Executive function in chronic pain patients and healthy controls: different cortical activation during response inhibition in fibromyalgia

The neurological effects of acute physical exhaustion on inhibitory function

OBJECTIVE

We aimed to investigate the neural mechanisms underlying the inhibitory function performance of maritime Search and Rescue (SAR) personnel in states of physical exhaustion.

BACKGROUND

SAR missions pose serious challenges to the cognitive function of SAR personnel, especially in extreme environments and physical exhaustion. It is important to understand SAR personnel's cognitive performance and neural activity under exhaustion to improve the efficiency of task execution and ensure work safety.

METHOD

Twenty-six maritime SAR personnel were recruited to simulate boat operations until they reached a self-imposed state of exhaustion. The exhaustion state was monitored by maximum heart rate and subjective fatigue scale. Two event-related potentials, N200 and P300, were measured during a Go-Nogo task before and after a session of acute exhaustive tasks.

RESULTS

After exhaustion, a marked reduction in accuracy, a notable increase in N200 amplitude, and a substantial decline in P300 amplitude under the Nogo condition were observed compared to the baseline phase. Pre- and post-exhaustion comparisons using standardized low-resolution brain electromagnetic tomography revealed reduced activations in the right middle temporal gyrus's N200 component after exhaustion in SAR personnel during the Nogo condition.

CONCLUSION

The results suggest that acute physical exhaustion significantly impacts the inhibition ability of SAR personnel, prolonging the conflict monitoring phase and weakening the response inhibition phase. These findings provide valuable insights into how physical exhaustion affects cognitive functions critical to the safety and effectiveness of SAR operations, and can inform strategies to improve training and equipment to enhance performance under extreme conditions.

Relation Between Abnormal Spontaneous Brain Activity and Altered Neuromuscular Activation of Lumbar Paraspinal Muscles in Chronic Low Back

OBJECTIVE

To investigate the neural mechanism underlying functional reorganization and motor coordination strategies in patients with chronic low back pain (cLBP).

DESIGN

A case-control study based on data collected during routine clinical practice.

SETTING

This study was conducted at a university hospital.

PARTICIPANTS

Fifteen patients with cLBP and 15 healthy controls.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Whole brain blood oxygen level-dependent signals were measured using functional magnetic resonance imaging and amplitude of low-frequency fluctuation (ALFF) method to identify pain-induced changes in regional spontaneous brain activity. A novel approach based on the surface electromyogram (EMG) system and fine-wire electrodes was used to record EMG signals in the deep multifidus, superficial multifidus, and erector spinae.

RESULTS

In cLBP, compared with healthy groups, ALFF was higher in the medial prefrontal, primary somatosensory, primary motor, and inferior temporal cortices, whereas it was lower in the cerebellum and anterior cingulate and posterior cingulate cortices. Furthermore, the decrease in the average EMG activity of the 3 lumbar muscles in the cLBP group was positively correlated with the ALFF values of the primary somatosensory cortex, motor cortex, precuneus, and middle temporal cortex but significantly negatively correlated with the ALFF values of the medial prefrontal and inferior temporal cortices. Interestingly, the correlation between the functional activity in the cerebellum and the EMG activity varied in the lumbar muscles.

CONCLUSIONS

These findings suggest a functional association between changes in spontaneous brain activity and altered voluntary neuromuscular activation patterns of the lumbar paraspinal muscles, providing new insights into the mechanisms underlying pain chronicity as well as important implications for developing novel therapeutic targets of cLBP.

Aberrant cerebral blood flow and functional connectivity in patients with vestibular migraine: a resting-state ASL and fMRI study

BACKGROUND

Prior neuroimaging studies on vestibular migraine (VM) have extensively certified the functional and structural alterations in multiple brain regions and networks. However, few studies have assessed the cerebral blood flow (CBF) in VM patients using arterial spin labeling (ASL). The present study aimed to investigate CBF and functional connectivity (FC) alterations in VM patients during interictal periods.

METHODS

We evaluated 52 VM patients and 46 healthy controls (HC) who received resting-state pseudo-continuous ASL and functional magnetic resonance imaging (fMRI) scanning. Comparisons of voxel-based CBF and seed-based FC were performed between the two groups. Brain regions showed significant group differences in CBF analyses were chosen as seeds in FC analyses. Additionally, the associations between abnormal imaging results and clinical features were explored.

RESULTS

Compared with HC, VM patients showed higher normalized CBF in the right precentral gyrus (PreCG), left postcentral gyrus (PostCG), left superior frontal gyrus and bilateral insular (p < 0.05, FDR corrected). Furthermore, VM patients exhibited increased FC between the right PreCG and areas of the left PostCG, left cuneus and right lingual gyrus (p < 0.05, FDR corrected). In addition, we observed decreased FC between the left insular and regions of the left thalamus and right anterior cingulate cortex, as well as increased FC between the left insular and right fusiform gyrus in VM patients (p < 0.05, FDR corrected). Moreover, these variations in brain perfusion and FC were significantly correlated with multiple clinical features including frequency of migraine symptoms, frequency of vestibular symptoms and disease duration of VM (all p < 0.05).

CONCLUSIONS

Patients with VM during interictal period showed hyperperfusion and abnormal resting-state FC in brain regions potentially contributed to disrupted multi-sensory and autonomic processing, as well as impaired ocular motor control, pain modulation and emotional regulation. Our study provided novel insights into the complex neuropathology of VM from a CBF perspective.

Executive Function as a Predictor of Pain Perception in Healthy Young Adults

OBJECTIVE

Pain's impact on executive function is understood and specific cognitive abilities may contribute to coping with pain, though past work is confounded by chronic pain populations. This study aims to understand how executive functioning may predict the experience of pain among healthy adults. It was hypothesized that poorer executive functioning would predict more intense pain perception.

METHOD

A total of 172 young adults were recruited for participation. Three aspects of executive functioning (i.e., impulsivity, cognitive flexibility, working memory) were assessed before randomizing participants to varying types and levels of stimulated pain.

RESULTS

Results supported the hypothesis that poorer performance on tasks of working memory predicts more intense pain perception.

CONCLUSIONS

Findings are counter to past work that has found inhibition may be important for coping, and future research is needed to understand the impact of specific cognitive abilities as well as how this may differ for chronic pain.

Lived Experiences of Cognitive Dysfunction in Fibromyalgia: How Patients Discuss Their Experiences and Suggestions for Patient Education

Cognitive dysfunction (CD) is a common, impairing symptom experienced by persons with fibromyalgia (FM). This study explored how individuals with FM describe their experience of CD in an online peer support environment. Posts referencing cognitive symptoms were extracted from two Facebook FM peer support groups at two timepoints. Using inductive Thematic Analysis, key discussion themes were identified and compared across groups and time. Four themes represented the way members described their cognitive experiences in FM: understanding and describing CD experiences, distrust of cognitive abilities, choosing between pain and medication side effects, and misunderstanding and judgement from others. Two themes represented the impact of CD on members' lives: impaired social interaction and loss of identity. Group members described broad impairments in daily functioning that significantly and negatively impacted their quality of life, indicating CD symptoms may play a more prominent role in the FM experience than previously understood. An infographic is included to aid patient education and help facilitate patient-provider discussions of CD symptoms.

Modulation of temporal and occipital cortex by acupuncture in non-menstrual MWoA patients: a rest BOLD fMRI study

OBJECTIVE

To investigate the changes in amplitude of low-frequency fluctuation (ALFF) and degree centrality (DC) values before and after acupuncture in young women with non-menstrual migraine without aura (MWoA) through rest blood-oxygen-level-dependent functional magnetic resonance imaging (BOLD fMRI).

METHODS

Patients with non-menstrual MWoA (Group 1, n = 50) and healthy controls (Group 2, n = 50) were recruited. fMRI was performed in Group 1 at 2 time points: before acupuncture (time point 1, TP1); and after the end of all acupuncture sessions (time point 2, TP2), and performed in Group 2 as a one-time scan. Patients in Group 1 were assessed with the Migraine Disability Assessment Questionnaire (MIDAS) and the Short-Form McGill Pain Questionnaire (SF-MPQ) at TP1 and TP2 after fMRI was performed. The ALFF and DC values were compared within Group 1 at two time points and between Group 1 and Group2. The correlation between ALFF and DC values with the statistical differences and the clinical scales scores were analyzed.

RESULTS

Brain activities increased in the left fusiform gyrus and right angular gyrus, left middle occipital gyrus, and bilateral prefrontal cortex and decreased in left inferior parietal lobule in Group 1, which had different ALFF values compared with Group 2 at TP1. The bilateral fusiform gyrus, bilateral inferior temporal gyrus and right middle temporal gyrus increased and right angular gyrus, right superior marginal gyrus, right inferior parietal lobule, right middle occipital gyrus, right superior frontal gyrus, right middle frontal gyrus, right anterior central gyrus, and right supplementary motor area decreased in activity in Group 1 had different DC values compared with Group 2 at TP1. ALFF and DC values of right inferior temporal gyrus, right fusiform gyrus and right middle temporal gyrus were decreased in Group1 at TP1 compared with TP2. ALFF values in the left middle occipital area were positively correlated with the pain degree at TP1 in Group1 (correlation coefficient r, r = 0.827, r = 0.343; P < 0.01, P = 0.015). The DC values of the right inferior temporal area were positively correlated with the pain degree at TP1 in Group 1 (r = 0.371; P = 0.008).

