Hippocampal-DMN disconnectivity in MS is related to WM lesions and depression

Environmental factors related to multiple sclerosis progression

Multiple Sclerosis (MS) is a complex neurological disease which prevalence is increasing worldwide. The impact of environmental factors on MS susceptibility has already been defined and highlighted in many previous reports, particularly vitamin D or ultraviolet B light exposure, Epstein-Barr virus (EBV) infection, obesity, and smoking. There is increasing evidence that environmental and lifestyle factors are not only important in triggering MS but are also implicated in MS progression. Low sun exposure and vitamin D deficiency exhibit a strong relationship with disease progression in both animal and human studies. The gestational period seems also to impact long-term disease progression as January's babies had a higher risk of requiring walking assistance than those born in other months. The implication of EBV in neurodegeneration and MS progression was also suggested even though its specific targets and mechanisms are still unclear. Cigarette smoking is correlated with faster clinical progression. The association of obesity and smoking seems to be associated with a faster progression and an increased rate of brain atrophy. Although the effect of air pollution on MS pathogenesis remains not fully understood, exposure to polluted air can stimulate several mechanisms that might contribute to MS severity. People with MS with active disease have an altered microbiota compared to patients in the remission phase. Cardiovascular comorbidities, epilepsy, and depression are also associated with a more severe disability accrual. Knowledge about MS modifiable risk factors of progression need to be incorporated into everyday clinical practice in order to ameliorate disease outcomes.

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.

A predictive study of the efficacy of transcutaneous auricular vagus nerve stimulation in the treatment of major depressive disorder: An fMRI-based machine learning analysis

BACKGROUND

In order to improve taVNS efficacy, the usage of fMRI to explore the predictive neuroimaging markers would be beneficial for screening the appropriate MDD population before treatment.

METHODS

A total of 86 MDD patients were recruited in this study, and all subjects were conducted with the clinical scales and resting-state functional magnetic resonance imaging (fMRI) scan before and after 8 weeks' taVNS treatment. A two-stage feature selection strategy combining Machine Learning and Statistical was used to screen out the critical brain functional connections (FC) that were significantly associated with efficacy prediction, then the efficacy prediction model was constructed for taVNS treating MDD. Finally, the model was validated by separated the responding and non-responding patients.

RESULTS

This study showed that taVNS produced promising clinical efficacy in the treatment of mild and moderate MDD. Eleven FCs were selected out and were found to be associated with the cortico-striatal-pallidum-thalamic loop, the hippocampus and cerebellum and the HAMD-17 scores. The prediction model was created based on these FCs for the efficacy prediction of taVNS treatment. The R-square of the conducted regression model for predicting HAMD-17 reduction rate is 0.44, and the AUC for classifying the responding and non-responding patients is 0.856.

CONCLUSION

The study demonstrates the validity and feasibility of combining neuroimaging and machine learning techniques to predict the efficacy of taVNS on MDD, and provides an effective solution for personalized and precise treatment for MDD.

Regional hippocampal atrophy reflects memory impairment in patients with early relapsing remitting multiple sclerosis

BACKGROUND

Research work has shown that hippocampal subfields are atrophic to varying extents in multiple sclerosis (MS) patients. However, studies examining the functional implications of subfield-specific hippocampal damage in early MS are limited. We aim to gain insights into the relationship between hippocampal atrophy and memory function by investigating the correlation between global and regional hippocampal atrophy and memory performance in early MS patients.

METHODS

From the Italian Neuroimaging Network Initiative (INNI) dataset, we selected 3D-T1-weighted brain MRIs of 219 early relapsing remitting (RR)MS and 246 healthy controls (HC) to identify hippocampal atrophic areas. At the time of MRI, patients underwent Selective-Reminding-Test (SRT) and Spatial-Recall-Test (SPART) and were classified as mildly (MMI-MS: n.110) or severely (SMI-MS: n:109) memory impaired, according to recently proposed cognitive phenotypes.

RESULTS

Early RRMS showed lower hippocampal volumes compared to HC (p < 0.001), while these did not differ between MMI-MS and SMI-MS. In MMI-MS, lower hippocampal volumes correlated with worse memory tests (r = 0.23-0.37, p ≤ 0.01). Atrophic voxels were diffuse in the hippocampus but more prevalent in cornu ammonis (CA, 79%) than in tail (21%). In MMI-MS, decreased subfield volumes correlated with decreases in memory, particularly in the right CA1 (SRT-recall: r = 0.38; SPART: r = 0.34, p < 0.01). No correlations were found in the SMI-MS group.

CONCLUSION

Hippocampal atrophy spreads from CA to tail from early disease stages. Subfield hippocampal atrophy is associated with memory impairment in MMI-MS, while this correlation is lost in SMI-MS. This plays in favor of a limited capacity for an adaptive functional reorganization of the hippocampi in MS patients.

Impact of Anxious and/or Depressive Reactive State on the Effectiveness of Rehabilitation of Patients with Multiple Sclerosis

Background and Objectives: Rehabilitation is a part of the comprehensive treatment of multiple sclerosis (MS). If present, psychological reactive states limit the results of the rehabilitation. The objectives were to determine the impact of psychological reactive states in these patients on the functionality obtained by rehabilitation and QoL, and to determine the connection between the objective and subjective evaluation. Materials and Methods: Based on the Hospital anxiety and depression scale, the patients were divided into a group with anxious and/or depressive reactive state and a group without the reactive state. The values of functional scores-the Berg Balance Scale (BBS) and the Expanded Disability Status Scale (EDSS), as well as the parameters of the QoL-Physical health Component Score (PCS) and the Mental health Component Score (MCS)-were determined at the beginning and at the end of the rehabilitation. Results: There was a statistically significant difference between the BBS, EDSS, PCS, and MCS groups at the beginning and the end of the rehabilitation in both groups. A statistically significant difference at the beginning and the end of the rehabilitation between the groups was found only in PCS and MCS. A highly statistically significant correlation between EDSS and PCS, and EDSS and MCS, was found only in the group without the reactive state. Conclusions: Although rehabilitation leads to an objective improvement of functionality in patients with MS, the presence of the anxious and/or depressive reactive state limits the results of rehabilitation and leads to discrepancies in the aforementioned objective assessment and the patient's subjective experience through the evaluation of their QoL.

