Theory of suicide and effects of school-based suicide prevention interventions 

Barzilay 

Introduction  

Suicide ideation (SI) and attempts (SA) peak during adolescence and young adulthood. The current study tests two psychological models of suicide. One prominent model is the interpersonal theory of suicide (IPTS). IPTS proposes that the interaction of two interpersonal constructs: “thwarted belongingness” (experience of loneliness/isolation) and “perceived burdensomeness” (perception of being a burden on others) predicts SI. This combination leads to SA only in the presence of “acquired capability for suicide", through exposure and thus habituation to painful or fearsome experiences such as prior self-injury or risk behaviors.  

An alternative model of suicidal behaviors is the two-pathway model. This model conceptualizes two separate mechanisms leading to SA among adolescents. One pathway is through reactive self-directed aggression and impulsivity, which may have underlying dysregulated serotonin metabolism. The other independent pathway is that of an internalizing process based on anxiety and depression that may be related to interpersonal distress. 

Methods 

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Results 

The modeling estimation indicated that the IPTS hypothesized model is superior to the two-pathway model in fitting the observed data.  

The IPTS hypothesized model 

• Predicting suicidal ideation 

• Results indicated that higher depression and anxiety, but not externalizing symptoms, predict a higher likelihood of endorsing SI at 12-month follow-up. Belongingness to parents (but not peers or burdensomeness) predict lower likelihood of endorsing SI. 

• Predicting the trajectories of change in suicide attempts over time 

• Results indicated that among the control group, the group with no SA was less likely to endorse SI, self-injury, and had lower risk behaviors at baseline than repeated SA group. 

• The interaction between SI and self-injury predicted repeated SA. 

• Thus: the likelihood of repeated SA compared with no SA was significantly higher for adolescents who reported SI and self-injury at baseline than those who only reported self-injury.  

Discussion 

Consistent with IPTS predictions and prior studies, in the present study, thwarted belongingness to parents predicted higher levels of SI as assessed one year later. This effect remained significant after controlling for depression and anxiety.  

The higher likelihood of repeated SA was related to risk behaviors and repetitive self-injury at baseline, with SI augmented self-injury risk for repeated SA. Thus, the IPTS interpretation that each repeated SA is evidence of increased acquired capability is supported.  

Comparison between the IPTS and the two-pathway model indicated a superior fit for IPTS. Nevertheless, some findings supported the two-pathway model such as the independent main effects of SI, risk behaviors, and self-injury on the likelihood of SA, which is consistent with the previous report. 

Limitations 

• The measures may not fully capture the end cognitions in belongingness and burdensomeness as well as pathways to acquired capability other than risk behaviors and self-injury. Therefore, other interpretations of the reported results may also apply. 

• Furthermore, not all the interactions suggested by IPTS model were tested in the current study. 

• Finally, the study time frame examined predictors over 12-months. This time interval was too long to allow examination of more proximal predictors to distinguish different patterns of SA with or without suicide premeditation as conceptualized by the two-pathway model.