Joint associations of problematic smartphone use and cyberbullying victimization with depressive and anxiety symptoms among Chinese primary and secondary school students: a large-scale school-based study

Problematic smartphone use (PSU) and cyberbullying victimization (CBV) are independently associated with emotional problems among adolescents. However, whether their co-occurrence is associated with a greater burden of depressive and anxiety symptoms remains unclear. This study examined the joint associations of PSU and CBV with depressive and anxiety symptoms among primary and secondary school students. A school-based cross-sectional survey was conducted among 27,586 students in Grades 5–12 in Hunan, China. PSU was assessed using the Smartphone Application-Based Addiction Scale, and CBV was assessed using the online harassment dimension of the Online Risk Exposure Scale. Depressive and anxiety symptoms were measured using the Patient Health Questionnaire-9 and Generalized Anxiety Disorder-7, respectively. Participants were classified into no-risk, PSU-only, CBV-only, and dual-risk groups. Multivariable logistic regression was used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs). Additive interaction was assessed using the relative excess risk due to interaction, attributable proportion due to interaction, and synergy index. The prevalence of depressive symptoms, anxiety symptoms, PSU, and CBV was 10.2%, 6.4%, 20.1%, and 27.9%, respectively. Among participants with PSU, 48.9% reported CBV; among those with CBV, 35.3% met the criteria for PSU. Compared with the no-risk group, the dual-risk group had the highest odds of depressive symptoms (OR = 5.39, 95% CI: 4.73–6.14) and anxiety symptoms (OR = 5.02, 95% CI: 4.29–5.88). Positive additive interaction was observed in the overall sample, with subgroup-specific evidence most consistently observed among males and gaming users. Co-occurring PSU and CBV were associated with the greatest emotional symptom burden. Concurrent assessment of dysregulated smartphone use and online victimization may help identify students with greater depressive and anxiety symptom burden, particularly males and those primarily engaged in gaming.