The effects of venlafaxine on depressive-like behaviors and gut microbiome in cuprizone-treated mice

Background

Cuprizone (CPZ)-treated mice show significant demyelination, altered gut microbiome, and depressive-like behaviors. However, the effects of venlafaxine (Ven) on the gut microbiome and depressive-like behavior of CPZ-treated mice are largely unclear.

Methods

Male C57BL/6J mice were fed a chow containing 0.2% cuprizone (w/w) for 5 weeks to induce a model of demyelination. Meanwhile, the gut microbiota and depressive-like behaviors were assessed after the mice were fed with Ven (20 mg/kg/day) or equal volumes of distilled water for 2 weeks by oral gavage from the third week onward during CPZ treatment.

Results

CPZ treatment decreased the sucrose preference rate in the sucrose preference test and increased the immobility time in the tail-suspension test, and it also induced an abnormality in β-diversity and changes in microbial composition. Ven alleviated the depressive-like behavior and regulated the composition of the gut microbiota, such as the increase of Lactobacillus and Bifidobacterium in CPZ-treated mice.

Conclusion

The anti-depressant effects of Ven might be related to the regulation of gut microbiota in the CPZ-treated mice.

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.

Brain connectivity changes underlying depression and fatigue in relapsing-remitting multiple sclerosis: A systematic review

Multiple Sclerosis (MS) is an autoimmune disease affecting the central nervous system, characterised by neuroinflammation and neurodegeneration. Fatigue and depression are common, debilitating, and intertwined symptoms in people with relapsing-remitting MS (pwRRMS). An increased understanding of brain changes and mechanisms underlying fatigue and depression in RRMS could lead to more effective interventions and enhancement of quality of life. To elucidate the relationship between depression and fatigue and brain connectivity in pwRRMS we conducted a systematic review. Searched databases were PubMed, Web-of-Science and Scopus. Inclusion criteria were: studied participants with RRMS (n ≥ 20; ≥ 18 years old) and differentiated between MS subtypes; published between 2001-01-01 and 2023-01-18; used fatigue and depression assessments validated for MS; included brain structural, functional magnetic resonance imaging (fMRI) or diffusion MRI (dMRI). Sixty studies met the criteria: 18 dMRI (15 fatigue, 5 depression) and 22 fMRI (20 fatigue, 5 depression) studies. The literature was heterogeneous; half of studies reported no correlation between brain connectivity measures and fatigue or depression. Positive findings showed that abnormal cortico-limbic structural and functional connectivity was associated with depression. Fatigue was linked to connectivity measures in cortico-thalamic-basal-ganglial networks. Additionally, both depression and fatigue were related to altered cingulum structural connectivity, and functional connectivity involving thalamus, cerebellum, frontal lobe, ventral tegmental area, striatum, default mode and attention networks, and supramarginal, precentral, and postcentral gyri. Qualitative analysis suggests structural and functional connectivity changes, possibly due to axonal and/or myelin loss, in the cortico-thalamic-basal-ganglial and cortico-limbic network may underlie fatigue and depression in pwRRMS, respectively, but the overall results were inconclusive, possibly explained by heterogeneity and limited number of studies. This highlights the need for further studies including advanced MRI to detect more subtle brain changes in association with depression and fatigue. Future studies using optimised imaging protocols and validated depression and fatigue measures are required to clarify the substrates underlying these symptoms in pwRRMS.

Role of resting-state functional MRI in detecting brain functional changes following radiotherapy for head and neck cancer: a systematic review and meta-analysis

PURPOSE

Increasing evidence implicates changes in brain function following radiotherapy for head and neck cancer as precursors for brain dysfunction. These changes may thus be used as biomarkers for early detection. This review aimed to determine the role of resting-state functional magnetic resonance imaging (rs-fMRI) in detecting brain functional changes.

METHODS

A systematic search was performed in the PubMed, Scopus, and Web of Science (WoS) databases in June 2022. Patients with head and neck cancer treated with radiotherapy and periodic rs-fMRI assessments were included. A meta-analysis was performed to determine the potential of rs-fMRI for detecting brain changes.

RESULTS

Ten studies with a total of 513 subjects (head and neck cancer patients, n = 437; healthy controls, n = 76) were included. A significance of rs-fMRI for detecting brain changes in the temporal and frontal lobes, cingulate cortex, and cuneus was demonstrated in most studies. These changes were reported to be associated with dose (6/10 studies) and latency (4/10 studies). A strong effect size (r = 0.71, p < 0.001) between rs-fMRI and brain changes was also reported, suggesting rs-fMRI's capability for monitoring brain alterations.

CONCLUSION

Resting-state functional MRI is a promising tool for detecting brain functional changes following head and neck radiotherapy. These changes are correlated with latency and prescription dose.

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.

