Associations between fronto-limbic white matter connections and internalizing symptoms in pediatric demyelinating disease

INTRODUCTION

Children with neuroinflammatory disorders, such as multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein-associated disorder (MOGAD), have high rates of anxiety and depression. These symptoms may be linked to disruptions in fronto-limbic white matter (WM) tracts, including the cingulum bundle (CB), inferior fronto-occipital fasciculus (IFOF), and uncinate fasciculus (UF), which support emotional regulation.

METHODS

We studied 33 children with neuroinflammatory disorders and 28 healthy controls. Diffusion tensor imaging and white matter tract integrity maps were generated, focusing on WM tracts of interest (CB, IFOF, UF) and a control tract (acoustic radiation). We examined differences in WM microstructure and internalizing symptoms between high and low symptom groups.

RESULTS

Participants with MS (40%), MOGAD (28%), and NMOSD (25%) reported high levels of internalizing symptoms. MOGAD participants showed lower axonal water fraction compared to MS and controls. Both MS and MOGAD groups exhibited reduced intra-axonal diffusivity and increased extra-axonal diffusivity, indicating demyelination and axonal changes. No significant differences were found between high and low internalizing groups, but higher relapse rates were linked to less WM disruption in those with high internalizing symptoms.

LIMITATIONS

The cross-sectional design limits causal interpretations, and medical covariates may affect WM structure.

CONCLUSION

Neuroinflammatory disorders are linked to fronto-limbic WM changes and high internalizing symptoms. Relapse may influence WM structure and psychological resilience in this population.

Dysphagia assessment in patients with multiple sclerosis - an additional piece to disability burden

OBJECTIVE

People with multiple sclerosis (MS) might experience symptoms that are usually underestimated. Dysphagia should be evaluated within the Expanded Disability Status Scale (EDSS), but clinicians often do not assess it properly. The objectives of this study are as follows: To assess the prevalence of dysphagia in patients with MS utilizing the Swallowing Disturbance Questionnaire (SDQ); to examine the correlation with the EDSS; to investigate the relationship between dysphagia and clinico-demographic characteristics of MS.

METHODS

In total, 177 MS patients underwent evaluations with EDSS, SDQ, cognitive functions, anxiety, depression, fatigue, and sleep quality tests. We compared clinico-demographic data of patients with and without dysphagia and native-EDSS to SDQ-EDSS.

RESULTS

Out of the 177 MS patients, 56% of individuals were identified having dysphagia according to the SDQ with 41 patients exhibiting mild dysphagia, 31 showing moderate dysphagia and 27 patients having severe dysphagia. Only 6 patients had dysphagia recorded in the EDSS. SDQ-EDSS scores were significantly higher than native scores. Dysphagia was associated with depressive symptoms and sleep quality.

INTERPRETATION

Dysphagia affects up to 56% of MS patients. The SDQ questionnaire is useful for identifying dysphagia, which can help in capturing disease progression and preventing complications like aspiration pneumonia. The SDQ-EDSS was higher than the native-EDSS, reflecting the poor ability of the native-EDSS to evaluate certain symptoms such as dysphagia. The SDQ correlated with depressive symptoms, which are associated with a greater perception of MS symptoms, and poor sleep quality, which could be associated with the triggering of pathogenic mechanisms responsible for disease progression.

Fatigue in Multiple Sclerosis: A Resting-State EEG Microstate Study

Fatigue affects approximately 80% of people with Multiple Sclerosis (PwMS) and can impact several domains of daily life. However, the neural underpinnings of fatigue in MS are still not completely clear. The aim of our study was to investigate the spontaneous large-scale networks functioning associated with fatigue in PwMS using the EEG microstate approach with a spectral decomposition. Forty-three relapsing-remitting MS patients and twenty-four healthy controls (HCs) were recruited. All participants underwent an administration of Modified Fatigue Impact scale (MFIS) and a 15-min resting-state high-density EEG recording. We compared the microstates of healthy subjects, fatigued (F-MS) and non-fatigued (nF-MS) patients with MS; correlations with clinical and behavioral fatigue scores were also analyzed. Microstates analysis showed six templates across groups and frequencies. We found that in the F-MS emerged a significant decrease of microstate F, associated to the salience network, in the broadband and in the beta band. Moreover, the microstate B, associated to the visual network, showed a significant increase in fatigued patients than healthy subjects in broadband and beta bands. The multiple linear regression showed that the high cognitive fatigue was predicted by both an increase and decrease, respectively, in delta band microstate B and beta band microstate F. On the other hand, higher physical fatigue was predicted with lower occurrence microstate F in beta band. The current findings suggest that in MS the higher level of fatigue might be related to a maladaptive functioning of the salience and visual network.

Being highly sensitive person negatively impacts on cognitive and psychosocial fatigue in multiple sclerosis patients: A cross-sectional, monocenter study

BACKGROUND

Fatigue is a common symptom in Multiple Sclerosis (MS), but its determinants are not clarified yet. Sensory processing sensitivity (SPS) is a personality trait characterized by enhanced sensitivity towards endogenous and exogenous stimuli, and higher attention toward minimal stimuli, resulting in overarousal and fatigue.

OBJECTIVE

to evaluate the association between SPS and fatigue in MS patients.

METHODS

192 consecutive MS patients (age of 43.3 ± 12.1 years; females 67.2 %; median EDSS of 2.5 (0 - 7)) underwent clinical (EDSS, age, gender), cognitive (BICAMS, Trial Making Test [TMT]), psychosocial (Beck Anxiety Inventory [BAI], Beck Depression Inventory [BDI], Modified Fatigue Impact Scale [MFIS]) and sensitivity evaluation (Highly Sensitive Person [HSP]Scale). Patients were classified as HSP if the score was greater than 14. A stepwise regression model was applied to explore association between SPS and MFIS total scores and sub-scores, by accounting for age, gender, education, EDSS, Cerebral FS scores, TMT-Part A and part B scores, BAI, BDI, and Pittsburgh Sleep Quality Index (PSQI).

RESULTS

Total HSP was 17.2 ± 6.8 and 129 patients (67 %) were classified as highly sensitive persons (HSP). HSP patients were more female patients (p = 0.02) with a longer disease duration (p = 0.03). HSP people showed higher total MFIS score (27.6 ± 20.6 vs 13.2 ± 14.1, p < 0.001), higher physical MFIS score (p < 0.001), higher cognitive MFIS score (p < 0.001), higher psychosocial MFIS score (p < 0.001) vs non-HSP patients. Higher total MFIS was associated with SPS trait (coeff. 6.9, p = 0.006). Specifically, SPS trait was associated with higher cognitive MFIS (coeff. 5.3, p < 0.001) and higher psychosocial MFIS (coeff. 0.7, p = 0.02).

CONCLUSION

SPS was associated with fatigue. Since SPS could be easily and quickly assessed in clinical settings, SPS could unveil a higher propensity of a patient toward fatigue occurrence over the disease course and could provide hints for possible preventive cognitive behavior therapy.

Depression and anxiety in multiple sclerosis. Review of a fatal combination

Depression and anxiety are the most frequent neuropsychiatric symptoms of multiple sclerosis (MS), an autoimmune-mediated demyelinating neurodegenerative disease. Their prevalence is 25-65% and 20-54%, respectively, often associated with chronic fatigue and cognitive impairment, but usually not correlated with motor and other deficits, suggesting different pathophysiological mechanisms. Both disorders often arise before MS diagnosis, lead to faster disability and impair the quality of life. Risk factors are (young) age, genetic and family history burden. While no specific neuropathological data for depression (and anxiety) in MS are available, modern neuroimaging studies showed bilateral fronto-temporal, subcortical and limbic atrophies, microstructural white matter lesions and disruption of frontoparietal, limbic and neuroendocrine networks. The pathogenesis of both depression and anxiety in MS is related to shared mechanisms including oxidative stress, mitochondrial dysfunction, neuroinflammation and neuroendocrine mechanisms inducing complex functional and structural brain lesions, but they are also influenced by social and other factors. Unfortunately, MS patients with anxiety, major depression or suicidal thoughts are often underassessed and undertreated. Current treatment, in addition to antidepressant therapy include transcranial magnetic stimulation, cognitive, relaxation, dietary and other healthcare measures that must be individualized. The present state-of- the-art review is based on systematic analysis of PubMed, Google Scholar and Cochrane Library until May 2024, with focus on the prevalence, clinical manifestation, neuroimaging data, immune mechanisms and treatment options. Depression and anxiety in MS, like in many other neuroimmune disorders, are related, among others, to multi-regional patterns of cerebral disturbances and complex pathogenic mechanisms that deserve further elucidation as a basis for early diagnosis and adequate management to improve the quality of life in this disabling disease.

