This project focuses on clinical translational research into personalized transcranial alternating current stimulation (tACS) for treating anhedonia in late-life depression (LLD). Key components include: (1) Optimizing individualized tACS treatment parameters through randomized, double-blind, controlled trials and establishing precise treatment protocols using deep learning algorithms; (2) Assessing the short-term (2 weeks) and long-term (3 months) efficacy of tACS on depressive symptoms and anhedonia using scales such as the HAMD, SHAPS, and DARS, while monitoring safety; (3) Integrating multimodal detection technologies (64-channel EEG, inflammatory factors/neurotransmitters, etc.) to elucidate the mechanisms by which tACS alleviates anhedonia through modulating prefrontal neural oscillations (y-band), improving synaptic plasticity (increased BDNF), and regulating neurotransmitters (5-HT, DA). This study will establish, for the first time, an individualized parameter system for tACS treatment of LLD, providing a novel non-pharmacological intervention strategy for clinical practice.