Structural-functional connectivity bandwidth predicts processing speed in mild traumatic brain Injury: A multiplex network analysis

An emerging body of work has revealed alterations in structural (SC) and functional (FC) brain connectivity following mild TBI (mTBI), with mixed findings. However, these studies seldom integrate complimentary neuroimaging modalities within a unified framework. Multilayer network analysis is an emerging technique to uncover how white matter organization enables functional communication. Using our novel graph metric (SC-FC Bandwidth), we quantified the information capacity of synchronous brain regions in 53 mild TBI patients (46 females; age mean = 40.2 years (y), σ = 16.7 (y), range: 18-79 (y). Diffusion MRI and resting state fMRI were administered at the acute and chronic post-injury intervals. Moreover, participants completed a cognitive task to measure processing speed (30 Seconds and Counting Task; 30-SACT). Processing speed was significantly increased at the chronic, relative to the acute post-injury intervals (p = <0.001). Nonlinear principal components of direct (t = -1.84, p = 0.06) and indirect SC-FC Bandwidth (t = 3.86, p = <0.001) predicted processing speed with a moderate effect size (R2 = 0.43, p < 0.001), while controlling for age. A subnetwork of interhemispheric edges with increased SC-FC Bandwidth was identified at the chronic, relative to the acute mTBI post-injury interval (pFDR = 0.05). Increased interhemispheric SC-FC Bandwidth of this network corresponded with improved processing speed at the chronic post-injury interval (partial r = 0.32, p = 0.02). Our findings revealed that mild TBI results in complex reorganization of brain connectivity optimized for maximum information flow, supporting improved cognitive performance as a compensatory mechanism. Moving forward, this measurement may complement clinical assessment as an objective marker of mTBI recovery.

Abnormal thalamic functional connectivity correlates with cardiorespiratory fitness and physical activity in progressive multiple sclerosis

BACKGROUND

Altered thalamic volumes and resting state (RS) functional connectivity (FC) might be associated with physical activity (PA) and cardiorespiratory fitness (CRF) in people with progressive multiple sclerosis (PMS).

OBJECTIVES

To assess thalamic structural and functional alterations and investigate their correlations with PA/CRF levels in people with PMS.

METHODS

Seven-day accelerometry and cardiopulmonary exercise testing were used to assess PA/CRF levels in 91 persons with PMS. They underwent 3.0 T structural and RS fMRI acquisition with 37 age/sex-matched healthy controls (HC). Between-group comparisons of MRI measures and their correlations with PA/CRF variables were assessed.

RESULTS

PMS people had lower volumes compared to HC (all p < 0.001). At corrected threshold, PMS showed decreased intra- and inter-thalamic RS FC, and increased RS FC between the thalamus and the hippocampus, bilaterally. At uncorrected threshold, decreased thalamic RS FC with caudate nucleus, cerebellum and anterior cingulate cortex (ACC), as well as increased thalamic RS FC with occipital regions, were also detected. Lower CRF, measured as peak oxygen consumption (VO_2peak), correlated with lower white matter volume (r = 0.31, p = 0.03). Moreover, lower levels of light PA correlated with increased thalamic RS FC with the right hippocampus (r = - 0.3, p = 0.05).

DISCUSSION

People with PMS showed widespread brain atrophy, as well as pronounced intra-thalamic and thalamo-hippocampal RS FC abnormalities. White matter atrophy correlated with CRF, while increased thalamo-hippocampal RS FC was associated to worse PA levels. Thalamic RS FC might be used to monitor physical impairment and efficacy of rehabilitative and disease-modifying treatments in future studies.

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.

Psychiatric symptoms in multiple sclerosis: a biological perspective on synaptic and network dysfunction

Psychiatric symptoms frequently occur in multiple sclerosis (MS), presenting with a complex phenomenology that encompasses a large clinical spectrum from clear-cut psychiatric disorders up to isolated psychopathological manifestations. Despite their relevant impact on the overall disease burden, such clinical features are often misdiagnosed, receive suboptimal treatment and are not systematically evaluated in the quantification of disease activity. The development of psychiatric symptoms in MS underpins a complex pathogenesis involving both emotional reactions to a disabling disease and structural multifocal central nervous system damage. Here, we review MS psychopathological manifestations under a biological perspective, highlighting the pathogenic relevance of synaptic and neural network dysfunction. Evidence obtained from human and experimental disease models suggests that MS-related psychiatric phenomenology is part of a disconnection syndrome due to diffuse inflammatory and neurodegenerative brain damage.

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.

The role of disconnection in explaining disability in multiple sclerosis

Background

In multiple sclerosis, the correlation between white matter lesion volumes (LV) and expanded disability status scale (EDSS) is at best moderate, leading to the “clinico-radiological paradox”, influenced by many factors, including the lack of information on the spatial localisation of each lesion on synthetic metrics such as LV. We used a probabilistic approach to provide the volume of WM tracts that may be disconnected by lesions and to evaluate its correlation with EDSS.

Methods

Forty-five patients (aged 37.4 ± 6.8 years, mean ± standard deviation; 30 females; 29 relapsing-remitting, 16 progressive) underwent 3-T magnetic resonance imaging. Both LV and the volume of the tracts crossing the lesioned regions (disconnectome volume, DV) were calculated using BCBtoolkit and correlated with EDSS.

Results

T1-weighted LV and DV significantly correlated with EDSS (p ≤ 0.006 r ≥ 0.413) as it was for T2-weighted LV and T2-weighted DV (p ≤ 0.004 r ≥ 0.430), but only T1-weighetd and T2-weighted DVs were EDSS significant predictors (p ≤ 0.001). The correlations of T1-weighted and T2-weighted LV with EDSS were significantly mediated by DV, while no effect of LV on the EDSS-DV correlation was observed.

Conclusion

The volume of disconnected WM bundles mediates the LV-EDSS correlation, representing the lonely EDSS predictor.

Migraine in Multiple Sclerosis Patients Affects Functional Connectivity of the Brain Circuitry Involved in Pain Processing

Migraine is particularly common in patients with multiple sclerosis (MS) and has been linked to the dysfunction of the brain circuitry modulating the peripheral nociceptive stimuli. Using MRI, we explored whether changes in the resting state-functional connectivity (RS-FC) may characterize the occurrence of migraine in patients with MS. The RS-FC characteristics in concerned brain regions were explored in 20 MS patients with migraine (MS+M) during the interictal phase, and compared with 19 MS patients without migraine (MS-M), which served as a control group. Functional differences were correlated to the frequency and severity of previous migraine attacks, and with the resulting impact on daily activities. In MS+M, the loss of periaqueductal gray matter (PAG) positive connectivity with the default mode network and the left posterior cranial pons was associated with an increase of migraine attacks frequency. In contrast, the loss of PAG negative connectivity with sensorimotor and visual network was linked to migraine symptom severity and related daily activities impact. Finally, a PAG negative connection was established with the prefrontal executive control network. Migraine in MS+M patients and its impact on daily activities, underlies RS-FC rearrangements between brain regions involved in pain perception and modulation.