An Online Single-Session Cognitive Behavioral Therapy for Depression and Anxiety Associated with Multiple Sclerosis-Pilot Study

Background: Multiple sclerosis (MS) is one of the most debilitating neurodegenerative diseases in youth, significantly affecting all life domains. Therefore, a strong association between MS, depression and anxiety symptoms has been established. The objective of the present interventional one-group pretest-posttest study is to assess the feasibility of an online single-session intervention (SSI) based on a cognitive behavioral therapy protocol targeting depressive and anxiety symptoms, psychological mechanisms, fatigue and overall health status. Methods: In this pilot study, 31 patients with MS (Mage = 42 years, SD = 12.2) received the online CBT SSI. The impact of the intervention was assessed using validated instruments two weeks after the intervention and after a two-month follow-up period. Results: Statistically significant effects were observed for the reduction of depression, with B = -7.58, 95% CI (-12.84, -2.31) and p < 0.01, and anxiety, with B = -15.17, 95% CI (-18.31, -12.02) and p < 0.001, at post-test and follow-up screening. Additionally, positive outcomes were seen for irrational beliefs at post-test, with B = -25.86, 95% CI (-46.10, -5.61), along with negative automatic thoughts, with B = -4.47, 95% CI (-10.65, 1.71), which were preserved at follow-up. Despite the health status also improving, no significant changes were observed for dysfunctional attitudes and fatigue. Conclusions: This research proves that the online CBT SSI was efficient for decreasing mild to moderate symptoms of depression and anxiety and reducing the intensity of dysfunctional psychological mechanisms in our sample.

Monoaminergic network dysfunction and development of depression in multiple sclerosis: a longitudinal investigation

BACKGROUND

Monoaminergic network dysfunction is thought to underpin depression in multiple sclerosis (MS) patients. However, longitudinal studies are lacking.

OBJECTIVES

Here, we investigated the association between development of depressive symptoms in MS and changes of resting-state functional connectivity (RS FC) within monoaminergic networks.

METHODS

Forty-nine MS patients without depression [Montgomery-Asberg Depression Scale (MADRS) ≤ 9] and 27 healthy controls underwent clinical and 3.0 T RS FC assessment at baseline and after a median follow-up of 1.6 years (interquartile range 1.0-2.1 years). Monoamine-related RS FC was derived by independent component analysis, constrained to PET atlases for dopamine, noradrenaline and serotonin transporters. Longitudinal changes of RS FC within monoaminergic networks and their correlations with MADRS scores were assessed.

RESULTS

At baseline, MS patients showed decreased RS FC vs healthy controls in all PET-guided monoaminergic networks in frontal, cingulate and cerebellar cortices, and increased RS FC in parieto-occipital regions. Fourteen (29%) MS patients developed depressive symptoms (MADRS > 9) at follow-up (D-MS) and exhibited widespread RS FC decrease over time in the PET-guided dopamine network, mainly in orbitofrontal, occipital, anterior cingulate and precuneal cortices compared to patients who did not develop depressive symptoms. In D-MS, decreased RS FC over time was also observed in parahippocampal and occipital regions of the PET-guided noradrenaline network. Decreased RS FC over time in dopamine and noradrenaline PET-guided networks correlated with concomitant increased MADRS scores (r = range - 0.65/- 0.61, p < 0.001).

CONCLUSIONS

The development of depressive symptoms in MS patients was associated with specific RS FC changes within the dopamine and noradrenaline networks.

Overview of the Current Pathophysiology of Fatigue in Multiple Sclerosis, Its Diagnosis and Treatment Options - Review Article

Fatigue is a common, debilitating and often underestimated symptom in patients with multiple sclerosis (MS). The exact pathophysiological mechanism of fatigue in MS is still unknown. However, there are many theories involving different immunological, metabolic and inflammatory mechanisms of fatigue. Owing to the subjective nature of this symptom, its diagnosis is still very limited and is still based only on diagnostic questionnaires. Although several therapeutic agents have been used in the past to try to influence fatigue in MS patients, no single effective approach for the treatment of fatigue has yet been found. This review article aims to provide the reader with information on the current theories on the origin and mechanism of fatigue in MS, as well as diagnostic procedures and, finally, current therapeutic strategies for the management of fatigue in MS patients.

Factors associated with depressive mood at the onset of multiple sclerosis - an analysis of 781 patients of the German NationMS cohort

Background

Depression has a major impact on the disease burden of multiple sclerosis (MS). Analyses of overlapping MS and depression risk factors [smoking, vitamin D (25-OH-VD) and Epstein-Barr virus (EBV) infection] and sex, age, disease characteristics and neuroimaging features associated with depressive symptoms in early MS are scarce.

Objectives

To assess an association of MS risk factors with depressive symptoms within the German NationMS cohort.

Design

Cross-sectional analysis within a multicenter observational study.

Methods

Baseline data of n = 781 adults with newly diagnosed clinically isolated syndrome or relapsing-remitting MS qualified for analysis. Global and region-specific magnetic resonance imaging (MRI)-volumetry parameters were available for n = 327 patients. Association of demographic factors, MS characteristics and risk factors [sex, age, smoking, disease course, presence of current relapse, expanded disability status scale (EDSS) score, fatigue (fatigue scale motor cognition), 25-OH-VD serum concentration, EBV nuclear antigen-1 IgG (EBNA1-IgG) serum levels] and depressive symptoms (Beck Depression Inventory-II, BDI-II) was tested as a primary outcome by multivariable linear regression. Non-parametric correlation and group comparison were performed for associations of MRI parameters and depressive symptoms.

Results

Mean age was 34.3 years (95% confidence interval: 33.6-35.0). The female-to-male ratio was 2.3:1. At least minimal depressive symptoms (BDI-II > 8) were present in n = 256 (32.8%), 25-OH-VD deficiency (<20 ng/ml) in n = 398 (51.0%), n = 246 (31.5%) participants were smokers. Presence of current relapse [coefficient (c) = 1.48, p = 0.016], more severe fatigue (c = 0.26, p < 0.0001), lower 25-OH-VD (c = -0.03, p = 0.034) and smoking (c = 0.35, p = 0.008) were associated with higher BDI-II scores. Sex, age, disease course, EDSS, month of visit, EBNA1-IgG levels and brain volumes at baseline were not.

Conclusion

Depressive symptoms need to be assessed in early MS. Patients during relapse seem especially vulnerable to depressive symptoms. Contributing factors such as fatigue, vitamin D deficiency and smoking, could specifically be targeted in future interventions and should be investigated in prospective studies.

Depressive symptoms, anxiety and cognitive impairment: emerging evidence in multiple sclerosis

Neuropsychiatric abnormalities may be broadly divided in two categories: disorders of mood, affect, and behavior and abnormalities affecting cognition. Among these conditions, clinical depression, anxiety and neurocognitive disorders are the most common in multiple sclerosis (MS), with a substantial impact on patients' quality of life and adherence to treatments. Such manifestations may occur from the earliest phases of the disease but become more frequent in MS patients with a progressive disease course and more severe clinical disability. Although the pathogenesis of these neuropsychiatric manifestations has not been fully defined yet, brain structural and functional abnormalities, consistently observed with magnetic resonance imaging (MRI), together with genetic and immunologic factors, have been suggested to be key players. Even though the detrimental clinical impact of such manifestations in MS patients is a matter of crucial importance, at present, they are often overlooked in the clinical setting. Moreover, the efficacy of pharmacologic and non-pharmacologic approaches for their amelioration has been poorly investigated, with the majority of studies showing marginal or no beneficial effect of different therapeutic approaches, possibly due to the presence of multiple and heterogeneous underlying pathological mechanisms and intrinsic methodological limitations. A better evaluation of these manifestations in the clinical setting and improvements in the understanding of their pathophysiology may offer the potential to develop tools for differentiating these mechanisms in individual patients and ultimately provide a principled basis for treatment selection. This review provides an updated overview regarding the pathophysiology of the most common neuropsychiatric symptoms in MS, the clinical and MRI characteristics that have been associated with mood disorders (i.e., depression and anxiety) and cognitive impairment, and the treatment approaches currently available or under investigation.

