Mechanisms of Change in the Prevention of Depression: An Indicated School-Based Prevention Trial at the Transition to High School

Objective: Depression represents a major public health concern, and prevalence increases significantly during adolescence. The high school transition may exacerbate the risk of depression for youth with pre-existing vulnerability. The High School Transition Program (HSTP) is a brief, skills-based intervention that has demonstrated efficacy in preventing depression in adolescents. The current study aimed to evaluate the theorized mechanisms of change of the HSTP intervention by testing a multiple mediation model including school attachment (SA) and self-esteem (SE) as two mediators of treatment outcomes. Method: Students (N= 497; 61.5% girls) with elevated depressive symptoms, identified for the intervention program via an eighth-grade screening, were randomized to a brief intervention (n = 247) or the HSTP (n = 233) from 2003 to 2008. Participants completed measures at five time points. The first assessment occurred at the start of the second semester of eighth grade and the last assessment occurred at the end of ninth grade. A multiple mediation model tested whether SA and SE contributed to changes in depression for youth in the HSTP. Results: The mediation model, including contemporaneously assessed SE and SA, was not supported. There was evidence of sequential mediation, such that students who participated in the HSTP intervention reported higher SA, which in turn predicted improved SE, and in turn contributed to amelioration of depressive symptoms. Conclusion: The HSTP intervention ameliorated depressive symptoms by targeting factors specific to the school transition (ie, SA). Results suggest youth at risk for depression may benefit from prevention efforts that enhance students' capacity to effectively manage identified environmental stressors, such as school transitions.