Carl Henegan, Professor of Evidence Based Medicine at Oxford University:
An Archive of Diseases in Childhood letter referred to GnRHa treatment as a momentous step in the dark. It set out three main concerns: 1) young people are left in a state of ‘developmental limbo’ without secondary sexual characteristics that might consolidate gender identity; 2) use is likely to threaten the maturation of the adolescent mind, and 3) puberty blockers are being used in the context of profound scientific ignorance.
The development of these interventions should, therefore, occur in the context of research, and treatments for under 18 gender dysphoric children and adolescents remain largely experimental. There are a large number of unanswered questions that include the age at start, reversibility; adverse events, long term effects on mental health, quality of life, bone mineral density, osteoporosis in later life and cognition. We wonder whether off label use is appropriate and justified for drugs such as spironolactone which can cause substantial harms and even death. We are also ignorant of the long-term safety profiles of the different GAH regimens. The current evidence base does not support informed decision making and safe practice in children.
blogs.bmj.com/bmjebmspotlight/2019/02/25/gender-affirming-hormone-in-children-and-adolescents-evidence-review/
From the GIDS website - England's only NHS service for gender dysphoric children - in their own words about how they have assessed the evidence:
Does a child's gender remain the same after a certain age or might it change as they get older?
There is evidence that many transgender children experience incongruence between their experienced and their assigned gender early in life (Steensma et al, 2013). At GIDS, about 15-25% of our referrals are for children aged under 12. Often these children do not identify with stereotypical behaviours and preferences of their assigned gender peers, and sometimes strongly dislike their physical sex characteristics.
In the majority of cases these feelings seem to discontinue either before, or early in, puberty (Steensma et al, 2013). In some children, however, gender dysphoric feelings will intensify during adolescence expressed by an aversion of their bodies in the context of secondary sex characteristics developing.
Across all studies approximately 16% continue with their gender identification (Steensma et al, 2013). The way gender identity develops and how gender identification is expressed seems to be influenced by biological, environmental and psychological factors (De Cuypere et al., 2013; de Vries et. al., 2014; Steensma & Cohen-Kettenis 2015).
Young people indicated that the period from 10 and 13 years to be most crucial in their feelings related to gender dysphoria. For those who continued to have feelings related to gender dysphoria, gender identity remained stable. Three main factors seem to have had a prominent impact on gender identity for those who continued to have these feelings and for those whose feelings of gender dysphoria became less prominent. Firstly, the changes in social environment (gender roles and expectations become more distinct during this period of their life); secondly, the effects of a changing body through puberty; and thirdly the experience of romantic feelings and falling in love (Steensma et al, 2011). For those who continued to experience. [sic]
The majority of our referrals at GIDS are adolescents who first presented with gender dysphoria or cross-gender identification at, or after, the onset of puberty. Traditionally, evidence has suggested that those who present to the service after puberty are more likely to continue to request service input for their gender in the long term (Steensma et. al., 2013; GIDS Audit: Retrospective Look at Cases Closed at GIDS, presented at WPATH 2016). However, we see a more diverse profile of young people presenting after puberty (e.g. Kaltiala-Heino et al, 2015), so it is unknown whether this is still the case.
Gender questioning children who do not continue with a cross-gender identification may be more likely to later identify as gay or lesbian than non-gender-questioning children (Drescher, 2013; Wallien & Cohen Kettenis, 2008).
gids.nhs.uk/continuing-and-not-continuing-studies
Social transition age
However, quantitative and qualitative follow-up studies by Steensma et al (2011; 2013) present evidence to strongly suggest that early social transition does not necessarily equate to an adult transgender identity. The qualitative study reports on two girls who had transitioned when they were in elementary school and struggled with the desire to return to their original gender role. Fear of teasing and feeling ashamed resulted in a prolonged period of stress. One girl even struggled to go back to her previous gender role for two years.
As such, in our approach, we would encourage exploration of gender roles in this younger cohort, with a view to keeping options open and not having any pre-conceived ideas as the longer term outcome.
gids.nhs.uk/evidence-base