CONCLUSION

Spontaneous brain activity and network changes in young women with non-menstrual MwoA were altered by acupuncture. The right temporal area may be an important target for acupuncture modulated brain function in young women with non-menstrual MwoA.

Topological alterations in white matter structural networks in fibromyalgia

PURPOSE

Neuroimaging studies employing analyses dependent on regional assumptions and specific neuronal circuits could miss characteristics of whole-brain structural connectivity critical to the pathophysiology of fibromyalgia (FM). This study applied the whole-brain graph-theoretical approach to identify whole-brain structural connectivity disturbances in FM.

METHODS

This cross-sectional study used probabilistic diffusion tractography and graph theory analysis to evaluate the topological organization of brain white matter networks in 20 patients with FM and 20 healthy controls (HCs). The relationship between brain network metrics and clinical variables was evaluated.

RESULTS

Compared with HCs, FM patients had lower clustering coefficient, local efficiency, hierarchy, synchronization, and higher normalized characteristic path length. Regionally, patients demonstrated a significant reduction in nodal efficiency and centrality; these regions were mainly located in the prefrontal, temporal cortex, and basal ganglia. The network-based statistical analysis (NBS) identified decreased structural connectivity in a subnetwork of prefrontal cortex, basal ganglia, and thalamus in FM. There was no correlation between network metrics and clinical variables (false discovery rate corrected).

CONCLUSIONS

The current research demonstrated disrupted topological architecture of white matter networks in FM. Our results suggested compromised neural integration and segregation and reduced structural connectivity in FM.

Projections from anteromedial thalamus nucleus to the midcingulate cortex mediate pain and anxiety-like behaviors in mice

Prior research has demonstrated the involvement of the midcingulate cortex (MCC) and its downstream pathway in pain regulation. However, the mechanism via which pain information is conveyed to the MCC remains unclear. The present study utilized immunohistochemistry, chemogenetics, optogenetics, and behavior detection methods to explore the involvement of MCC, anteromedial thalamus nucleus (AM), and AM-MCC pathway in pain and emotional regulation. Chemogenetics or optogenetics methods were employed to activate/inhibit MCCCaMKIIα, AMCaMKIIα, AMCaMKIIα-MCC pathway. This manipulation evokes/relieves mechanical and partial heat hyperalgesia, as well as anxiety-like behaviors. In the complete Freund,s adjuvant (CFA) inflammatory pain model, chemogenetic inhibition of the AMCaMKIIα-MCCCaMKIIα pathway contributed to pain relief. Notably, this study presented the first evidence implicating the AM in the regulation of nociception and negative emotions. Additionally, it was observed that the MCC primarily receives projections from the AM, highlighting the crucial role of this pathway in the transmission of pain and emotional information.

Inhibition and Heart Rate Variability in Experimentally Induced Pain

Introduction

Pain is a complex experience that requires executive functions (EFs) to be processed. The autonomic outcome of the neural networks involved in the cognitive evaluation of pain is reflected by heart rate variability (HRV), an index of self-regulation abilities. Although some results suggest a relationship between HRV, EFs, and pain, studies focusing on this three-way relationship are still scarce.

Objective

This study aims to investigate the relationship between pain, cognitive, and autonomic mechanisms, hypothesizing an association between resting HRV and both cognitive and motor inhibition as indices of executive functioning. This relationship was investigated after an experimental-induced pain.

Methods

Seventy-six young adults were exposed to the Cold Pressure Arm Warp to induce experimental pain. HRV was collected, and cognitive tasks were administered to assess executive performance.

Results

The results showed that (1) HRV indices significantly increased during pain stimulation, (2) cognitive inhibition was positively correlated with vagal indices and with pain parameters, (3) both inhibition tasks significantly predicted pain threshold while the performance on the Stroop Task predicted pain tolerance.

Conclusion

Results suggest a three-way relationship. Further research would focus on the role of HRV and cognitive strategies in pain management in chronic pain conditions.

Regional homogeneity alterations of resting-state functional magnetic resonance imaging of chronic rhinosinusitis with olfactory dysfunction

Objectives

The aim of this study was to assess the brain functional changes of patients with chronic rhinosinusitis with olfactory dysfunction (CRSwOD) using regional homogeneity (ReHo) of resting-state functional magnetic resonance imaging (MRI) scans, and to better explain the occurrence and development of olfactory decline in patients with chronic sinusitis provides a new idea for the study of more advanced olfactory therapy modalities.

Methods

A total of 28 CRSwOD patients, 24 patients with CRS without olfactory dysfunction (CRSsOD), and 25 healthy controls (HCs) were recruited. All subjects underwent olfactory testing, clinical and brief psychological assessments, and MRI scans. A two-sided two-sample t test with AlphaSim correction (voxel-p < 0.001, cluster size >54 voxels) was used to detect differences between CRSwOD, CRSsOD, and HC groups.

Results

Compared with HCs, the ReHo values in traditional olfactory regions (e.g., parahippocampal gyrus (PHG), hippocampal, olfactory cortex) were increased, and ReHo values in the frontal gyrus, middle temporal gyrus, precuneus, and posterior cingulate gyrus were decreased in CRSwOD patients. The ReHo values in the precuneus and posterior cingulate gyrus of CRSwOD patients were negatively correlated with Questionnaire of Olfactory Disorders-Negative Statements (QOD-NS) scores. Compared with CRSsOD patients, the ReHo values in cerebellar regions were increased and those in the inferior temporal gyrus, precuneus, postcentral, and paracentral gyrus were decreased in CRSwOD patients. The receiver operating characteristic (ROC) curve showed that the mean ReHo values significantly differed between the CRSwOD and CRSsOD groups.

Conclusion

Synchronization of regional brain activity in the regions of the secondary olfactory cortex orbitofrontal cortex (OFC), temporal gyrus, precuneus, and cerebellum may be closely related to the development of olfactory dysfunction. Precuneus and posterior cingulate gyrus may be critical brain areas of action for emotional dysfunction in CRSwOD patients.

Understanding the Experience and Impacts of Brain Fog in Chronic Pain: A Scoping Review

Introduction

Approximately 15% to 40% of persons with chronic pain as a primary disorder experience brain fog. Prior research has investigated the etiology of "brain fog" in conditions in which pain presents as a key feature (e.g., fibromyalgia). However, it remains understudied in the context of chronic 10 musculoskeletal pain. Following current scoping review guidelines, we obtained stakeholder input from patient and health care professionals (HCPs) to define this phenomenon. Specific aims of this review were to (1) identify factors contributing to brain fog, (2) identify the functional correlates of brain fog and assessments used to measure them, and (3) establish a definition of brain fog that can be employed by researchers and HCPs to advance research and care.

Methods

A scoping review was conducted using recommendations of the Joanna Briggs Institute methodology of scoping reviews and the Levac et al methodology. Embase, Cinahl, PsycINFO, and Medline was searched to identify relevant sources. Findings were verified with patient and healthcare professionals.

Results

We identified four 15 key features of brain fog: perceived variability, subjective cognitive dysfunction, participation limitations, and changes in functional activities. We developed a model of brain fog illustrating the overlapping categories of contributors to brain fog in chronic musculoskeletal pain: (1) neuroanatomical and neurophysiological, (2) mental health/emotional, and (3) environmental/lifestyle.

Conclusion

The results of this scoping review conclude that the inconsistency in research regarding brain fog in 20 chronic musculoskeletal pain is obstructing a clear understanding of the phenomenon and therefore may be impeding persons with chronic pain and brain fog from receiving optimal care.

Altered functional brain network patterns in patients with migraine without aura after transcutaneous auricular vagus nerve stimulation

Transcutaneous auricular vagus nerve stimulation (taVNS) shows excellent effects on relieving clinical symptoms in migraine patients. Nevertheless, the neurological mechanisms of taVNS for migraineurs remain unclear. In recent years, voxel-wise degree centrality (DC) and functional connectivity (FC) methods were extensively utilized for exploring alterations in patterns of FC in the resting-state brain. In the present study, thirty-five migraine patients without aura and thirty-eight healthy controls (HCs) were recruited for magnetic resonance imaging scans. Firstly, this study used voxel-wise DC analysis to explore brain regions where abnormalities were present in migraine patients. Secondly, for elucidating neurological mechanisms underlying taVNS in migraine, seed-based resting-state functional connectivity analysis was employed to the taVNS treatment group. Finally, correlation analysis was performed to explore the relationship between alterations in neurological mechanisms and clinical symptoms. Our findings indicated that migraineurs have lower DC values in the inferior temporal gyrus (ITG) and paracentral lobule than in healthy controls (HCs). In addition, migraineurs have higher DC values in the cerebellar lobule VIII and the fusiform gyrus than HCs. Moreover, after taVNS treatment (post-taVNS), patients displayed increased FC between the ITG with the inferior parietal lobule (IPL), orbitofrontal gyrus, angular gyrus, and posterior cingulate gyrus than before taVNS treatment (pre-taVNS). Besides, the post-taVNS patients showed decreased FC between the cerebellar lobule VIII with the supplementary motor area and postcentral gyrus compared with the pre-taVNS patients. The changed FC of ITG-IPL was significantly related to changes in headache intensity. Our study suggested that migraine patients without aura have altered brain connectivity patterns in several hub regions involving multisensory integration, pain perception, and cognitive function. More importantly, taVNS modulated the default mode network and the vestibular cortical network related to the dysfunctions in migraineurs. This paper provides a new perspective on the potential neurological mechanisms and therapeutic targets of taVNS for treating migraine.

