This study is a randomized controlled trial with a duration of 12 weeks (4 weeks of intervention + 8 weeks of follow-up). The participants are patients with treatment-resistant depression (TRD) and high inflammatory activity (n=52). The study aims to clarify the effectiveness of 15mA, 77.5Hz transcranial alternating current stimulation (tACS) in treating TRD with high inflammatory activity by comparing the changes in depressive symptoms and biological markers after active tACS stimulation versus sham stimulation. Additionally, the study seeks to explore potential underlying mechanisms of action.