Differences in brain activity could impact a person's sense of their own gender, according to a researcher who has tried to explain the cause of a condition experienced by some transgender people.
The article published in the journal eNeuro presents a new theory on what is known as "gender dysphoria," by looking at existing studies on the condition. Other experts in the field have said the findings should be regarded with caution.
Gender dysphoria, or gender incongruence, is where a person feels distressed because the gender they were assigned at birth does not match their internal feelings. For example, a person with a penis who is assigned as a boy at birth, but who identifies as a girl. Some, but not all, transgender people experience gender dysphoria.
While some argue the term wrongly pathologizes the legitimate experiences of transgender people, others say it is necessary in order for individuals to receive treatments, such as hormonal medications and surgeries.
Stephen Gliske, a research assistant professor in neurology at the University of Michigan, called his new take the "multisense theory," as opposed to what he dubbed the "opposite brain sex theory."
Gliske said evidence suggests brain networks linked to how individuals perceive the ownership of their body parts, that influence gender-typical behavior, and chronic distress are different in those with gender dysphoria. This stands in contrast to the theory which suggests those with the condition have brain regions similar in shape and size to the gender they identify with.
The researcher said he hopes the research could lead to therapies that reduce distress and address the biological causes of gender dysphoria rather than "subjective symptoms." This, in turn, may help to prevent conditions related to gender dysphoria, such as depression and suicide, he said.
The theory could also lead to gender dysphoria being treated without using invasive and irreversible gender reassignment surgery, Gliske told Newsweek.
Gliske said: "This new multisense theory of gender dysphoria connects the experience of gender dysphoria with the function of the associated brain regions and networks.
"This paradigm shift—from fixed anatomical sizes to dynamic activity in brain networks—means that there may be many more options to decrease the distress experienced with gender dysphoria than we have ever realized."
Asked whether brain scans could one day diagnose the condition, Gliske said: "A key point of this theory is that the changes in brain activity impact people's sense of their own gender.
"While brain scans may one day provide some useful information, I feel an individual's description of their distress and perception of gender will always be essential for diagnosis."
Simona Giordano, an expert in gender identity and Reader in Bioethics at The University of Manchester Law School, who did not work on the study, told Newsweek she was surprised Gliske suggested altering neural structures and networks is less invasive than providing gender-affirming treatment.
Giordano also argued Gliske's suggestions for treatment would "get rid of gender incongruence," and expressed concern this amounts to a form of "medical conversion."
While understanding the mechanisms of sexual orientation and gender identification is a "legitimate scientific effort," Giordano argued, she said "science that singles out gender minorities as subjects of study might inadvertently suggest that there is an underlying medical problem."
"Should we use these hypothetical therapies, we would no longer have gender dysphoria sufferers because we would no longer have transgender people," she said.
Giordano highlighted that various international organizations, such as UNESCO, and the Council of Europe, have called de-pathologization of gender diversity. Last year, the World Health Organisation renamed gender identity disorder as gender incongruence to "reflect the international consensus that gender diversity is not a disorder or illness," she said.
Professor Catherina Becker, acting director of the Centre for Discovery Brain Sciences at the U.K.'s University of Edinburgh, who did not work on the paper, also critiqued the work. She commented in a statement: "The present paper is a review and reinterpretation of other studies without providing significant new experimental or epidemiological data.
"The author suggests changing current clinical practice and to base treatments for gender dysphoria on his theory instead. What these treatments should be remains unspecified and these recommendations should therefore be taken with caution."
Derek Hill, professor of medical imaging at UCL, U.K., who also didn't work on the paper, said in a statement that the theory "must be considered quite speculative until further tested."
He said: "Brain scanning studies in this area tend to be on small numbers of subjects, with poorly standardized methodology for data collection and analysis, and with varying approaches to controlling for other conditions the individuals suffer from such as anxiety and depression, which could impact the results.
"It is quite possible, therefore, that some of the associations suggested here by the authors between gender dysphoria and brain function are chance random findings—the underlying data the authors have looked at is very noisy so the assumptions that underpin their theory are all subject to uncertainty," said Hill.
More work to test the theory "would be very helpful in determining whether the theory could be helpful in managing and planning treatment of these individuals," he said.
The work follows a study published in the American Journal of Psychiatry that suggested transgender people who have gender-affirming surgery are less likely to need mental health treatment.
This article has been updated with comment from Derek Hill.