Neurophysiological and Psychosocial Mechanisms of Fibromyalgia: A Comprehensive Review and Call for An Integrative Model

Research into the neurobiological and psychosocial mechanisms involved in fibromyalgia has progressed remarkably in recent years. Despite this, current accounts of fibromyalgia fail to capture the complex, dynamic, and mutual crosstalk between neurophysiological and psychosocial domains. We conducted a comprehensive review of the existing literature in order to: a) synthesize current knowledge on fibromyalgia; b) explore and highlight multi-level links and pathways between different systems; and c) build bridges connecting disparate perspectives. An extensive panel of international experts in neurophysiological and psychosocial aspects of fibromyalgia discussed the collected evidence and progressively refined and conceptualized its interpretation. This work constitutes an essential step towards the development of a model capable of integrating the main factors implicated in fibromyalgia into a single, unified construct which appears indispensable to foster the understanding, assessment, and intervention for fibromyalgia.

Mapping the aberrant brain functional connectivity in new daily persistent headache: a resting-state functional magnetic resonance imaging study

BACKGROUND AND PURPOSE

The pathogenesis of new daily persistent headache (NDPH) is not fully understood. We aim to map aberrant functional connectivity (FC) in patients with NDPH using resting-state functional magnetic resonance imaging (MRI).

METHODS

Brain structural and functional MRI data were acquired from 29 patients with NDPH and 37 well-matched healthy controls (HCs) in this cross-sectional study. Region of interest (ROI) based analysis was used to compare FC between patients and HCs, with 116 brain regions in the automated anatomical labeling (AAL) atlas were defined as seeds. The correlations between aberrant FC and patients' clinical characteristics, and neuropsychological evaluation were also investigated.

RESULTS

Compared with HCs, patients with NDPH showed increased FC in the left inferior occipital gyrus, right thalamus and decreased FC in right lingual gyrus, left superior occipital gyrus, right middle occipital gyrus, left inferior occipital gyrus, right inferior occipital gyrus, right fusiform gyrus, left postcentral gyrus, right postcentral gyrus, right thalamus and right superior temporal gyrus. There were no correlation between FC of these brain regions and clinical characteristics, neuropsychological evaluation after Bonferroni correction (p > 0.05/266).

CONCLUSIONS

Patients with NDPH showed aberrant FC in multiple brain regions involved in perception and regulation of emotion and pain.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05334927.

Altered social decision making in patients with chronic pain

BACKGROUND

Chronic pain affects up to 20% of the population, impairs quality of life and reduces social participation. Previous research reported that pain-related perceived injustice covaries with these negative consequences. The current study probed whether chronic pain patients responded more strongly to disadvantageous social inequity than healthy individuals.

METHODS

We administered the Ultimatum Game, a neuroeconomic social exchange game, where a sum of money is split between two players to a large sample of patients with chronic pain disorder with somatic and psychological factors (n = 102) and healthy controls (n = 101). Anonymised, and in truth experimentally controlled, co-players proposed a split, and our participants either accepted or rejected these offers.

RESULTS

Chronic pain patients were hypersensitive to disadvantageous inequity and punished their co-players for proposed unequal splits more often than healthy controls. Furthermore, this systematic shift in social decision making was independent of patients' performance on tests of executive functions and risk-sensitive (non-social) decision making .

CONCLUSIONS

Our findings indicate that chronic pain is associated with anomalies in social decision making (compared to healthy controls) and hypersensitivity to social inequity that is likely to negatively impact social partaking and thereby the quality of life.

Alterations of degree centrality and functional connectivity in classic trigeminal neuralgia

Objectives

Recent neuroimaging studies have indicated a wide range of structural and regional functional alterations in patients with classic trigeminal neuralgia (CTN). However, few studies have focused on the intrinsic functional characteristics of network organization in the whole brain. Therefore, the present study aimed to characterize the potential intrinsic dysconnectivity pattern of the whole brain functional networks at the voxel level using the degree centrality (DC) analysis in CTN patients.

Methods

Thirty-four patients with CTN and twenty-nine well-matched healthy controls (HCs) participated in this study. All subjects underwent resting-state functional magnetic resonance imaging (rs-MRI) examination and clinical and neuropsychologic assessments. DC is a graph theory-based measurement that represents the overall functional connectivity (FC) numbers between one voxel and other brain voxels. We first investigated brain regions exhibiting abnormal DC, and further identified their perturbation on FC with other brain regions using a seed-based FC analysis in patients with CTN. In addition, correlation analyses were performed to evaluate the relationship between the abnormal DC value and clinical variables in CTN patients.

Results

Compared with the HCs, the patients with CTN exhibited significantly greater DC values in the right pallidum and right putamen, and lower DC values in the right lingual gyrus, right calcarine sulcus, left paracentral lobule, and left midcingulate cortex. A further seed-based FC analysis revealed that the right lingual gyrus showed decreased FC within the visual network and with other core brain networks, including the sensorimotor network, default mode network, and salience network, relative to HCs. Additionally, the left midcingulate cortex exhibited decreased FC within the middle cingulate cortex and the visual network in CTN patients. Moreover, the DC value in the left midcingulate cortex was negatively correlated with the illness duration.

Conclusion

The present study shows that CTN patients exhibited specific functional connectivity network alterations in the basal ganglia, visual network, and salience network, which may reflect the aberrant neural network communication in pain processing and modulation. These findings may provide novel insight for understanding the mechanisms of pain chronicity in CTN patients.

Working memory dysfunction in fibromyalgia is associated with genotypes of the catechol- O-methyltransferase gene: an event-related potential study

Recent findings have associated different COMT genotypes with working memory capacity in patients with fibromyalgia. Although it is thought that the COMT gene may influence neural correlates (P2 and P3 ERP components) underlying working memory impairment in this chronic-pain syndrome, it has not yet been explored. Therefore, the aim of the present research was to investigate the potential effect of the COMT gene in fibromyalgia patients on ERP working memory indices (P2 and P3 components). For this purpose, 102 participants (51 patients and 51 healthy control participants) took part in the experiment. Event-related potentials and behavioral responses were recorded while participants performed a spatial n-back task. Participants had to decide if the stimulus coincided or not in the same location as the one presented one (1-back condition) or two (2-back condition) trials before. Genotypes of the COMT gene were determined through a saliva sample from all participants. Present results significantly showed lower working memory performance (p < 0.05) in patients with fibromyalgia as compared to control participants (higher rate of errors and slower reaction times). At neural level, we found that patients exhibited enhanced frontocentral and parieto-occipital P2 amplitudes compared to control participants (p < 0.05). Interestingly, we also observed that only fibromyalgia patients carrying the Val/Val genotype of the COMT gene showed higher frontocentral P2 amplitudes than control participants (p < 0.05). Current results (behavioral outcomes and P2 amplitudes) confirmed the presence of an alteration in working memory functioning in fibromyalgia. The enhancement of frontocentral P2 could be reflecting that these patients would manifest an inefficient way of activating executive attention processes, in carriers of the Val/Val genotype of COMT. To our knowledge, the present findings are the first linking neural indices of working memory dysfunctions and COMT genotypes in fibromyalgia. Applying a subgroup of patient's strategy based on this genetic marker could be useful to establish more tailored therapeutical approaches.

A true response of the brain network during electroacupuncture stimulation at scalp acupoints: An fMRI with simultaneous EAS study

OBJECTIVES

The aim of this study was to explore simultaneous brain network responses to electroacupuncture stimulation (EAS) at scalp acupoints by accounting for placebo effects.

MATERIALS AND METHODS

Sixty healthy subjects were recruited and randomly divided into two groups: Group 1 and Group 2. Functional magnetic resonance imaging (fMRI) was performed in Group 1 with sham acupuncture stimulation at acupoints Shenting (GV24) and Touwei (ST8) without EAS. Group 2 underwent verum EAS at the same acupoints during fMRI. Independent component analysis was used to analyze the fMRI data. Full-factor statistical analysis was used to compare the differences in fMRI data between the two groups and evaluate the changes in functional connectivity in brain networks after verum electrical stimulation (Group 1 [after sham electrical current stimulation - before sham electrical current stimulation] - Group 2 [after verum electrical current stimulation - before verum electrical current stimulation]) (p <.001, extent threshold k = 20 voxels).

