Aberrant Resting-State Functional Connectivity in the Salience Network of Adolescent Chronic Fatigue Syndrome

Associations Between Brain-Gut Axis and Psychological Distress in Fibromyalgia: A Microbiota and Magnetic Resonance Imaging Study

An altered brain-gut axis is suspected to be one of the pathomechanisms in fibromyalgia (FM). This cross-sectional study investigated the associations among altered microbiota, psychological distress, and brain functional connectivity (FC) in FM. We recruited 25 FM patients and 25 healthy people in the present study. Psychological distress was measured using standardized questionnaires. Microbiota analysis was performed on the participants' stools. Functional magnetic resonance imaging data were acquired, and seed-based resting-state FC (rs-FC) analysis was conducted with the salience network nodes as seeds. Linear regression and mediation analyses evaluated microbiota, symptoms, and rs-FCs associations. We found altered microbiota diversity in FM, of which Phascolarctobacterium and Lachnoclostridium taxa increased the most and Faecalibacterium taxon decreased the most compared to controls. The Phascolarctobacterium abundance significantly predicted Beck depression inventory (BDI-II) scores in FM (β = 6.83; P = .033). Rs-FCs from salience network nodes were reduced in FM, of which rs-FCs from the right lateral rostral prefrontal cortex (RPFC) to the lateral occipital cortex, superior division right (RPFC-sLOC) could be predicted by BDI-II scores in patients (β = -.0064; P = .0054). In addition, the BDI-II score was a mediator in the association between Phascolarctobacterium abundance and rs-FCs of RPFC-sLOC (ab = -.06; 95% CI: -.16 to -9.10-3). In conclusion, microbial dysbiosis might be associated with altered neural networks mediated by psychological distress in FM, emphasizing the critical role of the brain-gut axis in FM's non-pain symptoms and supporting further analysis of mechanism-targeted therapies to reduce FM symptoms. PERSPECTIVE: Our study suggests microbial dysbiosis might be associated with psychological distress and the altered salience network, supporting the role of brain-gut axis dysfunction in fibromyalgia pathomechanisms. Further targeting therapies for microbial dysbiosis should be investigated to manage fibromyalgia patients in the future.

Subcortical and default mode network connectivity is impaired in myalgic encephalomyelitis/chronic fatigue syndrome

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex chronic condition with core symptoms of fatigue and cognitive dysfunction, suggesting a key role for the central nervous system in the pathophysiology of this disease. Several studies have reported altered functional connectivity (FC) related to motor and cognitive deficits in ME/CFS patients. In this study, we compared functional connectivity differences between 31 ME/CFS and 15 healthy controls (HCs) using 7 Tesla MRI. Functional scans were acquired during a cognitive Stroop color-word task, and blood oxygen level-dependent (BOLD) time series were computed for 27 regions of interest (ROIs) in the cerebellum, brainstem, and salience and default mode networks. A region-based comparison detected reduced FC between the pontine nucleus and cerebellum vermis IX (p = 0.027) for ME/CFS patients compared to HCs. Our ROI-to-voxel analysis found significant impairment of FC within the ponto-cerebellar regions in ME/CFS. Correlation analyses of connectivity with clinical scores in ME/CFS patients detected associations between FC and 'duration of illness' and 'memory scores' in salience network hubs and cerebellum vermis and between FC and 'respiratory rate' within the medulla and the default mode network FC. This novel investigation is the first to report the extensive involvement of aberrant ponto-cerebellar connections consistent with ME/CFS symptomatology. This highlights the involvement of the brainstem and the cerebellum in the pathomechanism of ME/CFS.

Health outcomes of sensory hypersensitivities in myalgic encephalomyelitis/chronic fatigue syndrome and multiple sclerosis

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a poorly understood chronic illness with many case definitions that disagree on key symptoms, including hypersensitivities to noise and lights. The aim of the current study was to understand the prevalence rates and characteristics of these symptoms amongst people with ME/CFS and to compare them to people with another chronic illness, multiple sclerosis (MS). International datasets consisting of 2,240 people with either ME/CFS or MS have completed the DePaul Symptom Questionnaire (DSQ) and the Short Form Health Survey Questionnaire (SF-36). Hypersensitivities to noise and lights were indicated from items on the DSQ, and participants were analyzed against DSQ and SF-36 subscales through a multivariate analysis of covariance. There were significantly higher percentages of people with hypersensitivities in the ME/CFS sample compared to the MS sample. Regardless of illness, participants that exhibited both hypersensitivities reported greater symptomology than those without hypersensitivities. Healthcare providers and researchers should consider these symptoms when developing treatment plans and evaluating ME/CFS case diagnostic criteria.

