Pain

Nav1.7 voltage-gated sodium channels are strongly expressed in human primary painsensing neurons (nociceptors) and selective Nav1.7 inhibitors have been developed as possible therapeutic agents for treating pain, so far with disappointing clinical results. In contrast, a selective Nav1.8 channel inhibitor (suzetrigine) has had successful clinical trials. Because nociceptors express both Nav1.7 and Nav1.8 channels, it is of interest to compare effects of Nav1.7 and Nav1.8 inhibitors on the excitability of human nociceptors. To compare with previous results with suzetrigine, we characterized the effects of a selective Nav.7 inhibitor, AM-2099, on action potential generation and repetitive firing of dissociated human dorsal root ganglion neurons, studied at 37{degrees}C. Inhibition of Nav1.7 channels by 600 nM AM-2099 generally produced a substantial depolarizing shift of action potential threshold, an increase in rheobase, a decrease in action potential upstroke velocity, decrease in action potential peak, and prolongation of refractory period. Compared to inhibition of Nav1.8 channels, inhibition of Nav1.7 channels had larger effects on threshold and maximal upstroke velocity, while action potential peak was reduced similarly by both. Nav1.8 inhibition produced much more dramatic reduction of repetitive firing than Nav1.7 inhibition. The results show that although the excitability of human DRG neurons is affected by inhibition of Nav1.7 channels, most notably by an increase in threshold and increase in refractory period, repetitive firing of the neurons in response to strong stimuli is little affected. Significance statementNav1.7 sodium channels are highly expressed in primary pain-sensing neurons and humans with null mutations in Nav1.7 channels have loss of pain sensation. However, unlike the Nav1.8 inhibitor suzetrigine, Nav1.7 inhibitors have so far not reached clinical use. We compared effects of Nav1.7 on electrical excitability of human dorsal root ganglion neurons with those of suzetrigine and found that while Nav1.7 inhibition affects spike threshold more than suzetrigine, there is little effect on repetitive firing with strong stimuli.

Deficient descending pain inhibition assessed by conditioned pain modulation (CPM) is considered a common feature of various chronic pain disorders. Typically, CPM studies focus on one particular disorder making direct comparisons between disorders difficult. This cross-sectional study aimed to compare CPM effects between three clearly distinct chronic pain disorders and pain-free controls. Furthermore, patients were pooled with controls to explore whether subgroups showing different CPM effects could be separated independent of cohort membership. One hundred and forty participants (patients: 53 non-specific chronic low back pain [nsCLBP], 15 complex regional pain syndrome [CRPS], 14 neuropathic pain after spinal cord injury [painSCI]; 58 controls) were included. CPM effects were assessed in a remote, pain-free area using pressure pain thresholds as test stimulus and a cold water bath as conditioning stimulus. Cohort differences in CPM effects were analyzed using linear mixed models. The presence of subgroups showing different CPM effects was tested using latent class linear mixed models. CPM effects differed between cohorts (p = 0.011), driven mainly by reduced inhibitory CPM effects in patients with nsCLBP compared to patients with painSCI. Latent class analysis detected 3 subgroups with varying degrees of significant inhibitory CPM effects (ps [≤] 0.002). All subgroups comprised patients and controls. These results oppose deficient descending pain inhibition as a common feature of chronic pain disorders. Additionally, the failure to identify subgroups without inhibitory CPM effects within a heterogenous patient/control sample challenges the utility of deficient CPM as predictor of chronic pain or treatment efficacy. PerspectiveInhibitory conditioned pain modulation, a measure of descending pain inhibition, is not consistently impaired across distinct chronic pain disorders. Furthermore, identifying individuals with impaired conditioned pain modulation within a heterogenous sample is difficult. Thus, for conditioned pain modulation to be clinically useful, its variability needs to be better understood.