RESULTS

Six brain networks were identified. Significant increased functional connectivity was observed in the right and left executive control networks, sensorimotor network, and attention network, while decreased functional connectivity was mainly found in the default mode network. There were no statistically significant differences in the salience network.

CONCLUSIONS

fMRI with simultaneous EAS provides a method to explore brain network responses due to EAS at scalp acupoints. The networks responsible for cognition are differentially activated by EAS in a coordinated manner.

Chronic pain domains and their relationship to personality, abilities, and brain networks

Chronic pain is a multidimensional pathological state. Recent evidence suggests that specific brain properties and patients' psychological and physical traits are distorted in chronic pain patients. However, the relationship between these alterations and pain dimensions remains poorly understood. Here, we first evaluated multiple dimensions of chronic pain by assessing a broad battery of pain-related questionnaire scores (23 outcomes) of 107 chronic low back pain patients and identified 3 distinct chronic pain domains: magnitude, affect & disability, and quality. Second, we investigated the pain domains relationship with measures of personality, social interaction, psychological traits, and ability traits (77 biopsychosocial & ability [biopsy&ab] outcomes). Pain magnitude (out-of-sample [OOS] ) is associated with emotional control, attention, and working memory, with higher pain scores showing lower capacity to regulate and adapt behaviorally. Pain affect & disability (OOS associated with anxiety, catastrophizing and social relationships dysfunction. Pain quality did not relate significantly to biopsy&ab variables. Third, we mapped these 3 pain domains to brain functional connectivity. Pain magnitude mainly associated with the sensorimotor and the cingulo-opercular networks (OOS ). Pain affect & disability related to frontoparietal and default mode networks (OOS . Pain quality integrated sensorimotor, auditory, and cingulo-opercular networks (OOS ). Mediation analysis could link functional connectivity and biopsy&ab models to respective pain domains. Our results provide a global overview of the complexity of chronic pain, showing how underlying distinct domains of the experience map to different biopsy&ab correlates and underlie unique brain network signatures.

Fibromyalgia Pathophysiology

This article examines the biological, genetic, and environmental aspects of fibromyalgia that may have an impact on its pathogenesis. Symptoms of fibromyalgia may be related to aberrations in the endogenous inhibition of pain as well as changes in the central processing of sensory input. Genetic research has revealed familial aggregation of fibromyalgia and other related disorders like major depressive disorder. Dysfunctional pain processing may also be influenced by exposure to physical or psychological stressors, abnormal biologic reactions in the autonomic nervous system, and neuroendocrine responses. With more research the pathophysiology of fibromyalgia will be better understood, leading to more logical and focused treatment options for fibromyalgia patients.

Relations between short-term memory and the within-subject variability of experimental pain intensity reports: Results from healthy and Fibromyalgia patients

While factors contributing to between-subjects differences in pain have been studied extensively, factors contributing to the within-subjects variability of pain reports are yet unexplored. The aim of this investigation was to assess possible associations between short-term memory and the within-subjects variability of pain reports in healthy and chronic pain patients. Healthy participants were recruited at the University of Haifa, Israel, and Fibromyalgia patients were recruited at a rheumatology department in a central hospital in Lisbon, Portugal. Following consent, both cohorts underwent the same procedures, including the digit-span test, assessing short-term memory, and the FAST procedure, assessing within-subject variability of pain intensity reports in response to experimental pain. One-hundred twenty-one healthy volunteers and 29 Fibromyalgia patients completed the study. While a significant correlation was found between the within-subjects variability and the total score of the short-term memory task (Spearman's r = 0.394, P = 0.046) in the Fibromyalgia group, a marginal correlation emerged in the healthy cohort (r = 0.174, P = 0.056). A possible interpretation of these results is that in the patients' group, at least some of the within-subjects variability of pain intensity reports might be due to error measurement derived by poorer short-term memory, rather than true fluctuations in perception.

Altered pain sensitivity in 5×familial Alzheimer disease mice is associated with dendritic spine loss in anterior cingulate cortex pyramidal neurons

ABSTRACT

Chronic pain is highly prevalent. Individuals with cognitive disorders such as Alzheimer disease are a susceptible population in which pain is frequently difficult to diagnosis. It is still unclear whether the pathological changes in patients with Alzheimer disease will affect pain processing. Here, we leverage animal behavior, neural activity recording, optogenetics, chemogenetics, and Alzheimer disease modeling to examine the contribution of the anterior cingulate cortex (ACC) neurons to pain response. The 5× familial Alzheimer disease mice show alleviated mechanical allodynia which can be regained by the genetic activation of ACC excitatory neurons. Furthermore, the lower peak neuronal excitation, delayed response initiation, as well as the dendritic spine reduction of ACC pyramidal neurons in 5×familial Alzheimer disease mice can be mimicked by Rac1 or actin polymerization inhibitor in wild-type (WT) mice. These findings indicate that abnormal of pain sensitivity in Alzheimer disease modeling mice is closely related to the variation of neuronal activity and dendritic spine loss in ACC pyramidal neurons, suggesting the crucial role of dendritic spine density in pain processing.

Decision Making and Fibromyalgia: A Systematic Review

Decision making (DM) is the ability to choose among multiple options, considering external and internal variables and identifying potential paths of action that need to be assessed. Some brain areas involved in decision making are also implicated in pain processing, such as in fibromyalgia (FM). FM is a syndrome characterized by chronic widespread musculoskeletal pain and cognitive difficulties. We conducted a systematic review with the aim of identifying articles that evaluated DM in people with fibromyalgia, highlighting the main assessment tools. This work was conducted according to the PRISMA statement by consulting six online databases and providing a quality assessment of each search that met the inclusion criteria. In line with the limited interest in this in the scientific landscape to date, we found nine studies that evaluated the performance of DM in patients with FM; furthermore, we discovered that only certain types of DM were tested. The importance of our work lies in shedding light on a cognitive ability that is often undervalued in the scientific landscape but essential in everyday life. This review can serve as a starting point for further studies to clarify the relationship between DM and FM, improving understanding of the topic.

Variability of Reaction Time as a Marker of Executive Function Impairments in Fibromyalgia

In addition to chronic widespread pain and depression and anxiety symptoms, patients with fibromyalgia frequently experience cognitive problems. This study investigated executive functions in fibromyalgia via a Go/No-Go task. To obtain comprehensive information about performance, traditional and ex-Gaussian parameters of reaction time (RT) variability were used, in addition to speed and accuracy indices. Ex-Gaussian parameters show an excellent fit to empirical RT distributions. Fifty-two female fibromyalgia patients and twenty-eight healthy controls participated. The task included 60 visual stimuli, which participants had to respond to (Go stimuli) or withhold the response to (No-Go stimuli). After 30 trials, the task rule changed, such that previous No-Go stimuli had to be responded to. Performance was indexed by the hit rate, false alarm rate, and mean (M) and intraindividual standard deviation (SD) of RT and the ex-Gaussian parameters mu, sigma, and tau. Mu and sigma indicate the M and SD of the Gaussian distribution; tau reflects the M and SD of the exponential function. Patients exhibited a lower hit rate, higher M RT, and higher tau than controls. Moreover, patients showed greater decrease of the hit rate after the change of task rule. In the entire sample, SD, sigma, and tau were inversely associated with the hit rate and positively associated with the false alarm rate. While the greater decline in hit rate after the change in task rule indicates deficient cognitive flexibility, the lack of any difference in false alarm rate suggests intact response inhibition. Higher M RT reflects reduced cognitive or motor speed. Increased tau in fibromyalgia indicates greater fluctuations in executive control and more frequent temporary lapses of attention. For the first time, this study demonstrated that indices of RT variability, in particular those derived from the ex-Gaussian function, may complement speed and accuracy parameters in the assessment of executive function impairments in fibromyalgia. Optimized assessment may facilitate the personalization of therapies aimed at improving the cognitive function of those with the disorder.

Differences in Learning and Persistency Characterizing Behavior in Chronic Pain for the Iowa Gambling Task: Web-Based Laboratory-in-the-Field Study

Background

Chronic pain is a significant worldwide health problem. It has been reported that people with chronic pain experience decision-making impairments, but these findings have been based on conventional laboratory experiments to date. In such experiments, researchers have extensive control of conditions and can more precisely eliminate potential confounds. In contrast, there is much less known regarding how chronic pain affects decision-making captured via laboratory-in-the-field experiments. Although such settings can introduce more experimental uncertainty, collecting data in more ecologically valid contexts can better characterize the real-world impact of chronic pain.

Objective

We aim to quantify decision-making differences between individuals with chronic pain and healthy controls in a laboratory-in-the-field environment by taking advantage of internet technologies and social media.

Methods

A cross-sectional design with independent groups was used. A convenience sample of 45 participants was recruited through social media: 20 (44%) participants who self-reported living with chronic pain, and 25 (56%) people with no pain or who were living with pain for <6 months acting as controls. All participants completed a self-report questionnaire assessing their pain experiences and a neuropsychological task measuring their decision-making (ie, the Iowa Gambling Task) in their web browser at a time and location of their choice without supervision.

