Search

Investigating the effects of the gender-affirming hormone treatment of transgender people using neuroimaging provides a unique opportunity to study the impact of high dosages of sex hormones on human brain structure and function. This line of research is of relevance from a basic neuroscientific as well as from a psychiatric viewpoint. Prevalence rates, etiopathology, and disease course of many psychiatric disorders exhibit sex differences which are linked to differences in sex hormone levels. Here, we review recent neuroimaging studies from others and our group that investigate the effects of gender-affirming hormone treatment in a longitudinal design utilizing structural and functional magnetic resonance imaging and positron emission tomography. Studies point to a general anabolic and anticatabolic effect of testosterone on grey and white matter structure, whereas estradiol and antiandrogen treatment seems to have partly opposite effects. Moreover, preliminary research indicates that gender-affirming hormone treatment influences serotonergic neurotransmission, a finding that is especially interesting for psychiatry. A clear picture of a hormonal influence on brain activity has yet to emerge. In conclusion, the available evidence reviewed here clearly indicates that sex hormone applications influence brain structure and function in the adult human brain.

Approximately 7–9% of people develop posttraumatic stress disorder in their lifetime, but standard pharmacological treatment or psychotherapy shows a considerable individual variation in their effectiveness. Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) hold promise for the treatment of posttraumatic stress disorder. The objective of this meta-analysis was to summarize the existing evidence on the therapeutic effects of these brain stimulation treatments on posttraumatic core symptoms. We systematically retrieved articles published between 1st January 2000 and 1st January 2020 comparing the effects of active with sham stimulation or no intervention in posttraumatic patients from eight databases. Random-effects model was used for meta-analysis. Meta-regression and subgroup meta-analysis was performed to investigate the influence of stimulation dose and different stimulation protocols, respectively. 20 studies were included in this review, where of 11 randomized controlled trials were subjected to quantitative analysis. Active stimulation demonstrated significant reductions of core posttraumatic symptoms with a large effect size (Hedge’s g = −0.975). Subgroup analysis showed that both excitatory and inhibitory rTMS of the right dorsolateral prefrontal cortex led to symptom reductions with a large (Hedges’ g = −1.161, 95% CI, −1.823 to −0.499; p = 0.015) and medium effect size (Hedges’ g = −0.680, 95% CI: −0.139 to −0.322; p ≤ 0.001) respectively. Results further indicated significant durability of symptom-reducing effects of treatments during a two to four weeks period post stimulation (Hedges’ g = −0.909, 95% CI: −1.611 to −0.207; p = 0.011). rTMS of the right dorsolateral prefrontal cortex appears to have a positive effect in reducing core symptoms in patients with posttraumatic stress disorder.