Neuropilin-1 (NRP1) is a single pass transmembrane glycoprotein that can form a receptor complex with several tyrosine kinase receptors, including the vascular endothelial growth factor (VEGF) receptor. Previous studies have reported that binding of VEGFA to this receptor complex elicits mechanical allodynia and thermal hyperalgesia through potentiation of voltage-gated sodium and calcium channel activity. We find that Nrp1 mRNA and protein is widely distributed in naIve mouse and rat DRG neurons, including peptidergic afferents. A CGRPcreER: NRP1fl/fl transgenic mice was generated to investigate the role of peptidergic NRP1 in basal nociception. Following in vivo loss of NRP1, mice are hyposensitive to both noxious heat and mechanical stimuli. Under normal conditions, VEGFA elicits mechanical hypersensitivity, an effect that was absent in our NRP1 knockout mouse. Furthermore, VEGFA induced neuronal hyperexcitability was lost in CGRP expressing neurons isolated from this NRP1 knockout mouse. This study validates the NRP1 knockout mouse and confirms previous findings that VEGFA, often released during pathological pain conditions, requires peptidergic NRP1. Interestingly, we find that in the absence of ongoing injury or inflammation, peptidergic NRP1 regulates basal nociception and pain-like behaviors. PerspectiveNRP1 is expressed in sensory neurons including the peptidergic subpopulation. Genetic deletion of NRP1 in healthy adults alters nociception without altering innervation; NRP1 knockout mice are hyposensitive to noxious heat and mechanical stimuli, but lose sensitivity to VEGFA, confirming it is a therapeutic target for growth factor mediated pain conditions.

Objective: To quantify the effect size of four biopsychosocial amplifier loops on chronic pain outcomes through systematic review and meta-analysis, and to propose a composite meta-analytic risk index for interventional pain medicine requiring prospective validation. Methods: We searched PubMed/MEDLINE, Scopus, and the Cochrane Library through March 2026 for studies reporting adjusted odds ratios linking (1) sleep disturbance, (2) pain catastrophizing, (3) metabolic/inflammatory markers, and (4) preoperative opioid use/polypharmacy to chronic pain chronification or treatment failure. DerSimonian-Laird random-effects meta-analyses were performed per loop. Publication bias was assessed via Egger's test (k>=8). Effect sizes were integrated into a logistic regression model--the Pain Amplifier Loop Framework (PALF). Neurobiological convergence on TLR4/NF-kB microglial signaling was examined. Results: Forty-four studies (>500,000 participants) were included. Pooled odds ratios: sleep disturbance 1.80 (95% CI 1.65-1.96; k=16; I2=51%), pain catastrophizing 2.11 (1.71-2.61; k=8; I2=0%), metabolic/fat mass 2.02 (1.32-3.09; k=7), preoperative opioid use 4.48 (2.87-6.97; k=6; I2=84%), and opioid-benzodiazepine co-prescription 2.62 (1.76-3.89; k=7; I2=79%). Egger's test showed no significant asymmetry for sleep (p=0.21) or catastrophizing (p=0.84). All loops converge on TLR4/NF-kB microglial signaling. The PALF yields a Systemic Load Score and failure probability P=1/(1+e^-theta), enabling low (<0.30), moderate (0.30-0.60), and high (>=0.60) risk stratification. Conclusions: Four biopsychosocial amplifier loops independently and substantially increase chronic pain risk. The PALF proposes a transparent, hypothesis-driven composite risk index anchored in meta-analytic evidence from >500,000 participants. As a meta-analytic synthesis rather than a fitted prediction model, the PALF requires prospective multicenter validation with individual patient data before clinical application.