Results

Standard behavioral analysis revealed no differences in learning strategies between the 2 groups, although qualitative differences could be observed in the learning curves. However, computational modeling revealed that individuals with chronic pain were quicker to update their behavior than healthy controls, which reflected their increased learning rate (95% highest–posterior-density interval [HDI] 0.66-0.99) when fitted to the Values-Plus-Perseverance model. This result was further validated and extended on the Outcome-Representation Learning model as higher differences (95% HDI 0.16-0.47) between the reward and punishment learning rates were observed when fitted to this model, indicating that individuals with chronic pain were more sensitive to rewards. It was also found that they were less persistent in their choices during the Iowa Gambling Task compared with controls, a fact reflected by their decreased outcome perseverance (95% HDI −4.38 to −0.21) when fitted using the Outcome-Representation Learning model. Moreover, correlation analysis revealed that the estimated parameters had predictive value for the self-reported pain experiences, suggesting that the altered cognitive parameters could be potential candidates for inclusion in chronic pain assessments.

Conclusions

We found that individuals with chronic pain were more driven by rewards and less consistent when making decisions in our laboratory-in-the-field experiment. In this case study, it was demonstrated that, compared with standard statistical summaries of behavioral performance, computational approaches offered superior ability to resolve, understand, and explain the differences in decision-making behavior in the context of chronic pain outside the laboratory.

Working Memory Performance, Pain and Associated Clinical Variables in Women With Fibromyalgia

Working memory (WM) is a critical process for cognitive functioning in which fibromyalgia (FM) patients could show cognitive disturbances. Dyscognition in FM has been explained by interference from pain processing, which shares the neural substrates involved in cognition and may capture neural resources required to perform cognitive tasks. However, there is not yet data about how pain is related to WM performance, neither the role that other clinical variables could have. The objectives of this study were (1) to clarify the WM status of patients with FM and its relationship with nociception, and (2) to determine the clinical variables associated to FM that best predict WM performance. To this end, 132 women with FM undertook a neuropsychological assessment of WM functioning (Digit span, Spatial span, ACT tests and a 2-Back task) and a complete clinical assessment (FSQ, FIQ-R, BDI-1A, HADS, PSQI, MFE-30 questionnaires), including determination of pain thresholds and tolerance by pressure algometry. Patients with FM seem to preserve their WM span and ability to maintain and manipulate information online for both visuospatial and verbal domains. However, up to one-third of patients showed impairment in tasks requiring more short-term memory load, divided attention, and information processing ability (measured by the ACT task). Cognitive performance was spuriously related to the level of pain experienced, finding only that pain measures are related to the ACT task. The results of the linear regression analyses suggest that sleep problems and fatigue were the variables that best predicted WM performance in FM patients. Future research should take these variables into account when evaluating dyscognition in FM and should include dynamic measures of pain modulation.

Brain changes associated with impaired attention function in chronic pain

Attention function is thought to be important in chronic pain, with the pathology of chronic pain closely associated with cognitive-emotional components. However, there have been few neuroimaging studies of the relationship between attention function and chronic pain. We used the method of functional connectivity analysis for resting-state fMRI (rs-fMRI) data and the Attention Network Test-Revision (ANT-R) to clarify the attention-related pathology of chronic pain. We performed rs-fMRI and ANT-R on a group of 26 chronic pain (somatoform pain disorder) patients and 28 age-matched healthy controls. A significant group difference in validity effects, a component of ANT-R, emerged (F_1,46 = 5.91, p = 0.019), and the chronic pain group exhibited slower reaction times. Decreased brain connectivity of the left insula and left frontal regions was confirmed in chronic pain patients (p^FWE < 0.05), and connectivity was negatively correlated with validity effects (r = -0.29, permutation test p = 0.033). Further, decreased functional connectivity strength of the right insula and left temporal gyrus in the chronic pain group were confirmed (p^FWE < 0.05). We conclude that poor control of attention function results from deficits of functional connectivity in the left insula and left frontal regions in chronic pain.

How Pain Shapes Depression and Anxiety: A Hybrid Self-regulatory/Predictive Mind Perspective

Because many persons living with chronic pain achieve a relatively balanced lifestyle without experiencing functional disability, medical psychologists must explain the well-documented co-occurrence of pain complaints and DSM-5-disorders (including but not limited to depression and anxiety) in a significant subset of individuals. The question of differential resilience versus susceptibility has received modest theoretical and empirical attention, but remains open. In this review, I deconstruct the temporally extended pain adaptation process in order to address this vexing question, relying upon two complementary explanatory frames. The first is a motivational/cybernetic systems formulation labeled the Goal-Centered, Self-Regulatory, Automated Social Systems Psychology (GRASSP) model, erected upon feedback sensitive, goal-guided, hierarchically organized self-regulatory processes. Depression and anxiety presumably result from compromised regulatory functions undermining pain processing, goal pursuit, and everyday performance. The second perspective postulates a "Bayesian Brain"/"Predictive Mind" capable of unifying perception, action, and emotion via predictive processing. From a Bayesian perspective, predictive processing implies that our brains evolved to compare, without conscious direction, incoming environmental information against prior, model-based predictions in order to arrive at accurate perceptual representations of the world. Maladjustment results from failures of active inference. When applied to the perception of visceral information, the embodied process, termed interoceptive inference, can also yield pathogenic outcomes. The Bayesian model holds that depression and anxiety in individuals with pain result from error-prone (biased, rigid, or highly certain) prior evaluations of aversive feeling states and their relation to the external milieu. I consider how the hybrid conceptual framework advanced by the two models points to several novel and familiar avenues of intervention.

Impact of Affect Balance on Cognitive and Physical Function in Adults With and Without Fibromyalgia

OBJECTIVE

To identify the potential benefits of heightened levels of affect balance in older adults with and without chronic pain on various cognitive domains, physical performance, and perceived cognitive and physical health.

METHOD

Ninety-one older adults, some with and some without fibromyalgia (FM) participated. Objective tests included cognitive (immediate and delayed recall, delayed recognition-CERAD 10-item word list) and physical measures (Fullerton Advanced Balance Scale; lower body strength-30-s chair stand; gait velocity-30-ft. walk). Self-report measures were problems with forgetting, activities of daily living (perceived function), and affect (Positive and Negative Affect Scale [PANAS]). Affect balance was calculated as positive minus negative affect from the PANAS.

RESULTS

Hierarchical regression analyses revealed that-regardless of FM status-higher affect balance was associated with better episodic memory performance (immediate recall, delayed recognition), better balance, enhanced lower body strength (more chair stands), and healthier gait (30-ft. walk), as well as less forgetfulness and better perceived functional health.

CONCLUSION

Increased affect balance was associated with better objective and subjective health in older adults both without and with chronic pain. Positive psychology treatments which increase affect balance are easy to administer, cost effective, and may add an important, additional treatment modality for maintaining health in normal aging adults as well as those with chronic pain.

CLINICAL RELEVANCE

In order to help patients with healthy aging, nurses need to be aware of the potential long-term effect of emotional state on overall function and be able to counsel patients regarding potential treatments to enhance positive global emotions such as resilience.

Altered sub-processes of working memory in fibromyalgia patients: An ERP study using N-back task

OBJECTIVE

Cognitive dysfunction in fibromyalgia has become a key symptom considered by patients as more disabling than pain itself. Experimental evidence from neuropsychological and neuroimaging studies indicates that such cognitive impairments are especially robust when patients need to set in motion working memory processes, suggesting the existence of an altered functioning underlying the cerebral cortices of the frontoparietal memory network. However, the temporal dynamics of working memory sub-processes have not yet been explored in fibromyalgia.

SUBJECTS

Thirty-six right-handed women participated in the experiment: comprising eighteen patients with fibromyalgia and eighteen healthy controls.

METHODS

Event-related potentials (ERPs) and behavioural responses were recorded while participants were engaged in a 2-back working memory task. Principal Component Analyses (PCA) were used to define and quantify the ERP components associated with working memory processes.

RESULTS

Fibromyalgia patients exhibited worse performance than the control group, as revealed by their number of errors in the working memory task. Moreover, both scalp parieto-occipital P2 and parieto-occipital P3 amplitudes were lower for patients than for healthy control participants. Regression analyses revealed that lower P3 amplitudes were observed in those patients with fibromyalgia reporting higher pain ratings.

CONCLUSIONS

Current results suggest that both encoding of information (as reflected by P2) and subsequently, context updating and the replacement (as seen in lower P3 amplitudes), as a part of working memory sub-processes, are impaired in fibromyalgia. Studying the temporal dynamics of working memory using ERP methodology is a helpful approach to detect specific cognitive impaired mechanisms in this chronic pain syndrome. These new data could be used to develop more specific treatments adapted for each patient.

