Journal Club: A Genuine Broad Study of the Effects of HRT
Amidst papers being twisted and numerous bad faith studies being used against trans people, a new paper cuts through to shed some real light on the broad impacts of hormone replacement therapy. Journal Club dives in to look at this 2026 paper.
by Veronica Esposito
While there are numerous studies documenting the benefits of hormone replacement therapy (HRT) to trans people, a new paper from Australia takes a novel approach, adding a very large sample size and an interesting design feature to the mix. All in all, this new research from Karinna Saxby and colleagues is well worth a look.
Saxby’s innovation is to look at how utilization of mental health resources changes before and after the initiation of HRT, studying both the usage of therapy and therapeutic medications of antidepressants, such as Prozac and Zoloft, and anxiolytics, such as Xanax and Valium. Her research leaves us with some fascinating indications that help shed new light on the familiar facts about gender transitions.
One particularly noteworthy aspect of Saxby's work is that her study employs a difference-in-differences approach, letting her rebut one of the common critiques of studies of trans medicine—namely that they don’t use control groups, thereby relegating their findings to the status of “low quality” research.
For the record “low quality” as applied to research is not the same as the colloquial use of the word, as in “wow, this car is a low quality piece of crap.” It is a descriptive term meant to apply to research that does not employ design features, such as a control group, that would allow researchers to draw more definitive conclusions. Typically the gold standard of experimental design includes control and experimental groups that participants are randomly assigned to in order to control as much as possible for other variables so that the experiment can test for the variable in question.
However, control groups are rarely used in the study of gender-affirming medicine because it would be unethical to do so. If you have 500 trans people who desperately want HRT, it would be quite harmful to tell 250 of them to wait an extra year to so do in the name of science, so that they could be a “control group,” to be compared to the “experimental group” of those lucky 250 who got the hormones.
A difference-in-differences utilizes a “natural experiment,” which means that it takes as a control group people who chose not to access HRT for reasons of their own. As such, it’s not exactly an experimental design (as a true experiment would require random assignment to the control and experimental groups), but it’s about as close as we’re likely to get without seriously harming anyone in the name of science.
Another thing that makes this study impressive is the massive sample size—over 30,000 people studied over 11 years. (For reference, a sample size of 200 would be considered substantial by the standards of most studies.) In order to obtain such a large sample, Saxby and colleagues used “whole-of-population administrative data, which captures all trans Australians who accessed government-subsidised GAHT between 2012 and 2024.”
For both those taking testosterone and estrogen, the data shows an increase in mental health services used in the two and three years, respectively, prior to beginning HRT. This makes sense, as many trans people work through their coming out as trans and decide to access gender-affirming medical care in conjunction with a therapist.
Over the five-year period after accessing HRT, both the testosterone and the estrogen groups showed steady declines in the use of mental health resources, but the testosterone group got below baseline within the first year of HRT, compared to year five for users of estrogen.
Saxby et al. theorize multiple reasons for this discrepancy. There is research indicating that testosterone-based HRT leads to larger declines in gender dysphoria than estrogen-based, and there is also research indicating that trans women face greater stigma and reduced earnings as compared to trans men. Such adversities would naturally lead to a greater usage of mental health support.
It is also the case that those assigned female at birth tend to access mental healthcare more often than those assigned male—as Saxby explains, this is likely due to the latter group being “socialised to minimise distress, avoid formal help-seeking, and perceive mental healthcare as more stigmatising.” So it would make sense that as trans women begin to process and reverse the effects of that socialization, they would also begin to access more therapy.
The study also found that there is likely an unmet need for trans people to access high-quality therapy during transition. Saxby et al. inferred this from the right in use of prescription medications to manage mood among those accessing HRT. This indicates that having a greater number of affordable, competent therapists to treat trans people would likely be a benefit to the community.
Lastly, the study makes the interesting finding that trans women tended to access more HRT earlier in the study, but trans men began to close that gap in later years:
On average, [masculinizing HRT] recipients were younger at initiation than [feminizing HRT] recipients (25 vs 34 years) and were more likely to initiate in more recent years. For example, 35% of the [masculinizing HRT] sample initiated in 2023 or 2024, compared to 29% of the [feminizing HRT] sample. In contrast, a greater share of [feminizing HRT] recipients initiated in earlier years; 15% of the [feminizing HRT] sample initiated between 2013 and 2015, compared to just 4% of the masculinizing HRT] sample.
To conclude, it is important to reaffirm the overall findings of this paper: use of gender-affirming medical care led to overall reductions in the need for mental health support, be it via therapy or medications. To put it simply, HRT helped improve the mental health of trans Australians.
This paper makes clear that easy and safe access to HRT is a matter crucial to the mental health of trans people, and anyone trying to stand in the way of it is doing harm. It also makes clear just how crucial high-quality therapy is to the needs of trans people before and during medical transition. It is yet another piece of science demonstrating that those seeking to force trans people into conversion therapy and other alternative forms of care are simply malevolent actors.
Veronica Esposito (she/her) is a writer and therapist based in the Bay Area. She writes regularly for The Guardian, Xtra Magazine, and KQED, the NPR member station for Northern California, on the arts, mental health, and LGBTQ+ issues.