EDSS and infratentorial white matter lesion volume are considered predictors of fatigue severity in RRMS

Fatigue is a common disabling symptom of relapsing remitting multiple sclerosis (RRMS). Many studies have linked grey matter atrophy to fatigue, but white matter lesion load (WM-LL) has received less attention. Here we assess the relation between fatigue and regional WM-LL volumetric measures. 63 patients with RRMS participated in this study; mean age was 31.9 ± 8.1 years. Each patient provided demographic details and was scored on the expanded disability status scale (EDSS) and fatigue severity scale (FSS). VolBrain, a fully automated, operator-independent tool was used to assess WM-LL and whole brain volume. The patients were classified into three groups: no fatigue (FSS < 4), low to moderate fatigue (FSS ≥ 4 ≤ 5) and high fatigue (FSS > 5). 33.3% of patients had no significant fatigue, 25.4% had mild-to-moderate fatigue, and 41.3% had significant fatigue. Age, disease duration, relapses, and EDSS were positively correlated to fatigue severity (P = 0.034, 0.002, 0.009 and 0.001 respectively). Whole brain volume, total and regional WM-LL (juxtacortical, periventricular, infratentorial) were also correlated with fatigue severity. Ordinal regression analysis for fatigue severity showed EDSS and infratentorial lesion volume were the best predictors. In conclusion, EDSS and infratentorial lesion volume (cerebellar and brainstem) are the best predictors of fatigue severity.

Reduced clinical connectome fingerprinting in multiple sclerosis predicts fatigue severity

BACKGROUND

Brain connectome fingerprinting is progressively gaining ground in the field of brain network analysis. It represents a valid approach in assessing the subject-specific connectivity and, according to recent studies, in predicting clinical impairment in some neurodegenerative diseases. Nevertheless, its performance, and clinical utility, in the Multiple Sclerosis (MS) field has not yet been investigated.

METHODS

We conducted the Clinical Connectome Fingerprint (CCF) analysis on source-reconstructed magnetoencephalography signals in a cohort of 50 subjects: twenty-five MS patients and twenty-five healthy controls.

RESULTS

All the parameters of identifiability, in the alpha band, were reduced in patients as compared to controls. These results implied a lower similarity between functional connectomes (FCs) of the same patient and a reduced homogeneity among FCs in the MS group. We also demonstrated that in MS patients, reduced identifiability was able to predict, fatigue level (assessed by the Fatigue Severity Scale).

CONCLUSION

These results confirm the clinical usefulness of the CCF in both identifying MS patients and predicting clinical impairment. We hope that the present study provides future prospects for treatment personalization on the basis of individual brain connectome.

Distinct hemodynamic and functional connectivity features of fatigue in clinically isolated syndrome and multiple sclerosis: accounting for the confounding effect of concurrent depression symptoms

PURPOSE

This study aims to identify common and distinct hemodynamic and functional connectivity (FC) features for self-rated fatigue and depression symptoms in patients with clinically isolated syndrome (CIS) and relapsing-remitting multiple sclerosis (RR-MS).

METHODS

Twenty-four CIS, 29 RR-MS patients, and 39 healthy volunteers were examined using resting-state fMRI (rs-fMRI) to obtain whole-brain maps of (i) hemodynamic response patterns (through time shift analysis), (ii) FC (via intrinsic connectivity contrast maps), and (iii) coupling between hemodynamic response patterns and FC. Each regional map was correlated with fatigue scores, controlling for depression, and with depression scores, controlling for fatigue.

RESULTS

In CIS patients, the severity of fatigue was associated with accelerated hemodynamic response in the insula, hyperconnectivity of the superior frontal gyrus, and evidence of reduced hemodynamics-FC coupling in the left amygdala. In contrast, depression severity was associated with accelerated hemodynamic response in the right limbic temporal pole, hypoconnectivity of the anterior cingulate gyrus, and increased hemodynamics-FC coupling in the left amygdala. In RR-MS patients, fatigue was associated with accelerated hemodynamic response in the insula and medial superior frontal cortex, increased functional role of the left amygdala, and hypoconnectivity of the dorsal orbitofrontal cortex, while depression symptom severity was linked to delayed hemodynamic response in the medial superior frontal gyrus; hypoconnectivity of the insula, ventromedial thalamus, dorsolateral prefrontal cortex, and posterior cingulate; and decreased hemodynamics-FC coupling of the medial orbitofrontal cortex.

CONCLUSION

There are distinct FC and hemodynamic responses, as well as different magnitude and topography of hemodynamic connectivity coupling, associated with fatigue and depression in early and later stages of MS.

Monoaminergic network abnormalities: a marker for multiple sclerosis-related fatigue and depression

OBJECTIVE

To investigate monoaminergic network abnormalities in patients with multiple sclerosis (MS) according to their fatigue and depressive status through a positron emission tomography (PET)-based constrained independent component analysis (ICA) on resting state (RS) functional MRI (fMRI).

METHODS

In this prospective study, 213 patients with MS (mean age=40.6±12.5 years; 94/119 men/women; 153 relapsing-remitting; 60 progressive) and 62 healthy controls (HCs, mean age=39.0±10.4 years; 30/32 men/women) underwent neurological, fatigue, depression and RS fMRI assessment. Patterns of dopamine, norepinephrine-related and serotonin-related RS functional connectivity (FC) were derived by ICA, constrained to PET atlases for dopamine, norepinephrine and serotonin transporters, obtained in HCs' brain.

RESULTS

Compared with HCs, patients with MS showed abnormalities in all three explored monoaminergic networks, mostly with decreased RS FC within PET-guided monoaminergic networks in frontal regions and subcortical areas including the cerebellum and thalamus, and increased RS FC in temporo-parieto-occipital cortical areas, including bilateral precunei.MS-related fatigue was associated with decreased RS FC within the PET-guided dopamine network in the left thalamus and left cerebellum, and with increased RS FC within the PET-guided serotonin network in the left middle occipital gyrus. MS-related depression was associated with more distributed abnormalities involving the three explored monoaminergic networks, resulting in overall reduced RS FC in the frontal lobe, limbic areas and the precuneus.

CONCLUSIONS

Patients with MS present diffuse dysregulation in the monoaminergic networks. Specific alterations in these networks were associated with fatigue and depression, providing a pathological marker for these bothersome symptoms and putative targets for their treatment.

Correspondence among gray matter atrophy and atlas-based neurotransmitter maps is clinically relevant in multiple sclerosis

In multiple sclerosis (MS), gray matter (GM) atrophy progresses in a non-random manner, possibly in regions with a high distribution of specific neurotransmitters involved in several relevant central nervous system functions. We investigated the associations among regional GM atrophy, atlas-based neurotransmitter distributions and clinical manifestations in a large MS patients' group. Brain 3 T MRI scans, neurological examinations and neuropsychological evaluations were obtained from 286 MS patients and 172 healthy controls (HC). Spatial correlations among regional GM volume differences and atlas-based nuclear imaging-derived neurotransmitter maps, and their associations with MS clinical features were investigated using voxel-based morphometry and JuSpace toolbox. Compared to HC, MS patients showed widespread GM atrophy being spatially correlated with the majority of neurotransmitter maps (false discovery rate [FDR]-p ≤ 0.004). Patients with a disease duration ≥ 5 vs < 5 years had significant cortical, subcortical and cerebellar atrophy, being spatially correlated with a higher distribution of serotoninergic and dopaminergic receptors (FDR-p ≤ 0.03). Compared to mildly-disabled patients, those with Expanded Disability Status Scale ≥ 3.0 or ≥ 4.0 had significant cortical, subcortical and cerebellar atrophy being associated with serotonergic, dopaminergic, opioid and cholinergic maps (FDR-p ≤ 0.04). Cognitively impaired vs cognitively preserved patients had widespread GM atrophy being spatially associated with serotonergic, dopaminergic, noradrenergic, cholinergic and glutamatergic maps (FDR-p ≤ 0.04). Fatigued vs non-fatigued MS patients had significant cortical, subcortical and cerebellar atrophy, not associated with neurotransmitter maps. No significant association between GM atrophy and neurotransmitter maps was found for depression. Regional GM atrophy with specific neurotransmitter systems may explain part of MS clinical manifestations, including locomotor disability, cognitive impairment and fatigue.

