title: Effects of sex hormone treatment on white matter microstructure in individuals with gender dysphoria.
abstract: Sex steroid hormones such as estradiol and testosterone are known to have organizing, as well as activating effects on neural tissue in animals and humans. This study investigated the effects of transgender hormone replacement therapy on white matter microstructure using diffusion tensor imaging. Female-to-male and male-to-female transgender participants were measured at baseline, four weeks and four months past treatment start and compared to female and male controls. We observed androgenization-related reductions in mean diffusivity and increases in fractional anisotropy. We also observed feminization-related increases in mean diffusivity and reductions in fractional anisotropy. In both transgender participants and controls, hormonal fluctuations were correlated with changes in white matter microstructure. Although the present study does not preclude regression to the mean as a potential contributing factor, the results indicate that sex hormones are - at least in part - responsible for white matter variability in the human brain. Studies investigating the effects of sex hormones on adult human brain structure may be an important route for greater understanding of the psychological differences between females and males.
authors.affiliation: Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria.
authors.forename: Georg S
authors.initials: GS
authors.lastname: Kranz
authors.affiliation: Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria.
authors.forename: Rene
authors.initials: R
authors.lastname: Seiger
authors.affiliation: Department of Obstetrics and Gynecology, Medical University of Vienna, Austria.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Kaufmann
authors.affiliation: MR Centre of Excellence, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria.
authors.forename: Allan
authors.initials: A
authors.lastname: Hummer
authors.affiliation: Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hahn
authors.affiliation: Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Ganger
authors.affiliation: MR Centre of Excellence, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Tik
authors.affiliation: MR Centre of Excellence, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Windischberger
authors.affiliation: Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Kasper
authors.affiliation: Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria. Electronic address: rupert.lanzenberger@meduniwien.ac.at.
authors.forename: Rupert
authors.initials: R
authors.lastname: Lanzenberger
mesh_terms: D000328:Adult; D001921:Brain / Q000187:drug effects*; D056324:Diffusion Tensor Imaging; D005260:Female; D000068116:Gender Dysphoria / Q000188:drug therapy*; D012739:Gonadal Steroid Hormones / Q000627:therapeutic use*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D066127:White Matter / Q000187:drug effects*
chemical_list: D012739:Gonadal Steroid Hormones
keywords: Diffusion tensor imaging; Gender dysphoria; Hormone replacement therapy; Transgender