An investigation of the interpersonal theory of suicide in an inpatient sample of individuals with Bipolar Disorders

Bipolar spectrum disorders confer an exceptionally high risk for a range of suicide-related behaviors (Merikangas et al., 2011). However, no theoretical model of suicide has been comprehensively and empirically tested in an inpatient sample of individuals with bipolar disorders. The interpersonal theory of suicide (IPTS; Joiner, 2005; Van Orden et al., 2010) is a theoretical conceptualization of the etiology of suicide and suicidal behaviors. The interpersonal theory of suicide posits that the desire and ability to enact lethal or near-lethal suicidal behaviors are distinct. Additionally, when three theoretical constructs – thwarted belongingness, perceived burdensomeness, and acquired capability are present simultaneously, the highest risk for lethal and near-lethal suicidal outcomes are present. The present study aimed to empirically test the IPTS in an inpatient sample of individuals with bipolar disorders. Thirty psychiatric inpatients that met criteria for a bipolar spectrum disorder completed several self-report questionnaires, a diagnostic interview, and a structured clinical interview assessing history of serious suicidal behaviors. The current study aims to examine the relationships between perceived burdensomeness, thwarted belongingness, acquired capability for suicide, painful and provocative events, and bipolar disorder related-variables in predicting suicide-related outcomes. Hierarchical linear regression, simple linear regression, and Pearson’s correlation were used to test study hypotheses. Analyses were substantially under-powered and should be considered preliminary. Findings suggest that neither perceived burdensomeness, nor thwarted belongingness were significant predictors of passive suicide ideation, after controlling for depression. Additionally, the statistical interaction of these two constructs did not significantly predict overall suicide ideation. Number of elevated mood episodes did not significantly predict engagement in painful and provocative events. Painful and provocative events were not found to be significantly related to acquired capability for suicide. Acquired capability for suicide was a significant predictor of medical lethality for participants’ most lethal suicide attempt, after removing non-significant covariates. Clinical and theoretical implications, limitations, and future research directions are explored.