Analgesic Effects Evoked by Real and Imagined Acupuncture: A Neuroimaging Study

Proteomics and its application in the research of acupuncture: An updated review

As a complementary and alternative therapy, acupuncture is widely used in the prevention and treatment of various diseases. However, the understanding of the mechanism of acupuncture effects is still limited due to the lack of systematic biological validation. Notably, proteomics technologies in the field of acupuncture are rapidly evolving, and these advances are greatly contributing to the research of acupuncture. In this study, we review the progress of proteomics research in analyzing the molecular mechanisms of acupuncture for neurological disorders, pain, circulatory disorders, digestive disorders, and other diseases, with an in-depth discussion around acupoint prescription and acupuncture manipulation modalities. The study found that proteomics has great potential in understanding the mechanisms of acupuncture. This study will help explore the mechanisms of acupuncture from a proteomic perspective and provide information to support future clinical decisions.

The Emotion Regulation of Acupuncture in Chronic Low Back Pain: A Clinical Neuroimaging Protocol

Introduction

Acupuncture is effective for patients with chronic low back pain (CLBP), which can relieve pain intensity and regulate negative emotional states such as pain-related anxiety and depression. Previous studies mainly discuss the analgesic mechanism of acupuncture treatment of CLBP, but there are multiple dimensions to pain, including sensation, emotion and cognition. Therefore, this study aims to investigate the central mechanism of acupuncture for CLBP from the perspective of emotional regulation by functional magnetic resonance imaging (fMRI).

Methods and Analysis

A total of 72 patients with CLBP will be recruited in the study and randomly assigned to the verum acupuncture group or the sham acupuncture group. The trail will last for 18 weeks including a 2-week baseline, a 4-week treatment and a 12-week for follow-up period. The primary outcomes are the visual analog scale (VAS) and the Japanese Orthopaedic Association Scores (JOA) score. The secondary outcomes are the 12-item short form health survey (SF-12), the state trait anxiety inventory (STAI), the self-rating anxiety scale (SAS) and self-rating depression scale (SDS). The VAS, JOA, STAI SAS and SDS will be collected at baseline, week 2, week 4, and after follow-up. The SF-12 will be evaluated at baseline, week 2 and week 4. Functional magnetic resonance imaging (MRI) data will be collected at baseline and the end of treatment. Emotion-related brain regions will be chosen as regions of interest (ROIs). The gray matter volume (GMV), amplitude of low-frequency fluctuation (ALFF), regional homogeneity (ReHo), functional connectivity (FC), and large-scale functional brain network based on these ROIs will be analyzed within and between the two groups.

Discussion

This study will verify the emotional regulation of acupuncture and explore the mechanism of acupuncture for emotion regulation in patients with CLBP.

Trial Registration Number

https://www.chictr.org.cn/showproj.html?proj=195486, identifier: ChiCTR2300070557.

Graded brain fMRI response to somatic and visual acupuncture stimulation

Increased stimulation can enhance acupuncture clinical response; however, the impact of acupuncture stimulation as "dosage" has rarely been studied. Furthermore, acupuncture can include both somatic and visual components. We assessed both somatic and visual acupuncture dosage effects on sensory ratings and brain response. Twenty-four healthy participants received somatic (needle inserted, manually stimulated) and visual (needle video, no manual stimulation) acupuncture over the leg at three different dosage levels (control, low-dose, and high-dose) during functional magnetic resonance imaging (fMRI). Participants reported the perceived deqi sensation for each acupuncture dose level. Blood-oxygen-level dependent imaging data were analyzed by general linear model and multivariate pattern analysis. For both somatic and visual acupuncture, reported deqi sensation increased with increased dosage of acupuncture stimulation. Brain fMRI analysis demonstrated that higher dosage of somatic acupuncture produced greater brain responses in sensorimotor processing areas, including anterior and posterior insula and secondary somatosensory cortex. For visual acupuncture, higher dosage of stimulation produced greater brain responses in visual-processing areas, including the middle temporal visual areas (V5/MT+) and occipital cortex. Psychophysical and psychophysiological responses to both somatic and visual acupuncture were graded in response to higher doses. Our findings suggest that acupuncture response may be enhanced by the dosage of needling-specific and nonspecific components, represented by different neural mechanisms.

Thalamocortical Mechanisms Underlying Real and Imagined Acupuncture

Both acupuncture and imagery have shown potential for chronic pain management. However, the mechanisms underlying their analgesic effects remain unclear. This study aims to explore the thalamocortical mechanisms underlying acupuncture and video-guided acupuncture imagery treatment (VGAIT), a combination of acupuncture and guided imagery, using the resting-state functional connectivity (rsFC) of three thalamic subdivisions-the ventral posterolateral thalamus (VPL), mediodorsal thalamus (MD), and motor thalamus subregion (Mthal)-associated with somatosensory, limbic, and motor circuity. Twenty-seven healthy individuals participated in a within-subject randomized crossover design study. Results showed that compared to sham acupuncture, real acupuncture altered the rsFC between the thalamus and default mode network (DMN) (i.e., mPFC, PCC, and precuneus), as well as the prefrontal and somatosensory cortex (SI/SII). Compared to the VGAIT control, VGAIT demonstrated greater rsFC between the thalamus and key nodes within the interoceptive network (i.e., anterior insula, ACC, PFC, and SI/SII), as well as the motor and sensory cortices (i.e., M1, SMA, and temporal/occipital cortices). Furthermore, compared to real acupuncture, VGAIT demonstrated increased rsFC between the thalamus (VPL/MD/Mthal) and task-positive network (TPN). Further correlations between differences in rsFC and changes in the heat or pressure pain threshold were also observed. These findings suggest that both acupuncture- and VGAIT-induced analgesia are associated with thalamocortical networks. Elucidating the underlying mechanism of VGAIT and acupuncture may facilitate their development, particularly VGAIT, which may be used as a potential remote-delivered pain management approach.

