Reduction of rejection-related emotions by transcranial direct current stimulation over right ventrolateral prefrontal cortex in borderline personality disorder: A double-blind randomized pilot study.

Aims: Borderline personality disorder (BPD) patients show negative emotional reactions to both excluding and including social scenarios, with levels normalizing only during extreme inclusion. Prior research among healthy individuals highlights the right ventrolateral prefrontal cortex (rVLPFC) role in regulating emotional responses to social exclusion, since transcranial direct current stimulation (tDCS) of rVLPFC decreases rejection-related emotions following social exclusion. This pilot study investigated whether, in BPD patients, tDCS over the rVLPFC reduces rejection-related emotions not only after social exclusion but also after fair social inclusion.

Methods: Forty BPD patients randomly received either real or sham tDCS on rVLPFC before participating in the Cyberball paradigm, which involved phases of inclusion, exclusion, and over-inclusion. Participants self-reported their level of rejection-related emotions following each phase.

Results: Transcranial direct current stimulation reduced rejection-related emotions during both social exclusion and fair inclusion, but not during over-inclusion. Specifically, those in the Real tDCS group exhibited comparable emotional responses to fair and over-including scenarios, unlike those in the Sham group who experienced heightened rejection-related emotions during fair inclusion compared to over-inclusion.

Conclusions: Transcranial direct current stimulation over the rVLPFC reduces BPD patients' tendency to feel rejected both in fairly including and excluding scenarios. These findings confirm the rVLPFC involvement in emotional regulation and highlight a therapeutic potential for tDCS in moderating BPD's typical heightened rejection-related emotional responses to fairly including scenarios. This study supports the application of tDCS in BPD treatment, providing new insights into neuromodulatory interventions that can aid BPD patients to better regulate their emotions during varying social scenarios.