The pathophysiology of motor fatigue and fatigability in multiple sclerosis

Multiple Sclerosis (MS) is a heterogeneous immune mediated disease of the central nervous system (CNS). Fatigue is one of the most common and disabling symptom of MS. It interferes with daily activities on the level of cognition and motor endurance. Motor fatigue can either result from lesions in cortical networks or motor pathways (“primary fatigue”) or it may be a consequence of detraining with subsequent adaptions of muscle and autonomic function. Programmed exercise interventions are used frequently to increase physical fitness in MS-patients. Studies investigating the effects of training on aerobic capacity, objective endurance and perceived fatigability have yielded heterogenous results, most likely due to the heterogeneity of interventions and patients, but probably also due to the non-uniform pathophysiology of fatigability among MS-patients. The aim of this review is to summarize the current knowledge on the pathophysiology of motor fatigability with special reference to the basic exercise physiology that underlies our understanding of both pathogenesis and treatment interventions.

Symptom Interconnectivity in Multiple Sclerosis: A Narrative Review of Potential Underlying Biological Disease Processes

Introduction

Fatigue, cognitive impairment, depression, and pain are highly prevalent symptoms in multiple sclerosis (MS). These often co-occur and may be explained by a common etiology. By reviewing existing literature, we aimed to identify potential underlying biological processes implicated in the interconnectivity between these symptoms.

Methods

A literature search was conducted to identify articles reporting research into the biological mechanisms responsible for the manifestation of fatigue, cognitive impairment, depression, and pain in MS. PubMed was used to search for articles published from July 2011 to July 2021. We reviewed and assessed findings from the literature to identify biological processes common to the symptoms of interest.

Results

Of 693 articles identified from the search, 252 were selected following screening of titles and abstracts and assessing reference lists of review articles. Four biological processes linked with two or more of the symptoms of interest were frequently identified from the literature: (1) direct neuroanatomical changes to brain regions linked with symptoms of interest (e.g., thalamic injury associated with cognitive impairment, fatigue, and depression), (2) pro-inflammatory cytokines associated with so-called ‘sickness behavior,’ including manifestation of fatigue, transient cognitive impairment, depression, and pain, (3) dysregulation of monoaminergic pathways leading to depressive symptoms and fatigue, and (4) hyperactivity of the hypothalamic–pituitary-adrenal (HPA) axis as a result of pro-inflammatory cytokines promoting the release of brain noradrenaline, serotonin, and tryptophan, which is associated with symptoms of depression and cognitive impairment.

Conclusion

The co-occurrence of fatigue, cognitive impairment, depression, and pain in MS appears to be associated with a common set of etiological factors, namely neuroanatomical changes, pro-inflammatory cytokines, dysregulation of monoaminergic pathways, and a hyperactive HPA axis. This association of symptoms and biological processes has important implications for disease management strategies and, eventually, could help find a common therapeutic pathway that will impact both inflammation and neuroprotection.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-022-00368-2.

Brain Structural and Functional Alterations in Multiple Sclerosis-Related Fatigue: A Systematic Review

Fatigue is one of the most disabling symptoms of multiple sclerosis (MS); it influences patients’ quality of life. The etiology of fatigue is complex, and its pathogenesis is still unclear and debated. The objective of this review was to describe potential brain structural and functional dysfunctions underlying fatigue symptoms in patients with MS. To reach this purpose, a systematic review was conducted of published studies comparing functional brain activation and structural brain in MS patients with and without fatigue. Electronic databases were searched until 24 February 2021. The structural and functional outcomes were extracted from eligible studies and tabulated. Fifty studies were included: 32 reported structural brain differences between patients with and without fatigue; 14 studies described functional alterations in patients with fatigue compared to patients without it; and four studies showed structural and functional brain alterations in patients. The results revealed structural and functional abnormalities that could correlate to the symptom of fatigue in patients with MS. Several studies reported the differences between patients with fatigue and patients without fatigue in terms of conventional magnetic resonance imaging (MRI) outcomes and brain atrophy, specifically in the thalamus. Functional studies showed abnormal activation in the thalamus and in some regions of the sensorimotor network in patients with fatigue compared to patients without it. Patients with fatigue present more structural and functional alterations compared to patients without fatigue. Specifically, abnormal activation and atrophy of the thalamus and some regions of the sensorimotor network seem linked to fatigue.

Magnetoencephalography and High-Density Electroencephalography Study of Acoustic Event Related Potentials in Early Stage of Multiple Sclerosis: A Pilot Study on Cognitive Impairment and Fatigue

Cognitive impairment (CI) is a common and disabling symptom of Multiple Sclerosis (MS) with a negative impact on daily living. In this pilot study, we applied magnetoencephalography (MEG) and high density (hd) electroencephalography (EEG) study to evaluate acoustic P300 features in a cohort of early MS. Sixteen MS patients (pwMS) and 19 healthy controls (HCs) matched for age and gender underwent an MEG-/(hd)-EEG-co-recording, using 306-channel Vectorview and 64 scalp electrodes. CI was assessed using Rao's Brief Repeatable Battery (BRB). Moreover, we performed psychometric tests to assess depression and fatigue. In pwMS, we observed a slight latency prolongation of P300 peak compared to HCs, while P300 amplitude and scalp distribution were similar in the two groups. pwMS did not show an amplitude reduction and different scalp distribution of Event-Related Potentials (ERPs) and Event Related Fields (ERFs) related to an acoustic oddball paradigm. We found an inverse correlation between P300 amplitude and fatigue (r Spearman = -0.4; p = 0.019). In pwMS, phenomena of cortical adaptation to early dysfunction could preserve the cognitive performance of the P300 acoustic task, while the development of fatigue could prospectively lead to amplitude decline of P300, suggesting its possible role as a biomarker.

Altered in vivo brain GABA and glutamate levels are associated with multiple sclerosis central fatigue

PURPOSE

Fatigue is a common symptom in patients with multiple sclerosis (MS) with unknown pathophysiology. Dysfunction of the GABAergic/glutamatergic pathways involving inhibitory and excitatory neurotransmitters such as  γ-aminobutyric acid (GABA) and glutamine + glutamate pool (Glx) have been implicated in several neurological disorders. This study is aimed to evaluate the potential role of GABA and Glx in the origin of central fatigue in relapse remitting MS (RRMS) patients.

METHODS

24 RRMS patients and 16 age- and sex-matched healthy controls (HC) were scanned using Mescher-Garwood point resolved spectroscopy (MEGA-PRESS) with a 3 T system to quantify GABA+ and Glx from prefrontal (PFC) and sensorimotor (SMC) cortices. Self-reported fatigue status was measured on all participants using the Modified Fatigue Impact Scale (MFIS).

RESULTS

RRMS patients had higher fatigue scores relative to HC (p ≤  0.05). Compared to HC, Glx levels in RRMS patients were significantly decreased in SMC (p =  0.04). Significant correlations were found between fatigue scores and GABA+ (r = -0.531, p =  0.008) and Glx (r = 0.511, p =  0.018) in PFC. Physical fatigue was negatively correlated with GABA+ in SMC and PFC (r = -0.428 and -0.472 respectively, p ≤  0.04) and positively with PFC Glx (r = 0.480, p =  0.028).

CONCLUSION

The associations between fatigue and GABA + and Glx suggest that there might be dysregulation of GABAergic/glutamatergic neurotransmission in the pathophysiological mechanism of central fatigue in MS.

Contributing Factors to the Quality of Life in Multiple Sclerosis

Introduction:

Multiple sclerosis (MS) is a chronic, inflammatory, (auto) immune disease of the central nervous system (CNS). Quality of life (QoL) refers to the perception of an individual’s life in the context of the system of culture and values in which they live.

Aim:

The aim of the study was to determine the distribution of cognitive disorders in people with MS.

Methods:

The prospective study included 135 participants with MS and 50 healthy participants. Participants were divided into three groups: the first group consisted of 85 participants where the disease lasted longer than one year, the second group consisted of 50 participants with newly diagnosed MS, the third group consisted of 50 healthy participants. The instruments of clinical assessment were: Extended Disability Score in Multiple Sclerosis Patients, Mini Mental Status, Beck Depression Scale, and Quality of Life Scale (SF-36, Contemporary Health Survey).

