Children on puberty blockers saw mental health change - new analysis

The majority of children in a landmark study on puberty blockers experienced positive or negative changes in their mental health, new analysis suggests.

The original study of 44 children, who all took the controversial drugs for a year or more, found no mental health impact - neither benefits nor harm.

But a re-analysis of that data now suggests 34% saw their mental health deteriorate, while 29% improved.

The authors of the original report have welcomed the new evidence.

The re-analysis, which has been seen by BBC Newsnight, questions some of the conclusions from the 2021 study about the potential mental health impact of puberty blockers on under 16s. It also sheds some light on this much-debated, but little understood, area of children's medicine.

The new study has not been in a peer-reviewed journal yet. The authors say they felt there was an urgency in getting the information into the public domain.

In 2011, a team from the Tavistock's Gender Identity Development Service (GIDS) - England's only NHS specialist gender clinic for children - and University College London Hospitals (UCLH) embarked on what became known as the early intervention study.

They enrolled 44 children, aged between 12 and 15, over the following three years. The study looked at the impact taking puberty blockers - medicines used to postpone puberty in children - was having. It resulted in the age at which puberty blockers could be offered on the NHS being lowered.

When the landmark study's results were published in 2021, it revealed blockers brought "no changes in psychological function" to those taking them.

But this differed from earlier findings of Dutch researchers, who pioneered this approach to treating gender dysphoria. They reported a positive impact on young people's mental health and wellbeing.

The early intervention study used scores from both parent and child questionnaires, which assessed children's behavioural and emotional problems. These are widely and reliably used in psychology in many countries and include more than 100 questions on things like school, feelings, and relationships.

The overall finding of "no change" was based on a group average - or mean - of those scores, given at different points in time.

"That's a very standard way of doing things," Professor Chris Evans, a retired psychiatrist and psychotherapist, told Newsnight. "The problem is it doesn't pay attention to how much variation there was across the participants."

For example, a quarter could score extremely high, a quarter could score quite high, a quarter could score quite badly, and a quarter could score extremely badly. Yet the group average would be somewhere in the middle.

Prof Susan McPherson, from the University of Essex, and David Freedman, a retired social scientist, have since re-analysed the data. They instead looked at the individual trajectories of each of the young people in the early intervention study.

They found, after 12 months of puberty blocker injections - 34% of the children had reliably deteriorated, 29% had reliably improved, and 37% showed no change, according to their self-reported answers.

The proportions were a little lower in the parents' scores, but in three quarters of the cases, there was broad agreement between parents and their children.

The impact on each of the children varied.

For a child who "deteriorated", it could mean moving from being psychologically well and not needing treatment for their mental health, to meeting criteria for a psychiatric diagnosis such as depression or anxiety. Whereas a child who "improved" could move from needing mental health treatment to being considered mentally well.

However, what neither the original research paper, nor the re-analysis, can do is tell us why these young people fared so differently.

The study is small - just 44 young people. And because of the way the original study was designed - without a control group - experts can't infer cause and effect or say these changes in wellbeing were caused by being on puberty blockers.

But despite those limitations, the new analysis suggests the need for more research, both into this specific group and on the impact of puberty blockers more generally.

Mr Freedman argues it is vital that young people and their families have the "best information possible" when making decisions on medical treatment.

In June NHS England announced that puberty blockers will only be made available to young people taking part in clinical trials.

Dr Hilary Cass's interim report into children's gender services highlighted "gaps in evidence" around the drugs, and a systematic review carried out by NICE found the quality of the evidence for the use of puberty blockers in this context to be "very low".

Similar reviews have been undertaken in Sweden and Finland, with both reaching the same conclusion. A number of other European countries have begun taking a more cautious, less medical approach to helping young people questioning their gender identity.

Both the Tavistock and Portman Trust and UCLH said they welcomed new contributions to the evidence base around how to support young people with gender incongruence.

A spokesperson from Tavistock and Portman [NHS Foundation] Trust said data from the original study had been published to allow other researchers to conduct "further analyses". It said the analysis plan for the original study was independently produced by experts in medical statistics.

A spokesperson for UCLH said it supported Dr Cass's recommendation that "research should be fully embedded in the development of new services for children and young people expressing gender incongruence".

They added: "We will work closely with the new national [Children and Young People's Gender Dysphoria] research oversight board to support the collection and analysis of robust data in this area."

The board will oversee the design and conduct of the new puberty-blocker research trial, as well as ensure research is embedded at the heart of new children and young people's gender dysphoria services.

The Cass Review Team told the BBC that it has commissioned "an updated systematic review" of academic publications on puberty blockers.

This review, along with this new analysis will be taken into account in its final recommendations, which are expected by the end of the year.