The brains of transgender individuals share characteristics with those of the gender they identify with, according to new research.

Researchers used MRI scans to identify how adolescents’ brains responded to a pheromone that men and women are known to react to differently.

The brains of transgender people who identified as women reacted more like female brains, and transgender people who identified as men had brains that responded more like males than their biological sex.

The researchers, who presented their findings Tuesday at the European Society of Endocrinology’s annual symposium, focused on the brains of adolescents who had gender dysphoria. People with gender dysphoria have a conflict between their physical or assigned gender and the gender they identify with, according to the American Psychiatric Association. This can cause them considerable distress.

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There are sex differences in the brain at the structural level and also how male and female brains perform certain tasks, said neuroscientist Julie Bakker of the University of Liege in Belgium via email. Bakker’s research “found that adolescents with gender dysphoria had brain activity patterns very similar to their desired/experienced gender,” she wrote.

“At the moment, most available evidence suggests that it is a developmental effect, taking place before birth, but of course, we cannot rule out any effects of sex hormones later in life.”

Bakker’s study was small: looking at only about 150 individuals. As such, its findings should be interpreted with caution. Doug VanderLaan, an assistant professor of psychology at the University of Toronto, is currently working on a similar study at a larger scale, which has yet to publish results.

“This research area is still very much in its early days,” he said. “There have been relatively few studies and the methods have not been consistent. Consequently, there are few findings regarding specific brain areas that have been shown to be reliable and more research is needed.”

However, he said, across studies so far, it has generally been the case that the brains of transgender people share certain resemblances to those of their identified gender.

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“Overall, it seems there is merit to the idea that certain aspects of the brains of transgender people align with their experienced gender identity.” Tweet This

Bakker suggests that her research could be used to inform how young people with gender dysphoria are treated. “Although more research is needed, we now have evidence that sexual differentiation of the brain differs in young people with GD (gender dysphoria), as they show functional brain characteristics that are typical of their desired gender,” she said.

With more research, “We will then be better equipped to support these young people, instead of just sending them to a psychiatrist and hoping that their distress will disappear spontaneously.”

VanderLaan thinks it’s a little too soon to jump to that conclusion.

“At present, MRI is not a reliable tool for determining whether a person is transgender or cisgender, and there is debate about its utility for distinguishing cisgender males and females.” Tweet This

Because studies so far have focused on group averages, he said, individuals could vary considerably.

“Even if one day it were possible to use MRI to determine gender identity, I have a difficult time imagining that a care provider would give more weight to the result of a brain scan than to a person’s stated identity as transgender or cisgender.”

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