Increased belongingness as a mechanism of change of school-based programs mitigating suicidal ideation among adolescents

Suicide is a leading cause of death among adolescents, highlighting the importance of early intervention in school settings. Universal mental health awareness programs, aimed at improving mental health literacy and help-seeking behaviors, are a key preventive approach. This study examined whether changes in thwarted belongingness and perceived burdensomeness-two constructs from the Interpersonal Theory of Suicide (IPTS)-mediate the effects of school-based mental health interventions on suicidal ideation (SI). A total of 436 adolescents from central Israel (154 boys, 279 girls; M = 14.6, SD = 1.1) were randomly assigned to either a mental health awareness intervention (N = 256) or a minimal-intervention control group with attendance monitoring (N = 180). Belongingness, burdensomeness, and SI were assessed at baseline, 1-month, and 1-year post-intervention. Regression analyses showed that lower belongingness (β = -0.25, p < .001) and higher burdensomeness (β = 0.21, p < .01) predicted higher SI at 1-month, while only belongingness remained significant at 1-year (β = -0.19, p < .01). The mental health awareness intervention increased school-specific belongingness (β = 0.22, p < .001), whereas attendance monitoring intervention increased general belongingness (β = 0.18, p < .01). Mediation analysis indicated that the effects of the intervention type on SI were not significantly mediated by general and school belongingness. These findings suggest that promoting broader social connectedness beyond school environments may support reductions in adolescent suicide risk over time.