The Effects of Acupuncture on Glutamatergic Neurotransmission in Depression, Anxiety, Schizophrenia, and Alzheimer's Disease: A Review of the Literature

Neuropsychiatric diseases represent a significant global challenge, affecting more than 10% of people worldwide with some form of disability. In Brazil and other countries, disorders such as depression, anxiety, schizophrenia, and Alzheimer's disease cause considerable suffering and limit the quality of life of millions of people. Despite the conventional treatments available, many patients do not respond adequately to traditional medications or face significant side effects, creating an urgent need for complementary therapeutic approaches.

The present study is a comprehensive scientific review that investigates how acupuncture may influence the brain's glutamatergic system in the treatment of these neuropsychiatric conditions. Glutamate is the main excitatory neurotransmitter in the brain, essential for communication between neurons, memory formation, and learning processes. When this system is dysregulated, it may contribute to the development and maintenance of various mental and neurological disorders.

The researchers conducted a systematic analysis of the existing scientific literature, examining clinical and preclinical studies that investigated the effects of acupuncture in people with depression, anxiety, schizophrenia, and Alzheimer's disease. The methodology included both manual acupuncture and electroacupuncture, focusing specifically on how these interventions can modulate glutamate receptors and excitatory amino acid transporters in the central nervous system.

The results demonstrate promising, although still preliminary, evidence on the efficacy of acupuncture in these conditions. For depression, a Cochrane review involving more than 7,000 participants showed that acupuncture can moderately reduce the severity of depressive symptoms compared with usual care. Specific studies have found that women may be more responsive to acupuncture treatment for depression, with benefits maintained for up to three months after the end of sessions. Acupuncture has also been shown to improve sleep quality in patients with depression-related insomnia.

Regarding anxiety disorders, research indicates that both traditional acupuncture and electroacupuncture can produce significant improvements in anxious symptoms. A particularly interesting aspect is that acupuncture appears to modulate the autonomic nervous system, as evidenced by changes in heart rate variability that suggest a real calming effect on the organism. Studies in medical settings have shown that auricular acupuncture can effectively reduce preoperative anxiety.

For schizophrenia, although the number of studies is more limited, a meta-analysis of 13 randomized clinical trials involving nearly one thousand patients showed that acupuncture, when used as a complementary treatment alongside antipsychotic medications, can improve auditory hallucinations, positive symptoms, and treatment response rates. Clinical case reports described improvements in energy, motivation, sleep, and associated physical problems, with benefits lasting up to three months after treatment.

In Alzheimer's disease, a study with 87 patients showed that acupuncture as monotherapy produced greater cognitive improvements than donepezil, a standard medication for the condition. The improvements were maintained for up to 12 weeks after the end of treatment, and no patient dropped out of the study because of adverse effects of acupuncture, in contrast to four dropouts in the medication group. Neuroimaging studies suggest that acupuncture may indeed reorganize dysfunctional neural networks in the brain.

The clinical implications of these findings are significant for both patients and health professionals. For patients who do not respond adequately to conventional treatments or experience undesirable side effects, acupuncture emerges as a relatively safe and potentially effective therapeutic option. The low incidence of serious adverse events, reported in less than 2.2% of cases in a large German study with more than two million sessions, makes acupuncture an attractive alternative. For practitioners, these data support considering acupuncture as adjunctive treatment, especially in refractory cases or when a more integrative approach is sought.

The study proposes a fascinating mechanism to explain how acupuncture may exert its therapeutic effects. A dysregulated glutamatergic system is a common feature across all these neuropsychiatric conditions. In depression and anxiety, alterations in NMDA and AMPA receptors contribute to symptoms. In schizophrenia, the NMDA receptor hypofunction hypothesis explains many manifestations of the disease.

In Alzheimer's disease, the reduction of glutamate transporters leads to toxic accumulation of this neurotransmitter. Acupuncture appears to modulate these systems, restoring glutamatergic balance through regulation of receptor and transporter expression.

However, it is crucial to recognize the significant limitations of this area of research. Many studies present variable methodological quality, with small samples and experimental designs that hinder definitive conclusions. Most schizophrenia research has been conducted only in China, raising questions about the generalizability of the results to other populations. Differences in acupuncture protocols across studies, including point selection, frequency, and treatment duration, make it difficult to establish standardized guidelines.

In addition, the placebo effect remains an important consideration. Although some studies have attempted to control for this factor using sham acupuncture, the nature of the intervention makes complete blinding impossible. The quality of evidence was considered low or very low in many analyses, indicating the need for more rigorous studies.

Despite these limitations, the findings suggest that acupuncture may offer a valuable therapeutic approach for neuropsychiatric conditions, especially when integrated with conventional care. Modulation of the glutamatergic system provides a plausible scientific basis for the effects observed, going beyond purely placebo explanations. For patients and family members coping with these challenging conditions, acupuncture represents an additional option that warrants serious consideration, always in consultation with qualified health professionals.

The future of research in this area requires more rigorous clinical studies, with larger samples, adequate controls, and standardized protocols. Further investigations into the underlying neurobiological mechanisms will help optimize treatments and identify which patients are most likely to benefit. As our understanding of the interface between traditional Chinese medicine and modern neuroscience deepens, acupuncture may establish itself as a valuable component in the therapeutic arsenal against neuropsychiatric diseases.