Cognitive and affective interaction with somatosensory afference in acupuncture-a specific brain response to compound stimulus

Introduction

Acupuncture is a clinical intervention consisting of multiple stimulus components, including somatosensory stimulation and manipulation of therapeutic context. Existing findings in neuroscience consolidated cognitive modulation to somatosensory afferent process, which could differ from placebo mechanism in brain. Here, we aimed to identify intrinsic process of brain interactions induced by compound stimulus of acupuncture treatment.

Methods

To separately and comprehensively investigate somatosensory afferent and cognitive/affective processes in brain, we implemented a novel experimental protocol of contextual manipulation with somatosensory stimulation (real acupuncture: REAL) and only contextual manipulation (phantom acupuncture: PHNT) for fMRI scan, and conducted independent component (IC)-wise assessment with the concatenated fMRI data.

Results

By our double (experimentally and analytically) dissociation, two ICs (CA1: executive control, CA2: goal-directed sensory process) for cognitive/affective modulation (associated with both REAL and PHNT) and other two ICs (SA1: interoceptive attention and motor-reaction, SA2: somatosensory representation) for somatosensory afference (associated with only REAL) were identified. Moreover, coupling between SA1 and SA2 was associated with a decreased heart rate during stimulation, whereas CA1 was associated with a delayed heart rate decrease post-stimulation. Furthermore, partial correlation network for these components demonstrated a bi-directional interaction between CA1 and SA1/SA2, suggesting the cognitive modulation to somatosensory process. The expectation for the treatment negatively affected CA1 but positively affected SA1 in REAL, whereas the expectation positively affected CA1 in PHNT.

Discussion

These specific cognitive-somatosensory interaction in REAL were differed from vicarious sensation mechanism in PHNT; and might be associated with a characteristic of acupuncture, which induces voluntary attention for interoception. Our findings on brain interactions in acupuncture treatment elucidated the underlying brain mechanisms for compound stimulus of somatosensory afferent and therapeutic contextual manipulation, which might be a specific response to acupuncture.

Optimizing and Accelerating the Development of Precision Pain Treatments for Chronic Pain: IMMPACT Review and Recommendations

Large variability in the individual response to even the most-efficacious pain treatments is observed clinically, which has led to calls for a more personalized, tailored approach to treating patients with pain (ie, "precision pain medicine"). Precision pain medicine, currently an aspirational goal, would consist of empirically based algorithms that determine the optimal treatments, or treatment combinations, for specific patients (ie, targeting the right treatment, in the right dose, to the right patient, at the right time). Answering this question of "what works for whom" will certainly improve the clinical care of patients with pain. It may also support the success of novel drug development in pain, making it easier to identify novel treatments that work for certain patients and more accurately identify the magnitude of the treatment effect for those subgroups. Significant preliminary work has been done in this area, and analgesic trials are beginning to utilize precision pain medicine approaches such as stratified allocation on the basis of prespecified patient phenotypes using assessment methodologies such as quantitative sensory testing. Current major challenges within the field include: 1) identifying optimal measurement approaches to assessing patient characteristics that are most robustly and consistently predictive of inter-patient variation in specific analgesic treatment outcomes, 2) designing clinical trials that can identify treatment-by-phenotype interactions, and 3) selecting the most promising therapeutics to be tested in this way. This review surveys the current state of precision pain medicine, with a focus on drug treatments (which have been most-studied in a precision pain medicine context). It further presents a set of evidence-based recommendations for accelerating the application of precision pain methods in chronic pain research. PERSPECTIVE: Given the considerable variability in treatment outcomes for chronic pain, progress in precision pain treatment is critical for the field. An array of phenotypes and mechanisms contribute to chronic pain; this review summarizes current knowledge regarding which treatments are most effective for patients with specific biopsychosocial characteristics.

The effects of acupuncture therapy in migraine: An activation likelihood estimation meta-analysis

Background

Previous functional magnetic resonance imaging studies indicated that acupuncture could activate the brain regions in patients with migraine. However, these studies showed inconsistent results. This activation likelihood estimation (ALE) meta-analysis aimed to investigate the consistent activated change of brain regions between pre- and post-acupuncture treatment in migraineurs.

Methods

We conducted a literature search in PubMed, Embase, Web of Science, the Cochrane Library, the China National Knowledge Infrastructure, the Chinese Science and Technology Periodical Database, the Wanfang Database, and the Chinese Biomedical Literature Database from their inception to 18 August, 2022, to obtain articles assessing the functional magnetic resonance imaging changes of acupuncture for migraine. Two investigators independently performed literature selection, data extraction, and quality assessment. The methodological quality was assessed with a modified version of the checklist. The reporting quality of interventions among included studies was evaluated by the Revised Standards for Reporting Interventions in Clinical Trials of Acupuncture (STRICTA). Our meta-analysis was conducted according to the GingerALE software. The Jackknife sensitivity analysis was used to assess the robustness of the results.

Results

14 articles were finally included according to the eligible criteria. Regarding the immediate effect of acupuncture on migraine, the ALE meta-analysis demonstrated that the deactivation regions were mainly located in the superior frontal gyrus, and middle frontal gyrus (uncorrected P < 0.001). The ALE meta-analysis of the cumulative effect showed that the activation regions were the thalamus, superior frontal gyrus, posterior lobe of the cerebellum, insula, middle frontal gyrus, precentral gyrus, anterior cingulate, and the deactivation brain regions were located in the transverse temporal gyrus, postcentral gyrus, superior temporal gyrus, anterior cingulate, parahippocampal gyrus, inferior parietal lobule, and inferior occipital gyrus (uncorrected P < 0.001).

Conclusion

Acupuncture could activate multiple brain areas related with the regulation of pain conduction, processing, emotion, cognition, and other brain regions in patients with migraine. In the future, the combination of multiple imaging technologies could be a new approach to deeply investigate the central mechanism of acupuncture for migraine.

