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FULLY INFORMED NZ

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Research

The research section contains summaries of the medical literature and medical opinion. The Bone health and Mental health articles attempt to systematically collect the results of puberty blocker studies and analyse them in a comprehensive way. This effort ongoing and will be updated as time allows. The Expert statements article collects statements from pediatricians, endocrinologists and other experts on the appropriateness, safety, and reversibility of puberty blockers…

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EXPERT STATEMENTS: fullyinformed.nz

Expert Statements on Puberty Blockers

The Ministry of Health describes puberty blockers as “safe and fully reversible” on their website . We have written to the Ministry informing them of the lack of evidence for this statement and asked for its removal. The Ministry responded that the statement “remains appropriate”. The Ministry has abandoned their responsibility to provide accurate medical information.

The sections below collate expert statements on puberty blockers that contradict the “safe and fully reversible” claim.

Impacts on Cognitive Function

Cass Review – Letter to NHS England – July 2022 [link]

“A further concern is that adolescent sex hormone surges may trigger the opening of a critical period for experience-dependent rewiring of neural circuits underlying executive function (i.e. maturation of the part of the brain concerned with planning, decision making and judgement). If this is the case, brain maturation may be temporarily or permanently disrupted by puberty blockers, which could have significant impact on the ability to make complex risk-laden decisions, as well as possible longer-term neuropsychological consequences. To date, there has been very limited research on the short-, medium- or longer-term impact of puberty-blockers on neurocognitive development.”

— Dr Hilary Cass OBE , former President of the Royal College of Paediatrics and Child Health.

“…puberty blockers have profound effects on the developing body, and as part of the changes seen in adolescence involve hormonal effects on brain function, the impact of these drugs on the brain maturation are likely to be deleterious”

— Professor Sophie Scott , director of the Institute for Cognitive Neuroscience, University College London, UK

“IQ might be damaged by puberty blockers.”

— Professor Christopher Gillberg , Child and Adolescent Psychiatry at Gothenburg University in Gothenburg, Sweden

‘If you suppress puberty for three years the bones do not get any stronger at a time when they should be, and we really don’t know what suppressing puberty does to your brain development. We are dealing with unknowns.

— Professor Russell Viner , Professor of Adolescent Health at the UCL Great Ormond Street Institute of Child Health, UK

”…[puberty blockers are] likely to threaten the maturation of the adolescent mind.”

— Dr Christopher Richards – Paediatrician, Newcastle upon Tyne, UK

— Dr Julie Maxwell – Paediatrician, Hampshire, UK

— Dr Noel McCune – Psychiatrist (retired), Child and Adolescent Mental Health Service, Portadown, Northern Ireland, UK

“…there are reasons to suspect that [puberty suppression] could have negative consequences for neurological development.”

— Associate Professor Paul Hruz – Paediatrics and Endocrinology, Washington University School of Medicine, St. Louis, USA.
— Professor Lawrence S Mayer – Psychiatry, Johns Hopkins University School of Medicine and Statistics and Biostatistics, Arizona State University, USA.
— Professor Paul R. McHugh – Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, USA.

“the research has, in fact, reinforced concerns over the impact of GnRHas on cognitive performance in children.”

“Any findings which indicate that GnRHas cause a decline, even a modest decline, in IQ are likely to be of considerable interest to patients and their parents. It is a factor that they may well want to consider in deciding whether or not to take the drug.”

— Dr Peter Hayes – Faculty of Education and Society, University of Sunderland, Sunderland, UK

Hough et al, 2017

“…some cognitive functions may be irreversibly altered by [puberty supression]”

“[puberty suppression] may also have long lasting effects on other brain areas and/or aspects of cognitive function.”

“deficits in long-term spatial reference memory…are likely permanently altered”

“The observation that [puberty suppression] is associated with permanent changes in brain development raises particular concerns about the cognitive changes associated with the prolonged use of GnRHa-treatment in children and adolescents.”

— Dr Denise Hough – Lecturer in Biology, University of Glasgow.
— Dr Michelle Bellingham – Lecturer in Comparative Physiology, University of Glasgow.
— Dr Irah Haraldsen – Head of Cognitive Health in Brain Disorders Group, University of Oslo.
— Dr Mark McLaughlin – Senior Lecturer in Vetinary Science and Education, University of Glasgow.
— Dr Jane Robinson – College of Medical, Vetinary and Life Sciences, University of Glasgow.
— Associate Professor Anne-Kristin Solbakk – Department of Psychology, University of Oslo.
— Professor Neil Evans – Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow.

Schneider et al, 2017

The patient’s GIQ (global IQ) was further slightly reduced during the follow-up with GnRHa treatment. In fact, the low average GIQ together with impairment in the perceptual organization of intelligence and processing speed index presented even before treatment…suggest that any neurodevelopmental immaturity may have been potentiated by pubertal suppression.

Some questions emerge from these findings, especially regarding the influence of sex steroids on cognition during puberty. It is likely that the structural and microstructural changes in the brain during adolescence, as discussed above, may interfere on the achievement of complete cognitive potential.

