Independent contributions of cortical gray matter atrophy and ventricle enlargement for predicting neuropsychological impairment in multiple sclerosis

Cognitive performance and magnetic resonance imaging in people with multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

Several studies have shown the different relationships between cognitive functions and structural magnetic resonance imaging (MRI) measurements in people with multiple sclerosis (pwMS). However, there is an ongoing debate regarding the magnitude of correlation between MRI measurements and specific cognitive function tests. This systematic review and meta-analysis aimed to synthesize the most consistent correlations between MRI measurements and cognitive function in pwMS.

METHODS

PubMed/MEDLINE, Embase, Scopus, and Web of Science databases were systematically searched up to February 2023, to find relevant data. The search utilized syntax and medical subject headings (MeSH) relevant to cognitive performance tests and MRI measurements in pwMS. The R software version 4.3.3 with random effect models was used to estimate the pooled effect sizes.

RESULTS

13,559 studies were reviewed, of which 136 were included. The meta-analyses showed that thalamic volume had the most significant correlations with Symbol Digit Modalities Test (SDMT) r = 0.47 (95 % CI: 0.39 to 0.56, p < 0.001, I2 = 88 %), Brief Visual Memory Test-Revised-Total Recall (BVMT-TR) r = 0.51 (95 % CI: 0.36 to 0.66, p < 0.001, I2 = 81 %), California Verbal Learning Test-II-Total Recall (CVLT-TR) r = 0.47 (95 % CI: 0.34 to 0.59, p < 0.001, I2 = 69 %,), and Delis-Kaplan Executive Function System (DKEFS) r = 0.48 (95 % CI: 0.34 to 0.63, p < 0.001, I2 = 22 %,).

CONCLUSION

We conclude that thalamic volume exhibits highest relationships with information processing speed (IPS), visuospatial learning-memory, verbal learning-memory, and executive function in pwMS. A comprehensive understanding of the intricacies of the mechanisms underpinning this association requires additional research.

Emerging Perspectives on MRI Application in Multiple Sclerosis: Moving from Pathophysiology to Clinical Practice

MRI plays a central role in the diagnosis of multiple sclerosis (MS) and in the monitoring of disease course and treatment response. Advanced MRI techniques have shed light on MS biology and facilitated the search for neuroimaging markers that may be applicable in clinical practice. MRI has led to improvements in the accuracy of MS diagnosis and a deeper understanding of disease progression. This has also resulted in a plethora of potential MRI markers, the importance and validity of which remain to be proven. Here, five recent emerging perspectives arising from the use of MRI in MS, from pathophysiology to clinical application, will be discussed. These are the feasibility of noninvasive MRI-based approaches to measure glymphatic function and its impairment; T1-weighted to T2-weighted intensity ratio to quantify myelin content; classification of MS phenotypes based on their MRI features rather than on their clinical features; clinical relevance of gray matter atrophy versus white matter atrophy; and time-varying versus static resting-state functional connectivity in evaluating brain functional organization. These topics are critically discussed, which may guide future applications in the field.

The Complex Interplay Between Trait Fatigue and Cognition in Multiple Sclerosis

Cognitive impairments are frequent in patients with Multiple Sclerosis (MS). Yet, the influence of MS-related symptoms on cognitive status is not clear. Studies investigating the impact of trait fatigue along with anxio-depressive symptoms on cognition are seldom, and even less considered fatigue as multidimensional. Moreover, these studies provided conflicting results.

Twenty-nine MS patients and 28 healthy controls, matched on age, gender and education underwent a full comprehensive neuropsychological assessment. Anxio-depressive and fatigue symptoms were assessed using the HAD scale and the MFIS, respectively. Six composite scores were derived from the neuropsychological assessment, reflecting the cognitive domains of working memory, verbal and visual learning, executive functions, attention and processing speed. Stepwise regression analyses were conducted in each group to investigate if trait cognitive and physical fatigue, depression and anxiety are relevant predictors of performance in each cognitive domain. In order to control for disease progression, patient’s EDSS score was also entered as predictor variable.

In the MS group, trait physical fatigue was the only significant predictor of working memory score. Cognitive fatigue was a predictor for executive functioning performance and for processing speed (as well as EDSS score for processing speed). In the healthy controls group, only an association between executive functioning and depression was observed.

Fatigue predicted cognition in MS patients only, beyond anxio-depressive symptoms and disease progression. Considering fatigue as a multidimensional symptom is paramount to better understand its association with cognition, as physical and cognitive fatigue are predictors of different cognitive processes.

Relationship Between White Matter Lesions and Gray Matter Atrophy in Multiple Sclerosis: A Systematic Review

Background and Objectives

There is currently no consensus about the extent of gray matter (GM) atrophy that can be attributed to secondary changes after white matter (WM) lesions or the temporal and spatial relationships between the 2 phenomena. Elucidating this interplay will broaden the understanding of the combined inflammatory and neurodegenerative pathophysiology of multiple sclerosis (MS), and separating atrophic changes due to primary and secondary neurodegenerative mechanisms will then be pivotal to properly evaluate treatment effects, especially if these treatments target the different processes individually. To untangle these complex pathologic mechanisms, this systematic review provides an essential first step: an objective and comprehensive overview of the existing in vivo knowledge of the relationship between brain WM lesions and GM atrophy in patients diagnosed with MS. The overall aim was to clarify the extent to which WM lesions are associated with both global and regional GM atrophy and how this may differ in the different disease subtypes.

Methods

We searched MEDLINE (through PubMed) and Embase for reports containing direct associations between brain GM and WM lesion measures obtained by conventional MRI sequences in patients with clinically isolated syndrome and MS. No restriction was applied for publication date. The quality and risk of bias in included studies were evaluated with the Quality Assessment Tool for observational cohort and cross-sectional studies (NIH, Bethesda, MA). Qualitative and descriptive analyses were performed.

