Observed positive support and cortisol reactivity/recovery among heterosexual cisgender and sexually and gender diverse couples

Positive romantic relationships are linked to physical health via stress buffering. Although a growing number of studies have found that couple interactions before or after the Trier Social Stress Test (TSST) modulate cortisol reactivity and recovery in the stress-exposed individual, gaps remain concerning dyadic, cross-partner associations and specific positive support behaviors that could explain this buffering effect. Additionally, while sex assigned at birth, sociocultural gender, and sexual orientation have been shown to modulate stress reactive cortisol, such studies have not included sexual/gender diverse (SGD) couples. Therefore, the goal of this study was to examine dyadic associations between positive support behaviors and cortisol secretion among diverse couples. One hundred eighteen couples (51 SGD couples) took part in a two-hour laboratory protocol. One partner underwent the TSST and the other acted as a support during filmed discussions assessed by external coders using the Social Support Global Interaction Coding System's positive support dimensions (SCIS; problem description, emotional expression, attentiveness and listening, validation and emotional support, behavioral involvement, and interactional synchrony). Both partners provided seven saliva samples and completed sociodemographic measures. Multivariate analysis of variance and an independent sample t-test showed SGD partners displayed more behavioral involvement, and SGD couples displayed more interactional synchrony than their heterosexual cisgender (HC) counterparts. Path analyses based on the Actor-Partner Interdependence Moderation Model (APIMoM) showed within- and cross-partner associations between positive support behaviors and cortisol output and recovery among all couples. SGD stressed partners benefited from their own emotional expression during stress recovery, whereas HC stressed partners' display of attentiveness and listening was associated with their own delayed stress recovery. Findings suggest SGD couples may display more positive support behaviors than HC couples when facing stress. This study extends past research suggesting partner support can modulate reactivity and recovery by identifying specific support behaviors that relate to cortisol secretion among diverse couples.