Patients with borderline personality disorder (BPD) display severe difficulties in interpersonal relationships and impulse control. We explored the possibility that patients with BPD show less trust and more risk-taking behavior in experimental games as compared with controls and with depressed patients with other personality disorders. In the trust game, the participant played the role of an investor who interacted with a trustee via the Internet. The investor could choose a costly action by giving money units (MU) to the trustee. The trustee then could honor the investor's trust by sharing the monetary increase. In the risk game, the investor could transfer money to a lottery, and therefore the payoff depended on luck and not on the decision of another person. Results revealed that the patients with BPD (n = 25) transferred a smaller amount of MUs across 5 consecutive transactions in the trust game as compared with the controls (n = 25) and with the depressed patients (n = 25). In the risk game, the performance of the BPD patients was similar to that of the controls and depressed patients. Trust game performance was predicted by the interpersonal and cognitive sector scores of the Zanarini Rating Scale for Borderline Personality Disorder. Self reports indicated that the patients with BPD were less optimistic regarding the outcome (payoff) of the trust game, but not of the risk game. These results suggest that patients with BPD exhibit less trust during interpersonal interactions, which may be related to stress-related paranoia, dissociation, identity disturbance, and problems in interpersonal relationships.

Trust and cooperation are essential features of human interpersonal transactions. Recent evidence suggests that these processes are related to brain areas implicated in social decision-making. These novel data provide a unique opportunity to characterize psychopathological conditions in which trust and cooperation are potentially impaired. Using economic games, independent investigations revealed that trust and cooperation are disrupted in patients with borderline personality disorder who have severe difficulties in their personal relationships and exhibit abnormal emotion regulation. Data from functional neuroimaging indicated that the abnormal activation of the anterior insula might be a key factor during these processes, together with the cingulate cortex and the amygdala.

Disturbed interpersonal relationships specific to borderline personality disorder (BPD) suggest biased processing of social information. The goal of this study was to examine alterations in mental state decoding (MSD) and their associations with early maladaptive schemas (EMS) that may lead to the misinterpretation of incoming information. In addition, the authors' aim was to evaluate the effects of a co-occurring current major depressive episode (MDE) on the MSD performance of BPD patients. Seventy-eight BPD patients (34 with MDE) and 76 matched healthy controls (HC) were assessed for Reading the Mind in the Eyes Test (RMET) and the level of EMS. The authors found that impairment in the total RMET performance, as well as specific impairment regarding the recognition of positive and neutral items, was associated with EMS, and enhanced vigilance to negative mental states was characteristic to BPD with MDE. Results suggest that MSD ability is altered in two independent ways in BPD.

A single nucleotide polymorphism of the neuregulin 1 gene (SNP8NRG243177/rs6994992) increases the risk of psychosis, affects prefrontal activation and structural connectivity in the brain, and is related to the expression of a specific neuregulin 1 isoform. The purpose of this study was to investigate the interaction between this polymorphism and reactivity to psychosocial stress. Two hundred patients with schizophrenia were genotyped. The patients and one of their family members participated in neutral and conflict-related interactions in which the number of relatives' criticisms and patients' unusual thoughts was assessed. Patients with the risk T/T genotype expressed more unusual thoughts than C-carriers (C/T and C/C) during conflict-related interactions but not during neutral interactions. Two controls polymorphisms of the neuregulin 1 gene (rs10954867 and rs7005288) showed no such effect. These results raise the possibility that there is a significant gene by environment interaction regarding SNP8NRG243177/rs6994992 and psychosocial stress.

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