ME/CFS and Long COVID share similar symptoms and biological abnormalities: road map to the literature

Some patients remain unwell for months after "recovering" from acute COVID-19. They develop persistent fatigue, cognitive problems, headaches, disrupted sleep, myalgias and arthralgias, post-exertional malaise, orthostatic intolerance and other symptoms that greatly interfere with their ability to function and that can leave some people housebound and disabled. The illness (Long COVID) is similar to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) as well as to persisting illnesses that can follow a wide variety of other infectious agents and following major traumatic injury. Together, these illnesses are projected to cost the U.S. trillions of dollars. In this review, we first compare the symptoms of ME/CFS and Long COVID, noting the considerable similarities and the few differences. We then compare in extensive detail the underlying pathophysiology of these two conditions, focusing on abnormalities of the central and autonomic nervous system, lungs, heart, vasculature, immune system, gut microbiome, energy metabolism and redox balance. This comparison highlights how strong the evidence is for each abnormality, in each illness, and helps to set priorities for future investigation. The review provides a current road map to the extensive literature on the underlying biology of both illnesses.

Converging Evidence of Similar Symptomatology of ME/CFS and PASC Indicating Multisystemic Dyshomeostasis

The purpose of this article is to review the evidence of similar symptomatology of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and post-acute sequelae of SARS-CoV-2 infection (PASC). Reanalysis of data from a study by Jason comparing symptom reports from two groups of ME/CFS and PASC patients shows a notably similar symptomatology. Symptom scores of the PASC group and the ME/CFS group correlated 0.902 (p < 0.0001) across items. The hypothesis is presented that ME/CFS and PASC are caused by a chronic state of multisystemic disequilibrium including endocrinological, immunological, and/or metabolic changes. The hypothesis holds that a changed set point persistently pushes the organism towards a pathological dysfunctional state which fails to reset. To use an analogy of a thermostat, if the ‘off switch’ of a thermostat intermittently stops working, for periods the house would become warmer and warmer without limit. The hypothesis draws on recent investigations of the Central Homeostasis Network showing multiple interconnections between the autonomic system, central nervous system, and brain stem. The hypothesis helps to explain the shared symptomatology of ME/CFS and PASC and the unpredictable, intermittent, and fluctuating pattern of symptoms of ME/CFS and PASC. The current theoretical approach remains speculative and requires in-depth investigation before any definite conclusions can be drawn.

Tai Chi increases functional connectivity and decreases chronic fatigue syndrome: A pilot intervention study with machine learning and fMRI analysis

BACKGROUND

The latest guidance on chronic fatigue syndrome (CFS) recommends exercise therapy. Tai Chi, an exercise method in traditional Chinese medicine, is reportedly helpful for CFS. However, the mechanism remains unclear. The present longitudinal study aimed to detect the influence of Tai Chi on functional brain connectivity in CFS.

METHODS

The study recruited 20 CFS patients and 20 healthy controls to receive eight sessions of Tai Chi exercise over a period of one month. Before the Tai Chi exercise, an abnormal functional brain connectivity for recognizing CFS was generated by a linear support vector model. The prediction ability of the structure was validated with a random forest classification under a permutation test. Then, the functional connections (FCs) of the structure were analyzed in the large-scale brain network after Tai Chi exercise while taking the changes in the Fatigue Scale-14, Pittsburgh Sleep Quality Index (PSQI), and the 36-item short-form health survey (SF-36) as clinical effectiveness evaluation. The registration number is ChiCTR2000032577 in the Chinese Clinical Trial Registry.

RESULTS

1) The score of the Fatigue Scale-14 decreased significantly in the CFS patients, and the scores of the PSQI and SF-36 changed significantly both in CFS patients and healthy controls. 2) Sixty FCs were considered significant to discriminate CFS (P = 0.000, best accuracy 90%), with 80.5% ± 9% average accuracy. 3) The FCs that were majorly related to the left frontoparietal network (FPN) and default mode network (DMN) significantly increased (P = 0.0032 and P = 0.001) in CFS patients after Tai Chi exercise. 4) The change of FCs in the left FPN and DMN were positively correlated (r = 0.40, P = 0.012).

CONCLUSION

These results demonstrated that the 60 FCs we found using machine learning could be neural biomarkers to discriminate between CFS patients and healthy controls. Tai Chi exercise may improve CFS patients' fatigue syndrome, sleep quality, and body health statement by strengthening the functional connectivity of the left FPN and DMN under these FCs. The findings promote our understanding of Tai Chi exercise's value in treating CFS.

Mindfulness Meditation Interventions for Long COVID: Biobehavioral Gene Expression and Neuroimmune Functioning

Some individuals infected with SARS CoV-2 have developed Post-Acute Sequelae of SARS CoV-2 infection (PASC) or what has been referred to as Long COVID. Efforts are underway to find effective treatment strategies for those with Long COVID. One possible approach involves alternative medical interventions, which have been widely used to treat and manage symptoms of a variety of medical problems including post-viral infections. Meditation has been found to reduce fatigue and unrefreshing sleep, and for those with post-viral infections, it has enhanced immunity, and reduced inflammatory-driven pathogenesis. Our article summarizes the literature on what is known about mindfulness meditation interventions, and reviews evidence on how it may apply to those with Long COVID and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Evidence is reviewed suggesting effective and sustainable outcomes may be achieved for symptomatology and underlying pathology of post-viral fatigue (PASC and ME/CFS).

