Roberta Matković, Lucija Vejmelka
Background: Problematic Internet use (PIU) among adolescents has emerged as a significant public health concern, associated with the types of online activities and underlying psychological processes rather than screen time alone. Methods: This cross-sectional study included 750 adolescents (46.4% female) with a mean age of 15.39 years (SD = 1.76; range = 13–19) recruited from 7th and 8th grade primary school students and secondary school students in Split-Dalmatia County (Croatia). The study investigated the associations between specific online activities, psychological variables, and PIU using hierarchical regression and multiple mediation analyses. Results: Results revealed that time spent online remains the most strongly associated with PIU. While streaming and online shopping showed significant associations with problematic use, reading and browsing for information did not. Stress and loneliness were identified as variables associated with higher that significantly statistically mediate the relationships between online engagement and PIU, whereas emotional competence functioned as a protective factor, particularly in relation to social media use. These findings support theoretical models that conceptualize PIU as a maladaptive coping strategy for psychological distress. Conclusions: Based on these findings, prevention efforts should move beyond simple screen-time reduction and focus on strengthening adolescents’ emotional competence, stress management, and self-regulatory skills to promote healthier and more adaptive patterns of digital engagement.