Is problematic smartphone use an independent risk marker for adolescent suicidal-thought trajectories? A person-centered, depression-adjusted analysis

초록

A substantial cross-sectional literature links problematic smartphone use (PSU) to adolescent suicidal thoughts, yet few studies test whether this association is independent of co-occurring depressive symptoms or examine it across development. Using five-year longitudinal data from the Korea Children and Youth Panel Survey (N = 2590), we conducted latent class growth analysis to identify distinct trajectories of suicidal thoughts from seventh through eleventh grade (2018-2022) and tested PSU as a predictor of trajectory membership before and after adjustment for depressive symptoms. Four trajectories emerged: High-Decreasing (with a late rebound; 8.8%), Chronic-High (2.8%), Mid-Rising-Falling (19.5%), and Low-Maintaining (68.9%). Compared with the normative Low-Maintaining group, adolescents with higher PSU were more likely to follow the High-Decreasing trajectory in bivariate analyses. This link disappeared, however, once we accounted for depressive symptoms, which stood out as the strongest predictor. The within-person association between PSU and suicidal thoughts told a similar story: it was weak to begin with, and depression explained most of it. Family factors—parental warmth, rejection, and inconsistency—together with peer and teacher relationships and female gender, were far more reliable in distinguishing the higher-risk trajectories. Taken together, these results caution against casting PSU as an independent driver of adolescent suicidal thoughts; much of its apparent risk signal is shared with depression. In digitally saturated adolescent populations, then, prevention may gain more from screening for depression and strengthening family and school ties than from targeting smartphone use on its own. © 2026 Elsevier Ltd

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