Abnormal subgenual anterior cingulate circuitry is unique to women but not men with chronic pain

The subgenual anterior cingulate cortex (sgACC) plays an important role in pain modulation. We previously demonstrated sex differences in sgACC functional connectivity (FC) in healthy individuals. Given that many chronic pain conditions show sex differences in prevalence, here we tested the hypothesis that people with chronic pain exhibit a sex-specific pattern of abnormal sgACC FC. We acquired resting-state functional magnetic resonance imaging data from 156 (82 W: 74 M) healthy participants and 38 (19 W: 19 M) people with chronic low back pain resulting from ankylosing spondylitis, a condition that predominantly affects men. We confirmed that there are sex differences in sgACC FC in our large cohort of healthy adults; women had greater sgACC FC with the precuneus, a key node of the default mode network, and men had greater sgACC FC with the posterior insula and the operculum. Next, we identified an interaction effect between sex and pain status (healthy/chronic pain) for sgACC FC. Within the chronic pain group, women had greater sgACC FC than men to the default mode and sensorimotor networks. Compared to healthy women, women with chronic pain also had greater sgACC FC to the precuneus and lower FC to the hippocampus and frontal regions. No differences in sgACC FC were seen in men with vs without chronic pain. Our findings indicate that abnormal sgACC circuitry is unique to women but not men with ankylosing spondylitis-related chronic pain. These sex differences may impact the benefit of therapeutics that target the sgACC for chronic pain.

Magnetic resonance imaging of neuroinflammation in chronic pain: a role for astrogliosis?

Noninvasive measures of neuroinflammatory processes in humans could substantially aid diagnosis and therapeutic development for many disorders, including chronic pain. Several proton magnetic resonance spectroscopy (H-MRS) metabolites have been linked with glial activity (ie, choline and myo-inositol) and found to be altered in chronic pain patients, but their role in the neuroinflammatory cascade is not well known. Our multimodal study evaluated resting functional magnetic resonance imaging connectivity and H-MRS metabolite concentration in insula cortex in 43 patients suffering from fibromyalgia, a chronic centralized pain disorder previously demonstrated to include a neuroinflammatory component, and 16 healthy controls. Patients demonstrated elevated choline (but not myo-inositol) in anterior insula (aIns) (P = 0.03), with greater choline levels linked with worse pain interference (r = 0.41, P = 0.01). In addition, reduced resting functional connectivity between aIns and putamen was associated with both pain interference (whole brain analysis, pcorrected < 0.01) and elevated aIns choline (r = -0.37, P = 0.03). In fact, aIns/putamen connectivity statistically mediated the link between aIns choline and pain interference (P < 0.01), highlighting the pathway by which neuroinflammation can impact clinical pain dysfunction. To further elucidate the molecular substrates of the effects observed, we investigated how putative neuroinflammatory H-MRS metabolites are linked with ex vivo tissue inflammatory markers in a nonhuman primate model of neuroinflammation. Results demonstrated that cortical choline levels were correlated with glial fibrillary acidic protein, a known marker for astrogliosis (Spearman r = 0.49, P = 0.03). Choline, a putative neuroinflammatory H-MRS-assessed metabolite elevated in fibromyalgia and associated with pain interference, may be linked with astrogliosis in these patients.

The Effect of Multiprobiotics on Memory and Attention in Fibromyalgia: A Pilot Randomized Controlled Trial

Fibromyalgia syndrome (FMS) is a chronic, generalized and diffuse pain disorder accompanied by cognitive deficits such as forgetfulness, concentration difficulties, loss of vocabulary and mental slowness, among others. In recent years, FMS has been associated with altered intestinal microbiota, suggesting that modulating gut microbiota (for example, through probiotics) could be an effective therapeutic treatment. Thus, the aim of the present study was to continue exploring the role of probiotics in cognitive processes in patients with FMS. A pilot randomized controlled trial was conducted in 31 patients diagnosed with FMS to compare the effects of a multispecies probiotic versus a placebo on cognitive variables (memory and attention) after eight weeks. Results showed that treatment with a multispecies probiotic produced an improvement in attention by reducing errors on an attention task, but it had no effect on memory. More specifically, a tendency to reduce errors of omission (Go trials) during the Go/No-Go Task was observed after treatment. These findings, along with our previous results in impulsivity, underline the relevance of using probiotics as a therapeutic option in FMS, although more research with a larger sample size is required.

Memory complaints and cognitive performance in fibromyalgia and chronic pain: The key role of depression

To explore the relationship between perceived cognitive problems and cognitive performance in three different samples, taking into account the possible influence of depression, catastrophizing, pain intensity, or medication. Seventy individuals with fibromyalgia, 74 with non-malignant chronic pain and 40 pain-free controls, completed measures of verbal episodic memory, sustained attention, response inhibition, depression, catastrophizing, and pain intensity. Fibromyalgia and chronic pain patients performed worse than controls in verbal memory and sustained attention, but these differences disappeared when depressed participants were excluded from the analyses. Memory complaints were related with depression in all pain patients. However, in the case of fibromyalgia, memory complaints were also related by pain intensity and inversely related by short-term episodic memory. This case-control study shows the importance of jointly assessing cognitive performance and memory complaints and of controlling for variables such as depression, catastrophizing, pain intensity and medication in the studied samples. Accordingly, this study highlights the differences in memory complaints, between the patients with fibromyalgia and the patients with other chronic pain conditions. Finally, it has highlighted the important role played by depression in cognitive performance and memory complaints considering the Neurocognitive Model of Attention to pain.

Executive Functioning in Youth With and Without Chronic Pain: A Comparative Analysis

OBJECTIVES

Preliminary research in youth with chronic pain suggests differences in attention and working memory, which has been similarly demonstrated in adults with chronic pain. There has been little research on other aspects of executive functioning (EF) in this population despite its critical role in problem solving, school functioning, and coping. This study aimed to examine differences in several aspects of EF between youth with chronic pain and a nonchronic pain comparison group using performance-based neuropsychological tests and a behavior rating scale.

MATERIALS AND METHODS

Participants completed ratings of pain; physical, emotional, social, and school functioning; sleep quality; medication; and a general intelligence screener. Standardized neuropsychological tests were used to examine EF with a focus on working memory, divided and alternating attention, inhibition, flexibility, incidental memory, and planning. A parent-report and self-report behavior rating of EF was also administered.

RESULTS

Recruitment from 2 tertiary-care pain clinics resulted in a sample of 26 youth with chronic pain (80.8% girls) and their parents. A comparison group of 30 youth without chronic pain and their parents were recruited from the community. Participants with chronic pain had significantly lower scores on several performance-based tests of working memory/divided attention, inhibition, and flexibility/alternating attention than the comparison group. Statistically significant group differences were also found on behavior ratings of emotion control, shifting, task initiation and completion, working memory, planning and organization, overall emotion and cognitive regulation as well as global EF. Covariate analysis was conducted in all analyses where there were significant group differences and several observed group differences remained.

DISCUSSION

This study is one of few multidimensional examinations of EF in youth with chronic pain, using a comprehensive neuropsychological test battery combined with behavior ratings. Our findings suggest EF differences in youth with chronic pain, across a variety of domains and may suggest risk for specific cognitive processing weaknesses in this population. Medical and educational teams should work toward identification, treatment, and compensatory support for EF within individualized pain management for youth.

Cortical Modulation of Nociception

Nociception is the neuronal process of encoding noxious stimuli and could be modulated at peripheral, spinal, brainstem, and cortical levels. At cortical levels, several areas including the anterior cingulate cortex (ACC), prefrontal cortex (PFC), ventrolateral orbital cortex (VLO), insular cortex (IC), motor cortex (MC), and somatosensory cortices are involved in nociception modulation through two main mechanisms: (i) a descending modulatory effect at spinal level by direct corticospinal projections or mostly by activation of brainstem structures (i.e. periaqueductal grey matter (PAG), locus coeruleus (LC), the nucleus of raphe (RM) and rostroventral medulla (RVM)); and by (ii) cortico-cortical or cortico-subcortical interactions. This review summarizes evidence related to the participation of the aforementioned cortical areas in nociception modulation and different neurotransmitters or neuromodulators that have been studied in each area. Besides, we point out the importance of considering intracortical neuronal populations and receptors expression, as well as, nociception-induced cortical changes, both functional and connectional, to better understand this modulatory effect. Finally, we discuss the possible mechanisms that could potentiate the use of cortical stimulation as a promising procedure in pain alleviation.

Salivary cortisol is associated with cognitive changes in patients with fibromyalgia

Fibromyalgia (FM) is a stress-related chronic pain disorder with common cognitive complaints. This study characterized cognitive dysfunction in patients with FM and explored whether these changes are linked to altered cortisol levels. Consecutive 44 patients with FM and 48 healthy controls were enrolled for the assessments of subjective and objective cognitive functions and diurnal levels of salivary cortisol (sampled at awakening, 30 min after awakening, 3 pm, and bedtime). All measurements were compared between the groups and evaluated for clinical correlation. The FM group had more subjective cognitive complaints and performed poorer in objective cognitive testing in memory (delayed recall in Chinese Version Verbal Learning Test and Taylor Complex Figure Test), language (Boston Naming Test), and executive domains (Wisconsin Card Sorting Test) after adjustments for education. The diurnal cortisol levels of patients with FM tended to be lower, especially at 30 min after awakening and bedtime. Moreover, moderate positive correlations existed between the Chinese Version Verbal Learning Test, Boston Naming Test and the morning cortisol levels within the FM group. We suggested the altered cognitive function in FM may be linked to stress maladaptation. Future studies are warranted to elucidate whether stress management improves cognitive performance in patients with FM.

