A Structural Magnetic Resonance Imaging Study in Transgender Persons on Cross-Sex Hormone Therapy

Background: To date, research findings are inconsistent about whether the neuroanatomy in transgender persons resembles that of their natal sex or their gender identity. Moreover, few studies have examined the effects of longterm cross-sex hormonal treatment on neuroanatomy in this cohort. The purpose of the present study was to examine neuroanatomical differences in transgender persons after prolonged cross-sex hormone therapy. Methods: Eighteen transgender men (female-to-male), 17 transgender women (male-to-female), 30 nontransgender men (natal men), and 27 nontransgender women (natal women) completed a high-resolution structural magnetic resonance imaging scan at 3 T. Eligibility criteria for transgender persons were gender-affirming surgery and at least 2 years of cross-sex hormone therapy. Exclusion criteria for nontransgender persons were presence of psychiatric or neurological disorders. Results: The mean neuroanatomical volume for the amygdala, putamen, and corpus callosum differed between transgender women and natal women but not between transReceived: February 3, 2016 Accepted after revision: July 31, 2016 Published online: August 5, 2016 Sven C. Mueller Department of Experimental Clinical and Health Psychology Ghent University, Henri Dunantlaan 2 BE–9000 Ghent (Belgium) E-Mail sven.mueller @ ugent.be © 2016 S. Karger AG, Basel