Results

A total of 90 articles were included. WM lesion volumes were related mostly to global, cortical and deep GM volumes, and those significant associations were almost without exception negative, indicating that higher WM lesion volumes were associated with lower GM volumes or lower cortical thicknesses. The most consistent relationship between WM lesions and GM atrophy was seen in early (relapsing) disease and less so in progressive MS.

Discussion

The findings suggest that GM neurodegeneration is mostly secondary to damage in the WM during early disease stages while becoming more detached and dominated by other, possibly primary neurodegenerative disease mechanisms in progressive MS.

Interferons and Multiple Sclerosis: Lessons from 25 Years of Clinical and Real-World Experience with Intramuscular Interferon Beta-1a (Avonex)

Recombinant interferon (IFN) β-1b was approved by the US Food and Drug Administration as the first disease-modifying therapy (DMT) for multiple sclerosis (MS) in 1993. Since that time, clinical trials and real-world observational studies have demonstrated the effectiveness of IFN therapies. The pivotal intramuscular IFN β-1a phase III trial published in 1996 was the first to demonstrate that a DMT could reduce accumulation of sustained disability in MS. Patient adherence to treatment is higher with intramuscular IFN β-1a, given once weekly, than with subcutaneous formulations requiring multiple injections per week. Moreover, subcutaneous IFN β-1a is associated with an increased incidence of injection-site reactions and neutralizing antibodies compared with intramuscular administration. In recent years, revisions to MS diagnostic criteria have improved clinicians' ability to identify patients with MS and have promoted the use of magnetic resonance imaging (MRI) for diagnosis and disease monitoring. MRI studies show that treatment with IFN β-1a, relative to placebo, reduces T2 and gadolinium-enhancing lesions and gray matter atrophy. Since the approval of intramuscular IFN β-1a, a number of high-efficacy therapies have been approved for MS, though the benefit of these high-efficacy therapies should be balanced against the increased risk of serious adverse events associated with their long-term use. For some subpopulations of patients, including pregnant women, the safety profile of IFN β formulations may provide a particular benefit. In addition, the antiviral properties of IFNs may indicate potential therapeutic opportunities for IFN β in reducing the risk of viral infections such as COVID-19.

Prospective Memory Deficits in Multiple Sclerosis: Voxel-based Morphometry and Double Inversion Recovery Analysis

Objective Prospective memory (PM) is an important social cognitive function in everyday life. PM is one of the most affected cognitive domains in multiple sclerosis (MS) patients. Gray matter (GM) atrophy and plaques have been attracting attention for various cognitive impairments in MS patients. This study aimed to clarify the atrophic GM regions associated with PM deficits and investigate the relationship between the atrophic GM regions and GM plaques. Methods Twenty-one MS patients and 10 healthy controls (HCs) underwent neuropsychological tests and MRI. PM was assessed using subtests of the Rivermead Behavioural Memory Test. A lesion symptom analysis was performed using voxel-based morphometry (VBM). We then evaluated GM plaques in the corresponding areas using double inversion recovery (DIR). Results MS patients showed lower PM scores than HCs (p=0.0064). The GM volume of MS patients tended to be lower than those of HCs. VBM analyses revealed correlations of the PM score with the orbital part of the left inferior frontal gyrus, the left hippocampus, and the right parahippocampus. There was no GM plaque in the orbital part of the left inferior frontal gyrus and the right parahippocampus. Only one patient (4.8%) had GM plaque in the left hippocampus. Conclusion The left inferior frontal gyrus, the left hippocampus, and the right parahippocampus were associated with PM in MS, whereas these atrophic GM regions were not associated with GM plaque. Regardless of the location of plaques on DIR, both PM deficit and GM atrophy should be detected using neuropsychological tests and VBM in MS patients.

Sex differences in brain atrophy in multiple sclerosis

BACKGROUND

Women are more susceptible to multiple sclerosis (MS) than men by a ratio of approximately 3:1. However, being male is a risk factor for worse disability progression. Inflammatory genes have been linked to susceptibility, while neurodegeneration underlies disability progression. Thus, there appears to be a differential effect of sex on inflammation versus neurodegeneration. Further, gray matter (GM) atrophy is not uniform across the brain in MS, but instead shows regional variation. Here, we study sex differences in neurodegeneration by comparing regional GM atrophy in a cohort of men and women with MS versus their respective age- and sex-matched healthy controls.

METHODS

Voxel-based morphometry (VBM), deep GM substructure volumetry, and cortical thinning were used to examine regional GM atrophy.

RESULTS

VBM analysis showed deep GM atrophy in the thalamic area in both men and women with MS, whereas men had additional atrophy in the putamen as well as in localized cortical regions. Volumetry confirmed deep GM loss, while localized cortical thinning confirmed GM loss in the cerebral cortex. Further, MS males exhibited worse performance on the 9-hole peg test (9HPT) than MS females. We observed a strong correlation between thalamic volume and 9HPT performance in MS males, but not in MS females.

CONCLUSION

More regional GM atrophy was observed in men with MS than women with MS, consistent with previous observations that male sex is a risk factor for worse disease progression.

Brain magnetic resonance imaging features in multiple sclerosis and neuromyelitis optica spectrum disorders patients with or without aquaporin-4 antibody in a Latin American population

INTRODUCTION

There is scarce evidence comparing the behavior in magnetic resonance (MRI) between positive and negative aquaporin-4 antibody neuromyelitis optica spectrum disorders (P-NMOSD and NNMOSD, respectively). The aim of this study was to describe and compare MRI features through a quantitative and qualitative analysis between P-NMOSD and NNMOSD patients in a cohort from Latin American (LATAM) patients.

