Background and Aims: Internet Gaming Disorder (IGD) is a psychological condition that impairs various aspects of life, with adolescents being particularly vulnerable due to developmental factors and heightened digital exposure. This study aims to explore the interplay between behavioral and neural bases of the development of IGD, offering insights for possible prevention strategies. Methods: A large sample of young adults (n 5 1,205, age (SD) 5 18.80 (1.26)) was assessed for impulsivity, sensation seeking, and IGD tendency. Two year later, impulsivity and IGD tendency were evaluated again, to expose possible long-term effects. Resting-state MRI data were collected to measure the topological properties of functional networks through graph theory analysis, encompassing global efficiency, local efficiency, and degree centrality. Results: Sensation seeking was positively associated with impulsivity, which, in turn, was positively linked to IGD tendency. A cross-lagged effect between impulsivity and IGD tendency was evident over a two-year timeframe. Furthermore, whole-brain local efficiency was a positive predictor of impulsivity, with centrality and efficiency of the right thalamus, along with local efficiency of the right lingual gyrus, demonstrating positive correlations with IGD tendency. Conclusion: This study revealed that sensation seeking indirectly affects IGD tendency through impulsivity, which also directly impacts IGD. Neural correlates of impulsivity included local efficiency, and of IGD tendency, included the right thalamus and lingual gyrus. These findings offer insights into IGD mechanisms and possible prevention approaches.  Kulcsszavak: sensation seeking, impulsivity, internet gaming disorder, cross-lagged panel model, resting-state MRI, brain topology