Transcranial direct current stimulation (tDCS) targeting the medial prefrontal cortex (mPFC) modulates functional connectivity and enhances inhibitory safety learning in obsessive-compulsive disorder (OCD)

BackgroundPsychotherapy based on fear extinction is a mainstay of treatment for obsessive-compulsive disorder (OCD). The default mode network (DMN) is important to safety signal processing, fear extinction, and exposure-based therapies. The medial prefrontal cortex (mPFC) is an anchor of the DMN. Neuromodulation targeting the mPFC might augment therapeutic learning and thereby enhance response to exposure-based therapies. MethodsTo characterize the effects of mPFC neuromodulation, 17 community volunteers completed resting-state fMRI scans before and after receiving 20 minutes of frontopolar multifocal transcranial direct current stimulation (tDCS). To examine the effects of tDCS on therapeutic learning, 24 patients with OCD were randomly assigned (double-blind, 50:50) to receive active or sham tDCS immediately before completing a two-day exposure and response prevention (ERP) challenge. ResultsAfter tDCS, frontal pole functional connectivity with regions in the anterior insula and basal ganglia decreased, while connectivity in the middle and superior frontal gyri increased (ps<.001, corrected). Functional connectivity between DMN and salience network (SN) increased after tDCS (ps<.001). OCD patients who received active tDCS exhibited more rapid within- and between-trial therapeutic extinction learning (ps<.05) during the ERP challenge compared to those who received sham tDCS. ConclusiontDCS targeting the mPFC may modulate SN and DMN functional connectivity and can accelerate therapeutic learning. Though limited by small samples, these promising findings motivate further exploration of the effects of tDCS on neural and behavioral targets associated with exposure-based treatments for OCD and for other anxiety and related disorders.