Traditional Chinese medicine decoctions and Chinese patent medicines for the treatment of depression: Efficacies and mechanisms

Depression is a major mental disorder and it is currently recognized as the second-leading cause of disability worldwide. However, the therapeutic effect of antidepressants remains unsatisfactory. Traditional Chinese medicine (TCM) has been widely used for centuries, including commonly-used complementary and alternative medical therapies for depression. Recent clinical trials have been carried out to assess the efficacy and safety of TCM, and to explore the mechanisms of action in relation to the treatment of depression.To summarize frequently used TCM decoctions and Chinese patent medicines (CPM) for treating depression, review their clinical therapeutic effects in treating depressive disorders, consider their possible mechanisms, and characterize the relationships between their efficacy and mechanisms.We performed a computerized literature search using the electronic databases such as PubMed, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases, with the keywords "depression", "traditional Chinese medicine decoction", "Chinese patent medicine", "application", "mechanism", and their combinations, from January 1, 2000 to August 8, 2022 (inclusive).A total of 51 papers were identified. We reviewed studies on six each TCM decoctions and CPMs, which demonstrated their significant clinical efficacy for treating depression and examined their mechanisms of action. The anti-depressive effects were related to: 1) increased monoamine neurotransmitter levels, 2) inhibiting hyperactivity of the hypothalamic-pituitary-adrenal axis, 3) regulating hippocampal neurons and neurotrophic factors, 4) regulating immune cytokines, 5) counteracting excitatory amino acid toxicity, and 6) regulating microbe-gut-brain axis function.TCM plays an increasingly important role in the management of depression by enhancing the therapeutic effects and alleviating the side effects of antidepressant chemicals.