Augmenting Virtual Reality Exposure Therapy for Social and Intergroup Anxiety With Transcranial Direct Current Stimulation

OBJECTIVES: Exposure therapy is a cornerstone of social anxiety treatment, yet not all patients respond. Symptoms in certain social situations, including intergroup (ie, out-group) contexts, may be particularly resistant to treatment. Exposure therapy outcomes may be improved by stimulating neural areas associated with safety learning, such as the medial prefrontal cortex (mPFC). The mPFC also plays an important role in identifying others as similar to oneself. We hypothesized that targeting the mPFC during exposure therapy would reduce intergroup anxiety and social anxiety. METHODS: Participants (N = 31) with the public speaking subtype of social anxiety received active (anodal) or sham transcranial direct current stimulation (tDCS) targeting the mPFC during exposure therapy. Exposure therapy consisted of giving speeches to audiences in virtual reality. To target intergroup anxiety, half of the public speaking exposure trials were conducted with out-group audiences, defined in this study as audiences of a different ethnicity. RESULTS: Contrary to hypotheses, tDCS did not facilitate symptom reduction. Some evidence even suggested that tDCS temporarily increased in-group favoritism, although these effects dissipated at 1-month follow-up. In addition, collapsing across all participants, we found reductions across time for public speaking anxiety and intergroup anxiety. CONCLUSIONS: The data provide evidence that standard exposure therapy techniques for social anxiety can be adapted to target intergroup anxiety. Transcranial direct current stimulation targeting the mPFC may boost safety signaling, but only in contexts previously conditioned to signal safety, such as an in-group context.