¹University of Duisburg-Essen, General Psychology: Cognition, Duisburg, Germany, ²University of Hertfordshire, School of Life and Medical Sciences, Hatfield, United Kingdom

Background: Since Problematic Usage of the Internet (PUI) is a growing public health concern, identifying mechanisms that contribute to its development and maintenance is of utter importance. Mounting evidence suggests that there are at least two main mechanistic drivers which contribute to the development and maintenance of symptoms of PUI, namely difficulties in affect regulation and difficulties in inhibitory control.

Aims & Objectives: Whilst a knowledge base on cross-sectional associations between PUI and difficulties in affect regulation and inhibitory control has been established, less is known about the temporal development of PUI and reciprocal relationships between PUI and its underlying mechanisms.

Method: Data from two large-scale, (inter-)national, multi-center studies are presented. The first Cohort of the DFG-funded research unit “FOR2974” assessed adult participants who engage in specific online activities, involving gaming, buying-shopping, social networks use, and pornography use. Participants across Germany were systematically diagnosed with either non-problematic, at-risk, or pathological usage patterns through a structured diagnostic interview and then underwent a comprehensive test battery in the laboratory involving questionnaires, neurocognitive tasks, and sub-project specific methods such as fMRI. The “BootStRaP” project is an EU-Horizon-funded, nine-country study aiming to improve knowledge of PUI and deliver preventative, app-based interventions targeting its two hypothesized phenotypes (i.e., affect regulation and inhibitory control) in adolescents aged 12 to 16 years. Aggregated samples from both projects are presented, either across varying types and degrees of PUI (FOR2974), or across countries (BootStRaP), respectively.

Results: Structural equation modelling with data from the first Cohorts of both the FOR2974 (N=819; n=528 for the follow-up assessment) and BootStRaP (N=1807) projects supports the dominant roles of difficulties in affect regulation and difficulties in inhibitory control in predicting PUI in both adolescents and adults. In the BootStRaP cohort, the strongest indirect effect was found for negative reinforcement learning as a factor maintaining PUI from baseline to the six-month follow-up, whereas difficulties in inhibitory control were significantly involved to a lesser extent. Results from the FOR2974 project show a more differentiated pattern where, in addition to negative reinforcement and difficulties in inhibitory control, positive reinforcement mechanisms and habit-based drivers also exert their effects on PUI at baseline. Regarding the maintenance of PUI at six-month follow-up, negative reinforcement and compulsive mechanisms dominate the explanation of variance.

Discussion & Conclusions: In these two studies, PUI at follow-up assessments was not explained exclusively through vulnerability factors, but the direct effects were mediated by affective and cognitive mechanisms. Thus, the development and maintenance of PUI do not follow a single linear mechanistic pathway but rather involve multiple distinct processes which individually contribute to PUI symptoms. Systematically assessing whether difficulties in affect regulation, self-control, or overlearned repetitive behaviour patterns predominate in an individual’s aetiology of PUI may inform the selection of optimally tailored interventions targeting the specific mechanisms sustaining PUI.