Background: Chronic pain affects millions of patients globally and remains therapeutically chal-lenging. While conventional pharmacological approaches have limitations and side effects, pulsed electromagnetic field (PEMF) therapy represents a non-invasive biophysical approach. However, the biological mechanisms underlying PEMF efficacy remain poorly understood. Objective: This study starting from a multi-center post-market surveillance (PMS) data of 81 patients treated with Synth&eacuteXer (a CE-marked Class IIa PEMF device) proposes a mechanistic framework that links ob- served clinical effects to epigenetic modulation via the histone demethylase KDM6B. Materials and Methods: Patients with inflammatory and degenerative disorders causing chronic pain were treated with Synth&eacuteXer across four Italian rehabilitation centers. Pain was assessed using the Numerical Pain Rating Scale (NPRS) before and after treatment. Statistical analysis included descriptive statistics, ANOVA, correlations, and Cohen d effect size. Proposed mechanisms were based on and extrapolated from molecular and biochemical studies demonstrating KDM6B-dependent epigenetic changes in response to specific PEMF sequences. Results: Mean NPRS score decreased significantly from 8.07 {+/-} 1.65 (PRE) to 1.79 {+/-} 1.67 (POST), representing a 6.28-point reduction (p < 0.001; Cohen d = 3.1). Ninety-eight percent of patients showed pain reduction [&ge;] 2 points. No adverse effects were reported. Subset analysis revealed consistent responses across inflammatory (n=19) and degenerative (n=62) pathologies. Discussion: While the observational nature of these data precludes definitive causal attribution, the magnitude of clinical response combined with emerging evidence of KDM6B-mediated epigenetic remodeling suggests a plausible biological basis for PEMF efficacy. Specifically, sequence-depend- ent electromagnetic stimulation may promote the production of and release of anti-inflammatory cytokines and pain resolution through histone demethylation and chromatin remodeling ultimately acting on the expression modulation of such regulatory cytokines. Conclusions: These post-market surveillance data provide clinical evidence of PEMF effects in chronic pain management. The proposed epigenetic mechanism, while requiring further experimental validation and mechanistic confirmation, offers a science-based framework for understanding PEMF biological action and guiding future investigations.

High-impact chronic pain (HICP), defined as persistent pain that substantially limits daily activities, affects millions of adults and poses a public health challenge. Yet relatively little is known about how HICP manifests in people's daily lives. To address this gap, this study used the comprehensive Ecological Momentary Assessment of pain (cEMAp) to assess pain-related experiences four times per day over 7 days in individuals with chronic low back pain. Based on the classification using the Graded Chronic Pain Scale-Revised, we compared individuals with HICP (n = 66) with those in the next most severe pain category, bothersome chronic pain (n = 41), defined as having similar pain frequency but less frequent interference with daily activities. On each prompt, participants completed 2-hour assessments of pain intensity, interference, catastrophizing, behaviors, coping strategies, and pain characteristics. In line with prior research, both groups reported similar pain intensity levels, but the HICP group reported more frequent interference with physical, mental, and social activities. There were no group differences in daily mood or catastrophizing. Exploratory analyses suggested that many daily experiences were similar across groups, with differences observed in selected pain qualities, coping strategies, and pain behaviors. Additional analyses of response distributions showed some similarity across groups in many experiences. Overall, although individuals with HICP on average experience higher pain interference in daily life, levels of many day-to-day experiences are similar between the two groups. Data obtained with cEMAp complement traditional retrospective assessment by providing a detailed view of chronic pain in everyday life.

Objective: To quantify the effect size of four biopsychosocial amplifier loops on chronic pain outcomes through systematic review and meta-analysis, and to develop a logistic regression-based risk stratification tool for interventional pain medicine. Methods: We searched PubMed, Scopus, and Cochrane Library through March 2026 for studies reporting adjusted odds ratios for associations between (1) sleep disturbance, (2) pain catastrophizing, (3) metabolic/inflammatory markers, (4) preoperative opioid use/polypharmacy, and chronic pain chronification or treatment failure. Random-effects meta-analyses (DerSimonian-Laird) were performed for each loop. Effect sizes were translated into a composite logistic regression model, the Pain Amplifier Loop Framework (PALF), using ln(OR) as first-order coefficient approximations. Results: Forty-four studies with over 500,000 participants were included. Pooled odds ratios were: sleep disturbance OR=1.80 (95% CI 1.65-1.96; k=16), pain catastrophizing OR=2.11 (95% CI 1.71-2.61; k=8), metabolic/fat mass OR=2.02 (95% CI 1.32-3.09; k=7), preoperative opioid use OR=4.48 (95% CI 2.87-6.97; k=6), and opioid-benzodiazepine co-prescription OR=2.62 (95% CI 1.76-3.89; k=7). All four loops converge on TLR4/NF-kB microglial signaling. The PALF model produces a probability of interventional failure enabling stratification into low, moderate, and high risk categories. Conclusions: Four amplifier loops independently increase chronic pain risk. The PALF provides a transparent, clinically actionable risk score requiring prospective validation.

