common in boys, but it makes sense because girls with autism usually have fewer autistic traits than boys.