1. In the 13 studies included in this meta-analysis, the auricular acupressure group showed significant improvement in depression symptoms across all scores. This result indicates that auricular acupressure has a notable antidepressant effect in clinical practice.

2. The study results indicated that none of the included studies reported significant adverse reactions, proving that auricular acupressure is a safe and non-invasive treatment method. Compared with traditional drug therapy and other physical treatments, auricular acupressure offers a low-risk alternative.

3. This meta-analysis combined data from multiple depression assessment tools including the Hamilton Depression Scale (HAMD), Self-Rating Depression Scale (SDS), and Patient Health Questionnaire (PHQ-9). In all these different scale evaluations, the auricular acupressure group showed significant improvement in depression symptoms. This consistent verification across multiple tools enhances the reliability and generalizability of the study results, providing robust evidence for auricular acupressure as a complementary treatment for depression.

Depression refers to a type of affective mental disorder characterized by significant and persistent low mood, reduced activity ability, and slow thinking and cognitive functions [1]. According to statistics from the World Health Organization (WHO), more than 350 million people worldwide suffer from depression, and the number of patients has increased by approximately 18% in the past 10 years. Five percent of adults worldwide suffer from depression every year, and depression has become a common disease worldwide [2, 3]. Data from the China Mental Health Survey (CMHS) in 31 provinces and cities in China from 2012 to 2015 show that depressive disorder among adults in China has a lifetime prevalence rate of 6.8%; 8.0% for women and 5.0% for men [4]. In addition, the suicide mortality rate for people with depression is more than 10 times that of the general population [5]. The incidence rate, disability rate, and mortality rate of depression are high and continue to rise, placing a huge disease burden on society and families. Research shows that there is a bidirectional relationship between insomnia and depression [6, 7].

Epidemiological studies show that 40% to 92% of insomnia symptoms are caused by mental illness. About one third of people worldwide have insomnia symptoms and daytime dysfunction, and more than 70% of depressed people also have insomnia symptoms [8]. There are many treatment methods for depression in clinical practice, including antidepressants, psychotherapy, and physical therapy. However, due to an insufficient number of psychotherapists and high treatment costs, psychotherapy is not widely used, especially in low-income countries. Psychotherapy can also cause a series of problems and may lead to secondary damage to patients [9]. The treatment process may exacerbate the patient’s self-hatred owing to events he/she experienced. In addition, clinical practice also reported adverse events related to drug treatment, such as loss of appetite, drowsiness, dizziness, nausea, and vomiting, and a risk of cardiovascular and cerebrovascular incidents [10]. The above methods therefore have certain limitations in the treatment of depression. Physical therapy may also induce conditions such as epilepsy [11]. Therefore, clinical guidance needs to explore an effective complementary and alternative therapy for depression to alleviate symptoms and cure the disease.

Acupoint massage originated from traditional Chinese medicine (TCM) and is a non-invasive technique based on TCM meridian theory that uses slow and even pressure applied to acupoints rather than needles. Auricular acupuncture therapy is therefore very effective in promoting sleep, and its efficacy in treating depression is gradually emerging [12]. Moreover, this therapy has long-lasting effects, is easy to operate, is economical and cheap, and causes few adverse reactions. Previous systematic reviews have shown that the overall effectiveness of auricular acupoint therapy combined with other therapies in the treatment of depression is better than the use of other therapies alone [11]. While TCM auricular acupuncture continues to develop in China, it has also attracted widespread attention around the world. The French physician Paul Nogier published “Auricular Point Distribution Map Shaped Like an Embryo Reflection” in the German Journal of Acupuncture in 1957 [13], which promoted worldwide attention to auricular point therapy. Furthermore, it stimulated the enthusiasm of scholars at home and abroad for research on auricular acupuncture therapy. Based on original research results, Chinese researchers have further carried out a large number of experimental studies, which has led to the continuous progress and development of related research on auricular acupuncture therapy.

Because of its significant efficacy, auricular acupuncture has received widespread attention from relevant scholars. Since there are currently very few systematic reviews of auricular acupuncture for the treatment of depression, this study included clinical randomized controlled trial (RCT) literature on auricular acupuncture for the treatment of depression, at home and abroad. According to the requirements and standards of the Cochrane International Collaboration Network on Evidence-Based Medicine, the effectiveness and safety of auricular acupoint therapy in treating depression were quantitatively evaluated, and its principles of action were analyzed and summarized for a meta-analysis, in order to provide evidence-based medical evidence and a more comprehensive and objective basis for auricular acupoint therapy to treat depression.

The results of this analysis show that auricular acupoint therapy provides beneficial clinical effects in alleviating symptoms of clinical depression when compared with adjuncts to conventional treatments. In addition, it has fewer adverse effects and can also reduce HAMD and PSQI scores. The therapy is also simple, cheap, and highly accepted by patients. Although the level of evidence is moderate, acupressure shows promise as a potential treatment for depression.

The pathogenesis of depression is very complex, and the classic neurotransmitter theory still occupies a dominant position. However, new theories that include the interaction between genes and the environment, the neuroendocrine system, immune inflammation, neuroplasticity, brain structural changes, and brain functional circuitry are continuously being proposed [32]. Currently, the main clinical treatments for depression are antidepressants, tricyclic antidepressants, dopamine selective inhibitors, and 5-hydroxytryptamine receptor antagonists, etc. [33], supplemented by systemic treatments such as psychotherapy and physical therapy. Modern medicine is developing vigorously. Under ideal conditions, the cure rate for patients with depression can reach 70% to 80% after systemic treatment. However, the fact is that only 20% to 30% of depression patients in China have received a diagnosis and treatment [34], although most patients only choose drug treatment. Drug treatment has a slow onset of effect, many adverse reactions, and it is easy to relapse when the drug is discontinued. The above reasons lead to a low cure rate for depression in China. In addition, even patients who are cured of depression are still more likely to have residual symptoms. Insomnia is one of the main residual symptoms of depression, which leads to a vicious cycle of depression and insomnia [35].