— Assistant Professor Maiko Schneider – Psychiatry and Behavioural Neurosciences, McMaster University, Canada.
— Professor Poli Spritzer – Physiology and Endocrinology, Universidade Federal do Rio Grande do Sul, Brazil
— Bianca Machado Borba Soll – Doctoral Candidate in Psychiatry, Universidade Federal do Rio Grande do Sul, Brazil
— Dr Anna M V Fontanari – Gender Identity Program, Universidade Federal do Rio Grande do Sul, Brazil
— Dr Fernanda Tovar-Moll – Director, Instituto D’Or de Pesquisa e Ensino, Rio de Janeiro, Porto Alegre, Brazil
— Adjunct Professor Angelo B Costa – Psychology, Pontifical Catholic University of Rio Grande do Sul Porto Alegre, Brazil
— Dr Dhiordan Cardoso da Silva – Psychiatry, Universidade Federal do Rio Grande do Sul, Brazil
— Dr Karine Schwarz – Instituto da Voz, Universidade Federal do Rio Grande do Sul, Brazil
— Dr Silza Tramontina – Child and Adolescent Psychiatry Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
— Dr Maria I R Lobato – Psychiatry and Forensic Medicine Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil

Sexuality and Sexual Function

Trans & Gender Diverse Policies, Care, Practices, & Wellbeing [link] 

An observation that I have had is that every single child or adolescent who is truly blocked at Tanner stage two has never experienced orgasm. It really is about zero.

— Dr Marci Bowers President- elect (former), World Professional Association for Transgender Health (WPATH)

It’s Hip to be Trans

Blocking puberty with medication is, in my opinion, questionable from a medical ethics point of view. We know from studies that most children later reconcile with their birth [sex]. Gender atypical behaviour and gender identity insecurity in childhood often point to homosexuality in adulthood. Only very rarely does this lead to a transsexual identity. It is different for patients whose puberty has been arrested. They usually continue the transition, first through hormones and if necessary through surgery. So puberty blockers are early switchers. One can also say a homosexuality preventer.

— Dr Alexander Korte – Child and Adolescent Psychiatrist, Clinic for Child and Adolescent Psychiatry, Psychosomatic Medicine and Psychotherapy at the Ludwig Maximilian University in Munich

Safety and Reversibility

Karolinska Hospital [link]

“[Puberty blockers and cross-sex hormones] are potentially fraught with extensive and irreversible adverse consequences such as cardiovascular disease, osteoporosis, infertility, increased cancer risk, and thrombosis. This makes it challenging to assess the risk/benefit for the individual patient, and even more challenging for the minors and their guardians to be in a position of an informed stance regarding these treatments.”

“There is not enough evidence to say they’re reversible…We know that when you interrupt any process in the body…there are consequences…you can’t say ‘completely reversible’”

— Professor Donal O’Shea – Endocrinologist, St Vincent’s Private Hospital, Dublin, Ireland

‘The worry is that reversible treatments [such as hormone blocking drugs] can sometimes have irreversible effects,’

— Professor Russell Viner , Professor of Adolescent Health at the UCL Great Ormond Street Institute of Child Health, UK

Van Meter, 2020 [pdf]

“To treat puberty as a pathology that should be prevented by administration of puberty blocking drugs is to interrupt a major and necessary physiologic transformation at a critical age when such changes can effectively happen. The physiologic event of puberty cannot safely be put off to a later date.”

— Adjunct Associate Professor Quentin L Van Meter – Pediatric Endocrinologist, Emory University, Georgia, USA.

“The claim that puberty suppression for adolescents with gender dysphoria is “reversible” is based on speculation, not rigorous analysis of scientific data.”

“Whether puberty suppression is safe and effective when used for gender dysphoria remains unclear and unsupported by rigorous scientific evidence.”

“…whether blocking puberty is the best way to treat gender dysphoria in children remains far from settled and it should be considered not a prudent option with demonstrated effectiveness but a drastic and experimental measure.”

— Associate Professor Paul Hruz – Paediatrics and Endocrinology, Washington University School of Medicine, St. Louis, USA.
— Professor Lawrence S Mayer – Psychiatry, Johns Hopkins University School of Medicine and Statistics and Biostatistics, Arizona State University, USA.
— Professor Paul R. McHugh – Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, USA.

“If [researchers]…had extended their search to the effect of blockers on the brains of adult humans as well as laboratory and animal work…they would have been rewarded with many references that would have warned them that the effects of blockers are not “safe” and “reversible”…”

— Professor John Whitehall -Foundation Chair Paediatrics and Child Health, University of Western Sydney, Australia.

What people don’t usually consider is that puberty is also extraordinarily important in female pelvic maturation, and in the normal bone structure and brain development of both sexes. Additionally, the physical changes of puberty occur in the wider context of complex developmental milestones as the child progresses toward social independence from his or her parents…Disruption of a temporal process of development cannot be reversed.”

— Dr Michael Laidlaw – Endocrinologist, California, USA.

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