Elevated testosterone and prosocial behavior in female patients with borderline personality disorder independent of social exclusion.

Objective: Borderline personality disorder (BPD) is marked by unstable relationships and fear of abandonment. Earlier studies suggest that patients with BPD are highly sensitive to social exclusion and show deficits in trust and cooperation. The hormone testosterone influences such prosocial behavior and regulates aggressive and caring behavior. Previous studies show elevated testosterone levels in female patients with BPD at baseline and after psychosocial stress, while results after social exclusion are missing.

Method: We investigated the effects of social exclusion on prosocial behavior (sharing and punishment) and salivary testosterone in female patients with BPD. Ninety-eight patients with BPD and 98 healthy females matched for menstrual cycle were randomly assigned to an overinclusion or exclusion condition of the virtual ballgame Cyberball. Afterwards, participants played two games in which they could share money with a fictional player ("dictator game") and accept or reject (= punish) offers from a player ("ultimatum game").

Results: Female patients with BPD displayed higher testosterone levels than the control group before and after Cyberball. Social exclusion did not affect testosterone levels. Patients with BPD exhibited more prosocial behavior by sharing more money than controls and punished co-players for unfair offers equally often.

Conclusion: We replicated previous findings of elevated testosterone in female patients with BPD and showed that it is not affected by experimentally induced social exclusion. Regardless of social exclusion, patients with BPD showed more prosocial behavior, which may reflect a status-seeking strategy to secure their social standing.