Tag: Barnden

Stroop task and practice effects demonstrate cognitive dysfunction in long COVID and myalgic encephalomyelitis / chronic fatigue syndrome

Abstract:

Background: The Stroop task was used to investigate differences in cognitive function between Long COVID (LC), Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME/CFS) and healthy control subjects.

Methods: Subjects viewed four color words or neutral (XXXX) stimuli with the same (congruent) or different color ink (incongruent). Cognitive conflict was inferred from response times for pairings of prestimuli and subsequent stimuli. Overall effects were assessed by univariate analysis with time courses determined for binned response times.

Results: LC and ME/CFS had significantly longer response times than controls indicating cognitive dysfunction. Initial response times were ranked LC > ME > HC, and decreased according to power functions. At the end of the task (900s), times were ranked LC = ME > HC. Response times were significantly slower for stimuli following an incongruent prestimulus. Time series for Stroop effect, facilitation, interference, surprise index and practice power law parameters were generally similar in LC, ME/CFS and HC suggesting comparable patterns for recruitment of cognitive resources. The prestimulus data were analyzed and generated positive Stroop and interference effects that were distinct from stimulus effects.

Conclusion: LC and ME/CFS have global slowing of response times that cannot be overcome by practice suggesting impaired communications between network nodes during problem solving. Analysis of matched prestimulus – stimulus effects adds a new dimension for understanding cognitive conflict.

Brief summary: Cognitive dysfunction in Long COVID and ME/CFS was demonstrated using the Stroop task which found global slowing of response times and limitations of practice effects.

Source: Baraniuk JN, Thapaliya K, Inderyas M, Shan ZY, Barnden LR. Stroop task and practice effects demonstrate cognitive dysfunction in long COVID and myalgic encephalomyelitis / chronic fatigue syndrome. Sci Rep. 2024 Nov 5;14(1):26796. doi: 10.1038/s41598-024-75651-3. PMID: 39500939; PMCID: PMC11538523. https://pmc.ncbi.nlm.nih.gov/articles/PMC11538523/ (Full text)

Imbalanced Brain Neurochemicals in long COVID and ME/CFS: A Preliminary Study using MRI

Abstract:

Purpose: Long COVID and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) patients experience multiple complex symptoms, potentially linked to imbalances in brain neurochemicals. This study aims to measure brain neurochemical levels in long COVID and ME/CFS patients as well as healthy controls to investigate associations with severity measures.

Methods: Magnetic resonance spectroscopy (MRS) data was acquired with a 3T Prisma MRI scanner. We measured absolute levels of brain neurochemicals in the posterior cingulate cortex in long COVID (n=17), ME/CFS (n=17), and healthy controls (n=10) using Osprey software. The statistical analyses were performed using SPSS version 29. Age and sex were included as nuisance covariates.

Results: Glutamate levels were significantly higher in long COVID (p=0.02) and ME/CFS (p=0.017) than in healthy controls. No significant difference was found between the two patient cohorts. Additionally, N-acetyl-aspartate levels were significantly higher in long COVID patients (p=0.012). Importantly, brain neurochemical levels were associated with self-reported severity measures in long COVID and ME/CFS.

Conclusion: Our study identified significantly elevated Glutamate and N-acetyl-aspartate levels in long COVID and ME/CFS patients compared with healthy controls. No significant differences in brain neurochemicals were observed between the two patient cohorts, suggesting a potential overlap in their underlying pathology. These findings suggest that imbalanced neurochemicals contribute to the complex symptoms experienced by long COVID and ME/CFS patients.

Source: Thapaliya K, Marshall-Gradisnik S, Eaton-Fitch N, Eftekhari Z, Inderyas M, Barnden L. Imbalanced Brain Neurochemicals in long COVID and ME/CFS: A Preliminary Study using MRI. Am J Med. 2024 Apr 6:S0002-9343(24)00216-X. doi: 10.1016/j.amjmed.2024.04.007. Epub ahead of print. PMID: 38588934. https://www.sciencedirect.com/science/article/pii/S000293432400216X (Full text)

Subcortical and Default Mode Network connectivity is impaired in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

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 (HC) 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.

Region-based comparison detected reduced FC between the pontine nucleus and cerebellum vermis IX (p=0.027) for ME/CFS patients compared to HC. Our ROI-to-voxel analysis found significant impairment of FC within ponto-cerebellar regions in ME/CFS. Correlation analyses of connectivity with clinical scores in ME/CFS patients detected associations of FC with ‘duration of illness’ and ‘memory scores’ in salience network hubs and cerebellum vermis, and with ‘respiratory rate’ within medulla and the default mode network FC.

This novel investigation is the first to report 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.

