Longitudinal trajectories of depressive symptoms in adolescent students

Longitudinal studies examining depressive symptom trajectories in adolescents remain limited, particularly in school-based populations. This study aimed to identify psychosocial risk and protective factors associated with depressive symptom trajectories in a cohort of Chinese adolescents.

A four-semester longitudinal survey was conducted among 1,145 primary and secondary school students using the 9-item Patient Health Questionnaire (PHQ-9) and the Mental Health Diagnostic Test Scale (MHT). Quasi-Poisson generalized linear models adjusted for overdispersion in PHQ-9 scores. Latent class mixed models delineated distinct depressive symptom trajectories. Binary logistic regression evaluated predictors of high-risk group membership, and generalized linear mixed-effects models assessed time-by-group interactions, adjusting for age, sex, and grade.

Across four time points, 27.9%-32.2% of adolescents scored ≥ 5 on the PHQ-9, indicating elevated risk for depression. Learning anxiety was the most prevalent anxiety subtype (41.9%-49.1%). Significant risk factors associated with higher depressive symptom scores included learning anxiety, hopelessness, interpersonal anxiety, sensitiveness, impulsive tendency, and temper loss, whereas family warmth and help-seeking behavior served as protective. Depressive symptoms in the past year were strong predictors of current depressive symptom severity. Two distinct depressive symptom trajectories were identified: a stable low-risk group and a high-risk group with worsening symptoms. The high-risk group, particularly among sixth-grade students, exhibited a sharper increase in loneliness over time, with hopelessness and somatic anxiety as key predictors.

This study delineates the developmental trajectories of depressive symptoms in adolescents and identifies modifiable psychosocial factors associated with high-risk patterns. The findings underscore the importance of early identification and targeted, school-based interventions to improve adolescent mental health outcomes.