METHODS

We retrospectively reviewed the MRI and medical records of NMOSD patients as defined by the 2015 validated diagnostic criteria, and with at least 3 years of follow-up from disease onset (first symptom). We included patients from Argentina, Brazil and Venezuela. To be included, NMOSD patients must have had AQP4-ab status measured by a cell-based assay. Brain MRIs were obtained for each participant at disease onset and every 12 months for 3 years. Demographics, clinical and MRI variables (T2 lesion volume [T2LV], lesion distribution, cortical thickness [CT] and percentage of brain volume loss [PBVL]) were analyzed and compared between groups (P-NMOSD; NNMOSD) at disease onset and follow-up. A multiple sclerosis (MS) control group of patients was also included.

RESULTS

We included 24 P-NMOSD, 15 NNMOSD and 35 MS patients. No differences in age, gender and follow-up time were observed between groups. Nor were differences found in lesion distribution at disease onset or in brain volumes during follow-up between P-NMOSD and NNMOSD patients (T2LV = 0.43, CT = 0.12, PBVL p = 0.45). Significant differences were observed in lesion distribution at disease onset, as well as in brain volumes during follow-up between NMOSD and MS (T2LV = p<0.001, CT = p<0.001, PBVL p = 0.01).

CONCLUSION

Different MRI features were observed between MS and NMOSD. However, no quantitative nor qualitative differences were observed between P-NMOSD and NNMOSD, not allowing us to differentiate NMOSD conditions by MRI.

Assessment and Impact of Cognitive Impairment in Multiple Sclerosis: An Overview

Cognitive impairment affects 40⁻60% of patients with multiple sclerosis. It may be present early in the course of the disease and has an impact on a patient's employability, social interactions, and quality of life. In the last three decades, an increasing interest in diagnosis and management of cognitive impairment has arisen. Neuropsychological assessment and neuroimaging studies focusing on cognitive impairment are now being incorporated as primary outcomes in clinical trials. However, there are still key uncertainties concerning the underlying mechanisms of damage, neural basis, sensitivity and validity of neuropsychological tests, and efficacy of pharmacological and non-pharmacological interventions. The present article aimed to present an overview of the assessment, neural correlates, and impact of cognitive impairment in multiple sclerosis.

Predicting clinical progression in multiple sclerosis after 6 and 12 years

BACKGROUND AND PURPOSE

To predict disability and cognition in multiple sclerosis (MS) after 6 and 12 years, using early clinical and imaging measures.

METHODS

A total of 115 patients with MS were selected and followed up after 2 and 6 years, with 79 patients also being followed up after 12 years. Disability was measured using the Expanded Disability Status Scale (EDSS); cognition was measured only at follow-up using neuropsychological testing. Predictors of interest included EDSS score, baseline brain and lesion volumes and their changes over 2 years, baseline age, clinical phenotype, sex and educational level.

RESULTS

Higher 6-year EDSS score was predicted by early EDSS score and whole-brain volume changes and baseline diagnosis of primary progressive MS (adjusted R²  = 0.56). Predictors for 12-year EDSS score included larger EDSS score changes and higher T1-hypointense lesion volumes (adjusted R²  = 0.38). Year 6 cognition was predicted by primary progressive MS phenotype, lower educational level, male sex and early whole-brain atrophy (adjusted R²  = 0.26); year 12 predictors included male sex, lower educational level and higher baseline T1-hypointense lesion volumes (adjusted R²  = 0.14).

CONCLUSIONS

Patients with early signs of neurodegeneration and a progressive disease onset were more prone to develop both disability progression and cognitive dysfunction. Male sex and lower educational level only affected cognitive dysfunction, which remains difficult to predict and probably needs more advanced imaging measures.

Estriol-mediated neuroprotection in multiple sclerosis localized by voxel-based morphometry

INTRODUCTION

Progressive gray matter (GM) atrophy is a hallmark of multiple sclerosis (MS). Cognitive impairment has been observed in 40%-70% of MS patients and has been linked to GM atrophy. In a phase 2 trial of estriol treatment in women with relapsing-remitting MS (RRMS), higher estriol levels correlated with greater improvement on the paced auditory serial addition test (PASAT) and imaging revealed sparing of localized GM in estriol-treated compared to placebo-treated patients. To better understand the significance of this GM sparing, the current study explored the relationships between the GM sparing and traditional MRI measures and clinical outcomes.

METHODS

Sixty-two estriol- and forty-nine placebo-treated RRMS patients underwent clinical evaluations and brain MRI. Voxel-based morphometry (VBM) was used to evaluate voxelwise GM sparing from high-resolution T1-weighted scans.

RESULTS

A region of treatment-induced sparing (TIS) was defined as the areas where GM was spared in estriol- as compared to placebo-treated groups, localized primarily within the frontal and parietal cortices. We observed that TIS volume was directly correlated with improvement on the PASAT. Next, a longitudinal cognitive disability-specific atlas (DSA) was defined by correlating voxelwise GM volumes with PASAT scores, that is, areas where less GM correlated with less improvement in PASAT scores. Finally, overlap between the TIS and the longitudinal cognitive DSA revealed a specific region of cortical GM that was preserved in estriol-treated subjects that was associated with better performance on the PASAT.

CONCLUSIONS

Discovery of this region of overlap was biology driven, not based on an a priori structure of interest. It included the medial frontal cortex, an area previously implicated in problem solving and attention. These findings indicate that localized GM sparing during estriol treatment was associated with improvement in cognitive testing, suggesting a clinically relevant, disability-specific biomarker for clinical trials of candidate neuroprotective treatments in MS.

Comparison of Brain Atrophy, Cognition and Optical Coherence Tomography Results Between Multiple Sclerosis Patients and Healthy Controls

Introduction

Cognitive impairment is also an important cause of disability in MS in addition to motor, sensory, visual, and cerebellar affections. The aim of this study is to show the relation between the cognitive disability in MS with brain atrophy and retinal nerve fiber layer (RNFL).