Insights into the Pathophysiology of Psychiatric Symptoms in Central Nervous System Disorders: Implications for Early and Differential Diagnosis

Different psychopathological manifestations, such as affective, psychotic, obsessive-compulsive symptoms, and impulse control disturbances, may occur in most central nervous system (CNS) disorders including neurodegenerative and neuroinflammatory diseases. Psychiatric symptoms often represent the clinical onset of such disorders, thus potentially leading to misdiagnosis, delay in treatment, and a worse outcome. In this review, psychiatric symptoms observed along the course of several neurological diseases, namely Alzheimer’s disease, fronto-temporal dementia, Parkinson’s disease, Huntington’s disease, and multiple sclerosis, are discussed, as well as the involved brain circuits and molecular/synaptic alterations. Special attention has been paid to the emerging role of fluid biomarkers in early detection of these neurodegenerative diseases. The frequent occurrence of psychiatric symptoms in neurological diseases, even as the first clinical manifestations, should prompt neurologists and psychiatrists to share a common clinico-biological background and a coordinated diagnostic approach.

Mind the gap: from neurons to networks to outcomes in multiple sclerosis

MRI studies have provided valuable insights into the structure and function of neural networks, particularly in health and in classical neurodegenerative conditions such as Alzheimer disease. However, such work is also highly relevant in other diseases of the CNS, including multiple sclerosis (MS). In this Review, we consider the effects of MS pathology on brain networks, as assessed using MRI, and how these changes to brain networks translate into clinical impairments. We also discuss how this knowledge can inform the targeting of MS treatments and the potential future directions for research in this area. Studying MS is challenging as its pathology involves neurodegenerative and focal inflammatory elements, both of which could disrupt neural networks. The disruption of white matter tracts in MS is reflected in changes in network efficiency, an increasingly random grey matter network topology, relative cortical disconnection, and both increases and decreases in connectivity centred around hubs such as the thalamus and the default mode network. The results of initial longitudinal studies suggest that these changes evolve rather than simply increase over time and are linked with clinical features. Studies have also identified a potential role for treatments that functionally modify neural networks as opposed to altering their structure.

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.

Oligodendrocyte lineage cells and depression

Depression is a common mental illness, affecting more than 300 million people worldwide. Decades of investigation have yielded symptomatic therapies for this disabling condition but have not led to a consensus about its pathogenesis. There are data to support several different theories of causation, including the monoamine hypothesis, hypothalamic-pituitary-adrenal axis changes, inflammation and immune system alterations, abnormalities of neurogenesis and a conducive environmental milieu. Research in these areas and others has greatly advanced the current understanding of depression; however, there are other, less widely known theories of pathogenesis. Oligodendrocyte lineage cells, including oligodendrocyte progenitor cells and mature oligodendrocytes, have numerous important functions, which include forming myelin sheaths that enwrap central nervous system axons, supporting axons metabolically, and mediating certain forms of neuroplasticity. These specialized glial cells have been implicated in psychiatric disorders such as depression. In this review, we summarize recent findings that shed light on how oligodendrocyte lineage cells might participate in the pathogenesis of depression, and we discuss new approaches for targeting these cells as a novel strategy to treat depression.

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.

Impairments of white matter tracts and connectivity alterations in five cognitive networks of patients with multiple sclerosis

INTRODUCTION

MS is associated with structural and functional brain alterations leading to cognitive impairments across multiple domains including attention, memory, and speed of information processing. Here, we analyzed the white matter damage and topological organization of white matter tracts in specific brain regions responsible for cognition in MS.

METHODS

Brain DTI, rs-fMRI, T1, T2, and T2-FLAIR were acquired for 22 MS subjects and 22 healthy controls. Automatic brain parcellation was performed on T1-weighted images. Skull-stripped T1-weighted intensity inverted images were co-registered to the b0 image. Diffusion-weighted images were processed to perform whole brain tractography. The rs-fMRI data were processed, and the connectivity matrixes were analyzed to identify significant differences in the network of nodes between the two groups using NBS analysis. In addition, diffusion entropy maps were produced from DTI data sets using in-house software.

RESULTS

MS subjects exhibited significantly reduced mean FA and entropy in 38 and 34 regions, respectively, out of a total of 54 regions. The connectivity values in both structural and functional analyses were decreased in most regions of the default mode network and in four other cognitive networks in MS subjects compared to healthy controls. MS also induced significant reduction in the normalized hippocampus and corpus callosum volumes; the normalized hippocampus volume was significantly correlated with EDSS scores.

CONCLUSION

MS subjects have significant white matter damage and reduction of FA and entropy in various brain regions involved in cognitive networks. Structural and functional connectivity within the default mode network and an additional four cognitive networks exhibited significant changes compared with healthy controls.

