Neural processing of social participation in borderline personality disorder and social anxiety disorder

Patients with borderline personality disorder (BPD) and patients with social anxiety disorder (SAD) are known to be highly sensitive to social rejection. Social information processing is assumed to play a key role for this shared psychopathological phenomenon. The first steps in social information processing are to encode social cues and to create a mental representation of the social situation. The aim of the current study was to test whether the perception of social participation in patients with BPD and patients with SAD is biased in this initial stage of social processing. Focus was on the P3b, a brain potential related to stimulus evaluation that has been shown to be a sensitive indicator for the processes of interest. Twenty five unmedicated patients with BPD, 25 unmedicated patients with SAD and 25 healthy controls (HC) played an EEG-compatible version of Cyberball, a virtual ball-tossing paradigm that experimentally induces social inclusion and exclusion. All participants showed a pronounced P3b when excluded. Only patients with BPD showed an enhanced P3b also during the inclusion condition, indicating altered processing of social inclusion. The EEG results for the BPD group were consistent with their self-report data. Patients with BPD felt more excluded during the inclusion condition of Cyberball than both HC and patients with SAD. Furthermore, heightened rejection expectancy (subscale of the Rejection Sensitivity Questionnaire) was associated with a smaller difference in the P3b amplitude between inclusion and exclusion. Results indicate a negatively biased perception of social inclusion in BPD already during the initial stage of social processing.