Medical interventions such as cross-sex hormones and surgery, intended to alleviate gender distress in young people, may instead be associated with a significant worsening of their mental health, according to a landmark long-term study from Finland.
A Stark Trajectory of Decline
The research, published in the journal Acta Paediatrica, followed 2,083 adolescents referred to gender clinics in Finland between 1996 and 2019, tracking their outcomes for up to 25 years. It found that for those who proceeded with medical gender reassignment, the need for specialist mental health care rose sharply after treatment.
The statistics present a stark trajectory. Among youngsters transitioning from male to female, the proportion needing such psychiatric care soared from 9.8% before medical intervention to 60.7% afterwards. For those transitioning from female to male, the figure rose from 21.6% to 54.5%.
The researchers from Finland’s national health institute concluded that “Psychiatric needs do not subside after medical gender reassignment,” adding that the treatment may even have “a negative impact.” Crucially, even after accounting for previous mental illness, the cohort that received medical interventions remained far more likely to need mental health care than their peers—up to five times more likely in some cases.
A Wider Pattern of Distress
The study revealed that mental health struggles were a profound feature for the entire group referred to gender clinics, not just those who underwent medical treatment. Before any intervention, 45.7% had serious psychiatric problems. At least two years after referral, this had risen to more than six in ten (61.7%).
This pattern stands in stark contrast to the general population. When researchers compared the group to a control cohort of 16,643 individuals who had not been referred to gender services, they found no similar increase. Only about 15% of the control group needed specialist psychiatric care over the same period.
The study also noted a trend towards more severe distress in recent years. Nearly half (47.9%) of youths who first presented to gender clinics in 2010 or later required specialist psychiatric care before their first clinic visit—double the rate of those who presented in the earlier period from 1996-2010. The authors suggested that for some adolescents, gender dysphoria may be secondary to other mental health challenges, potentially representing a maladaptive coping mechanism.
Fuel for a British Debate
The Finnish findings are set to intensify the already fierce debate over youth gender medicine in Britain, a debate recently reshaped by the landmark Cass Review. Commissioned by NHS England and published in April 2024, the Cass Review found the evidence base for treatments like puberty blockers to be “remarkably weak” and recommended a more holistic approach to care.
In response to that review, the UK government has moved to a more restrictive policy. Health Secretary Wes Streeting announced an indefinite ban on the sale and supply of puberty blockers via private prescriptions for under-18s in December 2024, citing an “unacceptable safety risk.” This followed an earlier ban on their routine NHS prescription outside of clinical trials.
The issue has also been fought in the courts, most notably through the case of de-transitioner Keira Bell, who argued she had been too young to give informed consent to treatment at the Tavistock clinic. In January 2025, her lawyers reportedly wrote to Mr Streeting threatening judicial review if he did not extend the ban to cross-sex hormones for under-18s.
Expert Calls for Caution and Focus on Mental Health
Experts aligned with a cautious approach pointed to the Finnish study as critical evidence. Dr Louise Irvine of the Clinical Advisory Network on Sex and Gender said the research was “unique due to its comprehensiveness and long-term follow-up.” She stated it called into question why medical and surgical treatments were being offered, as “they do not improve mental health and may, in some cases, make it worse.”
Professor Carl Heneghan, Director of the University of Oxford’s Centre for Evidence-Based Medicine, emphasised the study’s revelation of a “significant unrecognised burden of mental health problems.” He argued that “radical interventions” are not a silver bullet and stressed it is “vital other conditions are ruled out before any clinician would consider such treatments.” He has previously called for a national registry to track long-term outcomes.
The physical risks associated with these interventions, noted in the research, add a further layer of concern. Cross-sex hormones have been linked to potential adverse effects including bone loss, infertility, sexual dysfunction, cardiovascular problems, and an increased risk of certain cancers. Gender confirmation surgery is irreversible.
The Finnish researchers underscored a fundamental point they believe must guide care: “Psychiatric disorders require their due treatment regardless of a young person’s gender identity.” Their data suggests that, for a significant number, that need not only persists but intensifies after medical gender reassignment.