Altered brain activity and functional connectivity in migraine without aura during and outside attack

BACKGROUND

Migraine is commonly seen as a cyclic disorder with variable cortical excitability at different phases. Herein, we investigated the cortical excitability in migraine without aura patients during an attack (MWoA-DA) and interictal period (MWoA-DI) and further explored the functional connectivity (FC) in brain regions with cortical excitability abnormalities in patients.

METHODS

Seven MWoA-DA patients, twenty-seven MWoA-DI patients, and twenty-nine healthy controls (HC) underwent resting-state functional magnetic resonance imaging (rs-fMRI) scan. The amplitude of low-frequency fluctuations (ALFF) was assessed to identify spontaneous brain activity. Then, brain regions showing significant differences across groups were identified as regions of interest (ROI) in FC analysis.

RESULTS

Compared with MWoA-DI patients and HC, the ALFF in the trigeminocervical complex (TCC) was higher in the MWoA-DA patients. Decreased FC in MWoA-DA patients was found between TCC and left postcentral gyrus compared with MWoA-DI patients. Compared with HC, ALFF was lower in the right cuneus but higher in the right rolandic operculum of MWoA-DI patients. Additionally, the ALFF in the right cuneus was negatively correlated with the Migraine Disability Assessment Scale (MIDAS) in MWoA-DI patients.

CONCLUSIONS

The trigeminovascular system and impairments in descending pain modulatory pathways participate in the pathophysiology of migraine during the ictal period. The defense effect exists in the interictal phase, and the dysfunction in the cuneus may be related to the disease severity. This dynamic change in different brain regions could deepen our understanding of the physiopathology underlying migraine.

The role of visual expectations in acupuncture analgesia: A quantitative electroencephalography study

Acupuncture is a complex treatment comprising multisensory stimulation, including visual and tactile sensations and experiences of body ownership. The purpose of this study was to investigate the role of these three components of acupuncture stimulation in acupuncture analgesia. 40 healthy volunteers participated in the study and received acupuncture treatment under three different conditions (real-hand, rubber-hand synchronous, and rubber-hand asynchronous). The tolerance for heat pain stimuli was measured before and after treatment. Brain oscillation changes were also measured using electroencephalography (EEG). The pain tolerance was significantly increased after acupuncture treatment under all three conditions. Noticeable deqi (needle) sensations in response to acupuncture stimulation of the rubber hand were found under both rubber-hand synchronous and rubber-hand asynchronous conditions. Deqi sensations were significantly correlated with acupuncture analgesia only under the rubber-hand synchronous condition. Increased delta and decreased theta, alpha, beta, and gamma waves were observed after acupuncture treatment under all three conditions. Our findings clarified the role of cognitive components of acupuncture treatment in acupuncture analgesia through the rubber-hand illusion. This study is a first step toward separating various components of acupuncture analgesia, i.e. visual, tactile, and body ownership, and utilizing those components to maximize analgesic effects.

Exploring Acupuncture Actions in the Body and Brain

Acupuncture's actions have been explained by biomedical research. However, the meridian system used in acupuncture needs further clarification. This review describes how acupuncture affects the body and brain. From the perspective of traditional East Asian medicine, the meridian system is closely connected with acupuncture's treatment effects. In the body, the indications of acupoints, primarily established based on the meridian system, have spatial symptom patterns. Spatial patterns of acupoint indications are distant from the stimulated sites and strongly associated with the corresponding meridian's route. Understanding how acupuncture works based on the original meridian system is important. From a neuroscience perspective, an acupuncture-induced sensation originates from the bottom-up action of simple needling in the peripheral receptor and the reciprocal interaction with top-down brain modulation. In the brain, enhanced bodily attention triggered by acupuncture stimulation can activate the salience network and deactivate the default mode network regardless of the actual stimulation. The application of data science technology to acupuncture research may provide new tools to uncover the principles of acupoint selection and enhance the clinical efficacy of acupuncture treatment in various diseases.

Effect of Acupuncture on the Cognitive Control Network of Patients with Knee Osteoarthritis: Study Protocol for a Randomized Controlled Trial

Purpose

Materials and Methods

Discussion

Study Registration

Selected needling techniques in pain associated with musculoskeletal disorders: a narrative review

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Memory-directed acupuncture as a neuromodulatory treatment for PTSD: Theory, clinical model and case studies

Posttraumatic stress disorder (PTSD) poses an ongoing challenge to society, to health systems, and to the trauma victims themselves. Today PTSD is often considered an incurable chronic problem that lacks effective treatment. While PTSD is closely related to memory, it also affects many physiological systems. PTSD is usually treated with medications and psychotherapy with moderate success, leaving a substantial proportion of patients with enduring distress and disability. Therefore, a search for better treatment options is vital. In this paper, we propose a model in which a conversation-based technique is integrated with bodily manipulation through acupuncture. This approach first emerged in clinical experience showing intriguing results from treating PTSD patients using acupuncture as a main strategy. Its theoretical foundations derive from the clinic and rely on contemporary neuroscience's understanding of memory consolidation and reconsolidation processes. Research shows that acupuncture can have potentially positive effects at three levels: (a) achieving a balance between sympathetic and parasympathetic neural activity; (b) reducing activation in the limbic system, hence inducing a calming effect; (c) reshaping the functional connectivity map within important and relevant cortical regions that encompass the default-mode network. We suggest that coupling traumatic memory retrieval leading to reconsolidation, combined with acupuncture, offers considerable potential for positive clinical improvement in patients with PTSD. This may explain the positive results of the described case studies and can pave the path for future advances in research and treatment in this field.

Bibliometric Analysis of Functional Magnetic Resonance Imaging Studies on Acupuncture Analgesia Over the Past 20 Years

Background

Researches on the central mechanisms of acupuncture analgesia have been widely conducted worldwide. However, there is no bibliometric analysis of functional magnetic resonance imaging (fMRI) studies on acupuncture analgesia. This study visualized the current status, hot spots and frontiers of fMRI studies on acupuncture analgesia in the past 20 years to provide a theoretical basis for its clinical application.

