Associational pathway analyses of depression and impulsivity in the relationship between internet addiction and non-suicidal self-injury among adolescents: a cross-sectional case–control study

Background: Adolescents undergo important developmental changes, characterized by profound biological and psychosocial changes. This period is also associated with increased vulnerability to mental health challenges and engagement in risky/problematic behaviors. Non-suicidal self-injury (NSSI) and internet addiction (IA) are increasingly recognized as prevalent and interconnected behavioral concerns among adolescents, particularly those with depressive disorders. Impulsivity has also been identified as a key psychological factor in both IA and NSSI. This study aimed to investigate the cross-sectional interrelationships among depression, impulsivity, IA, and NSSI in adolescents. Methods: A total of 110 adolescents (55 diagnosed with major depressive disorder [MDD] and 55 healthy controls) were recruited from the Child and Adolescent Psychiatry Outpatient Clinic at Suez Canal University Hospital. The severity of depression was assessed using the Children’s Depression Inventory (CDI). All participants completed the Internet Addiction Test (IAT), Deliberate Self-Harm Inventory (DSHI), and Barratt Impulsiveness Scale (BIS-11). Statistical analyses included group comparisons, correlation analyses, logistic regression. Cross-sectional pathway analyses using structural equation modeling (SEM) was conducted to examine indirect associations between IA and NSSI through depression and impulsivity. Results: Adolescents with MDD reported significantly higher levels of NSSI, IA, and impulsivity compared to controls. Significantly positive correlations between IAT, BIS-11, and CDI scores and lifetime NSSI frequency were demonstrated among the depression group. IA and NSSI were significantly associated by indirect pathways through both depression and impulsivity. In serial associational models, the cross-sectional indirect pathway from impulsivity to depression (B = 0.370) was stronger than the reverse direction (B = 0.310). Conclusion: Our findings highlighted the interrelated roles of IA, impulsivity, and NSSI among adolescents with MDD. Impulsivity may be a critical factor linking IA to emotional dysregulation and self-injurious behavior. These results highlight the need for integrated screening and prevention strategies targeting impulsivity and these risk behaviors.