Objectivization study of acupuncture Deqi and brain modulation mechanisms: a review

Acupuncture, an ancient therapy from traditional Chinese medicine with more than 3,000 years of history, has gained growing worldwide recognition for its effectiveness in treating a wide variety of health conditions. At the center of this practice is a fundamental concept known as "Deqi" or "arrival of qi," which represents the characteristic sensation experienced by both the patient and the acupuncturist during treatment. For the patient, Deqi manifests as sensations of numbness, heaviness, tingling, or fullness at the needle site, while the acupuncturist perceives increased resistance under the needle. This phenomenon has traditionally been considered a crucial indicator of treatment effectiveness and is described in the literature as an important prerequisite for acupuncture to achieve its best therapeutic outcomes.

This systematic review aimed to map and analyze modern scientific research on the objective mechanisms of Deqi in acupuncture, with particular focus on how this sensation modulates brain activity. The methodology adopted by the researchers involved a comprehensive analysis of the available scientific literature, examining studies that used various advanced technologies to investigate the effects of Deqi. The main research tools included functional magnetic resonance imaging to assess changes in brain activity, ultrasonography to examine structural changes at acupuncture points, infrared thermography to measure temperature changes, and flowmetry equipment to assess changes in blood circulation. The researchers also analyzed clinical studies that used validated scales to quantify Deqi sensations, such as Vincent's Acupuncture Sensation Scale and the MASS Scale developed by Massachusetts General Hospital.

The findings revealed a complex, multi-dimensional Deqi mechanism that operates at three main levels. At the local level of acupuncture points, needle insertion causes measurable changes in tissue structure, skin temperature, blood perfusion, energy metabolism, and muscle electrical activity. These alterations primarily involve muscle fibers, nerve endings, and deep receptors, with muscle contraction serving as an important basis for sensation generation. At the central nervous system level, Deqi demonstrated the ability to activate specific brain regions, including the thalamus, parahippocampal gyrus, postcentral gyrus, insula, middle temporal gyrus, and cingulate gyrus.

Particularly interesting was the finding that Deqi produces extensive effects on the limbic-paralimbic-neocortical network and the default mode network of the brain. Studies using functional magnetic resonance imaging showed that different needle manipulation techniques, such as lifting-thrusting versus rotation, activate different patterns of brain regions, with lifting-thrusting generally producing more intense signals. At the target-organ level, Deqi demonstrated the ability to correct functional abnormalities, as observed in studies showing improvements in cardiac function, gastrointestinal motility, and blood pressure regulation.

The clinical implications of these findings are significant for both clinicians and patients. For acupuncturists, the study provides objective scientific evidence that validates the traditional importance given to Deqi in clinical practice. The research confirms that adequate Deqi elicitation is positively correlated with better therapeutic outcomes in various conditions, including chronic pain, cardiovascular problems, gynecologic disorders, and gastrointestinal disorders. For patients, these findings offer a scientific explanation for the sensations they experience during treatment, helping to demystify the process and potentially improving treatment adherence.

The studies also suggest that different intensities and qualities of Deqi may be associated with different degrees of therapeutic efficacy, which can guide both clinicians and patients on what to expect during sessions. Furthermore, understanding the brain mechanisms involved opens possibilities for the development of more precise and personalized treatment protocols.

The study also identified several important limitations that should be considered when interpreting the results. A significant limitation is the variability among the different studies analyzed, which used different experimental designs, study populations, stimulation methods, and Deqi assessment systems, making direct comparison between results difficult. Most studies were conducted in healthy volunteers, limiting the applicability of findings to populations with specific diseases. In addition, there are controversies regarding the activation of certain brain regions, such as the putamen and thalamus, which showed different activation patterns depending on the acupuncture points used and the techniques employed.

Brain imaging processing methods also vary among studies, which can affect the accuracy of results.

In their final considerations, the authors emphasize that, although significant progress has been made in the objective understanding of Deqi, fundamental questions still require further investigation. The complete mechanism by which local changes at acupuncture points are transmitted to the central nervous system, integrated in the brain, and ultimately translated into therapeutic effects on target organs has not yet been fully elucidated. Future research should adopt multidisciplinary approaches that simultaneously examine the three levels of the Deqi mechanism — local, brain, and target-organ — to provide a more complete and dynamic understanding of this phenomenon. The researchers also recommend the development of standardized protocols for Deqi assessment and more rigorous studies that include both healthy individuals and patients with specific conditions.

This line of research is fundamental to the scientific advancement of acupuncture and its more effective integration into modern medicine, potentially leading to more precise and effective treatments for a wide range of health conditions.