Methods

Forty-three multiple sclerosis (MS) patients, and 15 healthy individuals as controls were included in the study. MS patients were divided into three groups as relapsing-remitting MS (RRMS), relapsing-remitting with optic neuritis (RRMS+ON), and secondary-progressive MS (SPMS). An experienced psychologist performed modified Wechsler Memory Scale Revised form (WMS-R), Lines Orientation test, Stroop Color Word Interference test (STROOP), Standard Raven Progressive Matrices (SRPM), Benton Facial Recognition Test, verbal fluency test, and Paced Auditory Serial Addition tests in all cases. Optic coherence tomographies (OCT) were done. Cranial subcortical volumes of all subjects were measured using 3-dimensonal T1A imagines obtained by the cranial subcortical 1.5 tesla MR device (fully automatic Freesurfer program). Brain parenchymal fractions were calculated by proportioning the obtained volume measurements to the total intracranial volume.

Results

Fifty-eight subjects (65.5% female, 34.5% male) were enrolled in the study. There were significant differences among the groups in terms of parenchymal thickness, volumes of third ventricle, and white matter. There was a significant correlation between the volumes of the deep gray matter, mesial temporal structures and lateral ventricular volumes, and the test results of the WMS-R. OCT scores of all MS patients, whether or not they experienced optic neuritis, had increased, being worse especially in the SPMS group. Correlation between RNFL and the brain parenchymal fractions of the patients were statistically significant.

Conclusion

Manual methods instead of automatic segmentation method are being more commonly used in the studies with brain atrophy and MS in our country. A significant correlation between OCT scores and brain atrophy is shown with our present study, and this is followed as a reflection of decrease in cognitive tests that provides valuable and reliable knowledge for the literature.

Establishing pathological cut-offs for lateral ventricular volume expansion rates

Background

A percent brain volume change (PBVC) cut-off of −0.4% per year has been proposed to distinguish between pathological and physiological changes in multiple sclerosis (MS). Unfortunately, standardized PBVC measurement is not always feasible on scans acquired outside research studies or academic centers. Percent lateral ventricular volume change (PLVVC) is a strong surrogate measure of PBVC, and may be more feasible for atrophy assessment on real-world scans. However, the PLVVC rate corresponding to the established PBVC cut-off of −0.4% is unknown.

Objective

To establish a pathological PLVVC expansion rate cut-off analogous to −0.4% PBVC.

Methods

We used three complementary approaches. First, the original follow-up-length-weighted receiver operating characteristic (ROC) analysis method establishing whole brain atrophy rates was adapted to a longitudinal ventricular atrophy dataset of 177 relapsing-remitting MS (RRMS) patients and 48 healthy controls. Second, in the same dataset, SIENA PBVCs were used with non-linear regression to directly predict the PLVVC value corresponding to −0.4% PBVC. Third, in an unstandardized, real world dataset of 590 RRMS patients from 33 centers, the cut-off maximizing correspondence to PBVC was found. Finally, correspondences to clinical outcomes were evaluated in both datasets.

Results

ROC analysis suggested a cut-off of 3.09% (AUC = 0.83, p < 0.001). Non-linear regression R² was 0.71 (p < 0.001) and a − 0.4% PBVC corresponded to a PLVVC of 3.51%. A peak in accuracy in the real-world dataset was found at a 3.51% PLVVC cut-off. Accuracy of a 3.5% cut-off in predicting clinical progression was 0.62 (compared to 0.68 for PBVC).

Conclusions

Ventricular expansion of between 3.09% and 3.51% on T2-FLAIR corresponds to the pathological whole brain atrophy rate of 0.4% for RRMS. A conservative cut-off of 3.5% performs comparably to PBVC for clinical outcomes.

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Pathological atrophy in MS can be measured on clinical T2-FLAIR images alone.

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Ventricular enlargement of 3.5% per year separates MS/HC as well as PBVC on T1 images.

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Ventricular cut-offs also correspond to clinical outcome.

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This cut-off can substitute in NEDA-4 when only clinical T2-FLAIR images are available.

Disability-Specific Atlases of Gray Matter Loss in Relapsing-Remitting Multiple Sclerosis

IMPORTANCE

Multiple sclerosis (MS) is characterized by progressive gray matter (GM) atrophy that strongly correlates with clinical disability. However, whether localized GM atrophy correlates with specific disabilities in patients with MS remains unknown.

OBJECTIVE

To understand the association between localized GM atrophy and clinical disability in a biology-driven analysis of MS.

DESIGN, SETTING, AND PARTICIPANTS

In this cross-sectional study, magnetic resonance images were acquired from 133 women with relapsing-remitting MS and analyzed using voxel-based morphometry and volumetry. A regression analysis was used to determine whether voxelwise GM atrophy was associated with specific clinical deficits. Data were collected from June 28, 2007, to January 9, 2014.

MAIN OUTCOMES AND MEASURES

Voxelwise correlation of GM change with clinical outcome measures (Expanded Disability Status Scale and Multiple Sclerosis Functional Composite scores).

RESULTS

Among the 133 female patients (mean [SD] age, 37.4 [7.5] years), worse performance on the Multiple Sclerosis Functional Composite correlated with voxelwise GM volume loss in the middle cingulate cortex (P < .001) and a cluster in the precentral gyrus bilaterally (P = .004). In addition, worse performance on the Paced Auditory Serial Addition Test correlated with volume loss in the auditory and premotor cortices (P < .001), whereas worse performance on the 9-Hole Peg Test correlated with GM volume loss in Brodmann area 44 (Broca area; P = .02). Finally, voxelwise GM loss in the right paracentral lobulus correlated with bowel and bladder disability (P = .03). Thus, deficits in specific clinical test results were directly associated with localized GM loss in clinically eloquent locations.

CONCLUSIONS AND RELEVANCE

These biology-driven data indicate that specific disabilities in MS are associated with voxelwise GM loss in distinct locations. This approach may be used to develop disability-specific biomarkers for use in future clinical trials of neuroprotective treatments in MS.