Selective Cerebellar Atrophy Associates with Depression and Fatigue in the Early Phases of Relapse-Onset Multiple Sclerosis

Cerebellar dysfunctions have been associated to depressive disorders and cognitive impairment in neurodegenerative diseases. The objective is to analyze the associations between cerebellar atrophy, depression, and fatigue in the early phases of relapse-onset multiple sclerosis (RRMS). Sixty-one RRMS patients and 50 healthy controls (HC) were enrolled and clinically evaluated by means of expanded disability status scale (EDSS), Rao's brief repeatable battery of neuropsychological tests (BRB-NT), Delis-Kaplan executive function system sorting test, beck depression inventory II (BDI-II), and fatigue severity scale (FSS). The relationships between MRI variables and clinical scores were assessed. Depressed RRMS (dRRMS) had significantly lower Vermis Crus I volume compared with not depressed RRMS (ndRRMS) (p = 0.009). Vermis Crus I volume was lower in dRRMS suffering from fatigue than in ndRRMS without fatigue (p = 0.01). The hierarchical regression models which included demographic and clinical data (age, sex, and disease duration, FSS or BDI-II) and cerebellar volumes disclosed that cerebellar lobule right V atrophy explained an increase of 4% of the variability in FSS (p = 0.25) and Vermis Crus I atrophy explained an increase of 6% of variability in BDI-II (p = 0.049). Since clinical onset, atrophy of specific cerebellar lobules associates with important clinical aspects of RRMS. Cerebellar pathology may be one of the determinants of fatigue and depression that contribute to worsen disability in RRMS.

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.

Combining magnetoencephalography with magnetic resonance imaging enhances learning of surrogate-biomarkers

Electrophysiological methods, that is M/EEG, provide unique views into brain health. Yet, when building predictive models from brain data, it is often unclear how electrophysiology should be combined with other neuroimaging methods. Information can be redundant, useful common representations of multimodal data may not be obvious and multimodal data collection can be medically contraindicated, which reduces applicability. Here, we propose a multimodal model to robustly combine MEG, MRI and fMRI for prediction. We focus on age prediction as a surrogate biomarker in 674 subjects from the Cam-CAN dataset. Strikingly, MEG, fMRI and MRI showed additive effects supporting distinct brain-behavior associations. Moreover, the contribution of MEG was best explained by cortical power spectra between 8 and 30 Hz. Finally, we demonstrate that the model preserves benefits of stacking when some data is missing. The proposed framework, hence, enables multimodal learning for a wide range of biomarkers from diverse types of brain signals.

Disability worsening among persons with multiple sclerosis and depression: A Swedish cohort study

OBJECTIVE

Depression is common in multiple sclerosis (MS), but its impact on disability worsening has not yet been determined. We explored the risk of disability worsening associated with depression in a nationwide longitudinal cohort.

METHODS

This retrospective cohort study used linked data from 3 Swedish nationwide registries: the MS Register, National Patient Register, and Prescribed Drug Register. Two incident cohorts were developed: cohort 1 included all registered cases of MS in the MS Registry (2001-2014) with depression defined as ≥1 ICD-10 code for depression; and cohort 2 comprised all cases of MS in the MS Registry (2005-2014) with depression defined as ≥1 prescription filled for an antidepressant. Cox regression models were used to compare the risk of reaching sustained disability milestone scores of 3.0, 4.0, and 6.0 on the Expanded Disability Status Scale (EDSS) between persons with MS with and without depression.

RESULTS

Cohort 1 included 5,875 cases; 502 (8.5%) had depression. Cohort 2 had 3,817 cases; 1,289 (33.8%) were prescribed an antidepressant. Persons with depression were at a significantly higher risk of reaching sustained EDSS scores of 3.0, 4.0, and 6.0, with hazard ratios of 1.50 (95% confidence interval [CI] 1.20-1.87), 1.79 (95% CI 1.40-2.29), and 1.89 (95% CI 1.38-2.57), respectively. A similar increased risk among persons exposed to antidepressants was observed, with hazard ratios of 1.37 (95% CI 1.18-1.60), 1.93 (95% CI 1.61-2.31), and 1.86 (95% CI 1.45-2.40) for sustained EDSS scores of 3.0, 4.0, and 6.0, respectively.

CONCLUSION

Persons with MS and comorbid depression had a significantly increased risk of disability worsening. This finding highlights the need for early recognition and appropriate treatment of depression in persons with MS.

Effects of Serotonin Transporter Gene Variation on Impulsivity Mediated by Default Mode Network: A Family Study of Depression

Serotonergic neurotransmission, potentially through effects on the brain's default mode network (DMN), may regulate aspects of attention including impulse control. Indeed, genetic variants of the serotonin transporter (5-HTT) have been implicated in impulsivity and related psychopathology. Yet it remains unclear the mechanism by which the 5-HTT genetic variants contribute to individual variability in impulse control. Here, we tested whether DMN connectivity mediates an association between the 5-HTT genetic variants and impulsivity. Participants (N = 92) were from a family cohort study of depression in which we have previously shown a broad distribution of 5-HTT variants. We genotyped for 5-HTTLPR and rs25531 (stratified by transcriptional efficiency: 8 low/low, 53 low/high, and 31 high/high), estimated DMN structural connectivity using diffusion probabilistic tractography, and assessed behavioral measures of impulsivity (from 12 low/low, 48 low/high, and 31 high/high) using the Continuous Performance Task. We found that low transcriptional efficiency genotypes were associated with decreased connection strength between the posterior DMN and the superior frontal gyrus (SFG). Path modeling demonstrated that decreased DMN-SFG connectivity mediated the association between low-efficiency genotypes and increased impulsivity. Taken together, this study suggests a gene-brain-behavior pathway that perhaps underlies the role of the serotonergic neuromodulation in impulse control.

Altered hippocampal GABA and glutamate levels and uncoupling from functional connectivity in multiple sclerosis

There is growing evidence for dysfunctional glutamatergic excitation and/or gamma-aminobutyric acid (GABA)ergic inhibition in patients with multiple sclerosis (MS). Cognitive impairment may occur during the early stages of MS and hippocampal abnormalities have been suggested as biomarkers. However, researchers have not clearly determined whether changes in hippocampal GABA and glutamate (Glu) levels are associated with cognitive impairment and aberrant neural activity in patients with MS. We used magnetic resonance spectroscopy to measure GABA+ and Glu levels in the left hippocampal region of 29 patients with relapsing-remitting MS and 29 healthy controls (HCs). Resting-state functional connectivity (FC) with the hippocampus was also examined. Compared to HCs, patients exhibited significantly lower GABA+ and Glu levels, which were associated with verbal and visuospatial memory deficits, respectively. Patients also showed decreased FC strengths between the hippocampus and several cortical regions, which are located within the default mode network. Moreover, hippocampal GABA+ levels and Glu/GABA+ ratios correlated with the FC strengths in HCs but not in patients with MS. This study describes a novel method for investigating the complex relationships among excitatory/inhibitory neurotransmitters, brain connectivity and cognition in health and disease. Strategies that modulate Glu and GABA neurotransmission may represent new therapeutic treatments for patients with MS.