Neuropathic pain (NP) affects approximately 60% of individuals with spinal cord injury (SCI). Existing pharmacological treatments provide only modest relief and are often limited by adverse effects, while non-pharmacological options show small effects at best. As such, there remains a need for accessible, mechanism-informed treatments for SCI-NP. This protocol describes a trial evaluating two promising home-based neuromodulatory interventions for SCI-NP - electroencephalography neurofeedback (EEG-NF) and transcranial direct current stimulation (tDCS) - tested both independently and when applied in combination. We will employ a partially double-blinded (i.e. 1 treatment blinded, the other not), 2x2 factorial randomised controlled trial. Adults with chronic SCI-NP (N=192) will be randomised to: (1) EEG-NF + active tDCS, (2) EEG-NF + sham tDCS, (3) active tDCS alone, or (4) sham tDCS alone, in addition to treatment as usual. Participants will complete 20 home-based sessions over 5 weeks. The primary outcome is change in overall pain severity with the primary endpoint being 6 weeks post-randomisation, with secondary endpoints at 16, 26 and 52 weeks post-randomisation. Secondary outcomes (worst pain intensity, pain interference, sleep, depressive symptoms, health-related quality of life) will be assessed at 6 weeks, 16 weeks, 26 weeks and 52 weeks post-randomisation. This will be the first large-scale trial of home-based EEG-NF and tDCS for SCI-NP. If found to be effective, these scalable interventions could be integrated into routine care and inform further optimisation of neuromodulation strategies for managing SCI-NP.

Chronic pain presents a leading challenge in the world today for both clinicians and researchers. Because chronic pain is difficult to explain and treat, it is often managed with opioids despite providing limited relief and contributing to dependence and misuse. Persistent pain can be maintained by altered central nervous system processing even in the absence of distinct tissue damage or disease, which may limit the efficacy of conventional pharmacological therapies that target nociceptive signal transmission rather than maladaptive central nervous system dynamics often present in those with chronic pain. Although neuroimaging studies have identified this shift from nociceptive to emotional circuits during pain chronification, a quantitative framework linking these neural changes to longitudinal pain trajectories or recovery is lacking. We present a parsimonious firing-rate model that can account for the development of and recovery from chronic pain, which is based on the theoretical framework established by Wilson and Cowan. The model provides a quantitative explanation of how sensitization, anxiety, and fear maintain pain even after an injury has healed, and how calming stimulus downregulates these processes to facilitate recovery. A study applying the same principles as the model produced an average pain decrease of 3.5 on the Visual Analog Scale (VAS), with all subjects experiencing a reduction in pain. These results, coupled with our model and findings in prior studies, suggest that increasing calming stimulus can reduce pain without necessitating pharmacological or invasive, resource-intensive interventions.

BackgroundThe transition from acute to chronic pain represents a failure of physiological resolution. While systemic immune cell counts and androgen levels have been associated with this transition, the specific molecular mediators remain poorly understood. We sought to identify the functional proteomic drivers of long-term pain persistence and determine their independence from systemic factors. MethodsWe identified a longitudinal persistence cohort (N=3,221) within the UK Biobank who reported acute pain at baseline and were followed for resolution or persistence. Using the Olink Explore 3072 platform, we screened 2,923 serum proteins. Multivariable competition models were employed to evaluate the independent predictive power of top proteomic hits alongside systemic monocyte counts and circulating free testosterone levels, adjusted for age and sex. ResultsOur proteome-wide screen identified Lactoperoxidase (LPO) as a dominant and highly significant predictor of pain persistence. In the fully adjusted competition model, each standard deviation increase in LPO was associated with a 59% increase in the odds of persistence (OR 1.59, 95% CI 1.25-2.07, p < 0.001). Notably, after accounting for LPO, systemic monocyte counts (OR 0.93, p = 0.55) and testosterone levels (OR 0.82, p = 0.46) were no longer significant predictors. Nogo Receptor (RTN4R) also remained a significant predictor in independent models (OR 1.44, p = 0.002). ConclusionsThese exploratory findings demonstrate that long-term pain persistence is associated with specific functional molecular signatures rather than broad systemic cell quantity. The dominance of LPO suggests that secretory peroxidase-driven pathways may be a primary barrier to pain resolution. Furthermore, the association of RTN4R identifies neural repair inhibition as a candidate driver of persistence. These proteins are candidates for further mechanistic investigation.

