Effects and mechanisms of acupuncture and electroacupuncture for functional dyspepsia: A systematic review

This systematic review published in the World Journal of Gastroenterology in 2020 investigated the effects and mechanisms of acupuncture and electroacupuncture in the treatment of functional dyspepsia, a digestive condition that affects approximately 20% of the world's population. Functional dyspepsia is characterized by symptoms such as early satiety, postprandial fullness, and epigastric pain, without an identifiable organic cause, with significant impact on patients' quality of life. The researchers conducted a systematic search across four databases (PubMed, EMBASE, Cochrane Library, and Web of Science) to identify randomized clinical trials that investigated the mechanisms of acupuncture in the treatment of functional dyspepsia. Eight studies involving 642 participants were included, published between 2008 and 2018.

The studies analyzed different acupuncture modalities, including manual acupuncture, electroacupuncture, and transcutaneous electrical stimulation at acupoints. The most frequently used points were PC-6 (Neiguan), ST-36 (Zusanli), ST-34, ST-40, ST-42, CV-12, LR-3, and SP-4. The methodology included control groups receiving sham acupuncture, conventional medications, or no treatment. The researchers identified 17 different mechanistic investigation techniques, classified into five main categories: gastric motility, gastric accommodation, mental status, gastrointestinal hormones, and central and autonomic functions.

All eight studies demonstrated significant reductions in dyspeptic symptom scores after treatment with acupuncture or electroacupuncture. Six studies (75%) reported improvement in patients' quality of life. Regarding mechanisms, four studies showed that acupuncture improved gastric myoelectric activity assessed by electrogastrography, with an increase in the percentage of normal slow waves and improvement in gastric slow-wave frequency. Two studies demonstrated acceleration of gastric emptying.

Gastric accommodation, evaluated by nutrient drink tests, improved in two studies, with an increase in maximum tolerable volume. Three studies evaluated mental status using anxiety and depression questionnaires, showing significant reductions in scores after treatment. The gastrointestinal hormones investigated included neuropeptide Y, motilin, ghrelin, calcitonin gene-related peptide (CGRP), and glucagon-like peptide-1 (GLP-1). Electroacupuncture was shown to increase levels of motilin, ghrelin, and GLP-1, while reducing CGRP levels.

Regarding central and autonomic functions, one study using positron emission tomography showed extensive deactivation of brain activities with electroacupuncture compared with the sham group. Two studies demonstrated increased vagal activity through spectral analysis of heart rate variability. Methodological assessment revealed that most studies had low risk of bias for random sequence generation, but information on allocation concealment and blinding methods was frequently unavailable. The review identified several limitations, including high heterogeneity among studies, different assessment scales that precluded meta-analyses, limited methodological quality in some aspects, and geographic concentration of studies primarily in China and South Korea.

The authors concluded that acupuncture and electroacupuncture demonstrate potential to alter the heterogeneous pathophysiology of functional dyspepsia through multiple mechanisms. The evidence suggests that these therapies act by improving gastric motility and accommodation, regulating gastrointestinal hormones, reducing anxiety and depression, and modulating central and autonomic functions. These findings are consistent with the current concept of functional dyspepsia as a disorder of gut-brain interaction. However, the researchers emphasize the need for high-quality studies with well-planned designs and multiregional investigations to provide more convincing and reliable evidence about the therapeutic mechanisms of acupuncture in functional dyspepsia.