The investigators assume that High-intensity transcranial Alternating Current Stimulation (HI-tACS) could improve gambling disorder patients' executive-control function by modulating abnormal neural activity, particularly gamma-band oscillations, which are closely associated with executive-control deficits. This study intends to validate the effect of HI-tACS treatment, which has been discovered in the previous pilot study. A three-month follow-up assessment will be conducted to test the changes in executive-control function and its underlying mechanism.