The influence of posterior visual pathway damage on visual information processing speed in multiple sclerosis

Background:

The injury of visual pathway and abnormalities of visual processing speed (VPS) are frequent in MS, but their association remains unexplored.

Objective:

To evaluate the impact of posterior visual pathway structural and functional integrity on VPS of MS patients.

Methods:

Cross-sectional study of 30 MS patients and 28 controls, evaluating the association of a VPS tests composite (Salthouse Perceptual Comparison test, Trail Making Test A and Symbol Digit Modalities Test) with 3T MRI visual cortex thickness, optic radiations (OR) diffusion tensor imaging indexes, and medial visual component (MVC) functional connectivity (FC) (MVC-MVC FC (iFC) and MVC-brain FC (eFC)) by linear regression, removing the effect of premorbid IQ, fatigue, and depression.

Results:

V2 atrophy, lower OR fractional anisotropy (FA) and MVC FC significantly influenced VPS in MS (at none or lesser extent in controls), even after removing the effect of Expanded Disability Status Scale and previous optic neuritis (V2 ( r2 = 0.210): β = +0.366, p = 0.046; OR FA ( r2 = 0.243): β = +0.378, p = 0.034; MVC iFC, for example, left cuneus ( r2 = 0.450): β = −0.613, p < 0.001; MVC eFC, for example, right precuneus-postcentral gyrus ( r2 = 0.368): β = −0.466, p = 0.002).

Conclusion:

Posterior visual pathway integrity, structural (V2 thickness and OR FA) and functional (MVC FC), may explain respectively up to 24% and 45% of VPS variability in MS.

Information processing speed in multiple sclerosis: Past, present, and future

BACKGROUND

Information processing speed (IPS) is a prevalent cognitive impairment in multiple sclerosis (MS).

OBJECTIVES

This review aims to summarize the methods applied to assess IPS in MS and its theoretical conceptualization. A PubMed search was performed to select articles published between 1 January 2004 and 31 December 2013, resulting in 157 articles included.

RESULTS

The majority (54%) of studies assessed IPS with heterogeneous samples (several disease courses). Studies often report controlling for presence of other neurological disorders (60.5%), age (58.6%), education (51.6%), alcohol history (47.8%), or use of steroids (39.5%). Potential confounding variables, such as recent relapses (50.3%), history of developmental disorders (19.1%), and visual problems (29.9%), were often neglected. Assessments used to study IPS were heterogeneous (ranging from simple to complex tasks) among the studies under review, with 62 different tasks used. Only 9.6% of articles defined the construct of IPS and 22.3% discussed IPS in relation to a theoretical model.

FUTURE DIRECTIONS

The challenges for the upcoming decade include clarification of the definition of IPS as well as its theoretical conceptualization and a consensus on assessment. Based on the results obtained, we propose a new theoretical model, the tri-factor model of IPS.

Widespread cortical thinning in patients with neuromyelitis optica spectrum disorder

BACKGROUND AND PURPOSE

Studies on cortical involvement and its relationship with cognitive function in patients with neuromyelitis optica spectrum disorder (NMOSD) remain scarce. The objective of this study was to compare cortical thickness on magnetic resonance imaging (MRI) between patients with NMOSD and multiple sclerosis (MS) and to investigate its relationship with clinical features and cognitive function.

METHODS

This observational clinical imaging study of 91 patients with NMOSD, 52 patients with MS and 44 healthy controls was conducted from 1 December 2013 to 30 April 2015 at the institutional referral center. Three tesla MRI of the brain and neuropsychological tests were performed. Cortical thickness was measured using three-dimensional surface-based analysis.

RESULTS

Both sets of patients exhibited cortical thinning throughout the entire brain cortex. Patients with MS showed a significantly greater reduction in cortical thickness over broad regions of the bilateral frontal and parieto-temporal cortices and the left precuneus compared to those with NMOSD. Memory functions in patients with MS were correlated with broad regional cortical thinning, whereas no significant associations were observed between cortical thickness and cognitive function in patients with NMOSD.

CONCLUSIONS

Widespread cortical thinning was observed in patients with NMOSD and MS, but the extent of cortical thinning was greater in patients with MS. The more severe cortical atrophy may contribute to memory impairment in patients with MS but not in those with NMOSD. These results provide in vivo evidence that the severity and clinical relevance of cortical thinning differ between NMOSD and MS.

Brain atrophy in multiple sclerosis: therapeutic, cognitive and clinical impact

ABSTRACT Multiple sclerosis (MS) was always considered as a white matter inflammatory disease. Today, there is an important body of evidence that supports the hypothesis that gray matter involvement and the neurodegenerative mechanism are at least partially independent from inflammation. Gray matter atrophy develops faster than white matter atrophy, and predominates in the initial stages of the disease. The neurodegenerative mechanism creates permanent damage and correlates with physical and cognitive disability. In this review we describe the current available evidence regarding brain atrophy and its consequence in MS patients.

Cortical thinning in the anterior cingulate cortex predicts multiple sclerosis patients' fluency performance in a lateralised manner

Cognitive impairment is as an important feature of Multiple Sclerosis (MS), and might be even more relevant to patients than mobility restrictions. Compared to the multitude of studies investigating memory deficits or basic cognitive slowing, executive dysfunction is a rarely studied cognitive domain in MS, and its neural correlates remain largely unexplored. Even rarer are topological studies on specific cognitive functions in MS. Here we used several structural MRI parameters - including cortical thinning and T2 lesion load - to investigate neural correlates of executive dysfunction, both on a global and a regional level by means of voxel- and vertex-wise analyses. Forty-eight patients with relapsing-remitting MS and 48 healthy controls participated in the study. Five executive functions were assessed, i.e. verbal and figural fluency, working memory, interference control and set shifting. Patients scored lower than controls in verbal and figural fluency only, and displayed widespread cortical thinning. On a global level, cortical thickness independently predicted verbal fluency performance, when controlling for lesion volume and central brain atrophy estimates. On a regional level, cortical thinning in the anterior cingulate region correlated with deficits in verbal and figural fluency and did so in a lateralised manner: Left-sided thinning was related to reduced verbal - but not figural - fluency, whereas the opposite pattern was observed for right-sided thinning. We conclude that executive dysfunction in MS patients can specifically affect verbal and figural fluency. The observed lateralised clinico-anatomical correlation has previously been described in brain-damaged patients with large focal lesions only, for example after stroke. Based on focal grey matter atrophy, we here show for the first time comparable lateralised findings in a white matter disease with widespread pathology.

