Oxytocin can hinder trust and cooperation in borderline personality disorder

Abstract

We investigated the effects of intranasal oxytocin (OXT) on trust and cooperation in borderline personality disorder (BPD), a disorder marked by interpersonal instability and difficulties with cooperation. Although studies in healthy adults show that intranasal OXT increases trust, individuals with BPD may show an altered response to exogenous OXT because the effects of OXT on trust and pro-social behavior may vary depending on the relationship representations and expectations people possess and/or altered OXT system functioning in BPD. BPD and control participants received intranasal OXT and played a social dilemma game with a partner. Results showed that OXT produced divergent effects in BPD participants, decreasing trust and the likelihood of cooperative responses. Additional analyses focusing on individual differences in attachment anxiety and avoidance across BPD and control participants indicate that these divergent effects were driven by the anxiously attached, rejection-sensitive participants. These data suggest that OXT does not uniformly facilitate trust and pro-social behavior in humans; indeed, OXT may impede trust and pro-social behavior depending on chronic interpersonal insecurities, and/or possible neurochemical differences in the OXT system. Although popularly dubbed the 'hormone of love', these data suggest a more circumspect answer to the question of who will benefit from OXT.

Fig. 1

Scatter-plot displaying individual differences in attachment anxiety (mean-centered) and attachment avoidance (mean-centered), as measured by the ECR, in healthy control and borderline personality disorder (BPD) participants. Consistent with prior research, BPD participants fell into either the high anxious, low avoidant (‘preoccupied’) or high anxious, high avoidant (‘fearful’) quadrants of the ECR indicating the heterogeneous nature of attachment in BPD.

Fig. 2

Assurance Game payoff matrix. Participants’ payoff for each round is a function of their strategic choice and their partner’s strategic choice. As depicted, participants make the most money ($6) when they and their partner choose strategy A; however, participants should only choose strategy A if they trust their partner will also chose strategy A. The decision involves an element of trust because participants must make their strategic choice before they know what choice their partner made on that round. (Note: to circumvent socially desirable responses, the words ‘cooperate’ and ‘defect’ were never used; participants only saw ‘Strategy A’ and ‘Strategy B’).

Fig. 3

Partner strategy expectations (‘trust’) following oxytocin or placebo for healthy control and BPD participants. Higher numbers reflect more cooperative partner expectations, or greater trust. Error bars represent standard errors of the difference between means. *P < 0.05 (two-tailed).

Fig. 4

Strategic response to partner hypothetical cooperation following oxytocin or placebo for healthy control and BPD participants. Higher numbers reflect more cooperative strategic choices. Error bars represent standard errors of the difference between means. *P < 0.05 (two-tailed).

Fig. 5

Actual cooperative behavior for all (BPD and control) participants as a function of OXT or placebo, and individual differences in attachment anxiety and attachment avoidance. Higher numbers reflect more cooperative behavior. Simple slope analyses showed that OXT primarily modulated cooperative behavior for the anxiously attached participants, but the direction of the effect depended on avoidance level, with OXT significantly increasing cooperative behavior for high anxious, low avoidant (‘preoccupied’) participants (B = 0.52, t(18) = 2.24, P < 0.05; bold dashed line), but significantly decreased cooperative behavior for high anxious, high avoidant (‘fearful’) participants (B = −0.41, t(18) = −2.09, P = 0.05; bold solid line). Low anxious participants showed no change in cooperative behavior as a function of OXT (both ps > 0.1).