Altered Effective Connectivity of Resting-State Networks by Tai Chi Chuan in Chronic Fatigue Syndrome Patients: A Multivariate Granger Causality Study

Numerous evidence has shown that patients with chronic fatigue syndrome (CFS) have changes in resting brain functional connectivity, but there is no study on the brain network effect of Tai Chi Chuan intervention in CFS. To explore the influence of Tai Chi Chuan exercise on the causal relationship between brain functional networks in patients with CFS, 21 patients with CFS and 19 healthy controls were recruited for resting-state functional magnetic resonance imaging (rs-fMRI) scanning and 36-item Short-Form Health Survey (SF-36) scale assessment before and after 1month-long training in Tai Chi Chuan. We extracted the resting brain networks using the independent component analysis (ICA) method, analyzed the changes of FC in these networks, conducted Granger causality analysis (GCA) on it, and analyzed the correlation between the difference causality value and the SF-36 scale. Compared to the healthy control group, the SF-36 scale scores of patients with CFS were lower at baseline. Meanwhile, the causal relationship between sensorimotor network (SMN) and default mode network (DMN) was weakened. The above abnormalities could be improved by Tai Chi Chuan training for 1 month. In addition, the correlation analyses showed that the causal relationship between SMN and DMN was positively correlated with the scores of Role Physical (RP) and Bodily Pain (BP) in CFS patients, and the change of causal relationship between SMN and DMN before and after training was positively correlated with the change of BP score. The findings suggest that Tai Chi Chuan is helpful to improve the quality of life for patients with CFS. The change of Granger causality between SMN and DMN may be a readout parameter of CFS. Tai Chi Chuan may promote the functional plasticity of brain networks in patients with CFS by regulating the information transmission between them.

Chronic Fatigue in Cancer, Brain Connectivity and Reluctance to Engage in Physical Activity: A Mini-Review

A large amount of evidence shows that after a cancer diagnosis, patients significantly reduce their level of physical activity. Usually, this reduction is attributed to cancer-related fatigue. However, to our knowledge, no study has clearly demonstrated that fatigue alters effort-based decision-making in cancer. This mini-review aimed to provide evidence that chronic fatigue in cancer patients causes changes in brain connectivity that impact effort-based decision-making. Indeed, three patterns of activation to compensate for dysfunctional networks have been reported: greater variability in the executive network and hyperactivation in the executive network, which account for less efficient and costly processes in the frontal cortex, and reduced deactivation in the default mode network. Nevertheless, these activation patterns are also observed with other factors, such as anticipatory stressors (worry, rumination or sleep loss), that might also cause reluctance to engage in physical activity. Effort-based decision-making involving weighing costs against benefits and physical activity interventions should increase immediate benefits to facilitate engagement in effortful activities.

Insights from myalgic encephalomyelitis/chronic fatigue syndrome may help unravel the pathogenesis of postacute COVID-19 syndrome

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause chronic and acute disease. Postacute sequelae of SARS-CoV-2 infection (PASC) include injury to the lungs, heart, kidneys, and brain that may produce a variety of symptoms. PASC also includes a post-coronavirus disease 2019 (COVID-19) syndrome ('long COVID') with features that can follow other acute infectious diseases and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Here we summarize what is known about the pathogenesis of ME/CFS and of 'acute' COVID-19, and we speculate that the pathogenesis of post-COVID-19 syndrome in some people may be similar to that of ME/CFS. We propose molecular mechanisms that might explain the fatigue and related symptoms in both illnesses, and we suggest a research agenda for both ME/CFS and post-COVID-19 syndrome.

Modulatory effects of cognitive exertion on regional functional connectivity of the salience network in women with ME/CFS: A pilot study

BACKGROUND

A common symptom of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is post-exertional malaise (PEM). Various brain abnormalities have been observed in patients with ME/CFS, especially in insular and limbic areas, but their link with ME/CFS symptoms is still unclear. This pilot study aimed at investigating the association between PEM in ME/CFS and changes in functional connectivity (FC) of two main networks: the salience network (SN) and the default-mode network (DMN).

METHODS

A total of 16 women, 6 with and 10 without ME/CFS, underwent clinical and MRI assessment before and after cognitive exertion. Resting-state FC maps of 7 seeds (3 for the SN and 4 for the DMN) and clinical measures of fatigue, pain and cognition were analysed with repeated-measure models. FC-symptom change associations were also investigated.

RESULTS

Exertion induced increases in fatigue and pain in patients with ME/CFS compared to the control group, while no changes were found in cognitive performance. At baseline, patients showed altered FC between some DMN seeds and frontal areas and stronger FC between all SN seeds and left temporal areas and the medulla. Significantly higher FC increases in patients than in controls were found only between the right insular seed and frontal and subcortical areas; these increases correlated with worsening of symptoms.