Statistical image analysis of longitudinal RAVENS images

Regional analysis of volumes examined in normalized space (RAVENS) are transformation images used in the study of brain morphometry. In this paper, RAVENS images are analyzed using a longitudinal variant of voxel-based morphometry (VBM) and longitudinal functional principal component analysis (LFPCA) for high-dimensional images. We demonstrate that the latter overcomes the limitations of standard longitudinal VBM analyses, which does not separate registration errors from other longitudinal changes and baseline patterns. This is especially important in contexts where longitudinal changes are only a small fraction of the overall observed variability, which is typical in normal aging and many chronic diseases. Our simulation study shows that LFPCA effectively separates registration error from baseline and longitudinal signals of interest by decomposing RAVENS images measured at multiple visits into three components: a subject-specific imaging random intercept that quantifies the cross-sectional variability, a subject-specific imaging slope that quantifies the irreversible changes over multiple visits, and a subject-visit specific imaging deviation. We describe strategies to identify baseline/longitudinal variation and registration errors combined with covariates of interest. Our analysis suggests that specific regional brain atrophy and ventricular enlargement are associated with multiple sclerosis (MS) disease progression.

Association between retinal nerve fiber layer thickness and magnetic resonance imaging findings and intelligence in patients with multiple sclerosis

Background:

Multiple Sclerosis (MS) is a neurological disease in which demyelination and axonal loss leads to progressive disability. Cognition impairment is among the most common complication. Studying axonal loss in the retina is a new marker for MS. The main goal of our study is to search for correlations between magnetic resonance imaging (MRI) findings and the retinal nerve fiber layer (RNFL) thickness at the macula and head of the optic nerve and Wechsler Adult Intelligence Scale-Revised (WAIS-R) Scores that assess multiple domains of intelligence, and to explore the relationship between changes in the RNFL thickness with intellectual and cognitive dysfunction.

Materials and Methods:

A prospective cross-sectional study was conducted at the University Hospital of Kashani, Isfahan, Iran, from September to December 2013. All patients were assessed with a full-scale intelligence quotient (IQ) on the WAIS-R. An optical coherence tomography study and brain MRI were performed in the same week for all the patients. Statistical analysis was conducted by using a bivariate correlation, by utilizing SPSS 20.0. A P value ≤ 0.05 was the threshold of statistical significance.

Results:

Examination of a 100 patients showed a significant correlation between the average RNFL thickness of the macula and the verbal IQ (P value = 0.01) and full IQ (P value = 0.01). There was a significant correlation between brain atrophy and verbal IQ.

Conclusion:

The RNFL loss was correlated with verbal IQ and full IQ.

Multi-parametric structural magnetic resonance imaging in relation to cognitive dysfunction in long-standing multiple sclerosis

BACKGROUND

Cognitive deficits are common in multiple sclerosis. Most previous studies investigating the imaging substrate of cognitive deficits in multiple sclerosis included patients with relatively short disease durations and were limited to one modality/brain region.

OBJECTIVE

To identify the strongest neuroimaging predictors for cognitive dysfunction in a large cohort of patients with long-standing multiple sclerosis.

METHODS

Extensive neuropsychological testing and multimodal 3.0T MRI was performed in 202 patients with multiple sclerosis and 52 controls. Cognitive scores were compared between groups using Z-scores. Whole-brain, white matter, grey matter, deep grey matter and lesion volumes; cortical thickness, (juxta)cortical and cerebellar lesions; and extent and severity of diffuse white matter damage were measured. Stepwise linear regression was used to identify the strongest predictors for cognitive dysfunction.

RESULTS

All cognitive domains were affected in patients. Patients showed extensive atrophy, focal pathology and damage in up to 75% of the investigated white matter. Associations between imaging markers and average cognition were two times stronger in cognitively impaired patients than in cognitively preserved patients. The final model for average cognition consisted of deep grey matter DGMV volume and fractional anisotropy severity (adjusted R²=0.490; p<0.001).

CONCLUSION

From all imaging markers, deep grey matter atrophy and diffuse white matter damage emerged as the strongest predictors for cognitive dysfunction in long-standing multiple sclerosis.

Decision-making under explicit risk is impaired in multiple sclerosis: relationships with ventricular width and disease disability

BACKGROUND

Decision-making is an essential function of everyday life. Decision-making under explicit risk requires developing advantageous decision strategies based on fixed outcomes (e.g., probabilities of winning or losing a bet). Decision-making and its neural substrates have been rarely studied in MS. We expected performance in decision-making under risk to be lowered in MS patients, and negatively correlated with disease-related disability, cognition, and ventricular width.

METHODS

Three groups were included: 32 MS patients and 20 healthy controls were examined with conventional neuropsychological tests and the Game-of-Dice Task (GDT) assessing decision-making under explicit risk. Linear 2-D ventricular width was assessed on MS patients' clinical MRIs and compared to a third group, 20 non-MS neurological control patients.

RESULTS

Compared to healthy controls, MS patients showed impaired GDT and neuropsychological performance, depending on the MS-subtype (relapsing-remitting (RR), n = 22; secondary progressive, n = 10) and disability severity among RR-MS patients. In MS patients, GDT performance correlated with processing speed, intercaudate ratio, and third ventricle ratio (p's < 0.05). Mediation analysis showed that the link between GDT performance and processing speed was fully explained by ventricular size.