Methods

All publications were obtained from Science Citation Index-Expanded (SCI-E) of Web of Science (WOS). We used CiteSpace to analyze publications, journals, cited journals, authors, cited authors, institutions, countries, references, and keywords. We also analyzed collaborative network maps and co-occurrence network maps.

Results

We retrieved a total of 797 articles. Regarding the volume of publications, the total number of annual publications showed a fluctuating but overall increasing trend. Evidence-based Complementary and Alternative Medicine (21 articles) was the most productive journal, and Pain (225 articles) was the most cited journal. The most productive author was Qin W (16 articles), and the most co-cited author was Hui KKS (111). The most prolific institution and country were Massachusetts General Hospital (34 articles) and USA (212 articles). “Pain” was the top-ranked for keyword frequency and centrality. “Functional connectivity” was the frontier hotspot for 2018–2021.

Conclusion

First, fMRI researches on acupuncture analgesia involved several countries (regions) and institutions, mainly located in the USA, China and Korea, and most of them were universities. In addition, the USA was a major contributor in this field. Second, in terms of disciplinary distribution, the literatures were mainly from clinical neurology, neuroscience, and radiology nuclear medicine medical imaging. Third, the keyword co-occurrence analysis showed that the hot keywords included pain, fMRI, and lower back pain. Fourth, through keyword clustering analysis, the hot disease was found to be lower back pain, and the hot contents were acupuncture specificity and frequency specificity. Fifth, a timeline analysis of the references identified that chronic low back pain and specificity will remain a hot topic for future research.

Multimodal cerebral imaging study on the effects of "Adjust Zang Dredge Meridian" electroacupuncture on cerebral central sensitization in PDPN patients: a study protocol for a sham-controlled, randomized trial

BACKGROUND

Painful diabetic peripheral neuropathy (PDPN) has a great impact on an individual's quality of life. The current researchers' previous trial suggested that acupuncture was a promising adjunctive treatment for PDPN. However, the underlying mechanism of action of acupuncture treatment for PDPN is still unclear, especially its effects at the cerebral level. The aim of this trial will be to explore how acupuncture works in treating PDPN by using multimodal cerebral imaging.

METHOD AND DESIGN

This will be a randomized controlled trial. A total of 150 participants will be recruited and assigned to one of three groups: the healthy group, the DM without PDPN group and the DM with PDPN group. Participants in the DM without PDPN and the DM with PDPN groups will each be further divided between an electroacupuncture group and a sham electroacupuncture group. Participants will receive six treatment sessions per week for 4 weeks. Multimodal cerebral imaging includes resting-state functional magnetic resonance imaging (rs-fMRI), diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS); this neurophysiological testing will be the primary outcome measure. Subjective pain scales and blood analysis will be a secondary outcome measure and will be used to assess the clinical efficacy of the intervention. Multimodal cerebral imaging will be used to detect cerebral activity changes in each treatment group. The clinical data and fMRI data will be analysed for all the groups. Multiple correlation regression analyses will be used to assess the association between changes in cerebral functional activity and the improvement of clinical outcomes after acupuncture treatment.

DISCUSSION

This study is based on the results of the researchers' previous study, and using combined clinical and cerebral function changes, it will help evaluate the effects of acupuncture on PDPN. The investigation of acupuncture's central mechanism of action will further expand the understanding of acupuncture treatment of PDPN.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR1900024109 . Registered on 26 June 2019.

Modulatory Effects of Actual and Imagined Acupuncture on the Functional Connectivity of the Periaqueductal Gray and Ventral Tegmental Area

OBJECTIVE

Both acupuncture and guided imagery hold promise for treating pain. The mechanisms underlying these alternative interventions remain unclear. The reported study aimed to comparatively investigate the modulation effect of actual and imagined acupuncture on the functional connectivity of descending pain modulation system and reward network.

METHODS

Twenty-four healthy participants (mean [standard error], 25.21 [0.77] years of age; 66.67% female) completed a crossover study that included five sessions, a training session and four intervention sessions administered in randomized order. We investigated the modulation effect of real acupuncture, sham acupuncture, video-guided acupuncture imagery treatment (VGAIT) and VGAIT control on the resting-state functional connectivity (rsFC) of periaqueductal gray (PAG) and ventral tegmental area (VTA). These are key regions of the descending pain modulatory system and dopaminergic reward system, respectively.

RESULTS

Compared with sham acupuncture, real acupuncture produced decreased PAG-precuneus (Pcu) rsFC and increased VTA-amygdala/hippocampus rsFC. Heat pain threshold changes applied on the contralateral forearm were significantly associated with the decreased PAG-Pcu (r = 0.49, p = .016) and increased VTA-hippocampus rsFC (r = -0.77, p < .001). Compared with VGAIT control, VGAIT produced decreased PAG-paracentral lobule/posterior cingulate cortex/Pcu, middle cingulate cortex (MCC), and medial prefrontal cortex rsFC, and decreased VTA-caudate and MCC rsFC. Direct comparison between real acupuncture and VGAIT showed that VGAIT decreased rsFC in PAG-paracentral lobule/MCC, VTA-caudate/anterior cingulate cortex/nucleus accumbens, and VTA-MCC.

CONCLUSIONS

Results suggest that both actual and imagined acupuncture can modulate key regions in the descending pain modulatory system and reward networks, but through different pathways. Identification of different pain relief mechanisms may facilitate the development of new pain management methods.

Efficacy and central mechanism of acupuncture treatment in patients with neck pain: study protocol for a randomized controlled trial

Background

Acupuncture is effective for reducing the symptoms of neck pain (NP). However, the underlying mechanisms are not fully elucidated. Based on evaluating the efficacy of two acupuncture prescriptions for treating NP, this study aims to investigate the potential central mechanism of acupuncture treatment for NP by functional magnetic resonance imaging (fMRI).

