Abstract
BACKGROUND: Acupuncture is a clinically recognized treatment for major depressive disorder (MDD), but the associations of efficacy with dosage, treatment course, frequency, acupuncture modality, needle retention time, and manipulation remain unclear. This study evaluated the efficacy and safety of acupuncture for MDD and explored potential moderating factors. METHODS: Randomized controlled trials of acupuncture for MDD were searched in CNKI, VIP Database, Wanfang Data, SinoMed, PubMed, Embase, Web of Science, and the Cochrane Library from inception to May 2025. Risk of bias was assessed using RoB 2, and certainty of evidence using GRADE. Data were analyzed in Stata 18.0. RESULTS: 36 trials involving 3843 participants were included. Compared with sham/placebo acupuncture, acupuncture showed greater antidepressant effects (SMD -1.12, 95% CI -1.57 to -0.67, P < 0.01). Very low-quality evidence suggested similar efficacy between acupuncture and antidepressants. Electroacupuncture was superior to manual acupuncture (SMD -0.24, 95% CI -0.42 to -0.07, P < 0.01). High- and moderate-dose acupuncture were more effective than low-dose regimens, and meta-regression suggested a linear dose-response relationship, with 30 sessions as the optimal dosage. Better outcomes were associated with treatment course >6 wk, 3 times weekly, needle retention time of 20-30 minutes, and electroacupuncture. No significant difference was found between needle manipulation and non-manipulation. CONCLUSIONS: Acupuncture significantly alleviates depressive symptoms in MDD. Efficacy appears to be influenced by dosage, acupuncture modality, treatment course, frequency, and needle retention time, with 30 sessions, treatment course > 6 wk, 3 sessions weekly, 20-30 minutes retention, and electroacupuncture showing the most favorable outcomes.