The secondary school transition as a turning point for internalizing symptoms: Trajectories, correlates, and early adulthood outcomes

Internalizing disorders are the most common adolescent mental disorders. Using complementary variable-centered and person-centered approaches, we examined whether internalizing symptoms across eight years of adolescence (Grades 5-12) followed a continuous developmental trend or were disrupted by the transition to secondary school, and if different subgroups followed different pathways. Participants were 701 Canadian youth (52.9% girls; 75.9% white). Annual self-reported internalizing symptoms (ages 11-18) were examined using piecewise latent growth curve analysis (LGCM), revealing significant curve and level discontinuity at the transition, with distinct developmental phases in elementary and secondary school. Girls, youth with lower household income, and those with higher bullying victimization and lower social support showed elevated symptoms and/or steeper growth. An LGCM yielded four classes: Low (51.8%), Moderate (32.5%), Increasing (10.6%), and Declining (5.1%). The Declining and Moderate classes had comparable risk for early adulthood outcomes, demonstrating equifinality. Although beginning with similar levels, the Increasing class was at elevated risk compared to the Moderate class, demonstrating multifinality. Findings underscore that the secondary school transition can be viewed as a transition-linked turning point for a subset of adolescents, with implications for targeted screening and intervention beginning in elementary school.