Beyond physiotherapy and pharmacological treatment for fibromyalgia syndrome: tailored tACS as a new therapeutic tool

Fibromyalgia syndrome (FMS) is a complex pain disorder, characterized by diffuse pain and cognitive disturbances. Abnormal cortical oscillatory activity may be a promising biomarker, encouraging non-invasive neurostimulation techniques as a treatment. We aimed to modulate abnormal slow cortical oscillations by delivering transcranial alternating current stimulation (tACS) and physiotherapy to reduce pain and cognitive symptoms. This was a double-blinded, randomized, crossover trial conducted between February and September 2018 at the Rehabilitation Unit of a teaching Hospital (NCT03221413). Participants were randomly assigned to tACS or random noise stimulation (RNS), 5 days/week for 2 weeks followed by ad hoc physiotherapy. Clinical and cognitive assessments were performed at T₀ (baseline), T₁ (after stimulation), T₂ (1 month after stimulation). Electroencephalogram (EEG) spectral topographies recorded from 15 participants confirmed slow-rhythm prevalence and provided tACS tailored stimulation parameters and electrode sites. Following tACS, EEG alpha1 ([8-10] Hz) activity increased at T₁ (p = 0.024) compared to RNS, pain symptoms assessed by Visual Analog Scale decreased at T₁ (T₁ vs T₀ p = 0.010), self-reported cognitive skills and neuropsychological scores improved both at T₁ and T₂ (Patient-Reported Outcomes in Cognitive Impairment, T₀-T₂, p = 0.024; Everyday memory questionnaire, T₁ compared to RNS, p = 0.012; Montréal Cognitive Assessment, T₀ vs T₁, p = 0.048 and T₀ vs T₂, p = 0.009; Trail Making Test B T₀-T₂, p = 0.034). Psychopathological scales and other neuropsychological scores (Trail Making Test-A; Total Phonemic Fluency; Hopkins Verbal Learning Test-Revised; Rey-Osterrieth Complex Figure) improved both after tACS and RNS but earlier improvements (T₁) were registered only after tACS. These results support tACS coupled with physiotherapy in treating FMS cognitive symptoms, pain and subclinical psychopathology.

Neuronal Correlates of Cognitive Control Are Altered in Women With Endometriosis and Chronic Pelvic Pain

Endometriosis is a debilitating women's health condition and is the most common cause of chronic pelvic pain. Impaired cognitive control is common in chronic pain conditions, however, it has not yet been investigated in endometriosis. The aim of this study was to explore the neuronal correlates of cognitive control in women with endometriosis. Using a cross-sectional study design with data collected at a single time-point, event-related potentials were elicited during a cued continuous performance test from 20 women with endometriosis (mean age = 28.5 ± 5.2 years) and 20 age- and gender-matched controls (mean age = 28.5 ± 5.2 years). Event-related potential components were extracted and P3 component amplitudes were derived with temporal principal components analysis. Behavioral and ERP outcomes were compared between groups and subjective pain severity was correlated with ERP component amplitudes. No significant behavioral differences were seen in task performance between the groups (all p > 0.094). Target P3b (all p < 0.034) and SW (all p < 0.040), and non-target early P3a (eP3a; all p < 0.023) and late P3a (lP3a; all p < 0.035) amplitudes were smaller for the endometriosis compared to the healthy control group. Lower non-target eP3a (p < 0.001), lP3a (p = 0.013), and SW (p = 0.019) amplitudes were correlated with higher pain severity scores. Findings suggest that endometriosis-associated chronic pelvic pain is linked to alterations in stimulus-response processing and inhibitory control networks, but not impaired behavioral performance, due to compensatory neuroplastic changes in overlapping cognitive control and pain networks.

Chronic jaw pain attenuates neural oscillations during motor-evoked pain

Motor- and pain-related processes separately induce a reduction in alpha and beta power. When movement and pain occur simultaneously but are independent of each other, the effects on alpha and beta power are additive. It is not clear whether this additive effect is evident during motor-evoked pain in individuals with chronic pain. We combined highdensity electroencephalography (EEG) with a paradigm in which motor-evoked pain was induced during a jaw force task. Participants with chronic jaw pain and pain-free controls produced jaw force at 2% and 15% of their maximum voluntary contraction. The chronic jaw pain group showed exacerbated motor-evoked pain as force amplitude increased and showed increased motor variability and motor error irrespective of force amplitude. The chronic jaw pain group had an attenuated decrease in power in alpha and lower-beta frequencies in the occipital cortex during the anticipation and experience of motor-evoked pain. Rather than being additive, motor-evoked pain attenuated the modulation of alpha and beta power, and this was most evident in occipital cortex. Our findings provide the first evidence of changes in neural oscillations in the cortex during motor-evoked jaw pain.

The Spontaneous Activity Pattern of the Middle Occipital Gyrus Predicts the Clinical Efficacy of Acupuncture Treatment for Migraine Without Aura

The purpose of the present study was to explore whether and to what extent the neuroimaging markers could predict the relief of the symptoms of patients with migraine without aura (MWoA) following a 4-week acupuncture treatment period. In study 1, the advanced multivariate pattern analysis was applied to perform a classification analysis between 40 patients with MWoA and 40 healthy subjects (HS) based on the z-transformed amplitude of low-frequency fluctuation (zALFF) maps. In study 2, the meaningful classifying features were selected as predicting features and the support vector regression models were constructed to predict the clinical efficacy of acupuncture in reducing the frequency of migraine attacks and headache intensity in 40 patients with MWoA. In study 3, a region of interest-based comparison between the pre- and post-treatment zALFF maps was conducted in 33 patients with MwoA to assess the changes in predicting features after acupuncture intervention. The zALFF value of the foci in the bilateral middle occipital gyrus, right fusiform gyrus, left insula, and left superior cerebellum could discriminate patients with MWoA from HS with higher than 70% accuracy. The zALFF value of the clusters in the right and left middle occipital gyrus could effectively predict the relief of headache intensity (R ² = 0.38 ± 0.059, mean squared error = 2.626 ± 0.325) and frequency of migraine attacks (R ² = 0.284 ± 0.072, mean squared error = 20.535 ± 2.701) after the 4-week acupuncture treatment period. Moreover, the zALFF values of these two clusters were both significantly reduced after treatment. The present study demonstrated the feasibility and validity of applying machine learning technologies and individual cerebral spontaneous activity patterns to predict acupuncture treatment outcomes in patients with MWoA. The data provided a quantitative benchmark for selecting acupuncture for MWoA.

Exploration of Functional Connectivity Changes Previously Reported in Fibromyalgia and Their Relation to Psychological Distress and Pain Measures

Neural functional connectivity changes in the default mode network (DMN), Central executive network (CEN), and insula have been implicated in fibromyalgia (FM) but stem from a sparse set of small-scale studies with limited power for the investigation of confounding effects. We investigated whether anxiety, depression, pain sensitivity, and pain intensity modulated functional connectivity related to DMN nodes, CEN nodes, and insula. Resting-state functional magnetic resonance imaging data were collected from 31 females with FM and 28 age-matched healthy controls. Connectivity was analysed with a region-based connectivity analysis between DMN nodes in ventromedial prefrontal cortex (vmPFC) and posterior cingulate cortex, CEN nodes in the intraparietal sulcus (IPS), and bilateral insula. FM patients displayed significantly higher levels of anxiety and depressive symptoms than controls. The right IPS node of the CEN showed a higher level of connectivity strength with right insula in FM with higher pain intensity compared to controls. More anxiety symptoms in FM correlated with higher levels of connectivity strength between the vmPFC DMN node and right sensorimotor cortex. These findings support the theory of altered insular connectivity in FM and also suggest altered IPS connectivity in FM. Interestingly, no change in insular connectivity with DMN was observed.

Cortical dynamics of movement-evoked pain in chronic low back pain

KEY POINTS

Cortical activity underlying movement-evoked pain is not well understood, despite being a key symptom of chronic musculoskeletal pain. We combined high-density electroencephalography with a full-body reaching protocol in a virtual reality environment to assess cortical activity during movement-evoked pain in chronic low back pain. Movement-evoked pain in individuals with chronic low back pain was associated with longer reaction times, delayed peak velocity and greater movement variability. Movement-evoked pain was associated with attenuated disinhibition in prefrontal motor areas, as evidenced by an attenuated reduction in beta power in the premotor cortex and supplementary motor area.