CONCLUSIONS

Cognitive exertion can induce worsening of ME/CFS-related symptoms. These changes were here associated with strengthening of FC of the right insula with areas involved in reward processing and cognitive control.

Using functional connectivity changes associated with cognitive fatigue to delineate a fatigue network

Cognitive fatigue, or fatigue related to mental work, is a common experience. A growing body of work using functional neuroimaging has identified several regions that appear to be related to cognitive fatigue and that potentially comprise a "fatigue network". These include the striatum of the basal ganglia, the dorsolateral prefrontal cortex (DLPFC), the dorsal anterior cingulate cortex (dACC), the ventro-medial prefrontal cortex (vmPFC) and the anterior insula. However, no work has been conducted to assess whether the connectivity between these regions changes as a function of cognitive fatigue. We used a task-based functional neuroimaging paradigm to induce fatigue in 39 healthy individuals, regressed the signal associated with the task out of the data, and investigated how the functional connectivity between these regions changed as cognitive fatigue increased. We observed functional connectivity between these regions and other frontal regions largely decreased as cognitive fatigue increased while connectivity between these seeds and more posterior regions increased. Furthermore the striatum, the DLPFC, the insula and the vmPFC appeared to be central 'nodes' or hubs of the fatigue network. These findings represent the first demonstration that the functional connectivity between these areas changes as a function of cognitive fatigue.

Using structural and functional MRI as a neuroimaging technique to investigate chronic fatigue syndrome/myalgic encephalopathy: a systematic review

OBJECTIVE

This systematic review aims to synthesise and evaluate structural MRI (sMRI) and functional MRI (fMRI) studies in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME).

METHODS

We systematically searched Medline and Ovid and included articles from 1991 (date of Oxford diagnostic criteria for CFS/ME) to first April 2019. Studies were selected by predefined inclusion and exclusion criteria. Two reviewers independently reviewed the titles and abstracts to determine articles for inclusion, full text and quality assessment for risk of bias.

RESULTS

sMRI studies report differences in CFS/ME brain anatomy in grey and white matter volume, ventricular enlargement and hyperintensities. Three studies report no neuroanatomical differences between CFS/ME and healthy controls. Task-based fMRI investigated working memory, attention, reward and motivation, sensory information processing and emotional conflict. The most consistent finding was CFS/ME exhibited increased activations and recruited additional brain regions. Tasks with increasing load or complexity produced decreased activation in task-specific brain regions.

CONCLUSIONS

There were insufficient data to define a unique neural profile or biomarker of CFS/ME. This may be due to inconsistencies in finding neuroanatomical differences in CFS/ME and the variety of different tasks employed by fMRI studies. But there are also limitations with neuroimaging. All brain region specific volumetric differences in CFS/ME were derived from voxel-based statistics that are biased towards group differences that are highly localised in space. fMRI studies demonstrated both increases and decreases in activation patterns in CFS/ME, this may be related to task demand. However, fMRI signal cannot differentiate between neural excitation and inhibition or function-specific neural processing. Many studies have small sample sizes and did not control for the heterogeneity of this clinical population. We suggest that with robust study design, subgrouping and larger sample sizes, future neuroimaging studies could potentially lead to a breakthrough in our understanding of the disease.

Myalgic encephalomyelitis/chronic fatigue syndrome: From pathophysiological insights to novel therapeutic opportunities

Myalgic encephalomyelitis (ME) or chronic fatigue syndrome (CFS) is a common and disabling condition with a paucity of effective and evidence-based therapies, reflecting a major unmet need. Cognitive behavioural therapy and graded exercise are of modest benefit for only some ME/CFS patients, and many sufferers report aggravation of symptoms of fatigue with exercise. The presence of a multiplicity of pathophysiological abnormalities in at least the subgroup of people with ME/CFS diagnosed with the current international consensus "Fukuda" criteria, points to numerous potential therapeutic targets. Such abnormalities include extensive data showing that at least a subgroup has a pro-inflammatory state, increased oxidative and nitrosative stress, disruption of gut mucosal barriers and mitochondrial dysfunction together with dysregulated bioenergetics. In this paper, these pathways are summarised, and data regarding promising therapeutic options that target these pathways are highlighted; they include coenzyme Q₁₀, melatonin, curcumin, molecular hydrogen and N-acetylcysteine. These data are promising yet preliminary, suggesting hopeful avenues to address this major unmet burden of illness.

Functional and structural magnetic resonance imaging correlates of fatigue in patients with rheumatoid arthritis

Objectives

Fatigue is a major burden among patients with RA, yet is poorly understood. We sought to conduct the first imaging study to investigate the neurobiological correlates of fatigue in RA and to improve upon the methodological limitations of previous neuroimaging studies that have investigated this symptom in other populations.