CONCLUSION

Decision-making under explicit risk was reduced in MS patients, but only those with more pronounced disability. Independent of processing speed, decision-making under explicit risk correlates inversely with central atrophy in MS.

MRI measures of neuroprotection and repair in multiple sclerosis

Magnetic resonance imaging (MRI) has had an enormous impact on multiple sclerosis, enabling early diagnosis and providing surrogate markers for monitoring treatment response in clinical trials. Despite these advantages, conventional MRI is limited by lack of pathological specificity and lack of sensitivity to grey matter lesions and to microscopic damage in normal appearing tissue. Quantitative MRI techniques such as measures of parenchymal volume loss, magnetisation transfer imaging, diffusion tensor imaging, and proton magnetic resonance spectroscopy have enhanced our understanding of the nature and mechanism of tissue injury and repair in multiple sclerosis, and provided more specific correlates of neurological deficits and disability accrual. Some of these techniques may be of potential use in clinical trials as surrogate outcome measures for measuring treatment effects on neurodegenerative injury, which is currently difficult to quantify in clinical trials. In this respect, measures of brain volume, T1 hypointensity and magnetisation transfer ratio, and optical coherence tomography appear to be the most promising in the short term. The evidence for a role of neurodegeneration in the pathogenesis of multiple sclerosis, and particularly in the accumulation of irreversible disability, has become increasingly strong over recent years. This has prompted the search for new treatments that can effectively slow down, halt or even reverse such neurodegenerative processes, and in this way restore nervous system function. For this reason, there has been much interest in the development and validation of surrogate markers of neurodegeneration and neuroprotection for use in clinical trials. Advances in magnetic resonance imaging (MRI) technology have allowed the development and implementation of a number of methods that may be promising in this respect. To assess the utility of these methods and to identify needs for further research, sixty experts in neuropathology, clinical measurement, imaging and statistics participated in a meeting held in Amsterdam in 2008 under the aegis of the National Multiple Sclerosis Society. In the proceedings of the meeting, published in 2009 [1], brain volume changes, T1 hypointensity, magnetisation transfer ratio and optical coherence tomography were deemed the most promising measures for screening the neuroprotective capacity of new agents. Other MRI techniques, such as DTI, (1)H-MRS and functional MRI, although potentially useful, require more observational data to help determine the optimal trial design. This article will review some of the issues that were discussed at this meeting, and present some of the imaging techniques that were considered to be the most promising.

Neuroimaging of dementia

Dementia, whether secondary to Alzheimer disease or another process, is a significant cause of morbidity and mortality worldwide. Although dementia remains a clinical diagnosis, for many years imaging has served as a key component in the assessment of patients with cognitive impairment. There have been tremendous advancements in the neuroimaging of dementia over the past decade, moving the field past the rule-out dogma toward ruling in specific pathophysiologic processes. This article is written for the practicing clinician, to provide a review of neuroimaging findings associated with selected degenerative and nondegenerative forms of dementia.

The Symbol Digit Modalities Test as sentinel test for cognitive impairment in multiple sclerosis

BACKGROUND AND PURPOSE

Cognitive impairment (CI) is found in about half of the multiple sclerosis (MS) population and is an important contributor to employment status and social functioning. CI is encountered in all disease stages and correlates only moderately with disease duration or Expanded Disability Status Scale scores. Most present neuropsychological test batteries are time-demanding and expensive. The Symbol Digit Modalities Test (SDMT) has been suggested as a screening tool for CI in MS. In this paper, we aim to assess the performance of the SDMT in predicting the outcome of an extensive battery.

METHODS

Neuropsychological test results from 359 patients were assessed in a multidisciplinary MS center (National MS Center Melsbroek, Belgium). Using receiver operating characteristic curves, the performance of the SDMT in predicting the general cognitive outcome of the extensive Neuropsychological Screening Battery for MS (NSBMS) could be assessed. The performance of the SDMT was assessed for different levels of CI and compared with other cognitive tests. Finally, useful covariates were included in a logistic regression model.

RESULTS

At a specificity of 0.60 a high sensitivity (0.91) was obtained indicating the potential of the SDMT as a sentinel test for CI in MS. The SDMT outperformed the individual tests included in the NSBMS, used as benchmark. As the logistic regression model did not result in a relevant improvement, it is concluded that most clinical variables influence both the SDMT and the NSBMS in a similar way. Excluding patients with possible practice effects, an optimal cutoff of 40 was found for the SDMT.

CONCLUSION

As the SDMT is an easy, low-cost and fast test, this result may help to detect CI in everyday clinical practice.

Gray matters in multiple sclerosis: cognitive impairment and structural MRI

Multiple sclerosis (MS) is an immune-mediated disease affecting central nervous system (CNS). Although MS is classically considered a white matter (WM) disease, the involvement of gray matter (GM) in the pathogenic process has been confirmed by pathology studies and MRI studies. Impairment of cognitive domains such as memory, mental processing speed, attention, and executive function can occur from the early stage of the disease and tends to worsen over time, despite stable physical symptoms. WM demyelination is moderately correlated with CI, suggesting that probably WM abnormalities alone cannot fully explain the extent of clinical symptoms in MS, including CI. Several MRI techniques have shown the involvement of GM in MS and the association between GM damage, physical disability, and CI. The aim of this review is to provide an overview of CI and GM damage assessed by structural brain MRI.

Chronic cerebrospinal venous insufficiency is not associated with cognitive impairment in multiple sclerosis

BACKGROUND

Chronic cerebrospinal venous insufficiency (CCSVI) has been reported in multiple sclerosis (MS) yet its significance in relation to cognitive function is undetermined.This study measured the association between the presence and severity of CCSVI and cognitive impairment in patients with MS.

