In summary, the present study identified abnormal phase synchrony patterns in patients with IGD and AUD relative to HCs using analyses of resting-state EEG. These results demonstrated that the IGD group had significantly greater high-frequency coherence, particularly for gamma, compared to the AUD patients and HCs. Additionally, the AUD group exhibited tendency of increased coherence in the slow-frequency theta band. The increased gamma coherence of the IGD patients appeared to be independent of the effects of the psychological comorbidities and the gamma coherence of the three groups positively predicted the degree of Internet addiction tendency. Moreover, the heightened tendency of theta coherence in the AUD patients relative to the HCs was influenced by their clinical and psychological status. These findings imply that IGD and AUD are associated with different neural activity patterns and that heightened phasic synchrony in the relatively fast-frequency bands of IGD patients during a resting state may be a useful indicator to distinguish IGD from AUD. Furthermore, the heightened phasic synchrony in the gamma band during the resting state may be an important neurophysiological marker of IGD. The present findings will help to broaden the current understanding of the neurophysiological mechanisms underlying the manifestation of IGD.