Multiple sclerosis and cognition: synaptic failure and network dysfunction

Cognitive impairment is increasingly recognized to be a core feature of multiple sclerosis (MS), with important implications for the everyday life of individuals with MS and for disease management. Unfortunately, the exact mechanisms that underlie this cognitive impairment are poorly understood and there are no effective therapeutic options for this aspect of the disease. During MS, focal brain inflammatory lesions, together with pathological changes of both CNS grey matter and normal-appearing white matter, can interfere with cognitive functions. Moreover, inflammation may alter the crosstalk between the immune and the nervous systems, modulating the induction of synaptic plasticity and neurotransmission. In this Review, we examine the CNS structures and cognitive domains that are affected by the disease, with a specific focus on hippocampal involvement in MS and experimental autoimmune encephalomyelitis, an experimental model of MS. We also discuss the hypothesis that, during MS, immune-mediated alterations of synapses' ability to express long-term plastic changes may contribute to the pathogenesis of cognitive impairment by interfering with the dynamics of neuronal networks.

Do people with multiple sclerosis benefit from PC-based neurorehabilitation? A pilot study

Multiple Sclerosis (MS) is an inflammatory degenerative disease of the central nervous system. Cognitive impairment is a frequent feature of MS at both the earlier and later stages of the disease, and it tends to worsen over time. Cognitive rehabilitation (CR) is becoming a standard component of neurorehabilitation in patients with MS. The aim of this study is to evaluate the effect of computerized CR, by using the Italian software ERICA, on cognitive and daily life performance in MS patients with mild to moderate cognitive impairment. We studied 40 individuals affected by MS, randomized into either traditional CR group (TCRG: n = 20), which performed a conventional cognitive training, or the computer-assisted CR group (CCRG: n = 20), which performed PC-based CR. The cognitive dysfunctions were investigated through a complete neuropsychological battery, administered before (T0) and after (T1) each different training. Both the trainings were well-tolerated and led to improvement in cognitive function. Notably, the CCRG had a significant effect in improving memory, attention, and processing speed, as compared to TCRG. ERICA training could be a valuable tool for the CR in patients affected by MS. Further studied are needed to confirm these promising results and evaluate the long-term effects.

Functional connectivity impairment of postcentral gyrus in relapsing-remitting multiple sclerosis with somatosensory disorder

PURPOSE

To characterize the spatial patterns of functional connectivity(FC) changes of whole brain in RRMS with somatosensory disorder(RRMS-SS) and to investigate the correlation between abnormal FC and clinical scores.

METHODS

Twenty-six RRMS-SS patients and 23 healthy controls(HC) underwent resting-state functional magnetic resonance imaging(RS-fMRI) scanning. The clinical scores were collected including Expanded Disability Status Scores(EDSS), Disease Duration and Somatosensory Evaluation by the Fugl-Meyer sensory score(FMSS). With the voxel-wise methods, RS-fMRI data were analyzed using REST software, to assess the FC of the postcentral gyrus(PoCG). Correlation between clinical variables and the strength of FC was analyzed.

RESULTS

Compared with HC, the left postcentral-based FC showed decreased FC of the right cerebellum_8, lingual lobe and Rolandic operculum gyrus, and increased FC of the left middle frontal lobe. The right postcentral-based FC revealed decreased FC with the right Heschl's gyrus lobule, and increased FC with bilateral middle frontal lobe (p <  0.001, AlphaSim corrected). Correlation analysis revealed that the FC of altered brain regions was associated with FMSS, EDSS and disease duration.

CONCLUSION

The functional connectivity of PoCG at RS-fMRI has multi-network changes in patients with RRMS-SS. This suggests a complex pattern of abnormal connections between the somatosensory network regions and the whole brain. Moreover, the correlation between the FC and the FMSS, such as the left middle frontal lobe and the right PoCG, indicate that these two brain regions play an important role in RRMS-SS.

Psychiatric disorders in multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is characterized by a large spectrum of symptoms, involving all functional systems. Psychiatric symptoms are common in people with MS (pwMS) having an important impact on quality of life and on some features of MS (fatigue, sleep, disability, adherence to disease-modifying drugs). The main psychiatric disturbances in MS are depressive, bipolar, anxiety, schizophrenic and obsessive-compulsive syndromes.

METHODS

Literature search for original articles and review in the databases, including PubMed and Scopus from 1959 to 2019.

RESULTS AND CONCLUSION

Studies answering the aim of this review were selected and reported. Epidemiological and clinical aspects of psychiatric syndromes (PS) in MS as well as self-report diagnostic scales and radiological correlates of PS in MS are described. Moreover, some radiological studies about primary psychiatric disorders (PD) are reported to underline how gray matter atrophy, white matter abnormalities and corpus callosum involvement in these diseases, as features in common with MS, may explain the more frequent occurrence of PD in MS than in the general population.

A complex relation between depression and multiple sclerosis: a descriptive review

BACKGROUND

Multiple sclerosis (MS) is a demyelinating neurodegenerative disease that affects central nervous system (CNS). MS patients are more likely to develop depressive symptoms than patients with other chronic diseases.

OBJECTIVE

In this review, we have analysed if there is a correlation between brain lesions (BL), structural damage (SD) and depressive symptoms (DS).

