Transcranial Direct Current Stimulation Over the Prefrontal Cortex in Depression Modulates Cortical Excitability in Emotion Regulation Regions as Measured by Concurrent Functional Magnetic Resonance Imaging: An Exploratory Study.

Background: A well-established impaired top-down network for effortful emotion regulation (ER) in major depressive disorder (MDD) includes the dorsal and ventromedial prefrontal cortex (PFC) and the amygdala. Transcranial direct current stimulation (tDCS) is a noninvasive neuromodulation method that has been used successfully to induce mood changes in MDD. Despite reliable findings, little is known regarding the precise effects of tDCS on cortical excitability in vivo in depression and how such changes relate to ER. Here, we addressed this question by combining-for the first time in a psychiatric sample-tDCS with functional magnetic resonance imaging in a single-blind randomized design.

Methods: We applied anodal tDCS over the left PFC (area F3 per the 10/20 system) together with cathodal tDCS over the right PFC (F4) or sham tDCS during functional magnetic resonance imaging in patients with moderate to severe MDD (n = 20) and gender- and age-matched control subjects (n = 20). Participants performed 2 runs of an ER task prior to tDCS and 2 runs of the task during tDCS, which was administered at 1.5 mA with 5-cm × 5-cm electrodes.

Results: Whole-brain, region of interest, and connectivity analyses revealed an impaired ER network in patients with MDD prior to stimulation. Active anodal tDCS over the left (with concurrent cathodal stimulation of the right) PFC during reappraisal of negative stimuli upregulated activity in ventromedial PFC, which was predictive of gains in reappraisal performance during stimulation for the patients with MDD.

Conclusions: The results of this study offer insights into the mechanisms of action of tDCS and support its potential as a treatment for depression.