Research Raises Concerns About the Impact of Puberty Blockers on the Development of Cognitive Function
By Sallie Baxendale, Professor of Clinical Neuropsychology at the UCL, Queen Square, Institute of Neurology.
It is often said by those who promote puberty blockers as treatments for adolescents with gender dysphoria that the effects are ‘completely reversible’. Since puberty is a critical window of development in brain structure and function, it is important to know what impact blocking puberty may have on cognitive development.
This systematic review of the literature sets out to examine the scientific evidence that has looked at the effect of puberty blockers on the development of cognitive function.
A search of the literature found a total of 16 studies that have specifically looked at the impact of puberty blockers on cognitive function. Most of these studies (11) had been conducted in animals. These studies found that puberty blockers interfered with cognitive development in the animals and that male and female animals reacted differently to the drugs. Only five studies have specifically looked at the impact of puberty blockers on cognitive development in young people. Two of these studies looked at the effects in children with precocious puberty and three looked at the effects in children who had been prescribed puberty blockers for gender dysphoria. Of these five studies, three reported lower IQs in patients treated with puberty blockers, with 2 reporting a drop in IQ in some patients following the administration of the drug, and 1 a lower IQ compared with controls.
The review of the literature found that no well-designed studies have ever been conducted to properly assess the impact of puberty blockers on cognitive function.
Our current understanding of the importance of puberty in the development of cognitive function, animal studies and very limited data from human studies do not support the notion that puberty blockers have no impact on cognitive development or that any effects are reversible.
Indeed, the evidence to date points in the other direction, but in reality, we simply do not know. Nobody has looked at this properly. The author of the review calls for urgent research to be conducted in this area to monitor the impact of these medications on cognitive development.
Key Points
1. Adolescence is a critical window of neurodevelopment and puberty plays a critical role in these neurodevelopmental processes.
2. The suppression of puberty impacts brain structure and the development of social and cognitive functions in mammals, the effects are complex and often sex specific.
3. No human studies have systematically explored the neuropsychological impact of pubertal suppression in transgender adolescents with an adequate baseline and follow up.
4. Animal studies, single case reports and studies of the impact of puberty blockers in children with precocious puberty indicate that these treatments may be associated with reductions in IQ.
4. The impact of pubertal suppression on measures of neuropsychological function should be an urgent priority for future research.
For more background on how the adolescent brain develops see this article by Prof. Baxendale on the CAN-SG website, and this article on the Teenage Brain on the Transgender Trend website.
For a discussion on the ethical aspects of gender affirmative medicine see this article by Prof. Baxendale: Lessons from the Wrong Side of History.