A group of scholars from the Massachusetts Institute of Technology (MIT) has issued an open letter denouncing philosophy professor Alex Byrne for his role in co-authoring the U.S. Department of Health and Human Services’s (HHS) report on pediatric gender dysphoria.
The report critically evaluated the evidence for gender-affirming medical care for minors, questioning the safety and effectiveness of interventions such as puberty blockers and cross-sex hormones. Byrne’s involvement in the report has ignited a contentious debate, not only about the ethics of gender medicine but also about academic freedom, the nature of expertise, and the standards of evidence in science.
At the heart of the controversy are two central claims made by Byrne’s colleagues.
First, that he lacks the professional qualifications to contribute to a document concerning medical treatment. Second, that his participation in a federal review carried out under the Trump administration constitutes a breach of academic responsibility and promotes harm to transgender youth.
Yet a closer examination of both the content of the HHS report and recent scientific reviews, including the Cass Review and a study published in Current Sexual Health Reports, suggests that the criticisms of Byrne may be more political than scientific.
The HHS report in question reflects growing international skepticism about gender-affirming care for minors. Critics of puberty blockers and gender hormones argue that these interventions are not supported by high-quality evidence and may carry significant long-term risks. A peer-reviewed article by Kathleen McDeavitt, J. Cohn, and Chan Kulatunga-Moruzi, titled “Pediatric Gender-Affirming Care is Not Evidence-Based,” published in Current Sexual Health Reports (2025), supports this concern.
The article systematically reviews studies from the past two decades and concludes that the body of evidence supporting pediatric gender-affirming care is weak and fraught with methodological flaws. While some individual studies show benefits in mental health outcomes, systematic reviews—which carry greater scientific weight—reveal significant quality issues and inconsistent results. The authors write that systematic reviews have found the evidence in this field is composed of studies with significant quality issues, and the overall body of research is considered weak and uncertain. McDeavitt, Cohn, and Kulatunga-Moruzi argue that clinical guidelines should be updated to reflect the limited evidence.
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Furthermore, the risks associated with these interventions are not minor.
Puberty blockers have been linked to decreased bone mineral density, impaired sexual function, infertility, and cognitive decline due to the disruption of hormonal processes during adolescence. The suppression of sex hormones during puberty, a critical period for brain development and bone growth, can compromise both cognition and skeletal health. Gonadotropin-releasing hormone (GnRH) agonists—commonly used as puberty blockers—halt the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), thereby suppressing the production of testosterone and oestrogen. These sex hormones are essential not only for physical maturation but also for neurological development, particularly in brain regions like the prefrontal cortex, hippocampus, and amygdala, which govern executive function, memory, and emotional regulation. Interrupting these hormonal signals during adolescence—a critical neurodevelopmental window—can impair synaptic pruning, myelination, and connectivity in these regions. This disruption has been associated with declines in IQ, working memory, and verbal comprehension, as documented in clinical and case studies. Notably, a study of girls treated for precocious puberty found an average seven-point drop in IQ, while a longitudinal case study of a transgender youth recorded a persistent 10-point IQ loss, underscoring the potential for lasting cognitive impairment.
Puberty blockers have been linked to decreased bone mineral density, impaired sexual function, infertility, and cognitive effects due to the disruption of hormonal processes during adolescence. The suppression of sex hormones during puberty, a critical period for brain development and bone growth, can compromise both cognition and skeletal health. Evidence also indicates that many youth who begin with puberty blockers proceed to irreversible cross-sex hormones, committing them to a lifelong medical pathway.
These concerns are echoed outside the United States.
In the United Kingdom—where the Supreme Court just defined “what is a woman?”—the independent Cass Review, commissioned by the National Health Service (NHS), concluded that the current evidence base for gender-affirming care in youth is inconclusive.
