Who is most at risk, and when? Gender-differentiated patterns and risk heterogeneity of adolescent depression in China: Evidence from a large-scale national study

Adolescent depression is a major public health concern involving well-documented gender differences that may vary across cultural contexts. In China's academically intensive educational environment, questions regarding when depression risk peaks across adolescence, how behavioral and social factors relate to depression differentially by gender, and how risks cluster into distinct vulnerability profiles remain underexplored. This cross-sectional study analyzed data from a nationwide survey of 414,175 Chinese adolescents. We used generalized additive models and latent profile analysis to examine gender-differentiated age patterns and behavioral–social risk configurations. Results showed that girls reported higher depression scores than boys. Age patterns differed by gender: girls exhibited persistently elevated depression between ages 14–18, whereas boys showed na less pronounced inverted U-shaped pattern with resurgence in late adolescence. Behavioral risks (substance use, screen time) were more strongly associated with depression among girls, whereas physical activity and perceived socioeconomic resources were stronger protective factors for girls. Latent profile analysis identified three subgroups—"Active Advantaged," "Inactive Disadvantaged," and "Screen-Dependent"—with girls in the Screen-Dependent profile (10 %; high screen time, low physical activity) showing markedly higher depression levels. The findings highlight the need for continuous mental health monitoring for girls throughout mid-to-late adolescence (ages 14–18), increased support for boys approaching late adolescence (ages 16–18), and targeted interventions addressing clustered risks in high-screen-use, low-activity subgroups.