Results:

The quality of life related to health is impaired in the physical, mental dimension and overall quality of life. In the first group of participants, 62% had mild depression, and in the second group 38% of participants, while more severe forms were recorded in 16% of participants in both groups. As depression increases, the quality of life decreases in all measured dimensions, which would mean that depression negatively affects the quality of life. The results of all dimensions as well as the overall quality of life score are worse with the increase in the degree of clinical disability, for both groups of study patients.

Conclusion:

Quality of life is impaired in MS patients, and a higher degree of clinical disability and an increase in depressive disorder are predictors of deteriorating quality of life in MS patients.

Imaging and depression in multiple sclerosis: a historical perspective

PURPOSE

Patients affected with multiple sclerosis suffer from depression more frequently than the general population. Beyond psychosocial, genetic and immune-inflammatory factors, also the brain damage which is peculiar of multiple sclerosis has been claimed to have a role in the aetiology of depression in those patients. The study of this interesting relation has been implemented with both conventional and advanced magnetic resonance imaging techniques. The aim of this review is to provide a historical perspective on the link between multiple sclerosis-related depression and structural and functional brain damage.

METHODS

In this review, the results of the MRI studies regarding multiple sclerosis-related brain damage and the presence of depression are presented.

RESULTS

The findings of the reports reveal a link between brain pathology and depressive symptoms or the diagnosis of depression in multiple sclerosis.

CONCLUSIONS

Although a multifactorial aetiology has been theorized for depression and depressive symptoms in patients with multiple sclerosis, this review supports the hypothesis that the structural and functional brain impairment might substantially be amongst those factors. Thus, depression itself might be a symptom with a neuro-biological basis and not only the consequence of the disability derived from the neurological impairment.

The emotional disorders associated with multiple sclerosis

Multiple sclerosis (MS) is associated with a high prevalence of emotional and mood disorders. Emotional disorders may worsen during illness progression and affect the quality of life of patients and their families. MS is often associated with depression, with an increased risk of suicide, poor adherence to treatment, decreased functional status, and quality of life. The diagnosis and treatment of emotional and mood disorders in these patients is often challenging since several symptoms of these disorders overlap with those of MS. Other prevalent emotional disorders in MS include bipolar disorder, anxiety disorders, emotional blunting (apathy), and pseudobulbar affect. Early recognition and treatment of these comorbidities could contribute to the reduction of disability and even to decreased mortality. The aim of this chapter is to provide an up-to-date review of mood and emotional disorders that are often associated with MS, focusing on their epidemiology, clinical features, pathogenesis, assessment, and treatment. The interplay between the psychosocial impact of the chronic disability and the demyelinating structural lesions of the brain in precipitating emotional and mood disorders is discussed, as well as its implications for diagnosis and treatment.

Depression mediates the relationship between fatigue and mental health-related quality of life in multiple sclerosis

BACKGROUND

Fatigue is among the most prevalent symptoms for people with multiple sclerosis (pwMS) and is significantly detrimental to mental health-related (mental) quality of life (QoL). We examined the role of depression and physical activity as mediators in the fatigue-QoL relationship in pwMS.

METHODS

Using baseline cross-sectional data from an international cohort of 2,104 pwMS, characteristics of fatigue and mental QoL, measured by Fatigue Severity Scale and MSQOL-54 respectively, were assessed using linear and log-binomial regression. Structural Equation Models (SEM) were used to explore the mediating roles of depression and physical activity between fatigue and mental QoL.

RESULTS

The median mental QoL score was 71.9/100. The mean fatigue score was 41.5/63, with 65.6% participants having clinically significant fatigue. In the SEM evaluating depression as a mediator of the fatigue-QoL relationship, mental QoL was 14.72 points lower (95% CI: -16.43 -13.01, p<0.001) in participants with clinically significant fatigue, of which depression accounted for 53.0% (-7.80, 95% CI: -9.03 -6.57, p<0.001). In the SEM evaluating physical activity as a mediator of the fatigue-QoL relationship, mental QoL was 10.89 points lower (95% CI: -12.47, -9.32, p<0.001) in participants with clinically significant fatigue, of which the indirect effect via physical activity accounted for only 4.4% (-0.48, 95% CI: -0.81, -0.14, p=0.005).

CONCLUSION

Depression accounted for the majority of the fatigue-mental QoL relationship when modelled as a mediator, while physical activity had only a minor role. Our findings may inform the development of treatments for reducing the impacts of fatigue and improving mental QoL in pwMS.

New Strategies for Rehabilitation and Pharmacological Treatment of Fatigue Syndrome in Multiple Sclerosis

Multiple sclerosis (MS) is the most common autoimmune disease of the central nervous system (CNS), with an inflammatory demyelinating basis and a progressive course. The course of the disease is very diverse and unpredictable. Patients face many problems on a daily basis, such as problems with vision; sensory, balance, and gait disturbances; pain; muscle weakness; spasticity; tremor; urinary and fecal disorders; depression; and rapidly growing fatigue, which significantly influences quality of life among MS patients. Excessive fatigue occurs in most MS patients in all stages of this disease and is named MS-related fatigue. The crucial issue is the lack of effective treatment; therefore, this review focuses not only on the most common treatment methods, but also on additional novel therapies such as whole-body cryotherapy (WBC), functional electrical stimulation (FES), and non-invasive brain stimulation (NIBS). We also highlight the advantages and disadvantages of the most popular clinical scales used to measure fatigue. The entire understanding of the origins of MS-related fatigue may lead to the development of more effective strategies that can improve quality of life among MS patients. A literature search was performed using MEDLINE, EMBASE, and PEDro databases.

Depression is associated with disconnection of neurotransmitter-related nuclei in multiple sclerosis

BACKGROUND

Depression is frequently associated with multiple sclerosis (MS). However, the biological background underlying such association is poorly understood.

OBJECTIVE

Investigating the functional connections of neurotransmitter-related brainstem nuclei, along with their relationship with white matter (WM) microstructure, in MS patients with depressive symptomatology (MS-D) and without depressive symptomatology (MS-nD).

METHODS

Combined resting-state functional magnetic resonance imaging (fMRI) and diffusion-weighted MRI (dMRI) study on 50 MS patients, including 19 MS-D and 31 MS-nD patients, along with 37 healthy controls (HC). Main analyses performed are (1) comparison between groups of raphe nuclei (RN)-related functional connectivity (FC); (2) correlation between RN-related FC and whole brain dMRI-derived fractional anisotropy (FA) map; and (3) comparison between groups of FA in the RN-related WM area.

RESULTS

(1) RN-related FC was reduced in MS-D when compared to MS-nD and HC; (2) RN-related FC positively correlated with FA in a WM cluster mainly encompassing thalamic/basal ganglia regions, including the fornix; and (3) FA in such WM area was reduced in MS-D.

CONCLUSION

Depressive symptomatology in MS is specifically associated to a functional disconnection of neurotransmitter-related nuclei, which in turn may be traced to a distinct spatial pattern of WM alterations mainly involving the limbic network.

Motor fatigue is associated with asymmetric connectivity properties of the corticospinal tract in multiple sclerosis

Multiple Sclerosis (MS) is characterized by demyelination and neurodegeneration of the central nervous system and causes excessive fatigue in more than 80% of the patients. The pathophysiologic mechanisms causing fatigue are still largely unknown. In 46 right-handed patients with relapsing-remitting MS and 25 right-handed controls, we performed diffusion MRI and applied streamline based probabilistic tractography to derive unilateral anatomical connectivity maps for the white matter of the right and left hemispheres. The maps provide an indication how often a streamline has passed through a given voxel. Since tractography based anatomical connectivity mapping (ACM) is sensitive to disease-induced changes in anatomical connectivity, we used ACM to test whether motor fatigue is associated with altered ipsi-hemispherical anatomical connectivity in the major motor output pathway, the corticospinal tract (CST). Patients had higher mean ACM values in the CST than healthy controls. This indicated that a higher number of streamlines, starting from voxels in the same hemisphere, travelled through the CST and may reflect an accumulated disease-induced disintegration of CST. The motor subscale of the Fatigue Scale for Motor and Cognitive functions (FSMCMOTOR) was used to define sub-groups with (n = 29, FSMCMOTOR score ≥ 27) and without motor fatigue (n = 17, FSMSMOTOR score ≤ 26). Patients without fatigue only showed higher ACM values in right CST, while mean ACM values were unaltered in left CST. The higher the mean ACM values in the left relative to the right CST, the more patients reported motor fatigue. Left-right asymmetry in anatomical connectivity outside the CST did not scale with individual motor fatigue. Our results link lateralized changes of tractography-based microstructural properties in the CST with motor fatigue in relapsing-remitting MS.

