The moderating role of infidelity on the relation between oxytocin and conflict behaviors among substance misusing couples.

Relationship conflict and distress negatively impacts psychological and physical health and is saliently associated with substance misuse (Baucom et al., 1998; McCrady et al., 2016; Schumm, O'Farrell, & Andreas, 2012). Conversely, adaptive couple functioning is central to positive treatment engagement and outcomes for substance use disorders (McCrady et al., 2016; Powers, Vedel, & Emmelkamp, 2008). The neuropeptide oxytocin (OT) has demonstrated beneficial effects on social cognition and prosocial behavior and has shown therapeutic potential in the treatment of various psychiatric conditions including substance use disorders (e.g., Flanagan, Sippel, Wahlquist, Moran-Santa Maria, & Back, 2018b). OT might prove useful as an adjunct treatment for behavioral therapies with couples, including those targeting substance-misusing individuals who are prone to have difficulty managing conflict in intimate relationships (Cranford, Floyd, Schulenberg, & Zucker, 2011) due to OT’s potential to ameliorate stress reactivity and to increase trust, emotional recognition, and cooperation (Bakermans-Kranenburg & van Ijzendoorn, 2013; Ditzen et al., 2009; Keri & Kiss, 2011; Kosfeld, Heinrichs, Zak, Fischbacher, & Fehr, 2005; Mitchell, Gillespie, & Abu-Akel, 2015). However, more research is needed given some findings that reveal a seemingly inconsistent effect of OT on social behavior (Bartz, Zaki, Bolger, & Ochsner, 2011b; Mitchell, Arcuni, Weinstein, & Woolley, 2016; Shamay-Tsoory & Abu-Akel, 2016). The social salience hypothesis posits that OT may amplify an individual’s pre-existing social inclinations, rather than universally enhance prosocial behavior and cognition (Shamay-Tsoory & Abu-Akel, 2016). For example, OT’s effects have been found to vary based on person and context (Bartz et al., 2011b), such as familiarity and anticipated threat. Although early evidence suggests beneficial effects of OT on couple functioning (Ditzen et al., 2009), more recent literature suggests that various individual and situational factors modulate social behavior responses to OT (Bartz et al., 2011a; DeWall et al., 2014; Jarnecke, Barden, Back, Brady, & Flanagan, 2018). Thus, OT may not exclusively promote adaptive conflict behaviors among couples, but could potentially increase negative affect and conflict behaviors in the context of specific individual or contextual vulnerabilities. It is necessary, therefore, to examine the contextual relationship factors that may moderate OT response in couples in order to identify for whom and under what circumstances OT is most beneficial. One relationship factor that might influence OT response is infidelity; that is, sexual, romantic, or emotional involvement that breaches the commitment to an exclusive romantic relationship (Glass, 2002). Both emotional infidelity and physical infidelity can cause deleterious relationship and health outcomes (Marin, Christensen, & Atkins, 2014; Whisman, 2016). Infidelity has been identified as the most frequent self-reported cause of divorce (Amato & Previti, 2003) and is associated with depression (Cano & O'Leary, 2000), low self-esteem (Charny & Parnass, 1995), and intimate partner violence (Carbone-Lopez, Kruttschnitt, & Macmillan, 2006; Nemeth, Bonomi, Lee, & Ludwin, 2012). Thus, infidelity may represent a relational vulnerability that modulates reactivity to OT; however no previous studies to date have examined the role of infidelity in OT response. In line with the social salience hypothesis of OT (Shamay-Tsoory & Abu-Akel, 2016), instead of OT generally increasing positive and decreasing negative communication, infidelity may serve as a maladaptive contextual vulnerability that influences OT-related effects on conflict behaviors. The current study is designed to address this gap in the literature. Specifically, we examined whether infidelity moderates the association between OT and dyadic conflict behaviors in a sample of couples with substance misuse. This study extends prior research by examining these associations within a dyadic framework to account for both actor (e.g., how much one’s current behavior is predicted by his/her own behavior) and partner effect (e.g., how much one’s behavior is influence by his/her partner’s behavior). We hypothesized that actor and partner infidelity would (1) be associated with less adaptive conflict behaviors, and (2) moderate the OT response, such that participants randomized to the OT condition, compared to placebo, who report more infidelity would show less adaptive conflict behaviors.