Source: Maira INDERYAS, Kiran Thapaliya, Sonya Marshall-Gradisnik, Markus Barth, Leighton Barnden. Subcortical and Default Mode Network connectivity is impaired in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Front. Neurosci. Sec. Brain Imaging Methods. Volume 17 – 2023 | doi: 10.3389/fnins.2023.1318094 https://www.frontiersin.org/articles/10.3389/fnins.2023.1318094/full (Full text)

Altered brain connectivity in Long Covid during cognitive exertion: a pilot study

Abstract:

Introduction: Debilitating Long-Covid symptoms occur frequently after SARS-COVID-19 infection.

Methods: Functional MRI was acquired in 10 Long Covid (LCov) and 13 healthy controls (HC) with a 7 Tesla scanner during a cognitive (Stroop color-word) task. BOLD time series were computed for 7 salience and 4 default-mode network hubs, 2 hippocampus and 7 brainstem regions (ROIs). Connectivity was characterized by the correlation coefficient between each pair of ROI BOLD time series. We tested for HC versus LCov differences in connectivity between each pair of the 20 regions (ROI-to-ROI) and between each ROI and the rest of the brain (ROI-to-voxel). For LCov, we also performed regressions of ROI-to-ROI connectivity with clinical scores.

Results: Two ROI-to-ROI connectivities differed between HC and LCov. Both involved the brainstem rostral medulla, one connection to the midbrain, another to a DM network hub. Both were stronger in LCov than HC. ROI-to-voxel analysis detected multiple other regions where LCov connectivity differed from HC located in all major lobes. Most, but not all connections, were weaker in LCov than HC. LCov, but not HC connectivity, was correlated with clinical scores for disability and autonomic function and involved brainstem ROI.

Discussion: Multiple connectivity differences and clinical correlations involved brainstem ROIs. Stronger connectivity in LCov between the medulla and midbrain may reflect a compensatory response. This brainstem circuit regulates cortical arousal, autonomic function and the sleep-wake cycle. In contrast, this circuit exhibited weaker connectivity in ME/CFS. LCov connectivity regressions with disability and autonomic scores were consistent with altered brainstem connectivity in LCov.

Source: Barnden L, Thapaliya K, Eaton-Fitch N, Barth M, Marshall-Gradisnik S. Altered brain connectivity in Long Covid during cognitive exertion: a pilot study. Front Neurosci. 2023 Jun 22;17:1182607. doi: 10.3389/fnins.2023.1182607. PMID: 37425014; PMCID: PMC10323677. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10323677/ (Full text)

Brainstem volume changes in myalgic encephalomyelitis/chronic fatigue syndrome and long COVID patients

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and long COVID patients have overlapping neurological, autonomic, pain, and post-exertional symptoms. We compared volumes of brainstem regions for 10 ME/CFS (CCC or ICC criteria), 8 long COVID (WHO Delphi consensus), and 10 healthy control (HC) subjects on 3D, T1-weighted MRI images acquired using sub-millimeter isotropic resolution using an ultra-high field strength of 7 Tesla.

Group comparisons with HC detected significantly larger volumes in ME/CFS for pons (p = 0.004) and whole brainstem (p = 0.01), and in long COVID for pons (p = 0.003), superior cerebellar peduncle (p = 0.009), and whole brainstem (p = 0.005). No significant differences were found between ME/CFS and long COVID volumes. In ME/CFS, we detected positive correlations between the pons and whole brainstem volumes with “pain” and negative correlations between the midbrain and whole brainstem volumes with “breathing difficulty.”

In long COVID patients a strong negative relationship was detected between midbrain volume and “breathing difficulty.” Our study demonstrated an abnormal brainstem volume in both ME/CFS and long COVID consistent with the overlapping symptoms.

Source: Thapaliya K, Marshall-Gradisnik S, Barth M, Eaton-Fitch N, Barnden L. Brainstem volume changes in myalgic encephalomyelitis/chronic fatigue syndrome and long COVID patients. Frontiers in Neuroscience, 2023 March 2; 17:1125208. https://www.frontiersin.org/articles/10.3389/fnins.2023.1125208/full (Full text)

Anti-Correlated Myelin-Sensitive MRI Levels in Humans Consistent with a Subcortical to Sensorimotor Regulatory Process-Multi-Cohort Multi-Modal Evidence

Abstract:

Differential axonal myelination synchronises signalling over different axon lengths. The consequences of myelination processes described at the cellular level for the regulation of myelination at the macroscopic level are unknown. We analysed multiple cohorts of myelin-sensitive brain MRI. Our aim was to (i) confirm a previous report of anti-correlation between myelination in subcortical and sensorimotor areas in healthy subjects, (ii) and thereby test our hypothesis for a regulatory interaction between them.