Methods

Chronically fatigued RA patients were clinically characterized before undertaking a combined functional and structural mode MRI brain scan. The functional sequences were acquired during a fatigue-evoking task, then network-to-whole-brain analyses were undertaken. The structural analyses employed voxel-based morphometry in order to quantify regional grey matter volume. The scan was repeated 6 months later to test reproducibility.

Results

Fifty-four participants attended both scans [n = 41 female; baseline mean (s.d.) age 54.94 (11.41) years]. A number of significant functional and structural neural imaging correlates of fatigue were identified. Notably, patients who reported higher levels of fatigue demonstrated higher levels of functional connectivity between the Dorsal Attention Network and medial prefrontal gyri, a finding that was reproduced in the repeat scans. Structurally, greater putamen grey matter volumes significantly correlated with greater levels of fatigue.

Conclusion

Fatigue in RA is associated with functional and structural MRI changes in the brain. The newly identified and reproduced neural imaging correlates provide a basis for future targeting and stratification of this key patient priority.

Myalgic encephalomyelitis or chronic fatigue syndrome: how could the illness develop?

A model of the development and progression of chronic fatigue syndrome (myalgic encephalomyelitis), the aetiology of which is currently unknown, is put forward, starting with a consideration of the post-infection role of damage-associated molecular patterns and the development of chronic inflammatory, oxidative and nitrosative stress in genetically predisposed individuals. The consequences are detailed, including the role of increased intestinal permeability and the translocation of commensal antigens into the circulation, and the development of dysautonomia, neuroinflammation, and neurocognitive and neuroimaging abnormalities. Increasing levels of such stress and the switch to immune and metabolic downregulation are detailed next in relation to the advent of hypernitrosylation, impaired mitochondrial performance, immune suppression, cellular hibernation, endotoxin tolerance and sirtuin 1 activation. The role of chronic stress and the development of endotoxin tolerance via indoleamine 2,3-dioxygenase upregulation and the characteristics of neutrophils, monocytes, macrophages and T cells, including regulatory T cells, in endotoxin tolerance are detailed next. Finally, it is shown how the immune and metabolic abnormalities of chronic fatigue syndrome can be explained by endotoxin tolerance, thus completing the model.

Attentional bias modification alters intrinsic functional network of attentional control: A randomized controlled trial

INTRODUCTION

Attentional bias modification (ABM) alleviates anxiety by moderating biased attentional processing toward threat; however, its neural mechanisms remain unclear. We examined how ABM changes functional connectivity (FC) and functional network measures, leading to anxiety reduction.

METHODS

Fifty-four healthy anxious individuals received either ABM or sham training for 1 month in a double-blind randomized controlled trial. Anxious traits, attentional control, and attentional bias were assessed. Thirty-five participants completed resting-state functional magnetic resonance imaging (MRI) scans before and after training.

RESULTS

ABM significantly mitigated an anxious traits regarding physical stress vulnerability (η² = 0.12, p = 0.009). As compared to sham training, ABM significantly strengthened FC between the pulvinar and transverse temporal gyrus along the temporoparietal junction (T = 3.90, ^{FDR-corrected}p = 0.010), whereas it decreased FC between the postCG and ventral fronto-parietal network (vFPN) regions such as the anterior insula and ventrolateral prefrontal cortex (all T ≤ - 3.19, ^{FDR-corrected}p ≤ 0.034). Although ABM diminished network measures of the postcentral gyrus (postCG) (all T ≤ - 4.30, ^{FDR-corrected}p ≤ 0.006), only the pulvinar-related FC increase was specifically correlated with anxiety reduction (r = - 0.46, p = 0.007).

LIMITATIONS

Per-protocol analysis and reduced sample size in MRI analysis.

CONCLUSIONS

ABM might augment the pulvinar's control over vFPN to maintain endogenous attention to a behavioral goal, while diminishing the information exchanges of the postCG with vFPN to inhibit the capture of exogenous attention by potential threats. The pulvinar might play a critical role in ABM anxiolytic efficacy.

Structural brain changes versus self-report: machine-learning classification of chronic fatigue syndrome patients

Chronic fatigue syndrome (CFS) is a disorder associated with fatigue, pain, and structural/functional abnormalities seen during magnetic resonance brain imaging (MRI). Therefore, we evaluated the performance of structural MRI (sMRI) abnormalities in the classification of CFS patients versus healthy controls and compared it to machine learning (ML) classification based upon self-report (SR). Participants included 18 CFS patients and 15 healthy controls (HC). All subjects underwent T1-weighted sMRI and provided visual analogue-scale ratings of fatigue, pain intensity, anxiety, depression, anger, and sleep quality. sMRI data were segmented using FreeSurfer and 61 regions based on functional and structural abnormalities previously reported in patients with CFS. Classification was performed in RapidMiner using a linear support vector machine and bootstrap optimism correction. We compared ML classifiers based on (1) 61 a priori sMRI regional estimates and (2) SR ratings. The sMRI model achieved 79.58% classification accuracy. The SR (accuracy = 95.95%) outperformed both sMRI models. Estimates from multiple brain areas related to cognition, emotion, and memory contributed strongly to group classification. This is the first ML-based group classification of CFS. Our findings suggest that sMRI abnormalities are useful for discriminating CFS patients from HC, but SR ratings remain most effective in classification tasks.