Depression belongs to the categories of “depressive disease”, “insomnia”, “forgetfulness”, “epileptic syndrome”, “lily disease”, and “plum core qi” in TCM [36]. Emotional factors are the causative factors of depression, and “weak internal qi” is an important internal factor in the onset of depression. In the beginning, it is more common to have syndromes of excess or deficiency and, as time goes by, syndromes of both deficiency and excess are common. TCM treatment is based on syndrome differentiation. For example, for kidney deficiency and liver stagnation, Zi Shui Qing Gan Yin is used. For liver stagnation and spleen deficiency, Xiaoyao Powder combined with Banxia Houpu Decoction is used. The suitable techniques of TCM are mainly acupuncture, moxibustion, massage, aromatherapy, and five-tone therapy [37]. Auricular acupoint therapy belongs to the category of acupuncture. There is no acupuncture pain during auricular acupoint therapy, which makes it more adaptable and easier to accept for the patient. Auricular acupoint therapy can simultaneously improve the patient’s depression and insomnia. With the continuous deepening of the integration of traditional Chinese and Western medicine, auricular acupuncture therapy has also been innovatively developed. The innovative research team of the China Academy of Chinese Medical Sciences confirmed the existence of projection fibers from the auricular branch of the vagus nerve directly to the nucleus of the solitary tract through nerve tracing technology. They also innovatively proposed the theory of “auricular point-vagus nerve connection” and developed the transcutaneous auricular vagus nerve stimulation (taVNS) method, which provided a novel solution for auricular point therapy to treat depression and insomnia [38].

The results of the present study showed that auricular acupuncture therapy had advantages over only using medicine in reducing HAMD score, SDS score, PSQI score, and improving quality of life. This therapy can reduce depression and improve the quality of life of patients.

Auricular acupuncture therapy can improve the depression and sleep state of patients with depression and insomnia. In terms of modern neuroanatomical discoveries, auricular acupuncture therapy often uses acupuncture points in the “visceral representative areas” to treat depression and insomnia, that is, acupoints such as the “heart”, “liver”, “kidney”, and “Shenmen” [39]. Its distribution coincides with the vagus nerve distribution area of the ear—the concha area [40]. The concha area is the only area in the human body with vagus nerve distribution. The afferent fibers of the vagus nerve in the concha can directly project to the nucleus of the solitary tract. It then projects directly or indirectly through other brainstem structures such as the locus coeruleus, parabrachial nucleus, and raphe greater nucleus to the reticular formation, limbic system, and other brain areas closely related to emotion regulation and sleep [41]. Auricular acupoint therapy can stimulate the acupoints in the concha area through the above-mentioned pathways to improve the depression and sleep state associated with depression and insomnia. At the same time, the explanation can also be constructed through the “ear, brain, and organ-related” theory created by Rong Peijing’s team [42]. The bladder meridian circulates and connects the ears and the brain. As the saying goes, “the two ears connect the brain”, and the ears treat the brain. The heart governs the gods, and the heart area of the ear points controls the five internal organs (heart, liver, soul, spleen, lungs, and kidneys). The heart area is used to regulate the five internal organs. The brain is the house of the Yuan Shen, and the five internal organs are connected to the brain. The five internal organs are adjusted to help the brain. Shen is used in the heart, and its body is in the brain. It should be in the five internal organs, connecting the heart, brain, and internal organs into a whole. Auricular acupoint therapy stimulates the auricular acupuncture center in the auricle area, which can not only directly regulate the mind, but also regulate the brain and spirit by “connecting the two ears to the brain”. It can also coordinate or indirectly stimulate the five internal organs in the auricle area to regulate the five internal organs and the spirit. Thereby achieving the effect of harmonizing the mind, body, and function. Auricular acupoint therapy regulates the mind, brain, and five internal organs to improve the depression and insomnia of patients with depression and insomnia.

Limitations of this study: (1) Some of the included studies did not describe specific random allocation methods, allocation concealment, and measurement bias. (2) It is difficult to implement double-blinding in auricular acupuncture therapy, and most of the included studies were not double-blinded. (3) The treatment methods of the control groups included in the studies were not uniform. As auricular acupoint therapy originated from TCM, its acceptance in countries other than China is low. Therefore, there were few studies by foreign scholars. Most foreign scholars had conducted a summary analysis on feasibility and national acceptance. Due to the large difference in years, the quality of the included studies was unequal.

Auricular acupuncture is very effective in treating depression. The results of this systematic review showed that auricular acupoint therapy is safe and effective in treating depression, and can reduce HAMD and PSQI scores, etc. There are no obvious adverse reactions. However, due to the limitations of the number and quality of included studies, our conclusions need to be supported by more high-quality research evidence. Moreover, this therapy has long-lasting clinical efficacy, is easy to operate, is economical and cheap, and has few adverse reactions. Therefore, it can be promoted and used clinically, based on its characteristics, in the future.

The datasets for this study are available from the corresponding author on reasonable request.

XY, QL and XW designed the research study. XY and QL performed the research. QL and XW collected and analyzed the data. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript. All authors have participated sufficiently in the work and agreed to be accountable for all aspects of the work.

Not applicable.

This research received no external funding.

The authors declare no conflict of interest.

Supplementary material associated with this article can be found, in the online version, at https://doi.org/10.31083/AP38776.