We analysed nine image-sets across three different human cohorts using six MRI modalities. Each image-set contained healthy controls (HC) and ME/CFS subjects. Subcortical and Sensorimotor regions of interest (ROI) were optimised for the detection of anti-correlations and the same ROIs were used to test the HC in all image-sets. For each cohort, median MRI values were computed in both regions for each subject and their correlation across the cohort was computed.

We confirmed negative correlations in healthy controls between subcortical and sensorimotor regions in six image-sets: three T1wSE (p = 5 × 10-8, 5 × 10-7, 0.002), T2wSE (p =2 × 10-6), MTC (p = 0.01), and WM volume (p = 0.02). T1/T2 was the exception with a positive correlation (p = 0.01). This myelin regulation study is novel in several aspects: human subjects, cross-sectional design, ROI optimization, spin-echo MRI and reproducible across multiple independent image-sets.

In multiple independent image-sets we confirmed an anti-correlation between subcortical and sensorimotor myelination which supports a previously unreported regulatory interaction. The subcortical region contained the brain’s primary regulatory nuclei. We suggest a mechanism has evolved whereby relatively low subcortical myelination in an individual is compensated by upregulated sensorimotor myelination to maintain adequate sensorimotor performance.

Source: Barnden L, Crouch B, Kwiatek R, Shan Z, Thapaliya K, Staines D, Bhuta S, Del Fante P, Burnet R. Anti-Correlated Myelin-Sensitive MRI Levels in Humans Consistent with a Subcortical to Sensorimotor Regulatory Process-Multi-Cohort Multi-Modal Evidence. Brain Sci. 2022 Dec 9;12(12):1693. doi: 10.3390/brainsci12121693. PMID: 36552153; PMCID: PMC9776387. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9776387/ (Full text)

Connectivity between Salience and Default Mode Networks and subcortical nodes distinguishes between two classes of ME/CFS

Abstract:

Myalgic Encephalomyelitis or Chronic Fatigue Syndrome (ME/CFS) is a debilitating disease with unknown pathophysiology. Functional MRI (fMRI) studies in ME/CFS have reported disparate connectivities for the brain salience (SA) and default mode (DMN) networks.

In this study, we acquired resting state and task fMRI with an advanced scanner for improved subject numbers: 24 healthy controls (HC) and 42 ME/CFS patients, 18 meeting International Consensus Criteria (ICC) and 24 meeting Fukuda criteria. We evaluated mean FC between SA and DMN network hub, and subcortical regions known to be involved in ME/CFS. We tested the hypothesis that ME/CFS connectivity differed from HC and the ICC and Fukuda classes are distinguished by different connectivities with HC for different pairs of SA, DMN or subcortical hubs.

During resting state fMRI only two connections differed from HC, both for Fukuda ME/CFS and both with an SA hub. During task fMRI 10 ME/CFS connections differed from HC, 5 for ICC and 5 for Fukuda. None were common to both classes. Eight of the 10 different connections involved an SA hub, six of 10 were weaker in ME/CFS, 4 stronger.

SA connections to the hippocampus and brainstem reticular activation system (RAS) differed from and were stronger than HC. The SA mediates the relative activity of the DMN and executive networks and imbalance will have functional consequences. The RAS and hippocampus modulate cortical activation. Different regulatory connections are consistent with the impaired cognitive performance and sleep-wake cycle of ME/CFS. Different neuropathology is involved in ICC and Fukuda classes.

Source: Su J, Thapaliya K, Eaton-Fitch N, Marshall-Gradisnik SM, Barnden LR. Connectivity between Salience and Default Mode Networks and subcortical nodes distinguishes between two classes of ME/CFS. Brain Connect. 2022 Nov 9. doi: 10.1089/brain.2022.0049. Epub ahead of print. PMID: 36352819. https://pubmed.ncbi.nlm.nih.gov/36352819/

Alteration of Cortical Volume and Thickness in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Myalgic Encephalomyelitis/Chronic fatigue syndrome (ME/CFS) patients suffer from neurocognitive impairment. In this study, we investigated cortical volumetric and thickness changes in ME/CFS patients and healthy controls (HC). We estimated mean surface-based cortical volume and thickness from 18 ME/CFS patients who met International Consensus Criteria (ICC) and 26 HC using FreeSurfer. Vertex-wise analysis showed significant reductions in the caudal middle frontal gyrus (p = 0.0016) and precuneus (p = 0.013) thickness in ME/CFS patients compared with HC.