Hyperintense sensorimotor T1 spin echo MRI is associated with brainstem abnormality in chronic fatigue syndrome

We recruited 43 Chronic Fatigue Syndrome (CFS) subjects who met Fukuda criteria and 27 healthy controls and performed 3T MRI T1 and T2 weighted spin-echo (T1wSE and T2wSE) scans. T1wSE signal follows T1 relaxation rate (1/T1 relaxation time) and responds to myelin and iron (ferritin) concentrations. We performed MRI signal level group comparisons with SPM12. Spatial normalization after segmentation was performed using T2wSE scans and applied to the coregistered T1wSE scans. After global signal-level normalization of individual scans, the T1wSE group comparison detected decreased signal-levels in CFS in a brainstem region (cluster-based inference controlled for family wise error rate, P_FWE= 0.002), and increased signal-levels in large bilateral clusters in sensorimotor cortex white matter (cluster P_FWE < 0.0001). Moreover, the brainstem T1wSE values were negatively correlated with the sensorimotor values for both CFS (R² = 0.31, P = 0.00007) and healthy controls (R² = 0.34, P = 0.0009), and the regressions were co-linear. This relationship, previously unreported in either healthy controls or CFS, in view of known thalamic projection-fibre plasticity, suggests brainstem conduction deficits in CFS may stimulate the upregulation of myelin in the sensorimotor cortex to maintain brainstem - sensorimotor connectivity. VBM did not find group differences in regional grey matter or white matter volumes. We argued that increased T1wSE observed in sensorimotor WM in CFS indicates increased myelination which is a regulatory response to deficits in the brainstem although the causality cannot be tested in this study. Altered brainstem myelin may have broad consequences for cerebral function and should be a focus of future research.

Brain function characteristics of chronic fatigue syndrome: A task fMRI study

The mechanism underlying neurological dysfunction in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is yet to be established. This study investigated the temporal complexity of blood oxygenation level dependent (BOLD) changes in response to the Stroop task in CFS patients. 43 CFS patients (47.4 ± 11.8 yrs) and 26 normal controls (NCs, 43.4 ± 13.9 yrs) were included in this study. Their mental component summary (MCS) and physical component summary (PCS) from the 36-item Short Form Health Survey (SF-36) questionnaire were recorded. Their Stroop colour-word task performance was measured by accuracy and response time (RT). The BOLD changes associated with the Stroop task were evaluated using a 2-level general linear model approach. The temporal complexity of the BOLD responses, a measure of information capacity and thus adaptability to a challenging environment, in each activated region was measured by sample entropy (SampEn). The CFS patients showed significantly longer RTs than the NCs (P < 0.05) but no significant difference in accuracy. One sample t-tests for the two groups (Family wise error adjusted PFWE < 0.05) showed more BOLD activation regions in the CFS, although a two sample group comparison did not show significant difference. BOLD SampEns in ten regions were significantly lower (FDR-q < 0.05) in CFS patients. BOLD SampEns in 15 regions were significantly associated with PCS (FDR-q < 0.05) and in 9 regions were associated with MCS (FDR-q < 0.05) across all subjects. SampEn of the BOLD signal in the medioventral occipital cortex could explain 40% and 31% of the variance in the SF-36 PCS and MCS scores, and those in the precentral gyrus could explain an additional 16% and 7% across all subjects. This is the first study to investigate BOLD signal SampEn in response to tasks in CFS. The results suggest the brain responds differently to a cognitive challenge in patients with CFS, with recruitment of wider regions to compensate for lower information capacity.

Resting-state fMRI signals in offspring of parents with bipolar disorder at the high-risk and ultra-high-risk stages and their relations with cognitive function

BACKGROUND

Bipolar disorder (BD) has been associated with dysfunctional resting-state brain functioning. However, it is still not known whether the aberrant functioning occurs and predict cognitive functioning before illness onset.

AIMS

We examined the resting-state regional and network dysfunctioning, and their correlates with neurocognitive performance, in the high-risk (HR) and ultra-high-risk (UHR) stages of bipolar disorder.

METHODS

Using amplitude of low-frequency fluctuations (ALFF), region homogeneity (ReHo) and hypothesis-driven region-of-interest (ROI)-based connectivity, we examined resting-state fMRI data of 8- to 25-year-old healthy offspring (HR, n = 28) and offspring with subthreshold syndromes (UHR, n = 22) of a BD parent, and age-matched healthy controls without any personal or family psychopathology (HC, n = 46). Participants' neurocognitive profiles were assessed using the MATRICS Consensus Cognitive Battery (MCCB).

