Testing a Dyadic Model of Proximal Suicide Risk in Young Adult Romantic Couples - PROJECT SUMMARY/ABSTRACT Suicide is a leading cause of death in young adults, especially among those with borderline personality disorder (BPD), of whom up to 10% of whom die by suicide. BPD is hallmarked by relationship threat sensitivity (e.g., hyperreactivity to perceived rejection) which predicts conflict in romantic relationships, and often immediately precedes suicide-related events (SREs; suicide ideation, suicide-related communication, preparatory behaviors, attempts). While most theories of suicide explicitly underscore the importance of relationship factors however, suicide research has focused almost exclusively on the suicidal individual and failed to consider the dyadic context in which the suicidal individual exists. Thus, the overarching goal of this project is to identify dyadic interpersonal mechanisms within romantic relationships of high-suicide-risk young adults that exacerbate and maintain suicide risk. We will test a dyadic model of suicide risk whereby multimodal indices of emotional reactivity and problematic communication during dyadic conflict function to increase and maintain risk for SREs over time. To achieve this goal, we will recruit 168 romantic couples (ages 18-35) in which at least one member has had recent SREs and is thus at high risk for suicide. We will stratify the sample to ensure a full range of relationship threat sensitivity and BPD severity, and these distal risk factors will be examined as predictors and moderators of all hypothesized effects. Participants will complete a baseline laboratory assessment including a laboratory-based dyadic conflict discussion task and a 14-day ecological momentary assessment (EMA) protocol with continuous ambulatory psychophysiology and brief samples of audio recordings. Additionally, dyads will complete three follow-up assessments of SREs and psychosocial functioning at 4-, 8- and 12-months post- baseline. Our specific aims are to: 1) Examine interdependent associations between emotional reactivity and problematic communication in romantic dyads with suicide risk; 2) Investigate whether within-individual and dyadic patterns of emotional reactivity and problematic communication predict proximal increases (over hours, days) in SREs; and 3) Assess whether emotional reactivity and problematic communication following SREs functions to reinforce future SREs and predict worsening trajectories of suicide risk and psychosocial functioning. Findings from this study will lead to improved assessment tools, identify novel couples-based intervention targets, and inform the development of evidence-based strategies to reduce suicide risk and psychosocial impairment in vulnerable individuals.