Distribution of Cortical Diffusion Tensor Imaging Changes in Multiple Sclerosis

Purpose

Diffuse cortical damage in relapsing–remitting multiple sclerosis (RRMS) is clinically relevant but cannot be directly assessed with conventional MRI. In this study, it was aimed to use diffusion tensor imaging (DTI) techniques with optimized intrinsic eddy current compensation to quantify and characterize cortical mean diffusivity (MD) and fractional anisotropy (FA) changes in RRMS and to analyze the distribution of these changes across the cortex.

Materials and Methods

Three-Tesla MRI acquisition, mapping of the MD providing information about the integrity of microstructural barriers and of the FA reflecting axonal density and surface-based analysis with Freesurfer were performed for 24 RRMS patients and 25 control subjects.

Results

Across the whole cortex, MD was increased in patients (p < 0.001), while surface-based analysis revealed focal cortical FA decreases. MD and FA changes were distributed inhomogeneously across the cortex, the MD increase being more widespread than the FA decrease. Cortical MD correlated with the Expanded Disability Status Scale (EDSS, r = 0.38, p = 0.03).

Conclusion

Damage of microstructural barriers occurs inhomogeneously across the cortex in RRMS and might be spatially more widespread than axonal degeneration. The results and, in particular, the correlation with the clinical status indicate that DTI might be a promising technique for the monitoring of cortical damage under treatment in larger clinical studies.

A novel classification of fatigue in multiple sclerosis based on longitudinal assessments

BACKGROUND

Magnetic resonance imaging (MRI) studies of multiple sclerosis-related fatigue had limited reproducibility. Temporal fatigue fluctuations have not been considered.

OBJECTIVE

To investigate whether a novel group allocation that reflects temporal dynamics of fatigue improves our ability to detect fatigue-associated structural brain abnormalities.

METHODS

Patient stratification based on biennial fatigue assessments: sustained fatigue (SF, n = 29, fatigued at the latest ⩾2 assessments), one time-point fatigue (1F, n = 15, fatigued at the latest, but non-fatigued at the penultimate assessment), reversible fatigue (RF, n = 31, non-fatigued at the latest assessment, but reported fatigue previously), and never fatigued (NF, n = 54). Brain parenchymal fraction (BPF) and T2 lesion volume (T2LV) were compared between these groups and were derived using a conventional, single time-point fatigued versus non-fatigued stratification.

RESULTS

The SF versus NF stratification yielded improved power. SF (p = 0.005) and RF (p = 0.043) showed significantly higher T2LV than NF. T2LV showed no significant differences in SF versus 1F, SF versus RF, or 1F versus RF. Fatigued versus non-fatigued patients showed significantly higher T2LV (p = 0.030). We found no significant differences in BPF between the groups.

CONCLUSION

Taking into account temporal fatigue dynamics increases the statistical power with respect to T2LV and may improve characterization of brain pathological correlates of MS-related fatigue.

Neuropsychiatric Symptoms of Multiple Sclerosis: State of the Art

Multiple Sclerosis (MS) is a chronic disabling neuroinflammatory disease. Psychiatric manifestations have a high prevalence in MS patients and may worsen the illness progression and the patients' quality of life (QoL). Depression is a highly prevalent condition in MS patients, associated with poorer adherence to treatment, decreased functional status and QoL, and increased suicide risk. Diagnosis and treatment of this disorder is challenging because of symptom overlap. Other prevalent psychiatric comorbidities are anxiety disorders, bipolar disorder, psychotic disorders, substance misuse and personality disorders. As the illness progresses, personality changes can happen, as well as affect abnormalities. Cognitive changes occur frequently in MS patients, and affect features like processing speed, attention, learning, memory, visual spatial capabilities, and some language deficits. Disease-modifying treatments may reduce cognitive impairment because of their container action on the brain's lesion burden. Other QoL determinants such as fatigue, pain, sexual dysfunction, exercise, resilience and social support should be taken into account, in order to promote the individuals' well-being. Further studies are needed in order to elucidate the effectiveness of pharmacotherapy and more neuroimaging studies are required to clarify the relationship between structural changes and psychiatric comorbidities.

History of fatigue in multiple sclerosis is associated with grey matter atrophy

Fatigue in multiple sclerosis (MS) has been associated with brain damage with low replicability. Temporal fatigue fluctuations have not been considered. We assessed whether sustained fatigue (SF) associates more strongly with grey matter (GM) changes than reversible fatigue (RF). Patients were stratified into three groups according to historical fatigue levels: SF (n = 30, i.e. patients who reported fatigue at the latest ≥2 assessments), RF (n = 31, i.e. patients not fatigued at the latest assessment, but reported fatigue previously), and never fatigued (NF, n = 37). Groups were compared for brain GM volume using cross-sectional voxel-based and volumetric analyses of 3T T1-weighted MRI. Confounding effects of depression and related medications were also investigated. SF and RF patients showed similar anatomical distribution of GM atrophy. While we robustly replicated the anatomical patterns of GM atrophy described in previous work, we also found an association between hippocampal atrophy and fatigue. Depression showed confounding effects in frontal, parietal, occipital, accumbal and thalamic regions. Assessed treatments showed confounding effects in frontal, parietal and striatal areas. Our results suggest that history of clinically-relevant fatigue in currently non-fatigued patients is associated with GM atrophy, potentially explaining inconsistent findings of previous studies that stratified patients using a single fatigue assessment.

Cortical quantitative MRI parameters are related to the cognitive status in patients with relapsing-remitting multiple sclerosis

OBJECTIVES

We aimed to assess cortical damage in patients with relapsing-remitting multiple sclerosis (RRMS)/clinically isolated syndrome (CIS) with a multiparametric, surface-based quantitative MRI (qMRI) approach and to evaluate the correlation of imaging-derived parameters with cognitive scores, hypothesizing that qMRI parameters are correlated with cognitive abilities.

METHODS

Multiparametric qMRI-data (T1, T2 and T2* relaxation times and proton density (PD)) were obtained from 34 patients/24 matched healthy control subjects. Cortical qMRI values were analyzed on the reconstructed cortical surface with Freesurfer. We tested for group differences of cortical microstructural parameters between the healthy and patient collectives and for partial Pearson correlations of qMRI parameters with cognitive scores, correcting for age.

RESULTS

Cortical T2-/T2*-/PD values and four cognitive parameters differed between groups (p ≤ 0.046). These cognitive scores, reflecting information processing speed, verbal memory, visuospatial abilities, and attention, were correlated with cortical T2 (p ≤ 0.02) and T2* (p ≤ 0.03). Cortical changes appeared heterogeneous across the cortex and their distribution differed between the parameters. Vertex-wise correlation of T2 with neuropsychological parameters revealed specific patterns of cortical damage being related to distinct cognitive deficits.

CONCLUSIONS

Microstructural changes are distributed heterogeneously across the cortex in RRMS/CIS. QMRI has the potential to provide surrogate parameters for the assessment of cognitive impairment in these patients for clinical studies. The characteristics of cognitive impairment in RRMS might depend on the distribution of cortical changes.

KEY POINTS

• The goal of the presented study was to investigate cortical changes in RRMS/CIS and their relation to the cognitive status, using multiparametric quantitative MRI. • Cortical T2, T2*, and PD increases observed in patients appeared heterogeneous across the cortex and their distribution differed between the parameters. • Vertex-wise correlation of T2 with neuropsychological scores revealed specific patterns of cortical changes being related to distinct cognitive deficits.

Brain anatomical correlates of fatigue in multiple sclerosis

Fatigue is one of the most debilitating symptoms in patients with multiple sclerosis (MS). Despite its clinical significance, the aetiology and pathophysiology of MS-related fatigue are not well understood. Current evidence and understanding of the neuroanatomical underpinnings of MS-related fatigue are reviewed in this article. The aims of this paper are to (1) review the findings of previous structural neuroimaging studies on MS-related fatigue and summarize consistent findings regarding brain circuitry associated with fatigue in MS, (2) contextualize these findings with the neurochemistry of the relevant circuits and (3) discuss future perspectives with regard to impact on fatigue management of MS patients and methodological challenges towards improved understanding of fatigue pathogenesis. The detailed understanding of the neuroanatomical underpinnings of fatigue might contribute to the identification of novel treatment targets and factors determining treatment resistance to drugs used in current clinical practice.