Region based analysis of sub-cortical volumes found that amygdala volume (p = 0.002) was significantly higher in ME/CFS patients compared with HC. We also performed interaction-with-group regressions with clinical measures to test for cortical volume and thickness correlations in ME/CFS with opposite slopes to HC (abnormal). ME/CFS cortical volume and thickness regressions with fatigue, heart-rate variability, heart rate, sleep disturbance score, respiratory rate, and cognitive performance were abnormal. Our study demonstrated different cortical volume and thickness in ME/CFS patients and showed abnormal cortical volume and thickness regressions with key symptoms of ME/CFS patients.

Source: Thapaliya Kiran, Marshall-Gradisnik Sonya, Staines Donald, Su Jiasheng, Barnden Leighton. Alteration of Cortical Volume and Thickness in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Frontiers in Neuroscience, Vol 16, 2022. DOI=10.3389/fnins.2022.848730 https://www.frontiersin.org/articles/10.3389/fnins.2022.848730/full   (Full text)

Volumetric differences in hippocampal subfields and associations with clinical measures in myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients suffer from a cognitive and memory dysfunction. Because the hippocampus plays a key role in both cognition and memory, we tested for volumetric differences in the subfields of the hippocampus in ME/CFS.

We estimated hippocampal subfield volumes for 25 ME/CFS patients who met Fukuda criteria only (ME/CFSFukuda ), 18 ME/CFS patients who met the stricter ICC criteria (ME/CFSICC ), and 25 healthy controls (HC). Group comparisons with HC detected extensive differences in subfield volumes in ME/CFSICC but not in ME/CFSFukuda . ME/CFSICC patients had significantly larger volume in the left subiculum head (p < 0.001), left presubiculum head (p = 0.0020), and left fimbria (p = 0.004).

Correlations of hippocampus subfield volumes with clinical measures were stronger in ME/CFSICC than in ME/CFSFukuda patients. In ME/CFSFukuda patients, we detected positive correlations between fatigue and hippocampus subfield volumes and a negative correlation between sleep disturbance score and the right CA1 body volume.

In ME/CFSICC patients, we detected a strong negative relationship between fatigue and left hippocampus tail volume. Strong negative relationships were also detected between pain and SF36 physical scores and two hippocampal subfield volumes (left: GC-ML-DG head and CA4 head).

Our study demonstrated that volumetric differences in hippocampal subfields have strong statistical inference for patients meeting the ME/CFSICC case definition and confirms hippocampal involvement in the cognitive and memory problems of ME/CFSICC patients.

Source: Thapaliya K, Staines D, Marshall-Gradisnik S, Su J, Barnden L. Volumetric differences in hippocampal subfields and associations with clinical measures in myalgic encephalomyelitis/chronic fatigue syndrome. J Neurosci Res. 2022 Mar 31. doi: 10.1002/jnr.25048. Epub ahead of print. PMID: 35355311. https://onlinelibrary.wiley.com/doi/10.1002/jnr.25048  (Full study)

Neuroimaging characteristics of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): a systematic review

Abstract:

Background: Since the 1990s, neuroimaging has been utilised to study Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), a debilitating illness with unknown aetiology. While brain abnormalities in ME/CFS have been identified, relatively little is known regarding which specific abnormalities are consistently observed across research groups and to what extent the observed abnormalities are reproducible.

Method: To identify consistent and inconsistent neuroimaging observations in ME/CFS, this retrospective and systematic review searched for studies in which neuroimaging was used to investigate brain abnormalities in ME/CFS in Ovid MEDLINE, PubMed (NCBI), and Scopus from January 1988 to July 2018. A qualitative synthesis of observations was performed to identify brain abnormalities that were consistently and inconsistently reported.

Results: 63 full-text articles were included in the synthesis of results from 291 identified papers. Additional brain area recruitment for cognitive tasks and abnormalities in the brain stem are frequent observations in 11 and 9 studies using different modalities from different research teams respectively. Also, sluggish blood oxygenation level-dependent (BOLD) signal responses to tasks, reduced serotonin transporters, and regional hypometabolism are consistent observations by more than two research teams. Single observations include abnormal brain tissue properties, regional metabolic abnormalities, and association of brain measures with ME/CFS symptoms. Reduced resting cerebral blood flow and volumetric brain changes are inconsistent observations across different studies.

Conclusion: Neuroimaging studies of ME/CFS have frequently observed additional brain area recruitment during cognitive tasks and abnormalities in the brain stem. The frequent observation of additional brain area recruitment and consistent observation of sluggish fMRI signal response suggest abnormal neurovascular coupling in ME/CFS.

Source: Shan ZY, Barnden LR, Kwiatek RA, Bhuta S, Hermens DF, Lagopoulos J. Neuroimaging characteristics of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): a systematic review. J Transl Med. 2020;18(1):335. Published 2020 Sep 1. doi:10.1186/s12967-020-02506-6  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7466519/ (Full text)