METHODS

We Searched on PubMed and Web of Science databases and screening references of included studied and some review article for additional citations. From initial 745 studies, only 9 met the inclusion criteria. All studies conducted research on 389 patients with MS associated with DS and 120 HC (healthy controls).

RESULTS

The selected researches highlighted the involvement of limbic system, the role of hippocampus and the impact of brain lesions on the emotional status of MS patients.

DISCUSSION

In the genesis of depression are implicated many mechanisms including genetic, biochemical, immunological and psychosocial factors, even if a prominent role in the onset of DS seem to be associated with structural and functional brain alterations.

Structural connectivity in multiple sclerosis and modeling of disconnection

BACKGROUND

Multiple sclerosis (MS) is characterized by focal white matter damage, and when the brain is modeled as a network, lesions can be treated as disconnection events.

OBJECTIVE

To evaluate whether modeling disconnection caused by lesions helps explain motor and cognitive impairment in MS.

METHODS

Pathways connecting 116 cortical regions were reconstructed with magnetic resonance imaging (MRI) tractography from diffusion tensors averaged across healthy controls (HCs); maps of pathways were applied to 227 relapse-onset MS patients and 50 HCs to derive structural connectivity. Then, the likelihood of individual connections passing through lesions was used to model disconnection. Patients were grouped according to clinical phenotype (113 relapsing-remitting multiple sclerosis (RRMS), 69 secondary progressive multiple sclerosis (SPMS), 45 benign MS), and then network metrics were compared between groups (analysis of variance (ANOVA)) and correlated with motor and cognitive scores (linear regression).

RESULTS

Global metrics differentiated RRMS from SPMS and benign MS patients, but not benign from SPMS patients. Nodal connectivity strength replicated global results. After disconnection, few nodes were significantly different between benign MS and RRMS patients. Correlations revealed nodes pertinent to motor and cognitive dysfunctions; these became slightly stronger after disconnection.

CONCLUSION

Connectivity did not change greatly after modeled disconnection, suggesting that the brain network is robust against damage caused by MS lesions.

Preventing suicidal behavior in patients with multiple sclerosis: a scoping review

INTRODUCTION

Suicidal behavior is a relatively rare occurrence among patients with multiple sclerosis (MS). Nonetheless, it is important to identify and be aware of the constituting risk factors to prevent suicidal behavior among vulnerable patients. Areas covered: This scoped review will shortly outline well-known biological and psychosocial risk factors for suicidal behavior among MS patients and suggest preventive initiatives. The preventive strategies should include a close monitoring of MS pharmacotherapy to prevent progression, and awareness and early identification of psychosocial risk factors across a variety of heathcare and social instances the patient may encounter during their life with the disease. The staff in these instances should be educated in detecting the MS patients at increased risk and refer them to relevant healthcare instances, including the general practitioner, neurologists, psychiatrist, etc. In addition, referral to social instances to support educational, vocational, and home environment to the state of the disease is of utmost importance. Expert commentary: Enhancing quality of life for as long as possible by these means may be held to reduce the risk for psychosocial problems and hence suicidal behavior.

Functional Connectivity in Multiple Sclerosis: Recent Findings and Future Directions

Multiple sclerosis is a debilitating disorder resulting from scattered lesions in the central nervous system. Because of the high variability of the lesion patterns between patients, it is difficult to relate existing biomarkers to symptoms and their progression. The scattered nature of lesions in multiple sclerosis offers itself to be studied through the lens of network analyses. Recent research into multiple sclerosis has taken such a network approach by making use of functional connectivity. In this review, we briefly introduce measures of functional connectivity and how to compute them. We then identify several common observations resulting from this approach: (a) high likelihood of altered connectivity in deep-gray matter regions, (b) decrease of brain modularity, (c) hemispheric asymmetries in connectivity alterations, and (d) correspondence of behavioral symptoms with task-related and task-unrelated networks. We propose incorporating such connectivity analyses into longitudinal studies in order to improve our understanding of the underlying mechanisms affected by multiple sclerosis, which can consequently offer a promising route to individualizing imaging-related biomarkers for multiple sclerosis.

The hippocampus in multiple sclerosis

Some of the clinical manifestations of multiple sclerosis, such as memory impairment and depression, are, at least partly, related to involvement of the hippocampus. Pathological studies have shown extensive demyelination, neuronal damage, and synaptic abnormalities in the hippocampus of patients with multiple sclerosis, and improvements in MRI technology have provided novel ways to assess hippocampal involvement in vivo. It is now accepted that clinical manifestations related to the hippocampus are due not only to focal hippocampal damage, but also to disconnection of the hippocampus from several brain networks. Evidence suggests anatomical and functional subspecialisation of the different hippocampal subfields, resulting in variability between regions in the extent to which damage and repair occur. The hippocampus also has important roles in plasticity and neurogenesis, both of which potentially contribute to functional preservation and restoration. These findings underline the importance of evaluation of the hippocampus not only to improve understanding of the clinical manifestations of multiple sclerosis, but also as a potential future target for treatment.

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

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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.

Explaining the heterogeneity of functional connectivity findings in multiple sclerosis: An empirically informed modeling study

To understand the heterogeneity of functional connectivity results reported in the literature, we analyzed the separate effects of grey and white matter damage on functional connectivity and networks in multiple sclerosis. For this, we employed a biophysical thalamo‐cortical model consisting of interconnected cortical and thalamic neuronal populations, informed and amended by empirical diffusion MRI tractography data, to simulate functional data that mimic neurophysiological signals. Grey matter degeneration was simulated by decreasing within population connections and white matter degeneration by lowering between population connections, based on lesion predilection sites in multiple sclerosis. For all simulations, functional connectivity and functional network organization are quantified by phase synchronization and network integration, respectively. Modeling results showed that both cortical and thalamic grey matter damage induced a global increase in functional connectivity, whereas white matter damage induced an initially increased connectivity followed by a global decrease. Both white and especially grey matter damage, however, induced a decrease in network integration. These empirically informed simulations show that specific topology and timing of structural damage are nontrivial aspects in explaining functional abnormalities in MS. Insufficient attention to these aspects likely explains contradictory findings in multiple sclerosis functional imaging studies so far.