RESULTS

ALFF signals in the left putamen and right rolandic operculum were lower in the HR group compared to the HC group. In contrast, ALFF signals were increased in the UHR group in the right middle pars orbitalis of the inferior frontal gyrus, right calcarine sulcus and right cerebellum. Connectivities between the right amygdala and left inferior temporal gyrus, between the left hippocampus and inferior occipital gyrus, and between the left hippocampus and middle pars orbitalis gyrus were decreased in the HR group compared to the HC group. In UHR versus HC group, connectivity between the right amygdala and the left hippocampus and left insula was increased, and connectivity between the left hippocampus and the left insula and the cerebellum was also increased. Among cognitive measures, processing speed was positively correlated with ALFF signals in the left putamen in the HR offspring. In the UHR offspring, processing speed, attention, and verbal learning/memory were positively correlated with the functional connectivity between the left hippocampus and cerebellum.

CONCLUSIONS

Offspring of parents with BD in the HR and UHR stages show largely non-overlapping patterns of atypical resting-state signals and functional connectivity that predicted cognitive functioning, possibly reflecting inherited abnormalities and/or complimentary reactions.

Neural mechanisms of mental fatigue elicited by sustained auditory processing

Despite growing evidence that prolonged episodes of effortful listening can lead to mental fatigue, little work has been done to examine the patterns of brain activation associated with listening over time. In order to gain a better understanding of the nature of listening-related mental fatigue, this study characterized the effects of sustained auditory processing on brain activation in 19 adults with normal hearing. A 50-min, auditory choice paradigm served as the fatiguing task. Mental fatigue was quantified using subjective (self-report) and behavioral (response time and accuracy) measures, as well as event-related potential (ERP) measures indexing motivation (error-related negativity; ERN) and general arousal (N1). Additional electrical neuroimaging analyses were carried out on ERP datasets. Subjective and behavioral results confirmed that participants became fatigued during the auditory task (data from the first 25min compared with the second 25min). ERPs revealed changes in neural activity consistent with decreased arousal (reduced N1 amplitude). Topographical analyses indicated decreased brain activation, without a change in underlying neural network configuration. Regions of decreased brain activation, as estimated via electrical neuroimaging, suggested a decrease in attention to task stimulus-response characteristics (reduced activation in regions associated with the dorsal attention network). The decrease in mean N1 amplitude revealed a significant, positive correlation with subjective report of reduced motivation. These findings support existing cognitive and neurophysiological models that suggest mental fatigue builds over time on task, and affects motivation to influence task performance. Furthermore, this study shows sustained auditory processing can elicit mental fatigue, and that dorsal parietal activity might provide a useful method of measuring its effects.

Medial prefrontal cortex deficits correlate with unrefreshing sleep in patients with chronic fatigue syndrome

Unrefreshing sleep is a hallmark of chronic fatigue syndrome/myalgic encephalomyelitis (CFS). This study examined brain structure variations associated with sleep quality in patients with CFS. 38 patients with CFS (34.8 ± 10.1 years old) and 14 normal controls (NCs) (34.7 ± 8.4 years old) were recruited. All subjects completed the Hospital Anxiety and Depression Scale, Pittsburgh Sleep Quality Index (PSQI), and Chalder Fatigue Scale (CFQ) questionnaires. Brain MRI measures included global and regional grey and white matter volumes, magnetization transfer T₁ weighted (MT-T1w) intensities, and T₁ weighted (T1w) and T₂ weighted spin echo signal intensities. We performed voxel based group comparisons of these regional brain MRI measures and regressions of these measures with the PSQI and CFQ scales adjusted for age, anxiety and depression, and the appropriate global measure. In CFS patients, negative correlations were observed in the medial prefrontal cortex (mPFC) between PSQI and MT-T1w intensities (family-wise error corrected cluster, P_FWE  < 0.05) and between PSQI and T1w intensities (P_FWE  < 0.05). In the same mPFC location, both MT and T1w intensities were lower in CFS patients compared with NCs (uncorrected voxel P < 0.001). This study is the first to report that brain structural differences are associated with unrefreshing sleep in CFS. This result refutes the suggestion that unrefreshing sleep is a misperception in CFS patients and further investigation of this symptom is warranted.

Grey and white matter differences in Chronic Fatigue Syndrome - A voxel-based morphometry study

OBJECTIVE

Investigate global and regional grey and white matter volumes in patients with Chronic Fatigue Syndrome (CFS) using magnetic resonance imaging (MRI) and recent voxel-based morphometry (VBM) methods.

METHODS

Forty-two patients with CFS and thirty healthy volunteers were scanned on a 3-Tesla MRI scanner. Anatomical MRI scans were segmented, normalized and submitted to a VBM analysis using randomisation methods. Group differences were identified in overall segment volumes and voxel-wise in spatially normalized grey matter (GM) and white matter (WM) segments.

RESULTS

Accounting for total intracranial volume, patients had larger GM volume and lower WM volume. The voxel-wise analysis showed increased GM volume in several structures including the amygdala and insula in the patient group. Reductions in WM volume in the patient group were seen primarily in the midbrain, pons and right temporal lobe.