ABSTRACT

Although experimental pain alters neural activity in the cortex, evidence of changes in neural activity in individuals with chronic low back pain (cLBP) remains scarce and results are inconsistent. One of the challenges in studying cLBP is that the clinical pain fluctuates over time and often changes during movement. The goal of the present study was to address this challenge by recording high-density electroencephalography (HD-EEG) data during a full-body reaching task to understand neural activity during movement-evoked pain. HD-EEG data were analysed using independent component analyses, source localization and measure projection analyses to compare neural oscillations between individuals with cLBP who experienced movement-evoked pain and pain-free controls. We report two novel findings. First, movement-evoked pain in individuals with cLBP was associated with longer reaction times, delayed peak velocity and greater movement variability. Second, movement-evoked pain was associated with an attenuated reduction in beta power in the premotor cortex and supplementary motor area. Our observations move the field forward by revealing attenuated disinhibition in prefrontal motor areas during movement-evoked pain in cLBP.

Electrophysiological investigation of the contribution of attention to altered pain inhibition processes in patients with irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder associated with chronic abdominal pain and altered pain processing. The aim of this study was to examine whether attentional processes contribute to altered pain inhibition processes in patients with IBS. Nine female patients with IBS and nine age-/sex-matched controls were included in a pain inhibition paradigm using counter-stimulation and distraction with electroencephalography. Patients with IBS showed no inhibition of pain-related brain activity by heterotopic noxious counter-stimulation (HNCS) or selective attention. In the control group, HNCS and selective attention decreased the N100, P260 and high-gamma oscillation power. In addition, pain-related high-gamma power in sensorimotor, anterior cingulate and left dorsolateral prefrontal cortex was decreased by HNCS and selective attention in the control group, but not in patients with IBS. These results indicate that the central pain inhibition deficit in IBS reflects interactions between several brain processes related to pain and attention.

Functional Alterations in the Posterior Insula and Cerebellum in Migraine Without Aura: A Resting-State MRI Study

Background: Hypothesis-driven functional connectivity (FC) analyses have revealed abnormal functional interaction of regions or networks involved in pain processing in episodic migraine patients. We aimed to investigate the resting-state FC patterns in episodic migraine by combining data-driven voxel-wise degree centrality (DC) calculation and seed-based FC analysis.

Methods: Thirty-nine patients suffering from episodic migraine without aura and 35 healthy controls underwent clinical assessment and functional MRI. DC was analyzed voxel-wise and compared between groups, and FC of regions with DC differences were further examined using a seed-based approach.

Results: Compared with the control group, the migraine group showed increased and decreased DC in the right posterior insula and left crus I, respectively. Seed-based FC analyses revealed that migraine patients demonstrated increased right posterior insula connections with the postcentral gyrus, supplementary motor area/paracentral lobule, fusiform gyrus and temporal pole. The left crus I showed decreased FC with regions of the default mode network (DMN), including the medial prefrontal cortex (mPFC), angular gyrus, medial and lateral temporal cortex in patients with migraine. Furthermore, pain intensity positively correlated with DC in the right amygdala/parahippocampal gyrus, and migraine frequency negatively correlated with FC between the left crus I and mPFC.

Conclusion: Patients with episodic migraine without aura have increased FC with the right posterior insula and decreased FC within the DMN, which may underlie disturbed sensory integration and cognitive processing of pain. The left crus I-mPFC connectivity may be a useful biomarker for assessing migraine frequency.

Effects of Mindfulness-Oriented Recovery Enhancement Versus Social Support on Negative Affective Interference During Inhibitory Control Among Opioid-Treated Chronic Pain Patients: A Pilot Mechanistic Study

BACKGROUND

Among opioid-treated chronic pain patients, deficient response inhibition in the context of emotional distress may contribute to maladaptive pain coping and prescription opioid misuse. Interventions that aim to bolster cognitive control and reduce emotional reactivity (e.g., mindfulness) may remediate response inhibition deficits, with consequent clinical benefits.

PURPOSE

To test the hypothesis that a mindfulness-based intervention, Mindfulness-Oriented Recovery Enhancement (MORE), can reduce the impact of clinically relevant, negative affective interference on response inhibition function in an opioid-treated chronic pain sample.

METHODS

We examined data from a controlled trial comparing adults with chronic pain and long-term prescription opioid use randomized to either MORE (n = 27) treatment or to an active support group comparison condition (n = 30). Participants completed an Emotional Go/NoGo Task at pre- and post-treatment, which measured response inhibition in neutral and clinically relevant, negative affective contexts (i.e., exposure to pain-related visual stimuli).

RESULTS

Repeated-measures analysis of variance indicated that compared with the support group, participants in MORE evidenced significantly greater reductions from pre- to post-treatment in errors of commission on trials with pain-related distractors relative to trials with neutral distractors, group × time × condition F(1,55) = 4.14, p = .047, η2partial = .07. Mindfulness practice minutes and increased nonreactivity significantly predicted greater emotional response inhibition. A significant inverse association was observed between improvements in emotional response inhibition and treatment-related reductions in pain severity by 3-month follow-up.

CONCLUSIONS

Study results provide preliminary evidence that MORE enhances inhibitory control function in the context of negative emotional interference.

Effects of COMT Genotypes on Working Memory Performance in Fibromyalgia Patients

Growing research has reported the presence of a clear impairment of working memory functioning in fibromyalgia. Although different genetic factors involving dopamine availability (i.e, the COMT gene) have been associated with the more severe presentation of key symptoms in fibromyalgia, scientific evidence regarding the influence of COMT genotypes on cognitive impairment in these patients is still lacking. To this end, 167 participants took part in the present investigation. Working memory performance was assessed by the application of the SST (Spatial Span Test) and LNST (Letter and Number Sequence Test) belonging to the Weschler Memory Scale III. Significant working memory impairment was shown by the fibromyalgia patients. Remarkably, our results suggest that performance according to different working memory measures might be influenced by different genotypes of the COMT gene. Specifically, fibromyalgia patients carrying the Val/Val genotype exhibited significantly worse outcomes for the span of SST backward, SST backward score, SST total score and the Working Memory Index (WMI) than the Val/Val healthy carriers. Furthermore, the Val/Val patients performed worse on the SST backward and SST score than heterozygotes. Our findings are the first to show a link between the COMT gene and working memory dysfunction in fibromyalgia, supporting the idea that higher COMT enzyme activity would contribute to more severe working memory impairment in fibromyalgia.

Do chronic pain and comorbidities affect brain function in sickle cell patients? A systematic review of neuroimaging and treatment approaches

Sickle cell disease (SCD) is a medical condition in which chronic pain is common and negatively impacts psychosocial function and quality of life. Although the brain mechanisms underlying chronic pain are well studied in other painful conditions, the brain mechanisms underlying chronic pain and the associated psychosocial comorbidities are not well established in SCD. A growing literature demonstrates the effect of treatment of chronic pain, including pharmacological and nonpharmacological treatments, on brain function. The present systematic review aimed to (1) determine the effects of chronic pain and psychosocial comorbidities on brain function of patients with SCD; (2) summarize pharmacological and nonpharmacological approaches to treat these symptoms; and (3) identify areas for further investigation of potential beneficial effects of treatments on brain function. Titles were screened using predefined criteria, including SCD, and abstracts and full texts were reviewed by 2 independent reviewers. A total of 1167 SCD articles were identified, and 86 full articles were included covering 3 sections: chronic pain (4 studies), psychosocial comorbidities (11 studies), and pharmacological and nonpharmacological treatments (71 studies). Neuroimaging evidence demonstrates aberrant neural processing related to chronic pain and psychosocial comorbidities in SCD beyond ischemic stroke and cerebral hemorrhage. Although neuroimaging studies show an important role for psychological factors, pain management is nearly exclusively based on opioids. Behavior therapy seems useful to improve psychological symptoms as well as chronic pain and quality of life. Further investigation is required with larger cohorts, matched controls, and examination of treatment-related neural mechanisms.

Abnormal medial prefrontal cortex functional connectivity and its association with clinical symptoms in chronic low back pain

Accumulating evidence has shown that complicated brain systems are involved in the development and maintenance of chronic low back pain (cLBP), but the association between brain functional changes and clinical outcomes remains unclear. Here, we used resting-state functional magnetic resonance imaging (fMRI) and multivariate pattern analysis to identify abnormal functional connectivity (FC) between the default mode, sensorimotor, salience, and central executive brain networks in cLBP and tested whether abnormal FCs are related to pain and comorbid symptoms. Fifty cLBP patients and 44 matched healthy controls (HCs) underwent an fMRI scan, from which brain networks were identified by independent component analysis. Multivariate pattern analysis, graph theory approaches, and correlation analyses were applied to find abnormal FCs that were associated with clinical symptoms. Findings were validated on a second cohort of 30 cLBP patients and 30 matched HCs. Results showed that the medial prefrontal cortex/rostral anterior cingulate cortex had abnormal FCs with brain regions within the default mode network and with other brain networks in cLBP patients. These altered FCs were also correlated with pain duration, pain severity, and pain interference. Finally, we found that resting-state FC could discriminate cLBP patients from HCs with 91% accuracy in the first cohort and 78% accuracy in the validation cohort. Our findings suggest that the medial prefrontal cortex/rostral anterior cingulate cortex may be an important hub for linking the default mode network with the other 3 networks in cLBP patients. Elucidating the altered FCs and their association with clinical outcomes will enhance our understanding of the pathophysiology of cLBP and may facilitate the development of pain management approaches.