Default mode network hub disruption links problematic use of the Internet to brain network disorganization.

Problematic use of the internet (PUI) is linked to altered brain network organization through its effect on the default mode network (DMN). In 190 healthy adults aged 20–69, higher PUI severity correlated with reduced functional connectivity among DMN regions. This reduced DMN connectivity strongly predicted changes in whole-brain network properties, including decreased clustering and local efficiency, and increased global efficiency and shorter path lengths—indicating a shift away from optimal small-world network organization. Mediation analyses showed that DMN connectivity substantially mediated the relationship between PUI severity and these network metrics, suggesting that DMN hub disruption is a key pathway by which PUI affects global brain network topology.

Study at a glance

Abstract

Problematic Use of the Internet (PUI) has been associated with functional alterations in the default mode network (DMN), which contains critical hubs in the entire brain network. Previous studies have predicted that hub disruption leads to widespread network alterations; however, whether DMN functional connectivity mediates the relationship between PUI and global network topology remains unclear. This study examined whether DMN connectivity mediates PUI-related brain network topology. Resting-state functional magnetic resonance imaging data were collected from 190 healthy participants aged 20-69 years. DMN functional connectivity was assessed using region of interest (ROI)-to-ROI analyses with the Generalized Problematic Internet Use Scale-2 (GPIUS-2) as the primary predictor, controlling for age, sex, and mean framewise displacement. Graph-theoretical analyses quantified whole-brain network properties, including the clustering coefficient (Cp), shortest path length (Lp), global efficiency (Eg), and local efficiency (Eloc). Mediation analyses were performed to determine whether DMN functional connectivity mediates the relationship between GPIUS-2 and each metric. The functional connectivity values of all 17 DMN cluster pairs showed negative partial correlations with PUI severity (p-FDR < 0.05). Mean DMN connectivity strongly predicted global network topology (|ρ| = 0.36-0.41, all p-FDR < 1 × 10-6). Mediation analyses revealed that DMN functional connectivity substantially mediated the relationship between PUI severity and each metric (indirect effects: all p-FDR < 0.001; all direct effects p > 0.49). Reduced DMN connectivity was associated with decreased Cp and Eloc, increased Eg, and decreased Lp, indicating a deviation from optimal small-world organization. DMN hub connectivity serves as a critical neurobiological pathway through which the PUI influences the whole-brain network organization.