Grant: Project Grant

About 1% of young Canadians are trans. Some trans adolescents are prescribed puberty blockers (GnRHa) to pause puberty-related changes and lower their gender-related distress. Blockers suppress sex hormones, which play a key role in brain development. However, few studies have investigated variations in trans adolescents' brains, and little is known about how blockers impact the developing brain. Before starting treatment, trans youths' brains likely show a mix of features-some aligning with their sex assigned at birth and others with their gender identity. Individual factors such as assigned sex, age, puberty stage, hormone levels, and sexual orientation may influence these patterns. Understanding these differences is crucial to interpreting how blockers might shape brain development. This study has two main goals. First, we will compare the brains of trans and cisgender (non-trans) adolescents before any treatment, identifying similarities, differences, and factors that contribute to individual variation. Second, we will track brain changes in trans youth before and after starting puberty blockers, comparing their development to cis peers over the same time period. We will examine how blockers affect brain structure and function and whether factors such as age, hormones, and treatment duration play a role. This international project spans Canada, Spain, Brazil, and Italy, allowing for a large and diverse sample of trans and cis youth. We will use advanced brain imaging techniques to measure brain structure and function. Our analyses will capture both group-level trends and individual variations in brain organization. Findings from this study will provide much-needed evidence on trans adolescent brain development and puberty blockers' effects, helping clinicians, policymakers, trans youth and their families make informed decisions. Through collaboration with community advisors, we will ensure that our results are shared widely and responsibly.