Methods

This is a randomized controlled trial; 86 patients will be randomly assigned into two acupuncture treatment groups at a ratio of 1:1. The whole study period includes 2 weeks baseline, 2 weeks treatments, and 12 weeks follow-up (4 and 12 weeks after treatment). The pain severity, the neck disability index, the cervical range of motion, and the pressure pain threshold, etc., will be used to evaluate the clinical efficacy of two acupuncture prescriptions for NP treatment. The MRI scans will be performed to detect cerebral activity changes of 20 patients in each group. The clinical data and MRI data will be analyzed, respectively. Pearson correlation coefficient will be used to evaluate the association between changes of cerebral activity features and improvement of clinical symptoms.

Discussion

The results will provide further evidence for the clinical application of acupuncture in the treatment of NP.

Trial registration

Chinese Clinical Trial Registry ChiCTR2000040930. Registered on 16 December 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05507-y.

Acupuncture Can Play an Antidepressant Role by Regulating the Intestinal Microbes and Neurotransmitters in a Rat Model of Depression

BACKGROUND Acupuncture, which has many good effects and few adverse effects, is widely recognized as an alternative therapy for depression in clinical practice. This study aimed to explore the mechanism of acupuncture in antidepressant treatment. MATERIAL AND METHODS In this experiment, Sprague-Dawley rats were randomly divided into 4 groups: control, chronic unpredictable mild stress (CUMS), acupuncture, and fluoxetine groups. The CUMS, acupuncture, and fluoxetine groups were orphaned and subjected to chronic unpredictable stress for 6 weeks, and the acupuncture and fluoxetine groups were treated with their respective intervention in weeks 4-6. The body weight of rats was monitored weekly. After behavioral tests were completed, serum, feces, and hippocampal tissue of rats were collected. RESULTS The results showed that the acupuncture and fluoxetine treatments could alleviate the behavioral changes caused by CUMS. The treatments increased the total distance of rat crossing in the open-field test, prolonged the activity time of the open cross maze in the open arm, and improved the rate of sucrose consumption in the sucrose preference test. In addition, both the decreased level of dopamine (DA) and 5-hydroxytryptamine (5-HT) in serum and hippocampus caused by CUMS were improved after the treatments with acupuncture and fluoxetine, and the decreased expression of brain-derived neurotrophic factor signaling and the astrocytes in the hippocampus caused by CUMS were increased after the treatments with acupuncture and fluoxetine. Acupuncture and fluoxetine also decreased the ß isoform of calmodulin-dependent protein kinase II in the hippocampus, which was increased by CUMS. Furthermore, acupuncture regulated intestinal microbial disorders caused by CUMS, which reduced the relative abundance ratio of Bacteroidetes/Firmicutes in rats. CONCLUSIONS Our experimental results indicate that acupuncture can alleviate depression-like performance in CUMS rats by regulating intestinal microbes and neurotransmitters.

Evidence of Potential Mechanisms of Acupuncture from Functional MRI Data for Migraine Prophylaxis

PURPOSE OF REVIEW

To summarize the clinical neuroimaging evidence pertaining to the potential mechanisms of acupuncture for migraine prophylaxis.

RECENT FINDINGS

From a descriptive perspective, converging evidence from recent neuroimaging studies, mainly from functional MRI (fMRI) studies, has demonstrated that when compared with sham acupuncture, verum acupuncture could normalize the decrease of the functional connectivity of the rostral ventromedial medulla-trigeminocervical complex (RVM/TCC) network, frontal-parietal network, cingulo-opercular networks, and default mode network and could normalize sensorimotor network connectivity with sensory-, affective-, and cognitive-related brain areas. These areas overlap with those of the pain matrix. Verum acupuncture works in a more targeted and unique manner compared with sham acupuncture in patients with migraine. These findings from neuroimaging studies may provide new perspectives on the validation of acupoints specificity and confirm the central modulating effects of acupuncture as a migraine prevention treatment. However, the exact mechanism by which acupuncture works for migraine prophylaxis remains unclear and warrants investigation. Future studies with larger sample sizes are still needed to confirm the current results and to further evaluate the complex and specific effects of acupuncture by analyzing different stimulus conditions, such as verum vs. sham acupuncture, deqi vs. no deqi, different acupuncture points or meridians, and different manipulation methods. Moreover, instead of focusing on the changes in a single area of the brain, researchers should focus more on the relationships among the functional connectivity network of brain areas such as the RVM/TCC, thalamus, anterior cingulate cortex (ACC), superior temporal gyrus (STG), and supplementary motor area (SMA) to explore the underlying mechanism of the effects of acupuncture.

Cognition and Pain: A Review

Cognition is defined as the brain's ability to acquire, process, store, and retrieve information. Pain has been described as an unpleasant sensory or emotional experience, and for experiencing pain consciously, cognitive processing becomes imperative. Moreover, evaluation of pain strongly depends on cognition as it requires learning and recall of previous experiences. There could be a possible close link between neural systems involved in cognition and pain processing, and studies have reported an association between pain and cognitive impairment. In this narrative review, we explore the available evidence that has investigated cognitive changes associated with pain. We also examine the anatomical, biochemical, and molecular association of pain and neuro-cognition. Additionally, we focus on the cognitive impairment caused by analgesic medications. There is a need to improve our understanding of pathophysiology and cognitive impairment mechanisms associated with chronic pain and its treatment. This area provides a diverse opportunity for grounding future research, aiding institution of timely interventions to prevent chronic pain and associated cognitive decline, ultimately improving patient care.

Neuroimaging in the Understanding of Acupuncture Analgesia: A Review of Acupuncture Neuroimaging Study Based on Experimental Pain Models

With the development of real-time and visualized neuroimaging techniques, the studies on the central mechanism of acupuncture analgesia gain increasing attention. The experimental pain models have been widely used in acupuncture-analgesia neuroimaging studies with quantitative and controlled advantages. This review aimed to analyze the study design and main findings of acupuncture neuroimaging studies to provide reference for future study. The original studies were collected and screened in English databases (PubMed, EMBASE, and Cochrane Library) and Chinese databases (Chinese Nation Knowledge Infrastructure, Chinese Biomedical Literature Database, the Chongqing VIP Database, and Wanfang Database). As a result, a total of 27 articles were included. Heat stimulation and electroacupuncture were the mostly used pain modeling method and acupuncture modality, respectively. The neuroimaging scanning process can be divided into two models and five subtypes. The anterior cingulate cortex and insula were the most commonly reported brain regions involved in acupuncture analgesia with experimental pain models.

