Persistent loneliness is often reported by patients with borderline personality disorder (BPD). However, empirical studies investigating this aspect of BPD psychopathology are sparse. Studies from social psychology revealed that social isolation and low social functioning contribute to loneliness, that is, the subjective feeling of being alone. The aim of the present study was to contribute to the understanding of loneliness in BPD by investigating its relation to social isolation and functioning in different domains of life. Subjective experience of loneliness was measured in 80 women (40 BPD patients, 40 healthy controls) with the UCLA Loneliness Scale. Social isolation and social functioning were assessed with the Social Network Inventory and the Social Functioning Scale. In addition, we assessed global functioning with the Global Assessment of Functioning. BPD patients reported stronger feelings of loneliness compared to healthy participants. In general, the level of loneliness was linked to network size, social engagement, and prosocial behavior. Diversity of social networks and functioning in the domain of interpersonal communication were associated with the level of loneliness only in BPD. A reduced variety of roles in social life together with impairments in interpersonal communication were particularly relevant for the experience of loneliness in BPD, suggesting an indirect path to target this psychopathological feature in therapeutic interventions. However, both social isolation and social functioning were not sufficient to explain the severely increased loneliness experienced by these patients, stressing the need for further investigation of determinants of loneliness in this clinical population. (PsycINFO Database Record

Anxious preoccupation with real or imagined abandonment is a key feature of borderline personality disorder (BPD). Recent experimental research suggests that patients with BPD do not simply show emotional overreactivity to rejection. Instead, they experience reduced connectedness with others in situations of social inclusion. Resulting consequences of these features on social behavior are not investigated yet. The aim of the present study was to investigate the differential impact of social acceptance and rejection on social expectations and subsequent social behavior in BPD. To this end, we developed the Mannheim Virtual Group Interaction Paradigm in which participants interacted with a group of computer-controlled avatars. They were led to believe that these represented real human coplayers. During these interactions, participants introduced themselves, evaluated their coplayers, assessed their social expectations and received feedback signaling either acceptance or rejection by the alleged other participants. Subsequently, participants played a modified trust game, which measured cooperative and aggressive behavior. Fifty-six nonmedicated BPD patients and 56 healthy control participants were randomly and double-blindly assigned to either the group-acceptance or group-rejection condition. BPD patients showed lower initial expectations of being socially accepted than healthy controls. After repeated presentation of social feedback, they adjusted their expectations in response to negative, but not to positive feedback. After the experience of social acceptance, BPD patients behaved less cooperatively. These experimental findings point to a clinically relevant issue in BPD: Altered cognitive and behavioral responses to social acceptance may hamper the forming of stable cooperative relationships and negatively affect future interpersonal relationships. (PsycINFO Database Record (c) 2018 APA, all rights reserved).