Efficacy and Safety of Auricular Acupuncture for Depression: A Randomized Clinical Trial

Depression represents one of the largest global public health challenges, affecting more than 300 million people and being one of the leading causes of disability worldwide. In Brazil, this condition is even more concerning, affecting 5.8% of the Brazilian population, one of the highest rates globally. Despite the seriousness of the problem, fewer than 10% of those affected receive adequate treatment, and those who start antidepressant medications often discontinue treatment, with adherence rates ranging between 40% and 90%. Against this backdrop, there is growing interest in non-pharmacologic therapies, such as auricular acupuncture, which consists of applying semi-permanent needles to specific points on the ear.

This technique is considered simpler to implement than traditional body acupuncture, requires less application time, has low technical complexity, and offers continuous, daily physiologic stimulation.

This Brazilian study aimed to evaluate the efficacy and safety of specific auricular acupuncture in the treatment of depression. It was a randomized controlled clinical trial conducted between March and July 2023 at four university research centers in Santa Catarina. The researchers enrolled 74 adult participants aged 18 to 50 years who had moderate or moderately severe depressive symptoms, measured by the Patient Health Questionnaire-9. Participants were randomly divided into two groups: one received specific auricular acupuncture at six traditional Chinese medicine points related to the treatment of depression, while the control group received non-specific auricular acupuncture at points unrelated to mental health symptoms.

Both groups received 12 sessions over six weeks, with applications twice a week, alternating between the right and left ears. Participants were instructed to manually stimulate the points three times a day. Importantly, all continued their usual treatments for ethical reasons, and both participants and assessors remained blinded to the type of treatment received.

The main results showed that, although there was no statistically significant difference between groups in the primary outcome at three months, several important findings emerged from the study. In the group that received specific auricular acupuncture, 58% of participants showed at least 50% improvement in depressive symptoms, compared with 43% in the control group, a difference that did not reach statistical significance. However, a notable finding was observed in complete symptom remission: 46% of participants in the specific treatment group achieved complete remission of depression at three months, compared with only 13% in the control group, a statistically significant and clinically important difference. This 33% difference in remission rate is considerable, especially because complete symptom remission is crucial for adequate psychosocial functioning and better long-term prognosis.

Regarding safety, the study demonstrated that the technique is very safe, with most participants reporting only mild pain at the site of needle application. No serious adverse events were recorded, and only five participants discontinued the study due to mild adverse effects.

For patients and healthcare professionals, these findings suggest that auricular acupuncture may represent a valuable and safe therapeutic option for the treatment of depression, especially for those who prefer to avoid medications or who do not respond adequately to conventional treatments. The recovery and remission rates observed in the study are comparable to those found in analyses of pharmacologic treatments and superior to those of psychotherapy alone. The technique offers significant practical advantages, such as ease of application, low cost, good tolerability, and the possibility of continuous stimulation. The effects may be related to stimulation of the auricular branch of the vagus nerve, which increases parasympathetic activity and may lead to improvement in depressive symptoms through normalization of the hypothalamic-pituitary-adrenal axis, often hyperactive in depression.

The fact that the benefits became more evident at three months suggests that auricular acupuncture may have delayed effects, consistent with its possible neurologic mechanism of action.

The study has some important limitations that should be considered. The sample size was relatively small, which may have limited the statistical power to detect significant differences in the primary outcome. The predominance of women in the sample prevented analysis of possible gender differences. There was considerable loss to follow-up during the three-month follow-up, although this rate is similar to that observed in other depression treatment studies, reflecting characteristics of the disease itself, such as apathy and hopelessness.

The researchers suggest that future studies with larger samples, longer interventions, and objective outcome assessments are needed to definitively confirm the efficacy of specific auricular acupuncture. Despite these limitations, this study represents an important advance in research on complementary treatments for depression, providing promising preliminary evidence on the safety and potential efficacy of auricular acupuncture, especially for the complete remission of depressive symptoms.