Women are disproportionately affected by chronic pain, yet the neural mechanisms underlying sex differences in affective pain processing remain incompletely understood. The bed nucleus of the stria terminalis (BNST), a sexually dimorphic structure implicated in aversion and chronic pain, receives dense input from aversive calcitonin gene-related peptide (CGRP)-expressing neurons arising from the parabrachial nucleus (PBN). Although CGRP signaling has been implicated in sex differences in clinical pain conditions, whether CGRP transmission within the PBN[-&gt;]BNST pathway is sexually dimorphic has not been determined. Here, we tested the hypothesis that CGRP signaling in the BNST differs between sexes. Contrary to our prediction, PBN CGRP neurotransmitter release in the BNST was sex-independent. However, CGRP neuromodulation of BNST excitability exhibited sex-dependent features. While CGRP potentiated PBN[-&gt;]BNST glutamatergic signaling in both sexes, spontaneous inhibitory signaling was selectively increased in males. Together, these findings indicate that sex differences in this circuit arise not from differential peptide release, but from downstream modulation of inhibitory tone, biasing female BNST neurons toward greater excitation. Such circuit-specific sex differences may contribute to the enhanced susceptibility of females to affective components of chronic pain and highlight targets for sex-informed therapeutic interventions.

Despite being essential mediators of pain processing, the molecular identity of N-methyl-D-aspartate receptor (NMDAR) subtypes in nociceptive dorsal horn circuits is poorly understood, especially between sexes and in humans. Given the importance of GluN2 subunits in shaping NMDAR function and plasticity, we investigated the expression and localization of specific GluN2 NMDAR variants in the dorsal horn of viable spinal cord tissue from male and female rodents and human organ donors. Analysis of single-cell/nuclei sequencing datasets and quantitative reverse transcriptase polymerase chain reactions (qRT-PCR) revealed that the GluN2A (GRIN2A) and GluN2B (GRIN2B) subunits are robustly expressed in dorsal horn neurons of mice, rats and humans, with moderate expression of GluN2D (GRIN2D). Immunohistochemistry (IHC) with antigen retrieval demonstrated that GluN2A, GluN2B, and GluN2D proteins are all preferentially localized to the superficial dorsal horn of both adult rats and humans, which is conserved between males and females. Surprisingly, we found that these GluN2 NMDAR subunits are enriched in the lateral superficial dorsal horn in rats but not in humans, while presynaptic and neuronal markers are symmetrically distributed across the rat mediolateral axis. A dramatic shift in localization of GluN2A to the lateral superficial dorsal horn was observed across later postnatal development (PD21-PD90) in both male and female rats, with a corresponding change in synaptic NMDAR currents. This discovery of changes in NMDAR subunit distribution during maturation and between species will shed light on the physiological roles of NMDARs and their potential as therapeutic targets for pain. SIGNIFICANCE STATEMENTWe used complementary single-cell/nuclei analysis, immunostaining, quantitative reverse transcriptase polymerase chain reactions, RNAscope in situ hybridization, and electrophysiological approaches to compare the relative expression of N-methyl-D-aspartate receptor (NMDAR) GluN2 subunits in dorsal horn spinal cord pain circuits of mouse, rat, and human spinal cord tissue. Through these comparisons, we find that the transcripts and proteins of the GluN2A, GluN2B, and GluN2D NMDAR subunits are robustly expressed in superficial dorsal horn neurons, with conserved expression across sex but important differences in expression and localization patterns across late development and between species. These discoveries shed light on the physiological roles of NMDARs and their utility as potential therapeutic targets for pain.

