Administration of Testosterone Increases Functional Connectivity in a Cortico-Cortical Depression Circuit.

Increasing evidence suggests that the steroid hormone testosterone (T) enhances libido and decreases depression. Even a single administration of T (0.5 mg sublingually) in healthy young women is sufficient to enhance physiological sexual responsiveness. Such physiological evidence is not yet available for the link between T and depression. Recent research has revealed that lowered functional connectivity in a specific corticocortical pathway may be a sensitive physiological index for depression. This pathway, comprised of the left prefrontal and right parietal cortex, has been named a cortical depression circuit. In the present study, a single dose of T was administered to healthy young women to investigate the effects on the functional connectivity in this corticocortical depression circuit. It was hypothesized that administration of T would lead to an increase of functional connectivity. In a double-blind placebo-controlled, crossover design, fourteen healthy females received (sublingually) a single dose of 0.5 mg T or placebo in a randomly assigned fashion. Three hours after drug administration the functional coupling between the left prefrontal and right parietal cortex was established by measuring the inter-hemispheric electroencephalogram (EEG) coherence for the different frequency bands. Compared to placebo, T administration significantly increased the functional connectivity in the a (1-3 Hz) frequency range between the left prefrontal and right parietal cortex. Reductions in inter-hemispheric coherence in the a frequency range have been observed in clinically depressed patients. Thus the present findings may provide a first insight into the neurobiological mechanism by which T decreases depression. The fact that only a single dose of T was able to induce the effect in healthy female subjects suggests that the mechanism is highly sensitive. A feasible application of T treatment in the struggle against depression is discussed. (PsycInfo Database Record (c) 2021 APA, all rights reserved)