CONCLUSION

Elevated GM volume in CFS is seen in areas related to processing of interoceptive signals and stress. Reduced WM volume in the patient group partially supports earlier findings of WM abnormalities in regions of the midbrain and brainstem.

Altered right anterior insular connectivity and loss of associated functions in adolescent chronic fatigue syndrome

Impairments in cognition, pain intolerance, and physical inactivity characterize adolescent chronic fatigue syndrome (CFS), yet little is known about its neurobiology. The right dorsal anterior insular (dAI) connectivity of the salience network provides a motivational context to stimuli. In this study, we examined regional functional connectivity (FC) patterns of the right dAI in adolescent CFS patients and healthy participants. Eighteen adolescent patients with CFS and 18 aged-matched healthy adolescent control participants underwent resting-state functional magnetic resonance imaging. The right dAI region of interest was examined in a seed-to-voxel resting-state FC analysis using SPM and CONN toolbox. Relative to healthy adolescents, CFS patients demonstrated reduced FC of the right dAI to the right posterior parietal cortex (PPC) node of the central executive network. The decreased FC of the right dAI–PPC might indicate impaired cognitive control development in adolescent CFS. Immature FC of the right dAI–PPC in patients also lacked associations with three known functional domains: cognition, pain and physical activity, which were observed in the healthy group. These results suggest a distinct biological signature of adolescent CFS and might represent a fundamental role of the dAI in motivated behavior.

A Comparison of Neuroimaging Abnormalities in Multiple Sclerosis, Major Depression and Chronic Fatigue Syndrome (Myalgic Encephalomyelitis): is There a Common Cause?

There is copious evidence of abnormalities in resting-state functional network connectivity states, grey and white matter pathology and impaired cerebral perfusion in patients afforded a diagnosis of multiple sclerosis, major depression or chronic fatigue syndrome (CFS) (myalgic encephalomyelitis). Systemic inflammation may well be a major element explaining such findings. Inter-patient and inter-illness variations in neuroimaging findings may arise at least in part from regional genetic, epigenetic and environmental variations in the functions of microglia and astrocytes. Regional differences in neuronal resistance to oxidative and inflammatory insults and in the performance of antioxidant defences in the central nervous system may also play a role. Importantly, replicated experimental findings suggest that the use of high-resolution SPECT imaging may have the capacity to differentiate patients afforded a diagnosis of CFS from those with a diagnosis of depression. Further research involving this form of neuroimaging appears warranted in an attempt to overcome the problem of aetiologically heterogeneous cohorts which probably explain conflicting findings produced by investigative teams active in this field. However, the ionising radiation and relative lack of sensitivity involved probably preclude its use as a routine diagnostic tool.

Role of Inflammation in Human Fatigue: Relevance of Multidimensional Assessments and Potential Neuronal Mechanisms

Fatigue is a highly disabling symptom in various medical conditions. While inflammation has been suggested as a potential contributor to the development of fatigue, underlying mechanisms remain poorly understood. In this review, we propose that a better assessment of central fatigue, taking into account its multidimensional features, could help elucidate the role and mechanisms of inflammation in fatigue development. A description of the features of central fatigue is provided, and the current evidence describing the association between inflammation and fatigue in various medical conditions is reviewed. Additionally, the effect of inflammation on specific neuronal processes that may be involved in distinct fatigue dimensions is described. We suggest that the multidimensional aspects of fatigue should be assessed in future studies of inflammation-induced fatigue and that this would benefit the development of effective therapeutic interventions.

Low putamen activity associated with poor reward sensitivity in childhood chronic fatigue syndrome

Motivational signals influence a wide variety of cognitive processes and components of behavioral performance. Cognitive dysfunction in patients with childhood chronic fatigue syndrome (CCFS) may be closely associated with a low motivation to learn induced by impaired neural reward processing. However, the extent to which reward processing is impaired in CCFS patients is unclear. The aim of the present functional magnetic resonance imaging (fMRI) study was to determine whether brain activity in regions related to reward sensitivity is impaired in CCFS patients. fMRI data were collected from 13 CCFS patients (mean age, 13.6 ± 1.0 years) and 13 healthy children and adolescents (HCA) (mean age, 13.7 ± 1.3 years) performing a monetary reward task. Neural activity in high- and low-monetary-reward conditions was compared between CCFS and HCA groups. Severity of fatigue and the reward obtained from learning in daily life were evaluated by questionnaires. Activity of the putamen was lower in the CCFS group than in the HCA group in the low-reward condition, but not in the high-reward condition. Activity of the putamen in the low-reward condition in CCFS patients was negatively and positively correlated with severity of fatigue and the reward from learning in daily life, respectively. We previously revealed that motivation to learn was correlated with striatal activity, particularly the neural activity in the putamen. This suggests that in CCFS patients low putamen activity, associated with altered dopaminergic function, decreases reward sensitivity and lowers motivation to learn.