Microstructural fronto-striatal and temporo-insular alterations are associated with fatigue in patients with multiple sclerosis independent of white matter lesion load and depression

BACKGROUND

Fatigue in multiple sclerosis (MS) has been inconsistently associated with disruption of specific brain circuitries. Temporal fluctuations of fatigue have not been considered.

OBJECTIVE

The aim of this study was to investigate the association of fatigue with brain diffusion abnormalities, using robust criteria for patient stratification based on longitudinal patterns of fatigue.

METHODS

Patient stratification: (1) sustained fatigue (SF, n = 26): latest two Modified Fatigue Impact Scale (MFIS) ⩾ 38; (2) reversible fatigue (RF, n = 25): latest MFIS < 38 and minimum one previous MFIS ⩾ 38; and (3) never fatigued (NF, n = 42): MFIS always < 38 (five assessments minimum). 3T brain magnetic resonance imaging (MRI) was used to perform voxel-wise comparison of fractional anisotropy (FA) between the groups controlling for age, sex, disease duration, physical disability, white matter lesion load (T2LV), and depression.

RESULTS

SF and, to a lesser extent, RF patients showed lower FA in multiple brain regions compared to NF patients, independent of age, sex, disease duration, and physical disability. In cingulo-postcommissural-striato-thalamic regions, the differences in FA between SF and NF (but not between RF and NF or SF) patients were independent of T2LV, and in ventromedial prefronto-precommissuro-striatal and temporo-insular areas, independent of T2LV and depression.

CONCLUSION

Damage to ventromedial prefronto-precommissuro-striatal and temporo-insular pathways appears to be a specific substrate of SF in MS.

Pathophysiological and cognitive mechanisms of fatigue in multiple sclerosis

Fatigue is one of the most common symptoms in multiple sclerosis (MS), with a major impact on patients' quality of life. Currently, treatment proceeds by trial and error with limited success, probably due to the presence of multiple different underlying mechanisms. Recent neuroscientific advances offer the potential to develop tools for differentiating these mechanisms in individual patients and ultimately provide a principled basis for treatment selection. However, development of these tools for differential diagnosis will require guidance by pathophysiological and cognitive theories that propose mechanisms which can be assessed in individual patients. This article provides an overview of contemporary pathophysiological theories of fatigue in MS and discusses how the mechanisms they propose may become measurable with emerging technologies and thus lay a foundation for future personalised treatments.

Evaluation of MS related central fatigue using MR neuroimaging methods: Scoping review

BACKGROUND

Fatigue is a common and debilitating symptom in multiple sclerosis (MS). Over the past decade, a growing body of research has focussed on the pathophysiological mechanisms underlying central (cognitive and physical) fatigue in MS. The precise mechanisms causing fatigue in MS patients are complex and poorly understood, and may differ between patients. Advanced quantitative magnetic resonance imaging (MRI) techniques allow for objective assessment of disease pathology and have been used to characterise the pathophysiology of central fatigue in MS.

OBJECTIVE

To systematically review the existing literature of MRI-based studies assessing the pathophysiological mechanisms of MS-related central fatigue.

METHODS

A systematic literature search of four major databases (PubMed, Medline, Embase, Scopus and Google Scholar) was conducted to identify MRI-based studies of MS-related fatigue published in the past 20 years. Studies using the following MRI-based methods were included: structural (lesion load/atrophy), T1 relaxation time/magnetisation transfer ratio (MTR), diffusion tensor imaging (DTI), functional MRI (fMRI) and magnetic resonance spectroscopy (MRS).

RESULTS

A total of 92 studies were identified as meeting the search criteria and included for review. Structurally, regional gray/white matter atrophy, cortical thinning, decreased T1 relaxation times and reduced fractional anisotropy were associated with central fatigue in MS. Functionally, hyperactivity and reduced functional connectivity in several regional areas of frontal, parietal, occipital, temporal and cerebellum were suggested as causes of central fatigue. Biochemically, a reduction in N-acetyl aspartate/creatine and increased (glutamine+glutamate)/creatine ratios were correlated with fatigue severity in MS.

CONCLUSION

Several advanced quantitative MRI methods have been employed in the study of central fatigue in MS. Central fatigue in MS is associated with macro/microstructural and functional changes within specific brain regions (frontal, parietal, temporal and deep gray matter) and specific pathways/networks (cortico-cortical and cortico-subcortical). Alternations in the cortico-striatal-thalamocortical (CSTC) loop are correlated with the development of fatigue in MS patients.

Structural and cognitive correlates of fatigue in progressive multiple sclerosis

BACKGROUND

Fatigue in multiple sclerosis (MS) is a debilitating symptom and experienced by most patients. In recent studies investigating this phenomenon, the majority of patients had a relapsing-remitting disease course.

METHODS

Patients with progressive MS participating in one of three treatment trials during a period from 2010 to 2014 were included. Fatigue was assessed with the Fatigue Scale for Motor and Cognitive Functions (FSMC) and patients were further examined with a cognitive test battery, including Symbol Digit Modalities Test (SDMT), and 3 T MRI with subsequent quantitative analyses of 13 cortical regions of interest, deep grey matter and lesion volume.

RESULTS

Twenty-two patients were enrolled. The thickness of the pre-central gyrus correlated significantly with motor fatigue. We found only a non-significant trend towards a correlation between cognitive fatigue and the thickness of the pre-central gyrus, the parietal inferior supra-marginal gyrus and the opercular part of the inferior frontal gyrus. 36% of participants had impaired processing speed and 9% had normal function on all tests. The scores on the FSMC-cognitive scale were related to performance on SDMT.

CONCLUSION

In this exploratory study of patients with progressive MS, fatigue was related to processing speed. Motor fatigue was also related to the cortical thickness of the primary motor cortex and there was a trend towards a relationship between cognitive fatigue and the thickness of cortical areas involved in attentional processes. Additional studies are needed to further elucidate the relationship between regional cortical atrophy, cognitive functioning and the perception of fatigue.

ABBREVIATIONS

FSMC: Motor and Cognitive Functions; MS: Multiple Sclerosis; SDMT: Symbol Digit Modalities Test; MRI: Magnetic Resonance Imaging; RRMS: Relapsing-Remitting Disease Course; EDSS: Kurtzke Expanded Disability Status Scale; FLAIR: Fluid Attenuated Inversion Recovery; NAWM: Normal-Appearing White Matter; CGM: Cortical Grey Matter; CTh: Cortical Thickness; ROIs: Regions of Interest; Raven: Raven Progressive Matrices; TM A: Trail Making A; TM B: Trail Making B; Rey: Rey Complex Figure; Similarities: WAIS III Similarities; Stroop: Stroop Colour Naming Test; BDI: Becks Depression Inventory II.

Characterization of relapsing-remitting multiple sclerosis patients using support vector machine classifications of functional and diffusion MRI data

Multiple Sclerosis patients' clinical symptoms do not correlate strongly with structural assessment done with traditional magnetic resonance images. However, its diagnosis and evaluation of the disease's progression are based on a combination of this imaging analysis complemented with clinical examination. Therefore, other biomarkers are necessary to better understand the disease. In this paper, we capitalize on machine learning techniques to classify relapsing-remitting multiple sclerosis patients and healthy volunteers based on machine learning techniques, and to identify relevant brain areas and connectivity measures for characterizing patients. To this end, we acquired magnetic resonance imaging data from relapsing-remitting multiple sclerosis patients and healthy subjects. Fractional anisotropy maps, structural and functional connectivity were extracted from the scans. Each of them were used as separate input features to construct support vector machine classifiers. A fourth input feature was created by combining structural and functional connectivity. Patients were divided in two groups according to their degree of disability and, together with the control group, three group pairs were formed for comparison. Twelve separate classifiers were built from the combination of these four input features and three group pairs. The classifiers were able to distinguish between patients and healthy subjects, reaching accuracy levels as high as 89% ± 2%. In contrast, the performance was noticeably lower when comparing the two groups of patients with different levels of disability, reaching levels below 63% ± 5%. The brain regions that contributed the most to the classification were the right occipital, left frontal orbital, medial frontal cortices and lingual gyrus. The developed classifiers based on MRI data were able to distinguish multiple sclerosis patients and healthy subjects reliably. Moreover, the resulting classification models identified brain regions, and functional and structural connections relevant for better understanding of the disease.

