Applying the Interpersonal Theory of Suicide to Middle Childhood: A Longitudinal Analysis Using the ABCD Study

Background: Suicide rates among children aged 5 to 11 years in the United States have increased over the past decade, with suicide now ranking as the eighth leading cause of death in this age group. Despite this concerning trend, most empirical research on suicidality has focused on adolescents and young adults, leaving early childhood relatively understudied. Similarly, prominent theories such as the Interpersonal Theory of Suicide (IPTS) have been extensively validated in older populations but remain largely untested among younger children. Given developmental differences, it is unclear whether key IPTS constructs—such as thwarted belongingness and acquired capability for suicide—manifest similarly in younger cohorts. This study provides a preliminary examination of these constructs using developmentally appropriate proxies within a large, nationally representative cohort of U.S. youth. Specifically, it evaluates whether early experiences of school connectedness and exposure to life stressors prospectively predict suicidal ideation, acquired capability for suicide, and subsequent suicide attempts over time.

Method: Data were drawn from baseline, Wave I, and Wave II (2017–2020) of the Adolescent Brain Cognitive Development (ABCD) Study, a nationally representative U.S. cohort (n = 11,878; 48% female). Structural equation modeling (SEM) was used to examine longitudinal trajectories of suicidal ideation and suicide attempts, using constructs derived from the IPTS, specifically thwarted belongingness and acquired capability for suicide. Thwarted belongingness was modeled as a latent factor comprising school environment, school involvement, and school disengagement indicators at baseline. Suicidal ideation was assessed at Wave I and suicide attempts was assessed at Wave II through clinical indicators of past or present diagnoses, while acquired capability for suicide was measured at Wave I using a latent construct of life stressors (family strain, friendship loss, health stressors, and financial difficulties). Covariates included sex, race/ethnicity (White [reference], Black, Asian, American Indian/Native, and other), and household income.

Results: Model fit indices indicated good fit (RMSEA = 0.023; CFI = 0.93; TLI = 0.92). Males had a negative association with belongingness (b = -0.653), while Black and Latinx youth reported higher associations with belongingness relative to White youth. Belongingness was negatively associated with suicidal ideation (b = -0.134), and suicidal ideation was positively associated with both capability for suicide (b = 0.155) and suicide attempts (b = 0.496). Capability for suicide at Wave I was significantly associated with suicide attempts at Wave II (b = 0.487). Indirect effects showed that belongingness predicted suicide attempts through suicidal ideation (b = -0.067), but not through capability. Suicidal ideation also indirectly predicted suicide attempts via capability for suicide (b = 0.027).

Conclusion and Implications: Findings provide initial empirical support for applying the IPTS to middle childhood. Thwarted belongingness predicted using a life stressors suicidal ideation, which increased acquired capability for suicide and risk for suicide attempts over time. Results highlight the importance of promoting early social connectedness to reduce suicide risk. Interventions targeting school belongingness and early life stressors may prevent progression from suicidal thoughts to behaviors. Future research should refine IPTS constructs for younger populations and examine long-term trajectories into adolescence.