What happens during puberty? And what happens if we try to stop it? It’s one of the most fraught questions of our time. Given its significance and the vulnerability of the people it involves, you might be surprised to learn that there have been more studies assessing the impact of puberty blockers on cognitive function in animals than humans. Of the 16 studies that have specifically examined the impact of puberty blockers on cognitive function, 11 have been conducted in animals. And most found some detrimental impact on cognitive function when the researchers gave these drugs to mice, sheep or monkeys.
The sheep studies were particularly interesting as they used twin lambs, administering the puberty blockers to only one in the pair. More than one year after stopping the medication, the sheep who had taken the puberty blockers had still not “caught up” with their untreated siblings in their ability to complete a test of spatial memory. It can, however, be fairly argued that we can only extrapolate so much from the abilities of sheep to remember the way through a maze of hay bales. It is really the studies in humans that are of most interest to those considering prescribing or taking these drugs.
Yet such studies are hard to come by. There are only five that have looked at the impact of puberty blockers on cognitive function in children, and only three of these have looked at these effects in adolescents given the medication for gender dysphoria. In one of these studies, the researchers didn’t measure how well the children were doing before they administered the drugs, so it is difficult to know whether the subsequent difficulties they had on a strategy task could be attributed to the medication. A second study established an excellent baseline, and the researchers employed a gold-standard measure to test the cognitive abilities of the children in the programme before they started the puberty blockers.
Unfortunately, they didn’t re-administer these tests to assess the impact of the medication, but chose instead to report how many of a subset of these children completed a vocational education and how many completed a higher vocational education years later. No outcomes at all were reported on 40% of the children who started out in the study. The final study, however, was beautifully designed: the researchers assessed IQ prior to the administration of puberty blockers and regularly monitored the impact of the treatment over 28 months on a comprehensive battery of cognitive tasks. The results were concerning and suggested an overall drop in IQ of 10 points which extended to 15 points in verbal comprehension. But regrettably, this was a single case study, and while alarming, the conclusions we can draw from one person’s experience are limited.
Last year, I wrote a paper to summarise the results of these studies. The paper explained in relatively simple terms why we might think that blocking puberty in young people could impact their cognitive development. In a nutshell: puberty doesn’t just trigger the development of secondary sex characteristics; it is a really important time in the development of brain function and structure. My review of the medical literature highlighted that while there is a fairly solid scientific basis to suspect that any process that interrupts puberty will have an impact on brain development, nobody has really bothered to look at this properly in children with gender dysphoria.
I didn’t call for puberty blockers to be banned. Most medical treatments have some side effects and the choice of whether to take them depends on a careful analysis of the risk/benefit ratio for each patient. My paper didn’t conduct this kind of analysis, although others have and have judged the evidence to be so weak that these treatments can only be viewed as experimental. My summary merely provided one piece of the jigsaw. I concluded my manuscript with a list of outstanding questions and called for further research to answer these questions, as every review of the medical literature in any field always does.
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