Multiple Immune-Inflammatory and Oxidative and Nitrosative Stress Pathways Explain the Frequent Presence of Depression in Multiple Sclerosis

Patients with a diagnosis of multiple sclerosis (MS) or major depressive disorder (MDD) share a wide array of biological abnormalities which are increasingly considered to play a contributory role in the pathogenesis and pathophysiology of both illnesses. Shared abnormalities include peripheral inflammation, neuroinflammation, chronic oxidative and nitrosative stress, mitochondrial dysfunction, gut dysbiosis, increased intestinal barrier permeability with bacterial translocation into the systemic circulation, neuroendocrine abnormalities and microglial pathology. Patients with MS and MDD also display a wide range of neuroimaging abnormalities and patients with MS who display symptoms of depression present with different neuroimaging profiles compared with MS patients who are depression-free. The precise details of such pathology are markedly different however. The recruitment of activated encephalitogenic Th17 T cells and subsequent bidirectional interaction leading to classically activated microglia is now considered to lie at the core of MS-specific pathology. The presence of activated microglia is common to both illnesses although the pattern of such action throughout the brain appears to be different. Upregulation of miRNAs also appears to be involved in microglial neurotoxicity and indeed T cell pathology in MS but does not appear to play a major role in MDD. It is suggested that the antidepressant lofepramine, and in particular its active metabolite desipramine, may be beneficial not only for depressive symptomatology but also for the neurological symptoms of MS. One clinical trial has been carried out thus far with, in particular, promising MRI findings.

The neuropsychiatry of multiple sclerosis

Multiple sclerosis (MS), an immune-mediated demyelinating condition, is the most common neurological disease affecting young adults in the UK. It has a high psychiatric comorbidity and over half of patients have some degree of cognitive impairment that adds to the burden of disability. This article reviews the psychiatric and cognitive manifestations of MS and their detection and treatment. Recent advances in the treatment of the disease are briefly reviewed and the impact of disease-modifying therapies on psychiatric morbidity and cognitive impairment is discussed.

LEARNING OBJECTIVES

•

DECLARATION OF INTEREST

None.

Fronto-limbic disconnection in patients with multiple sclerosis and depression

Background:

The biological mechanism of depression in multiple sclerosis (MS) is not well understood. Based on work in major depressive disorder, fronto-limbic disconnection might be important.

Objective:

To investigate structural and functional fronto-limbic changes in depressed MS (DMS) and non-depressed MS (nDMS) patients.

Methods:

In this retrospective study, 22 moderate-to-severe DMS patients (disease duration 8.2 ± 7.7 years), 21 nDMS patients (disease duration 15.3 ± 8.3 years), and 12 healthy controls underwent neuropsychological testing and magnetic resonance imaging (MRI; 1.5 T). Brain volumes (white matter (WM), gray matter, amygdala, hippocampus, thalamus), lesion load, fractional anisotropy (FA) of fronto-limbic tracts, and resting-state functional connectivity (FC) between limbic and frontal areas were measured and compared between groups. Regression analysis was performed to relate MRI measures to the severity of depression.

Results:

Compared to nDMS patients, DMS patients (shorter disease duration) had lower WM volume (p < 0.01), decreased FA of the uncinate fasciculus (p < 0.05), and lower FC between the amygdala and frontal regions (p < 0.05). Disease duration, FA of the uncinate fasciculus, and FC of the amygdala could explain 48% of variance in the severity of depression. No differences in cognition were found.

Conclusion:

DMS patients showed more pronounced (MS) damage, that is, structural and functional changes in temporo-frontal regions, compared to nDMS patients, suggestive of fronto-limbic disconnection.

Multidimensional fatigue in pulmonary hypertension: prevalence, severity and predictors

Pulmonary hypertension is a potentially fatal disease. Despite pharmacological advances in pulmonary hypertension, fatigue remains common in patients with pulmonary hypertension.

A convenience sample of 120 participants at an international patient conference completed the Multidimensional Fatigue Inventory (MFI)-20 scale. Data on New York Heart Association Functional Class, body mass index, oxygen use and medication type/use were also collected.

There was a high prevalence of “severe” to “very severe” fatigue for each dimension: General Fatigue (60%), Physical Fatigue (55.8%), Reduced Activity (41.7%), Reduced Motivation (32.5%) and Mental Fatigue (27.5%). The mean±sd overall MFI-20 score was 58±5.1. Dimensions with the highest averaged levels were General Fatigue (13.40±3.61), Physical Fatigue (13.23±3.67) and Reduced Activity (11.33±4.16). Body mass index correlated with higher fatigue scores. Phosphodiesterase inhibitor plus endothelin receptor antagonist combination negatively predicted General Fatigue, Physical Fatigue, Reduced Motivation and Reduced Activity. Triple therapy was a significant predictor of General Fatigue, Physical Fatigue and Reduced Activity. There were no significant predictors of Mental Fatigue.

Multidimensional fatigue is common and severe in patients with pulmonary hypertension. Phosphodiesterase inhibitor plus endothelin receptor antagonist combination resulted in lower scores in most fatigue dimensions. Comprehensive assessment of fatigue should be considered in the clinical care of patients with pulmonary hypertension and clinical research to develop formal interventions that target this disabling symptom.

Fatigue is common and severe in PH, and impacted by medications; targeted strategies to mitigate fatigue are neededhttp://ow.ly/EISN30i0WWU

Depression in Multiple Sclerosis: Epidemiology, Aetiology, Diagnosis and Treatment

Depressive disorders are common in patients with multiple sclerosis, influencing their quality of life and adherence to treatments, as well as becoming more frequent with the progression of the disease and in the secondary progressive form of multiple sclerosis. Patients with multiple sclerosis often experience a typical cluster of symptoms in association with depression, such as fatigue, pain and cognitive impairment. However, the pathogenesis of multiple sclerosis-related depression remains partially unclear, even though genetic, immune-inflammatory and psychosocial factors might be seen to play a role, in addition to the brain structural alterations documented by magnetic resonance imaging studies. The high incidence and burden of depression in people affected with multiple sclerosis are matters of crucial importance. Despite such importance, the efficacy of pharmacologic treatments has been poorly studied and, for the most part, the access to non-pharmacological treatments is partially dependent on the local health system availability. It has been determined that interferon-beta and glatiramer acetate do not cause depressive symptoms; however, no definitive data in this regard are avaible for the newer disease-modifyng medications. In this review, we discuss the diagnosis, prevalence, pathogenesis, clinical aspects, magnetic resonance imaging findings and treatments available in patients experiencing multiple sclerosis-related depression.

Neural correlates of effort-dependent and effort-independent cognitive fatigue components in patients with multiple sclerosis

Background:

Among patients with multiple sclerosis (MS), fatigue is the most commonly reported symptom. It can be subdivided into an effort-dependent (fatigability) and an effort-independent component (trait-fatigue).

Objective:

The objective was to disentangle activity changes associated with effort-independent “trait-fatigue” from those associated with effort-dependent fatigability in MS patients.

Methods:

This study employed behavioral measures and functional magnetic imaging to investigate neural changes in MS patients associated with fatigue. A total of 40 MS patients and 22 age-matched healthy controls performed in a fatigue-inducing N-back task. Effort-independent fatigue was assessed using the Fatigue Scale of Motor and Cognition (FSMC) questionnaire.

Results:

Effort-independent fatigue was observed to be reflected by activity increases in fronto-striatal-subcortical networks primarily involved in the maintenance of homeostatic processes and in motor and cognitive control. Effort-dependent fatigue (fatigability) leads to activity decreases in attention-related cortical and subcortical networks.

Conclusion:

These results indicate that effort-independent (fatigue) and effort-dependent fatigue (fatigability) in MS patients have functionally related but fundamentally different neural correlates. Fatigue in MS as a general phenomenon is reflected by complex interactions of activity increases in control networks (effort-independent component) and activity reductions in executive networks (effort-dependent component) of brain areas.