Problematic smartphone use in early adolescence: Developmental heterogeneity and bidirectional links with risk factors.

Smartphones offer convenience but have raised concerns about problematic smartphone use (PSU), particularly among early adolescents whose cognitive control is still developing. Examining developmental heterogeneity in PSU and its associated risk factors during this period has important theoretical and practical implications. Participants were 1821 Chinese children transitioning into early adolescence (Mage = 9.57 years; 48.5% female), followed annually for three years. Growth mixture modelling identified distinct PSU trajectories, and bidirectional associations with internal (e.g., shyness, depression, anxiety) and external factors (e.g., parental neglect, peer exclusion) were examined. Cross-lagged network analysis further assessed interval-specific variation in predictive associations. Two trajectories emerged: a low-decreasing group (intercept = 1.845, slope = -0.120) and a high-increasing group (intercept = 2.110, slope = 0.348). Early adolescents in the high-increasing group experienced more adverse environments and reported higher levels of risk factors. PSU was primarily predicted by external factors in early intervals, whereas both personal and environmental factors became influential in later intervals. These findings highlight the heterogeneous and dynamic nature of PSU and support early, targeted family-focused interventions.