Co-developmental trajectories of specific problematic usage of the internet: Associations with microsystem predictors...

The Spectrum Hypothesis posits that various forms of problematic usage of the internet (PUI) constitute distinct yet related constructs. However, empirical validation of this hypothesis has largely relied on cross-sectional data, leaving gaps in understanding the co-developmental trajectories of these behaviors during adolescence, their microsystem predictors, and how identified trajectories are associated with mental health outcomes. This study thus aimed to: (a) identify the heterogeneous co-developmental trajectories of problematic social media use, short video use, and internet game use; (b) examine the microsystem-level factors that predict membership in these distinct trajectories; and (c) investigate how these trajectory classes are associated with mental health outcomes.

A total of 1,975 Chinese middle school students (Mage = 13.51, 52.56% girls) completed measures on three occasions across one year.Results: Parallel process latent class growth modeling revealed five distinct trajectory groups: Low-Stable (61.0%), High-Increasing (8.1%), High-Stable Gaming and Moderate-Decreasing Social Media (15.5%), High-Stable Social Media and Short Video (6.9%), and Moderate-Increasing Social Media (8.4%). Harsh parenting, teacher-student conflict, and bullying victimization predicted worsening co-developmental trajectories. In addition, the High-Increasing class had higher risks for adverse mental health outcomes (i.e., depression, anxiety, and suicidality) compared to the Low-Stable class, whereas other high-risk classes also showed poorer outcomes (though less severe).

These findings support the Spectrum Hypothesis from a developmental perspective, highlighting the importance of considering heterogeneity in understanding the co-developmental patterns of PUI forms, their microsystem predictors, and cumulative effects on adolescent mental health.