Background Chronic pain is associated with structural and functional brain alterations, particularly within prefrontal, insular, and cingulate cortices. The dorsolateral prefrontal cortex (DLPFC) shows consistent structural abnormalities across chronic pain conditions, whereas findings on intrinsic functional connectivity (FC) remains inconsistent. Anchoring FC analyses to structural alterations may help identify consistent patterns across chronic pain conditions. Methods We employed a voxel-based morphometry (VBM)-guided, seed-based resting-state FC approach. Structural and functional MRI data were obtained from patients with chronic neck pain (CNP; n=21) and healthy controls (HC; n=25). Regions showing significant gray matter volume (GMV) differences were used as seeds for whole-brain FC analysis. Associations with pain intensity and pain-related fear were examined. Findings were further evaluated in an independent cohort with chronic primary pain (CPP; n=38). Results VBM revealed reduced GMV in the left DLPFC in CNP compared with HC, replicated in CPP. Seed-based FC analysis demonstrated reduced connectivity between the left DLPFC and the right hippocampus in CNP, with a similar pattern in CPP. In CNP, GMV in the DLPFC was positively associated with DLPFC-hippocampal connectivity (r = 0.45, 95% CI 0.02 to 0.74, p = 0.043). Reduced DLPFC-hippocampal connectivity was associated with higher activity avoidance (r = -0.50, 95% CI -0.77 to -0.09, p = 0.021), whereas no associations were observed with pain intensity. Conclusions These findings indicate consistent structural and functional alterations across chronic pain cohorts. Reduced DLPFC-hippocampal connectivity may reflect altered interactions between prefrontal and hippocampal circuits involved in pain-related cognitive and affective processes.

Inflammatory bowel disease (IBD) is characterised by chronic pain, a debilitating symptom for which effective treatments are few and far between. IBD pathogenesis includes the prevalence of a variety of pro-inflammatory cytokines, including the Interleukin-6 (IL-6) family members Il-6 and Oncostatin M (OSM). Previous research has shown disruption of OSM signaling can modulate nociceptor sensitization and activation, however the downstream signalling pathway is unknown. When an in silico analysis of murine colonic sensory neuronal populations was undertaken for receptor expression for OSM and other factors necessary for intracellular signaling, we can find diverse expression indicative of functional signaling. We were able to observe that hyper Il-6 (Il-6 bound to the soluble Il-6 receptor) and OSM can elicit activation of a subset of murine sensory neurons by finding an increase in calcium mobilization following superfusion. This could then be attenuated by the pharmacologic inhibition of all janus kinases or interestingly, TYK2 alone. Furthermore, inhibition of transient receptor potential vanilloid 1 or transient receptor potential ankyrin 1 ion channels, which are known to be sensitized by OSM in other sensory neurons also reduced the proportion of OSM-responsive neurons. This further understanding of OSM signaling in sensory neurons creates avenues for more extensive research into the molecular mechanisms occurring as well as the potential to exploit these therapeutically to induce analgesia in a subset of neurons.

Cognitive dysfunction is increasingly recognized as an important feature of chronic pain (CP). However, subjective cognitive complaints and objectively measured cognitive performance frequently diverge. Whether and how these two aspects of cognitive functioning differentially relate to the broad symptomatology and brain function in CP remains unclear. Here, 114 individuals with CP completed patient-reported outcome measures on cognitive functioning and multidimensional CP symptoms, as well as a visuospatial working memory task, and resting-state EEG. Bayesian correlations, network analyses, and Bayesian regression models examined how subjective and objective cognitive functioning relate to multidimensional CP symptoms and EEG activity/connectivity, while controlling for age and sex. Additional models tested whether EEG associations were independent of broader symptom burden. Results indicated that subjective and objective cognitive functioning were uncorrelated. Subjective cognitive functioning was strongly associated with psychosocial symptoms, whereas objective cognitive functioning was largely independent of broader symptom burden. EEG revealed associations between subjective cognitive functioning and bilateral frontotemporal beta connectivity; however, these relationships were substantially attenuated after accounting for broader CP symptom burden. Objective cognitive functioning showed no robust associations with EEG. These findings indicate a dissociation between subjective cognitive complaints and objective cognitive performance in CP. Subjective cognitive complaints were primarily associated with psychosocial symptom burden and beta-band hypoconnectivity. In contrast, objective cognitive performance was unrelated to the broader symptomatology of CP and EEG measures. This dissociation may inform more targeted interventions, optimize the allocation of cognitive assessment resources, and ultimately improve long-term functional outcomes in CP.