Daily Caffeine Consumption Does Not Influence Acupuncture Analgesia in Healthy Individuals: A Preliminary Study

Animal studies suggest that caffeine may interfere with acupuncture analgesia. This study investigated the modulation effect of daily caffeine intake on acupuncture analgesia in 27 healthy subjects using a crossover design. We found that real acupuncture increased pain thresholds compared to sham acupuncture. Further, there was no association between caffeine intake measurements of daily caffeine use, duration of caffeine consumption, or their interaction and preacupuncture and postacupuncture pain threshold changes. Our findings suggest that daily caffeine intake may not influence acupuncture analgesia in the cohort of healthy subjects who participated in study.

Test-retest reliability of laser evoked pain perception and fMRI BOLD responses

Pain perception is a subjective experience and highly variable across time. Brain responses evoked by nociceptive stimuli are highly associated with pain perception and also showed considerable variability. To date, the test–retest reliability of laser-evoked pain perception and its associated brain responses across sessions remain unclear. Here, an experiment with a within-subject repeated-measures design was performed in 22 healthy volunteers. Radiant-heat laser stimuli were delivered on subjects’ left-hand dorsum in two sessions separated by 1–5 days. We observed that laser-evoked pain perception was significantly declined across sessions, coupled with decreased brain responses in the bilateral primary somatosensory cortex (S1), right primary motor cortex, supplementary motor area, and middle cingulate cortex. Intraclass correlation coefficients between the two sessions showed “fair” to “moderate” test–retest reliability for pain perception and brain responses. Additionally, we observed lower resting-state brain activity in the right S1 and lower resting-state functional connectivity between right S1 and dorsolateral prefrontal cortex in the second session than the first session. Altogether, being possibly influenced by changes of baseline mental state, laser-evoked pain perception and brain responses showed considerable across-session variability. This phenomenon should be considered when designing experiments for laboratory studies and evaluating pain abnormalities in clinical practice.

Applying the Power of the Mind in Acupuncture Treatment of Pain

Background: Healing is a complicated process that can have several components including the self-healing properties of the body, the nonspecific effects of treatment (e.g., the power of the mind), and the specific effects of an intervention. This article first discusses the brain imaging studies on placebo acupuncture analgesia and the modulation effects of expectancy on real acupuncture in healthy subjects. Then, it introduces some attempts to translate findings from healthy subjects to patient population using power of the mind as a way to enhance acupuncture's treatment effects on chronic pain. After that, a new alternative method which merges acupuncture and imagery, while also drawing on power of the mind, is presented. Finally, the specific effects of acupuncture are discussed. Conclusions: Elucidating the mechanism underlying power of the mind would provide new opportunities for boosting the therapeutic effect of acupuncture treatment and furthering the development of new alternative interventions.

Neurological and psychological mechanisms of the specific and nonspecific effects of acupuncture on knee osteoarthritis: study protocol for a randomized, controlled, crossover trial

Background

Acupuncture, as one of the promising non-pharmacological interventions, has been proved to be beneficial for patients. However, the magnitude of acupuncture’s specific and nonspecific effects, as well as their neurological and psychological determinants, remains unclear. Therefore, this study is designed to examine the acupuncture efficacy, investigate whether the brain mechanisms between the specific and nonspecific effects of acupuncture are different, and to evaluate how psychological factors affect the acupuncture effects.

Methods

This is a randomized, controlled, crossover clinical trial. A total of 60 patients with knee osteoarthritis will receive 4 weeks of acupuncture treatment and 4 weeks of sham acupuncture treatment in a random order separated by a washout period of 2 weeks. The changes in clinical characteristics based on pain-related scales will be assessed to investigate the clinical efficacy of acupuncture. Resting state functional magnetic resonance imaging (fMRI) scans will be used to identify the brain activity changes related to the specific and nonspecific effects of acupuncture. The questionnaires of psychological factors will be used to evaluate patients’ psychological properties. Correlation and mediation analyses will be conducted among psychological factors, brain activity changes, and symptoms improvement to explore the neurological and psychological correlates of the acupuncture effects.

Discussion

This study will concentrate on distinguishing and clarifying the specific and nonspecific effects of acupuncture. The results of this study may contribute to rationally optimize the acupuncture therapies by flexible application of the specific and nonspecific effects of acupuncture.

Trial registration

Chinese Clinical Trial Registry ChiCTR1900025807. Registered on 9 September 2019

Supplementary information

The online version contains supplementary material available at 10.1186/s13063-020-04908-9.

Magnetic resonance imaging for chronic pain: diagnosis, manipulation, and biomarkers

Pain is a multidimensional subjective experience with biological, psychological, and social factors. Whereas acute pain can be a warning signal for the body to avoid excessive injury, long-term and ongoing pain may be developed as chronic pain. There are more than 100 million people in China living with chronic pain, which has raised a huge socioeconomic burden. Studying the mechanisms of pain and developing effective analgesia approaches are important for basic and clinical research. Recently, with the development of brain imaging and data analytical approaches, the neural mechanisms of chronic pain have been widely studied. In the first part of this review, we briefly introduced the magnetic resonance imaging and conventional analytical approaches for brain imaging data. Then, we reviewed brain alterations caused by several chronic pain disorders, including localized and widespread primary pain, primary headaches and orofacial pain, musculoskeletal pain, and neuropathic pain, and present meta-analytical results to show brain regions associated with the pathophysiology of chronic pain. Next, we reviewed brain changes induced by pain interventions, such as pharmacotherapy, neuromodulation, and acupuncture. Lastly, we reviewed emerging studies that combined advanced machine learning and neuroimaging techniques to identify diagnostic, prognostic, and predictive biomarkers in chronic pain patients.