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.

Radiation-induced brain structural and functional abnormalities in presymptomatic phase and outcome prediction

Radiation therapy, a major method of treatment for brain cancer, may cause severe brain injuries after many years. We used a rare and unique cohort of nasopharyngeal carcinoma patients with normal-appearing brains to study possible early irradiation injury in its presymptomatic phase before severe, irreversible necrosis happens. The aim is to detect any structural or functional imaging biomarker that is sensitive to early irradiation injury, and to understand the recovery and progression of irradiation injury that can shed light on outcome prediction for early clinical intervention. We found an acute increase in local brain activity that is followed by extensive reductions in such activity in the temporal lobe and significant loss of functional connectivity in a distributed, large-scale, high-level cognitive function-related brain network. Intriguingly, these radiosensitive functional alterations were found to be fully or partially recoverable. In contrast, progressive late disruptions to the integrity of the related far-end white matter structure began to be significant after one year. Importantly, early increased local brain functional activity was predictive of severe later temporal lobe necrosis. Based on these findings, we proposed a dynamic, multifactorial model for radiation injury and another preventive model for timely clinical intervention. Hum Brain Mapp 39:407-427, 2018. © 2017 Wiley Periodicals, Inc.

Remodeling Functional Connectivity in Multiple Sclerosis: A Challenging Therapeutic Approach

Neurons in the central nervous system are organized in functional units interconnected to form complex networks. Acute and chronic brain damage disrupts brain connectivity producing neurological signs and/or symptoms. In several neurological diseases, particularly in Multiple Sclerosis (MS), structural imaging studies cannot always demonstrate a clear association between lesion site and clinical disability, originating the "clinico-radiological paradox." The discrepancy between structural damage and disability can be explained by a complex network perspective. Both brain networks architecture and synaptic plasticity may play important roles in modulating brain networks efficiency after brain damage. In particular, long-term potentiation (LTP) may occur in surviving neurons to compensate network disconnection. In MS, inflammatory cytokines dramatically interfere with synaptic transmission and plasticity. Importantly, in addition to acute and chronic structural damage, inflammation could contribute to reduce brain networks efficiency in MS leading to worse clinical recovery after a relapse and worse disease progression. These evidence suggest that removing inflammation should represent the main therapeutic target in MS; moreover, as synaptic plasticity is particularly altered by inflammation, specific strategies aimed at promoting LTP mechanisms could be effective for enhancing clinical recovery. Modulation of plasticity with different non-invasive brain stimulation (NIBS) techniques has been used to promote recovery of MS symptoms. Better knowledge of features inducing brain disconnection in MS is crucial to design specific strategies to promote recovery and use NIBS with an increasingly tailored approach.

Neuropsychology of Multiple Sclerosis: Looking Back and Moving Forward

The neuropsychological aspects of multiple sclerosis (MS) have evolved over the past three decades. What was once thought to be a rare occurrence, cognitive dysfunction is now viewed as one of the most disabling symptoms of the disease, with devastating effects on patients' quality of life. This selective review will highlight major innovations and scientific discoveries in the areas of neuropathology, neuroimaging, diagnosis, and treatment that pertain to our understanding of the neuropsychological aspects of MS. Specifically, we focus on the recent discovery that MS produces pathogical lesions of gray matter (GM) that have consequences for cognitive functions. Methods for imaging these GM lesions in MS are discussed along with multimodal imaging studies that integrate structural and functional imaging methods to provide a better understanding of the relationship between cognitive test performance and functional reserve. Innovations in the screening and comprehensive assessment of cognitive disorders are presented along with recent research that examines cognitive dysfunction in pediatric MS. Results of innovative outcome studies in cognitive rehabilitation are discussed. Finally, we highlight trends for potential future innovations over the next decade. (JINS, 2017, 23, 832-842).

Gray matter trophism, cognitive impairment, and depression in patients with multiple sclerosis

BACKGROUND

Cognitive impairment and depression frequently affects patients with multiple sclerosis (MS). However, the relationship between the occurrence of depression and cognitive impairment and the development of cortical atrophy has not been fully elucidated yet.

OBJECTIVES

To investigate the association of cortical and deep gray matter (GM) volume with depression and cognitive impairment in MS.

METHODS

Three-dimensional (3D) T1-weighted scans were obtained from 126 MS patients and 59 matched healthy controls. Cognitive impairment was assessed using the Brief Repeatable Battery of Neuropsychological Tests and depression with the Montgomery-Asberg Depression Rating Scale (MADRS). Using FreeSurfer and FIRST software, we assessed cortical thickness (CTh) and deep GM volumetry. Magnetic resonance imaging (MRI) variables explaining depression and cognitive impairment were investigated using factorial and classification analysis. Multivariate regression models correlated GM abnormalities with symptoms severity.

RESULTS

Compared with controls, MS patients exhibited widespread bilateral cortical thinning involving all brain lobes. Depressed MS showed selective CTh decrease in fronto-temporal regions, whereas cognitive impairment MS exhibited widespread fronto-parietal cortical and subcortical GM atrophy. Frontal cortical thinning was the best predictor of depression ( C-statistic = 0.7), whereas thinning of the right precuneus and high T2 lesion volume best predicted cognitive impairment ( C-statistic = 0.8). MADRS severity correlated with right entorhinal cortex thinning, whereas cognitive impairment severity correlated with left entorhinal and thalamus atrophy.

CONCLUSION

MS-related depression is linked to circumscribed CTh changes in areas deputed to emotional behavior, whereas cognitive impairment is correlated with cortical and subcortical GM atrophy of circuits involved in cognition.