Efficacy of acupuncture for depression: a systematic review and meta-analysis

This systematic review and meta-analysis represents an important milestone in acupuncture research for depression, being the first to focus exclusively on the efficacy of acupuncture as monotherapy. The investigators conducted a comprehensive search across six databases (CNKI, Wanfang, VIP, Embase, MEDLINE, and CENTRAL), covering publications from July 2013 to July 2023. Of 7,015 articles initially identified, only 20 randomized controlled trials met the strict inclusion criteria, encompassing 1,376 participants with a diagnosis of primary depression. The methodology was particularly rigorous, excluding studies that combined acupuncture with other therapies, cases of secondary depression, and those with fewer than 20 participants per group.

The diagnostic criteria combined perspectives from traditional Chinese medicine and Western medicine, using standards such as ICD-10, DSM-IV, and CCMD-3. The Hamilton Depression Rating Scale (HAMD) was the primary assessment instrument, supplemented by scales for side effects (SERS) and adverse events (TESS). The meta-analytic findings were striking, showing that after 4 weeks of treatment, acupuncture demonstrated efficacy significantly superior to that of conventional medications. Analysis of HAMD scores revealed an effect size of -1.63 (95% CI: -2.49 to -0.76; p = 0.0002), indicating substantial clinical improvement.

More importantly, HAMD-derived response rates showed that acupuncture had a relative risk of 2.6 (95% CI: 1.6 to 4.23; p = 0.0001) compared with medications, suggesting that patients treated with acupuncture were 2.6 times more likely to achieve significant improvement. In terms of safety, acupuncture showed a superior profile, with significant reductions in side effects measured by the SERS scale (RR: -1.51; p < 0.00001) and in adverse events assessed by the TESS scale (RR: -5.94; p < 0.00001). This is particularly relevant given that approximately 40% of patients on antidepressants experience side effects such as dizziness, somnolence, and weight gain. The analysis of acupoints revealed that 43 different points were used across the studies, with GV-20 (Baihui) being the most frequent, appearing in more than 70% of the studies.

This point, located at the top of the head, is traditionally used to lift yang and supplement qi, and is considered crucial for neurologic disorders. Other frequent points included EX-HN3, LR-3, and PC-6, each appearing in 40–50% of the studies. The number of selected points ranged from 2 to 15 per patient, reflecting the individualized approach of traditional Chinese medicine. The methodologic quality of the studies was generally good, with low risk of bias on most assessed domains.

However, blinding of participants and clinicians was problematic owing to the inherent nature of acupuncture treatment, resulting in a high risk of performance bias across all studies. This represents a known limitation of acupuncture research but does not invalidate the findings when outcomes are objectively measured. Proposed mechanisms for the efficacy of acupuncture in depression include modulation of neurotransmitters in the hippocampus, particularly serotonin, norepinephrine, and GABA, as well as effects on the JNK signaling pathway in the prefrontal cortex. Animal-model studies suggest that acupuncture can significantly increase the levels of these neurotransmitters, which are crucial for the regulation of emotion, learning, and memory.

The clinical implications of this study are substantial. Acupuncture emerges as a viable alternative to conventional antidepressants, particularly for patients who prefer non-pharmacologic approaches, experience significant side effects with medications, or have an inadequate response to pharmacotherapy. The 4-week minimum to observe benefits provides a useful clinical benchmark for evaluating treatment response. Important limitations include the fact that all studies were of Chinese origin, calling into question the global generalizability of the findings.

Heterogeneity in acupoint selection, specific techniques, and treatment protocols also represents a challenge to replication. In addition, the inability to achieve adequate blinding remains an inherent methodologic limitation. Future research should focus on protocol standardization, investigation of specific mechanisms, multicenter international studies, and direct comparisons with other non-pharmacologic therapies. The optimal duration of treatment and ideal frequency of sessions also require further investigation.