The regulation of emotions associated with social exclusion: modulating effects of tDCS on patients with borderline personality disorder

Abstract Background. Patients with Borderline Personality Disorder (BPD) show negative emotional reactions following both social exclusion and normally including scenarios; only experimental conditions of extreme inclusion decrease BPD patients’ rejection-related emotions to levels comparable to healthy individuals. At the brain level, emotional reactions to social exclusion are mediated by the right Ventrolateral Prefrontal Cortex (rVLPFC). Among healthy subjects, the neuromodulation of this region by means of transcranial direct current stimulation (tDCS) decreases negative emotional responses and pain following social exclusion. However, no study yet evaluated whether, among BPD patients, tDCS on rVLPFC reduces the intense negative emotions elicited by both social exclusion and social inclusion. Methods: Forty BPD patients (36 females) were randomly assigned to receive either real or sham tDCS on rVLPFC while, in a one session experiment, they were socially included, then excluded, and finally overincluded by using the Cyberball paradigm. Participants self-reported their level of rejection-related emotions after each Cyberball condition. Results. Overall, BPD patients reported high levels of rejection-related emotions in the ostracism condition, intermediate in the inclusion condition, and low in the overinclusion condition. tDCS, compared to sham stimulation, reduced the overall levels of rejection-related emotions following both the exclusion and inclusion conditions. tDCS stimulation on rVLPFC did not influence patients’ negative emotions in the overinclusion condition. Conclusion: Our results showed that tDCS applied to rVLPFC helped to downregulate negative emotions of BPD patients in both excluding and including interactions. Conversely, the sham group manifested higher negative reactions in both these conditions. A ceiling effect was hypothesized for the overinclusion condition. Overall, these findings improve evidence of rVLPFC involvement in responses to perceived social exclusion in BPD and provide new data on neuromodulation effects in BPD patients. Research Category and Technology and Methods Clinical Research: 9. Transcranial Direct Current Stimulation (tDCS) Keywords: Borderline Personality Disorder, Ventrolateral Prefrontal Cortex, Transcranial Direct Current Stimulation, Social exclusion