Objective: To evaluate whether glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are associated with improvements in pain severity, disability, quality of life, and physical function in adults with obesity and chronic low back pain (cLBP), and to explore potential mechanisms. Design: Prospective, single-arm cohort study. Subjects: Thirty-five adults (median age 41 years; 86% women) with obesity (median BMI 39.9 kg/m2) and cLBP initiating GLP-1 RAs (tirzepatide, n=24; semaglutide, n=11). Methods: Participants completed questionnaires at baseline, 3, 6, 9, and 12 months. The primary outcome was Brief Pain Inventory-Short Form (BPI-SF) pain severity. Secondary outcomes included body mass index (BMI), BPI-SF pain interference, Numerical Rating Scale (NRS) back pain, Oswestry Disability Index (ODI), and Short Form-12 (SF-12). At baseline and 6 months, a subset (n=24) underwent quantitative sensory testing, physical performance testing, and blood draws for inflammatory biomarkers (C-reactive protein, TNF-, IL-6, IL-10), adipokines (leptin, adiponectin), and hemoglobin A1c. Results: Over 12 months, BMI decreased by 12.5% (median 39.9 to 34.9 kg/m2, 95% CI [-6.6, -4.2]). BPI-SF pain severity improved (median 4.8 to 2.0, 95% CI [-2.1, -0.8]), as did pain interference, ODI, NRS back pain, and SF-12 physical component scores. Hemoglobin A1c, leptin, and C-reactive protein decreased. Adiponectin increased and physical performance improved, but neither reached significance. Experimental pain sensitivity was unchanged. Conclusions: GLP-1 RAs were associated with clinically meaningful improvements in pain, disability, and quality of life. These findings suggest GLP-1 RAs may be a promising nonsurgical therapy for cLBP; randomized controlled trials are needed to establish causality and mechanisms.

Pain is commonly described in sensory terms, yet its spatial characteristics-localization and distribution-are rarely quantified. We investigated whether lay beliefs about pain distribution (PD) influence theoretical decisions to seek care and treatment preferences. In a representative cross-sectional survey (N=503; 49% with pain), participants completed thought experiments in which both visually presented PD patterns (small, moderate or large) and pain intensity (NRS 2, 5, 8/10) were systemically varied. For each scenario, they rated the likelihood of (i) seeking professional help (LoSH) and (ii) taking analgesic medication (LoTM). Participants also completed a spatial-intensity trade-off task (SITT), in which they chose between a fixed 20% reduction in intensity and variable reductions in PD (20-80%). A reversed version contrasted a fixed 80% reduction in PD with variable reductions in pain intensity. LoSH and LoTM increased significantly with greater PD (p<0.001), mirroring the gradient observed for pain intensity. In the SITT, participants' choice followed a sigmoid-like function (p<0.001): 1% reduction in intensity was treated as equivalent to approximately a 3% reduction in distribution, indicating a systematic valuation of PD. This ratio was lower in individuals experiencing pain compared to pain-free individuals. Moreover, 63% reported that PD should be routinely considered in pain management alongside intensity. Results suggest that PD is not merely a trivial descriptor, but a meaningful determinant of healthcare-related decision-making beliefs. Incorporating spatial metrics into clinical assessment and research may better capture how individuals implicitly evaluate pain severity.

Chronic pain is often accompanied by cognitive complaints, but evidence for global working memory problems is mixed. We tested whether working memory performance differences in chronic pain are global or task-specific and whether model-based analysis could help distinguish differences in processing efficiency, response caution or sensory/motor speed. In a preregistered online case-control study, 99 adults with mixed chronic pain conditions and 87 pain-free controls completed visuo-verbal, visuo-spatial and auditory-temporal n-back tasks at low (0/1-back) and high (2-back) load. Accuracy and reaction times were analysed with mixed effects models. Drift diffusion modelling decomposed performance into processing efficiency (drift rate), response caution (threshold separation) and non-decision (sensory/motor) time. Higher load reduced accuracy and slowed responses in both groups. There was no evidence of a global working-memory deficit in the chronic pain group. The clearest group difference was a larger load-related drop in accuracy in the auditory-temporal task (odds ratio 0.64, 95% CI 0.56 to 0.73), persisting after adjustment for mood, sleep and fatigue. Load-related slowing in visuo-verbal (6.7% slower, 5.1% to 8.2%) and auditory-temporal tasks (3.6% slower, 1.7% to 5.4%) were attenuated after adjustment. Diffusion modelling showed no evidence for sensory/motor slowing, but rather greater response caution in the auditory-temporal task and small efficiency (drift rate) reductions in low-load visual conditions. The results do not support a global working-memory capacity loss account in this mixed chronic pain sample. Rather, they suggest task-specific performance differences, most evident in auditory-temporal processing, with response caution as a plausible contributor.

