A Multimethod Approach to Understanding the Association Between Interpersonal Stress, Proinflammatory Response, and Suicidality



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Suicide is the second leading cause of death among adolescents and young adults. Peer-related interpersonal stress increases suicide risk within this age group. However, not all individuals who undergo peer-related interpersonal stress experience suicidal thoughts and behaviors. Thus, the identification of factors that affect this relationship is critical. Consistent with the Social Signal Transduction Theory of Depression (Slavich & Irwin, 2014), a “primed” proinflammatory response to acute stress is one factor that may influence the relationship between suicidal thoughts and behaviors and interpersonal stress. While it is possible that a “primed” proinflammatory response serves as a pathway through which mental health difficulties develop, it is equally plausible that it enhances risk for mental health problems among individuals already experiencing psychopathology. This dissertation examined the nature of this relationship using a mixed methods approach in a sample of 42 emerging adults with recent suicidal thoughts and behaviors. Study 1 examined the relation between interpersonal stress and two proinflammatory cytokines. Participants completed self-report measures of suicidal thoughts and behaviors, recent peer-related stressors, interpersonal sensitivity, and general perceived stress. They also participated in an acute laboratory social stress task and provided three saliva samples to measure their proinflammatory responses (IL-6 and TNF-a) to the stressor. Results demonstrated that greater sensitivity to interpersonal interactions was marginally associated with a lower IL-6 proinflammatory response to the acute lab stressor (small-to-medium effect). Study 2 examined the relation between interpersonal stress and suicidal ideation in real time, as well as whether the proinflammatory response (drawn from Study 1) moderated this association. Participants completed 28 days of ecological momentary assessment that assessed for suicidal ideation (presence vs. absence, ideation intensity), the occurrence of negative peer stressors, and feelings of exclusion. Results demonstrated a trend for within-person increases in feelings of exclusion to be associated with increases in suicidal ideation intensity at the same time point (medium effect). Additionally, within-person increases in number of negative peer events were associated with increased odds of the presence of suicidal ideation at the next time point among individuals with a very low IL-6 response to acute interpersonal stress. However, this finding is considered preliminary and requires replication in larger samples, and thus must be interpreted with caution. Implications and methodological considerations are discussed to guide future research in this area.