Multimodal assessment of social disconnection as a proximal risk for suicide ideation in late life. - Abstract/Project Summary Globally, and in the United States, older adults exhibit the highest rates of suicide deaths. Research has shown that social disconnection and interpersonal negative life events (NLEs) are both significantly linked with suicide ideation, attempts, and deaths in late life, yet few studies have examined moderators of the relationship between social disconnection and suicide ideation or considered social disconnection as a mediator of the relationship between interpersonal NLEs and suicide ideation in late life, despite compelling evidence to do so. In addition, existing studies are mostly cross-sectional and provide little insight into how suicide risk unfolds over hours, days, weeks, and months in older adults. The overarching goal of this proposal is to leverage a multimodal assessment of behavioral and social mechanisms to improve our ability to identify specific predictors relating social disconnection to suicidal ideation in late life. We will examine how a crucial social- cognitive vulnerability, rejection sensitivity (RS), moderates the relationship between social disconnection and suicidal ideation in late life. RS is the predisposition to subjectively perceive, anxiously expect, and intensely react to social rejection, and reflects the Research Domain Criteria (RDoC) of Social Processes: Affiliation and Attachment. Using an intensive longitudinal design over the course of 1-year, we will also examine social disconnection as a mediator of the relationship between interpersonal NLEs and suicidal ideation over different timescales. Participants will include a diagnostically diverse sample of 250 men and women ages 60 and older who report elevated suicidal ideation. Multimodal assessments will include interviews, self-report measures, two laboratory-based social rejection paradigms, and a 14-day ecological momentary assessment (EMA) protocol. Follow-up assessments will be conducted every 3 months over the course of 1-year to fully assess rare, low base rate interpersonal NLEs (e.g., death, illness, loss of relationships), and the 14-day EMA protocol will be repeated at 6-months and 12-months. The proposed project has two specific aims: 1) to investigate RS as a static and time-varying moderator of the relationship between social disconnection and suicidal ideation in late life; and 2) to examine the mediating effect of social disconnection on the relationship between interpersonal NLEs and suicidal ideation in late life. Results will aid in the development of evidence-based personalized treatment recommendations targeting key dimensions of social disconnection, rejection sensitivity, interpersonal NLEs, and suicidal ideation in late life.