Testing the interpersonal theory of suicide in adolescents: A multi-wave longitudinal study

Abstract

Background: Suicide is a major public health crisis among youth. Several prominent theories, including the Interpersonal Theory of Suicide (IPTS), aim to characterize the factors leading from suicide ideation to action. These theories are largely based on findings in adults and require testing and elaboration in adolescents.

Methods: Data were examined from high-risk 13-18-year-old adolescents (N = 167) participating in a multi-wave, longitudinal study; 63% of the sample exhibited current suicidal thoughts or recent behaviors (n = 105). The study included a 6-month follow-up period with clinical interviews and self-report measures at each of the four assessments as well as weekly smartphone-based assessments of suicidal thoughts and behaviors. Regression and structural equation models were used to probe hypotheses related to the core tenets of the IPTS.

Results: Feelings of perceived burdensomeness were associated with more severe self-reported suicidal ideation (b = 0.58, t(158) = 7.64, p < .001). Similarly, burdensomeness was associated with more frequent ideation based on weekly smartphone ratings (b = 0.11, t(1460) = 3.41, p < .001). Contrary to IPTS hypotheses, neither feelings of thwarted belongingness, nor interactions between burdensomeness and thwarted belongingness were significantly associated with ideation (ps > .05). Only elevated depression severity was associated with greater odds of suicide events (i.e., suicide attempts, psychiatric hospitalizations, and/or emergency department visits for suicide concerns) during the follow-up period (OR = 1.83, t(158) = 2.44, p = .01). No effect of acquired capability was found.

Conclusions: Perceptions of burdensomeness to others reflect a critical risk factor for suicidal ideation among high-risk adolescents. Null findings with other IPTS constructs may suggest a need to adopt more developmentally sensitive models or measures of interpersonal and acquired capability risk factors for youth. Refining methods and theoretical models of suicide risk may help improve the identification of high-risk cases and inform clinical intervention.

Keywords: Suicide; adolescence; longitudinal studies; risk factors; social factors.

Figure 1:. Associations between Perceived Burdensomeness and Suicide Ideation

The correlation between sum scores on the INQ Perceived Burdensome subscale at baseline and suicide ideation is presented here. Baseline ideation severity based on sum scores of the Scale for Suicide Ideation (SSI) is presented in panel A. The average of weekly smartphone assessments of ideation is presented in panel B. Participants with a prior attempt history are indicated by red circles, those with ideation but no attempt history are in green triangles, and psychiatric controls with no ideation or attempt history are indicated by blue plus signs.

Figure 2:. Structural Equation Model Test of IPTS Hypotheses

Results of an a priori structural equation model probing hypotheses of the IPTS over longitudinal timepoints are summarized here. Scores on the INQ subscales are considered at baseline; their covariances is denoted by a dotted line. INQ subscales and their interaction were tested as predictors of suicide ideation severity at the 1-month follow-up. Ideation, acquired capability, and their interaction were tested as predictors of the absence/presence of suicide events across the remaining follow-up period (months 1–6). Standardized coefficients and their corresponding Z-statistic are presented for each path. Significant paths are in black (p<.05); non-significant paths are in gray. * p<0.05 ** p<0.01 *** p<0.001