Resting-State Functional Connectivity Patterns Predict Acupuncture Treatment Response in Primary Dysmenorrhea

Primary dysmenorrhea (PDM) is a common complaint in women throughout the menstrual years. Acupuncture has been shown to be effective in dysmenorrhea; however, there are large interindividual differences in patients’ responses to acupuncture treatment. Fifty-four patients with PDM were recruited and randomized into real or sham acupuncture treatment groups (over the course of three menstrual cycles). Pain-related functional connectivity (FC) matrices were constructed at baseline and post-treatment period. The different neural mechanisms altered by real and sham acupuncture were detected with multivariate analysis of variance. Multivariate pattern analysis (MVPA) based on a machine learning approach was used to explore whether the different FC patterns predicted the acupuncture treatment response in the PDM patients. The results showed that real but not sham acupuncture significantly relieved pain severity in PDM patients. Real and sham acupuncture displayed differences in FC alterations between the descending pain modulatory system (DPMS) and sensorimotor network (SMN), the salience network (SN) and SMN, and the SN and default mode network (DMN). Furthermore, MVPA found that these FC patterns at baseline could predict the acupuncture treatment response in PDM patients. The present study verified differentially altered brain mechanisms underlying real and sham acupuncture in PDM patients and supported the use of neuroimaging biomarkers for individual-based precise acupuncture treatment in patients with PDM.

Acupuncture and Chronic Musculoskeletal Pain

PURPOSE OF REVIEW

Chronic musculoskeletal pain (CMP) attributable to conditions such as osteoarthritis, rheumatoid arthritis, fibromyalgia, and chronic low back pain is the most common cause of disability globally, for which no effective remedy exists. Although acupuncture is one of the most popular sensory stimulation therapies and is widely used in numerous pain conditions, its efficacy remains controversial. This review summarizes and expands upon the current research on the therapeutic properties of acupuncture for patients with CMP to better inform clinical decision-making and develop patient-focused treatments.

RECENT FINDINGS

We examined 16 review articles and 11 randomized controlled trials published in the last 5 years on the clinical efficacy of acupuncture in adults with CMP conditions. The available evidence suggests that acupuncture does have short-term pain relief benefits for patients with symptomatic knee osteoarthritis and chronic low back pain and is a safe and reasonable referral option. Acupuncture may also have a beneficial role for fibromyalgia. However, the available evidence does not support the use of acupuncture for treating hip osteoarthritis and rheumatoid arthritis. The majority of studies concluded the superiority of short-term analgesic effects over various controls and suggested that acupuncture may be efficacious for CMP. These reported benefits should be verified in more high-quality randomized controlled trials.

Imagined and Actual Acupuncture Effects on Chronic Low Back Pain: A Preliminary Study

Background

Research suggests that imagined experiences can produce brain responses similar to those produced by actual experiences. Shared brain responses that support both imagination and perception may underlie the functional nature of mental imagery. In a previous study, we combined acupuncture and imagery to develop a new treatment method, video-guided acupuncture imagery treatment (VGAIT). We found that VGAIT significantly increased pain thresholds in healthy subjects. The aim of this study is to extend our previous finding by investigating whether VGAIT can relieve symptoms in patients with chronic low back pain.

Methods

We first performed a single-arm study in which we administered video-guided acupuncture imagery treatment (VGAIT) on patients with chronic low back pain (cLBP) (Study 1, n = 18, 12 females). We then compared our findings to those from a recently published study in which real or sham acupuncture treatment was applied on patients with cLBP (Study 2, n = 50, 31 females) using a similar protocol. All patients in Studies 1 and 2 received 6 treatments over 4 weeks.

Results

All three treatments (VGAIT, real, and sham acupuncture) significantly reduced pain severity as measured by a low back pain bothersomeness score. VGAIT produced similar effects to real acupuncture (p = 0.97) and nonsignificantly greater pain bothersomeness relief compared to sham acupuncture (p = 0.14). Additional analysis showed that there was no significant difference on the sensations evoked by different treatment modalities.

Conclusion

These findings support VGAIT as a promising method for pain management.

Characterizing the analgesic effects of real and imagined acupuncture using functional and structure MRI

Acupuncture and imagery interventions for pain management have a long history. The present study comparatively investigated whether acupuncture and video-guided acupuncture imagery treatment (VGAIT, watching a video of acupuncture on the participant's own body while imagining it being applied) could modulate brain regional connectivity to produce analgesic effects. The study also examined whether pre-intervention brain functional and structural features could be used to predict the magnitude of analgesic effects. Twenty-four healthy participants were recruited and received four different interventions (real acupuncture, sham acupuncture, VGAIT, and VGAIT control) in random order using a cross-over design. Pain thresholds and magnetic resonance imaging (MRI) data were collected before and after each intervention. We first compared the modulatory effects of real acupuncture and VGAIT on intra- and inter-regional intrinsic brain connectivity and found that real acupuncture decreased regional homogeneity (ReHo) and functional connectivity (FC) in sensorimotor areas, whereas VGAIT increased ReHo in basal ganglia (BG) (i.e., putamen) and FC between the BG subcortical network and default mode network. The altered ReHo and FC were associated with changes in pain threshold after real acupuncture and VGAIT, respectively. A multimodality fusion approach with pre-intervention ReHo and gray matter volume (GMV) as features was used to explore the brain profiles underlying individual variability of pain threshold changes by real acupuncture and VGAIT. Variability in acupuncture responses was associated with ReHo and GMV in BG, whereas VGAIT responses were associated with ReHo and GMV in the anterior insula. These results suggest that, through different pathways, both real acupuncture and VGAIT can modulate brain systems to produce analgesic effects.

The cerebral mechanism of the specific and nonspecific effects of acupuncture based on knee osteoarthritis: study protocol for a randomized controlled trial

Background

Research on the effect of acupuncture has been limited. Whether the effect of acupuncture is equivalent to placebo has been the focus of debate in this field. This study will explore the specific and non-specific effects of acupuncture for knee osteoarthritis (KOA) by functional magnetic resonance imaging (fMRI).