Led by Dr. Hilary Cass, the review found that puberty blockers did not reliably improve mental health outcomes and that gender-related distress in adolescents often coexists with complex mental health challenges such as autism, trauma, and depression. The report called for a more cautious and individualized model of care, rather than automatic affirmation.
Byrne and his co-authors reflect this shift toward evidence-based skepticism.
Their report does not call for outright bans on gender-affirming interventions, but instead raises reasonable questions about long-term safety, consent, and the rationale for medicalizing adolescent gender distress. The backlash against this position from some of Byrne’s MIT colleagues appears to confuse scientific dissent with political hostility.
One of the core accusations in the MIT scholars’ open letter is that Byrne lacks the expertise to speak on pediatric gender medicine. The letter claims that contributing to a document as an expert in a field where one lacks the necessary credentials is contrary to professional standards. Yet this criticism relies on a narrow understanding of academic competence.
Byrne is a tenured professor of philosophy at MIT who has published extensively not only in philosophy of mind but also in the interdisciplinary fields of sexology and gender studies. His recent book Trouble With Gender: Sex Facts, Gender Fictions draws heavily on psychology, biology, anthropology, and medical literature. He also serves on the editorial board of the Archives of Sexual Behavior, one of the most respected journals in the field of sexuality.
In response to his colleagues, Byrne defended the breadth and relevance of his expertise. He pointed out that his research has been published in leading sexology journals, including articles assessing the persistence of gender dysphoria. He has reviewed submissions for top journals and contributed to discussions of terminology, ethics, and evidence—all crucial elements of the HHS report. In his words, philosophers value clear language and the unravelling of confused arguments, and the writings of pediatric gender specialists often display precisely the sort of conceptual ambiguity that benefits from philosophical scrutiny.
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Far from being unqualified, Byrne brought analytical tools and cross-disciplinary insight that are essential to interpreting contentious, ethically charged medical debates.
His critics overlook that the HHS report spans multiple domains, including the history of gender medicine, the collapse of medical safeguarding, the structure of evidence hierarchies, and the meaning of terms like gender identity. These are not issues that lie solely within the purview of endocrinologists or psychiatrists.
The implications of the open letter are deeply concerning for academic freedom. Byrne warned that public condemnations of this sort signal to younger scholars that even engaging in controversial inquiry may be professionally risky. He argued that the letter sends a message: unless your research aligns with the prevailing consensus, you may be ostracized. This climate discourages honest investigation and deters emerging scholars from exploring politically sensitive subjects, even when those subjects carry profound implications for public health and ethics.
In the letter, Byrne’s critics defend the American Academy of Pediatrics’ continued endorsement of gender-affirming care, including the widely cited Rafferty et al. 2018 policy paper. Yet as Byrne notes, this document is well known among specialists for misrepresenting the underlying literature and failing to reflect the nuanced findings of systematic reviews. Endorsing a guideline without engaging its empirical foundation does not strengthen the case for gender-affirming care; it merely illustrates how ideology can obscure scientific judgment.
This episode raises a fundamental question. Is gender-affirming medical care for minors grounded in robust science, or has it been shielded from scrutiny by appeals to political virtue and emotional urgency?
The findings of the Cass Review, the systematic analysis by McDeavitt and colleagues, and the reasoned arguments of the HHS report suggest that the current model of pediatric gender medicine is built on uncertain foundations. The risks are real, and the evidence of long-term benefit remains weak.
Byrne’s contribution to the HHS report is not an act of hostility or transphobia, but an example of intellectual engagement with a complex and morally weighty topic. Whether one agrees or disagrees with his conclusions, the attempt to silence him through public denunciation betrays the core mission of the university: the pursuit of truth through critical inquiry. Gender-affirming care, like any other medical practice, must be evaluated based on evidence, not ideology.
Academic freedom and scientific integrity depend on our willingness to ask hard questions, especially when the answers are uncomfortable.
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Image: “MIT Building 10 and the Great Dome, Cambridge MA” by John Phelan on Wikimedia Commons
