Effect of transcranial direct current stimulation on functional neural networks in internet gaming disorder: a double-blind, randomized, resting-state electroencephalography source-level study

Purpose: This study assessed the neuromodulatory effect of transcranial direct current stimulation (tDCS) in internet gaming disorder (IGD), using source-level electroencephalography (EEG) to measure functional connectivity within the default mode network (DMN) and reward/salience network (RSN).Methods: Thirty-one patients with IGD participated in the study. After excluding five dropouts, 26 individuals (tDCS group n= 14; sham group n= 12) completed 10 sessions of either tDCS or sham stimulation. Resting-state EEG, IGD severity, and craving were measured before and 1 month after the intervention. Changes in connectivity within the DMN and RSN were assessed at each frequency band. <i>Post hoc</i> analysis was used to investigate the correlation between tDCS-induced connectivity changes and clinical improvement.Results: In the DMN, tDCS decreased delta and theta connectivity, and suppressed the increase in beta connectivity. Neural connections between the prefrontal cortex and parietal lobe were the main regions affected. In the RSN, tDCS increased neural connectivity in the theta and beta bands. The connections between the right dorsolateral prefrontal cortex (DLPFC) and cingulate cortex were the main regions affected. <i>Post hoc</i> analysis revealed a significant correlation between changes in right DLPFC connectivity and reduced craving.Conclusion: tDCS induces neural connectivity changes in the DMN and RSN. These findings support the potential use of tDCS as a neuromodulatory treatment for IGD, particularly in individuals with altered DLPFC connectivity patterns.