Background. A substantial minority (~20%) of patients fail to achieve meaningful pain reduction following surgery intended to relieve pain. Risk is elevated in patients with nociplastic pain features, but available self-report measures were not designed for pre-surgical screening. We aimed to develop a brief, data- driven screener for poor analgesic response to surgery. Methods. Participants were recruited from tertiary orthopedic and chronic pelvic pain clinics. Total hip arthroplasty participants had Kellgren-Lawrence grades III-IV with hip pain greater than or equal to 1 year; hysterectomy participants had chronic pelvic pain greater than or equal to 6 months. The primary outcome was a 50% reduction in worst pain at six months. Items were selected via elastic net regression with k-fold cross-validation from 68 candidates. Results. Of 428 participants (81% female; mean age 51), 35% failed to achieve a 50% pain reduction. The resulting 11-item screener - the GenerAlized sensory sensitivity for sUrGical rEsponsiveness (GAUGE) - comprises pain across seven body regions and four symptom items measuring interoception (nausea, numbness/tingling) and exteroception (sensitivity to sound, sensitivity to odors). GAUGE outperformed the Central Sensitization Inventory, Fibromyalgia Survey Criteria, and PainDETECT for predicting surgical non-response (RR 1.535, 95% CI 1.342-1.55; AUC 0.738; sensitivity 0.741, specificity 0.635) and for predicting Patient Global Impression of Change. In an independent validation cohort of 54 total knee arthroplasty patients, GAUGE outperformed the Fibromyalgia Survey Criteria in predicting pain severity at six-months. Conclusions. GAUGE is a data-driven, theoretically grounded screener for poor analgesic response to surgery, with potential utility for pre-surgical counseling and clinical trial enrichment.

Purpose: To evaluate the efficacy and safety of oral L-ergothioneine (EGT) in alleviating pain and associated symptoms in women with primary dysmenorrhea (PD). Methods: In this randomized, double-blind, placebo-controlled trial, 40 women with PD (aged 18-30 years) were randomized (1:1) to receive EGT capsules (120 mg/day) or a matching placebo for 3 consecutive menstrual cycles. Outcomes evaluated at baseline and post-cycle included peak pain (Visual Analog Scale, VAS), Dysmenorrhea Symptom Score, and the COX Menstrual Symptom Scale (CMSS). Results: EGT significantly improved PD symptoms over 3 cycles. Mean VAS for peak pain decreased from 4.80 {+/-} 1.12 to 2.32 {+/-} 1.59 in the EGT group (p < 0.001), compared to a non-significant reduction (4.10 {+/-} 1.30 to 3.45 {+/-} 1.69) in the placebo group. The between-group difference at cycle 3 was significant (p < 0.01). A linear mixed-model confirmed a significant Time x Group interaction (p < 0.001), showing an accelerated decline in symptom severity for EGT. Furthermore, 84% of EGT-treated patients achieved [&ge;]50% VAS reduction versus 35% in the placebo group (p = 0.003). Serum inflammatory biomarkers showed no significant between-group differences or correlation with VAS improvements, suggesting EGT's analgesic effects likely operate via cytoprotective pathways independent of classical inflammatory cascades. No adverse events were reported. Conclusion: Oral EGT supplementation (120 mg/day) effectively and progressively mitigates menstrual pain and systemic symptoms in PD, offering a well-tolerated, non-pharmacological intervention. Trial Registration: ChiCTR2500112557; Retrospectively registered on 2025-11-17.