Internet addiction is associated with differences in static and dynamic hippocampal functional connectivity in young adults: the mediating role of emotion regulation difficulties.

BACKGROUND: Internet addiction (IA) has emerged as a pervasive public health issue among young adults, frequently accompanied by severe emotion regulation difficulties. However, the precise static and dynamic functional architecture of the hippocampus and its interplay with emotion dysregulation in IA remain incompletely understood. METHODS: This study enrolled 45 young adults with IA and 29 healthy controls (HC). Utilizing resting-state functional magnetic resonance imaging (fMRI), we computed both static functional connectivity (sFC) and dynamic functional connectivity (dFC) seeded from the rostral hippocampus. Partial correlation analyses were conducted to examine the associations between aberrant connectivity and clinical symptoms. Furthermore, we investigated whether emotion dysregulation mediates the relationship between altered hippocampal connectivity and internet addiction severity. RESULTS: Compared to HCs, individuals with IA exhibited significantly increased sFC between the left rostral hippocampus and nodes of the default mode network (DMN; precuneus and inferior parietal lobule). Furthermore, the IA group displayed heightened temporal variability between the bilateral hippocampus and visual-temporal regions (superior temporal pole, lingual gyrus, middle, and superior occipital gyri). These aberrant sFC and dFC were significantly and positively correlated with IA severity and emotion regulation difficulties. Mediation analyses further revealed that emotion dysregulation significantly and partially mediated the relationship between altered hippocampal connectivity and internet addiction severity. CONCLUSIONS: Static hyper-connectivity with the DMN and dynamic instability with visual-temporal networks constitute distinct neurobiological signatures of IA. Crucially, emotion dysregulation bridges these hippocampal network anomalies with addictive behaviors, highlighting targeted emotion regulation interventions as a promising therapeutic strategy for internet addiction.