Methods and design

Ninety participants diagnosed with KOA will be randomly divided into the acupuncture group, sham acupuncture group, and waiting list group in a ratio of 1:1:1. Except for the waiting list group, the other participants will receive acupuncture or sham acupuncture three sessions per week for 4 weeks respectively. The primary outcome will be the response rate which is defined on an individual basis as at least a 2-point decrease in the numerical rating scale (NRS) of pain at the end of intervention period compared with the baseline. fMRI scans will be performed at baseline and the end of the intervention period to examine the response of various brain regions. The secondary outcomes will include the Western Ontario and McMaster Osteoarthritis Index (WOMAC), State-Trait Anxiety Scale-State Anxiety Subscale (STAI-S), and Stanford Expectations of Treatment Scale (SETS). Pearson’s correlation coefficient will be performed to investigate the changes in brain activity and clinical variables.

Discussion

The results of our study will help to evaluate the specific and nonspecific effects of acupuncture combined with clinical and brain function changes based on KOA.

Trial registration

Chinese Clinical Trial Registry ChiCTR1900025799. Registered on 9 September 2019.

Acupuncture Treatment Modulates the Connectivity of Key Regions of the Descending Pain Modulation and Reward Systems in Patients with Chronic Low Back Pain

Chronic low back pain (cLBP) is a common disorder with unsatisfactory treatment options. Acupuncture has emerged as a promising method for treating cLBP. However, the mechanism underlying acupuncture remains unclear. In this study, we investigated the modulation effects of acupuncture on resting state functional connectivity (rsFC) of the periaqueductal gray (PAG) and ventral tegmental area (VTA) in patients with cLBP. Seventy-nine cLBP patients were recruited and assigned to four weeks of real or sham acupuncture. Resting state functional magnetic resonance imaging data were collected before the first and after the last treatment. Fifty patients completed the study. We found remission of pain bothersomeness in all treatment groups after four weeks, with greater pain relief after real acupuncture compared to sham acupuncture. We also found that real acupuncture can increase VTA/PAG rsFC with the amygdala, and the increased rsFC was associated with decreased pain bothersomeness scores. Baseline PAG-amygdala rsFC could predict four-week treatment response. Our results suggest that acupuncture may simultaneously modulate the rsFC of key regions in the descending pain modulation (PAG) and reward systems (VTA), and the amygdala may be a key node linking the two systems to produce antinociceptive effects. Our findings highlight the potential of acupuncture for chronic low back pain management.

Different exercise modalities relieve pain syndrome in patients with knee osteoarthritis and modulate the dorsolateral prefrontal cortex: A multiple mode MRI study

OBJECTIVES

Knee osteoarthritis (KOA) is a common degenerative joint disease with no satisfactory intervention. Recently, both physical and mindfulness exercises have received considerable attention for their implications in KOA pain management, and the dorsolateral prefrontal cortex (DLPFC) has displayed a critical role in pain modulation. This study aimed to comparatively investigate the modulation effects of different exercises using multidisciplinary measurements.

METHODS

140 KOA patients were randomized into Tai Chi, Baduanjin, stationary cycling, or health education control groups for 12 weeks. Knee Injury and Osteoarthritis Outcome Score (KOOS), resting state functional magnetic resonance imaging (fMRI), structural MRI, and serum biomarkers were measured at baseline and at the end of the study.

RESULTS

We found: 1) increased KOOS pain subscores (pain reduction) and serum programmed cell death protein 1 (PD-1) levels in the three exercise groups compared to the control group; 2) decreased resting state functional connectivity (rsFC) of the DLPFC-supplementary motor area (SMA) and increased rsFC between the DLPFC and anterior cingulate cortex in all exercise groups compared to the control group; 3) significant associations between DLPFC-SMA rsFC with KOOS pain subscores and serum PD-1 levels at baseline; 4) significantly increased grey matter volume in the SMA in the Tai Chi and stationary cycling groups, and a trend toward significant increase in the Baduanjin group compared to the control group; 5) significant DLPFC rsFC differences among different exercise groups; and 6) that baseline DLPFC-SMA rsFC can predict the effect of mind-body exercise on pain improvement in KOA.

CONCLUSION

Our results suggest that different exercises can modulate both common and unique DLPFC (cognitive control) pathways, and altered DLPFC-SMA rsFC is associated with serum biomarker levels. Our findings also highlight the potentials of neuroimaging biomarkers in predicting the therapeutic effect of mind-body exercises on KOA pain.

Multivariate resting-state functional connectivity predicts responses to real and sham acupuncture treatment in chronic low back pain

Despite the high prevalence and socioeconomic impact of chronic low back pain (cLBP), treatments for cLBP are often unsatisfactory, and effectiveness varies widely across patients. Recent neuroimaging studies have demonstrated abnormal resting-state functional connectivity (rsFC) of the default mode, salience, central executive, and sensorimotor networks in chronic pain patients, but their role as predictors of treatment responsiveness has not yet been explored. In this study, we used machine learning approaches to test if pre-treatment rsFC can predict responses to both real and sham acupuncture treatments in cLBP patients. Fifty cLBP patients participated in 4 weeks of either real (N = 24, age = 39.0 ± 12.6, 16 females) or sham acupuncture (N = 26, age = 40.0 ± 13.7, 15 females) treatment in a single-blinded trial, and a resting-state fMRI scan prior to treatment was used in data analysis. Both real and sham acupuncture can produce significant pain reduction, with those receiving real treatment experiencing greater pain relief than those receiving sham treatment. We found that pre-treatment rsFC could predict symptom changes with up to 34% and 29% variances for real and sham treatment, respectively, and the rsFC characteristics that were significantly predictive for real and sham treatment differed. These results suggest a potential way to predict treatment responses and may facilitate the development of treatment plans that optimize time, cost, and available resources.