The ability to engage in pro-social, cooperative behavior is essential for developing and maintaining stable relationships. The neuropeptide oxytocin (OXT) has been shown to play a central role in pro-social behavior (Carter et al., 1992
; Panksepp, 1992
; Carter, 1998
; Insel and Young, 2001
). Specifically, research in animals indicates that OXT is critically involved in pair-bond formation, separation distress and other aspects of attachment and affiliation (Lim and Young, 2006
). Some evidence suggests that OXT is also involved in human pro-social behavior. For example, OXT, administered nasally, increased trusting behavior in a social dilemma game (Kosfeld et al., 2005
) and increased the perceived trustworthiness of faces (Theodoridou et al., 2009
). OXT may thus be a useful agent to increase pro-social behavior in individuals who have difficulties with such behaviors.
Borderline personality disorder (BPD) is characterized by affective instability, impulsivity—including impulsive aggression—and identity confusion (American Psychiatric Association, 2000
). Interpersonal instability is also a core feature of BPD: individuals with BPD tend to have intense relationships marked by desperate attempts to avoid abandonment. Ironically, these reassurance-seeking strategies are often accompanied by efforts to downplay the importance of closeness and/or aggressive acts aimed at punishing significant others (Gunderson, 1996
), leading to relationships marked by frequent arguments, repeated breakups and overall emotional volatility (Lieb et al., 2004
). Although interpersonal difficulties are most apparent in established relationships, individuals with BPD were shown to have difficulty sustaining cooperation in a social dilemma game played with a stranger (King-Casas et al., 2008
), suggesting that their difficulties can extend beyond their existing relationships. Given that OXT promotes pro-social, trusting behavior in healthy adults, OXT may be helpful in facilitating such behaviors in BPD.
Other research, however, suggests that the effects of OXT may differ in those with BPD. First, a recent study found that OXT (vs
placebo) increased negative social emotions like envy and ‘schadenfreude’ (Shamay-Tsoory et al., 2009
); it was suggested that rather than having broad positive effects on social perception and behavior, OXT may increase the salience of social cues, thereby triggering the positive or
negative emotions associated with them. Others have suggested that OXT increases approach behaviors (Kemp and Guastella, 2010
), or affiliative drive more specifically (Taylor et al., 2006
). These alternate explanations of OXT function all suggest that individual differences—especially differences in the relationship representations and expectations people possess—and/or situational factors may critically moderate the effects of OXT on social perception and behavior. With respect to BPD, if OXT increases the salience of social cues, or increases affiliative drive, OXT may in fact exacerbate BPD individuals’ chronic concerns about abandonment and trust, and their difficulties with cooperation, especially when administered in situations where such issues are salient.
Second, the OXT system may be dysregulated in BPD and, for this reason, may produce a differential response to exogenous OXT. Research shows that negative interpersonal experiences can impact the endogenous OXT system: lower cerebrospinal fluid (CSF) OXT levels have been observed in nursery- vs
mother-reared monkeys (Winslow et al., 2003
), and in women who experienced childhood abuse and/or neglect (Heim et al., 2008
), and higher (in contrast to CSF) plasma OXT levels have been associated with self-reports of relationship distress (Taylor et al., 2006
), anxiety over relationships (Turner et al., 1999
) and social anxiety symptom severity in social phobia (Hoge et al., 2008
). Moreover, there is preliminary evidence that such socially ‘at risk’ individuals may differentially respond to exogenous OXT (Meinlschmidt and Heim, 2007
). Given the centrality of interpersonal dysfunction in BPD, these individuals may be good candidates for neurochemical alterations within the OXT system (also see Stanley and Siever, 2009
) and, thus, differential responsivity to intranasal OXT.
The present investigation
In this study, we investigated the effects of intranasal OXT on trust and cooperative behavior in healthy adults and adults with BPD. We tested two competing hypotheses about OXT function. On the one hand, studies in healthy adults suggest that intranasal OXT should facilitate trust and cooperation in both healthy control and BPD participants. On the other hand, individuals with BPD may show an altered response to intranasal OXT because the effects of OXT on trust and pro-social behavior vary as a function of the relationship representations one possesses and/or because of possible neurobiological differences in the OXT system in BPD.
In addition to investigating OXT response as a function of diagnostic status, we investigated whether individual differences in attachment anxiety and attachment avoidance moderate the effects of OXT on trust and pro-social behavior. Our rationale for this more nuanced approach was two-fold. First, individual differences in attachment anxiety and avoidance are important moderators of pro-social behavior. Avoidance is negatively associated with empathy (Mikulincer et al., 2001
), compassion and willingness to help (Mikulincer et al., 2005
), volunteering (Gillath et al., 2005
), adhering to the communal script (Bartz and Lydon, 2008
), identifying with values like benevolence and universalism (Mikulincer et al., 2003
) and cooperative helping on group tasks (Rom and Mikulincer, 2003
). Attachment anxiety, by comparison, is associated with more ambivalent pro-social behavior, and data suggests a desire to affiliate that is sometimes hindered by interpersonal anxiety (e.g. Mikulincer et al., 2001
; Rom and Mikulincer, 2003
; Bartz and Lydon, 2006
). Second, several studies have shown considerable attachment heterogeneity in BPD, with some BPD individuals showing high levels of both anxiety and avoidance (i.e. ‘fearful’ types), and others showing high levels of anxiety only (i.e. ‘preoccupied’ types) (Agrawal et al., 2004
; Levy et al., 2005
; Aaronson et al., 2006
). If attachment anxiety and avoidance differentially affect pro-social behavior, failing to account for attachment heterogeneity could obscure important differences in the effects of OXT on pro-social behavior, especially in BPD participants.