METHODS

CCSVI was assessed using extra-cranial and trans-cranial Doppler sonography in 109 MS patients (79 with relapsing-remitting, 23 with secondary-progressive and 7 with primary-progressive disease subtype). A subject was considered CCSVI-positive if ≥2 venous hemodynamic criteria were fulfilled. The Minimal Assessment of Cognitive Function in MS (MACFIMS) battery was administered assessing the full spectrum of cognitive domains known to be affected by MS. Depression was quantified using the Beck Depression Inventory Fast Screen (BDIFS). Partial correlations, analysis of variance (or covariance) and linear regression were used to examine the hypothesis that CCSVI status is related to cognition or depression after controlling for education and gender.

RESULTS

There were 64 (58.7%) patients who were considered CCSVI-positive. The regression models predicting venous hemodynamic insufficiency severity score were not statistically significant for any of the MACFIMS predictor variables. The analysis of variance tests showed a significant effect of CCSVI-positive diagnosis on cognitive ability in only one of the 10 MACFIMS outcomes, and that one was in the opposite direction of the tested hypothesis. There was no correspondence between CCSVI diagnosis and depression, as measured by the BDIFS.

CONCLUSIONS

We find no evidence of an association between the presence and severity of CCSVI with cognitive impairment and depression in patients with MS.

Sex differences in resting-state functional connectivity in multiple sclerosis

BACKGROUND AND PURPOSE

Multiple studies have demonstrated evidence of sex differences in patients with MS, including differences in disease progression, cognitive decline, and biologic markers. This study used functional connectivity MRI to investigate sex differences in the strength of functional connectivity of the default mode network in patients with MS and healthy control subjects.

MATERIALS AND METHODS

A total of 16 men and 16 women with MS and 32 age- and sex-matched healthy control subjects underwent a whole-brain resting-state functional connectivity MRI scan. A group-based seed in the posterior cingulate was used to create whole-brain correlation maps. A 2 × 2 ANOVA was used to assess whether disease status and sex affected the strength of connectivity to the posterior cingulate.

RESULTS

Patients with MS showed significantly stronger connectivity from the posterior cingulate to the bilateral medial frontal gyri, the left ventral anterior cingulate, the right putamen, and the left middle temporal gyrus (P < .0005). In the left dorsal lateral prefrontal cortex, female patients showed significantly stronger connectivity to the posterior cingulate cortex compared with female control subjects (P = 3 × 10(4)), and male control subjects showed stronger posterior cingulate cortex-left dorsal lateral prefrontal cortex connectivity in comparison to female control subjects (P = .002). Male patients showed significantly weaker connectivity to the caudate compared with female patients (P = .004).

CONCLUSIONS

Disease status and sex interact to produce differences in the strength of functional connectivity from the posterior cingulate to the caudate and the left dorsal lateral prefrontal cortex.

Progression in disability and regional grey matter atrophy in relapsing-remitting multiple sclerosis

BACKGROUND

In multiple sclerosis (MS) regional grey matter (GM) atrophy has been associated with disability progression.

OBJECTIVE

The aim of this study was to compare regional GM volume changes in relapsing-remitting MS (RRMS) patients with progressive and stable disability, using voxel-based morphometry (VBM).

METHODS

We acquired baseline and 1-year follow-up 3-dimensional (3D) T1-weighted magnetic resonance imaging (MRI) data of RRMS patients, using two 1.5-Tesla scanners. Patients were matched pair-wise with respect to age, gender, disease duration, medication, scanner and baseline Expanded Disability Status Scale (EDSS) into 13 pairs, with either progressive EDSS (≥ 1 point change y(-1)) or stable EDSS, as well as into 29 pairs with either progressive Multiple Sclerosis Functional Composite (MSFC) at ≥ 0.25% decrease in y(-1) in any component, or stable MSFC. We analysed longitudinal regional differences in GM volumes in the progressive and stable EDSS and MSFC groups, respectively, using VBM.

RESULTS

Significant GM volume reductions occurred in the right precuneus, in the progressive EDSS group. Differential between-group effects occurred in the right precuneus and in the postcentral gyrus. Further longitudinal GM volume reductions occurred in the right orbicular gyrus, in the progressive MSFC group, but no between-group differences were observed (non-stationary cluster-wise inference, all P(corrected) < 0.05).

CONCLUSION

These results suggested a direct association of disability progression and regional GM atrophy in RRMS.

Updating the mild encephalitis hypothesis of schizophrenia

Schizophrenia seems to be a heterogeneous disorder. Emerging evidence indicates that low level neuroinflammation (LLNI) may not occur infrequently. Many infectious agents with low overall pathogenicity are risk factors for psychoses including schizophrenia and for autoimmune disorders. According to the mild encephalitis (ME) hypothesis, LLNI represents the core pathogenetic mechanism in a schizophrenia subgroup that has syndromal overlap with other psychiatric disorders. ME may be triggered by infections, autoimmunity, toxicity, or trauma. A 'late hit' and gene-environment interaction are required to explain major findings about schizophrenia, and both aspects would be consistent with the ME hypothesis. Schizophrenia risk genes stay rather constant within populations despite a resulting low number of progeny; this may result from advantages associated with risk genes, e.g., an improved immune response, which may act protectively within changing environments, although they are associated with the disadvantage of increased susceptibility to psychotic disorders. Specific schizophrenic symptoms may arise with instances of LLNI when certain brain functional systems are involved, in addition to being shaped by pre-existing liability factors. Prodrome phase and the transition to a diseased status may be related to LLNI processes emerging and varying over time. The variability in the course of schizophrenia resembles the varying courses of autoimmune disorders, which result from three required factors: genes, the environment, and the immune system. Preliminary criteria for subgrouping neurodevelopmental, genetic, ME, and other types of schizophrenias are provided. A rare example of ME schizophrenia may be observed in Borna disease virus infection. Neurodevelopmental schizophrenia due to early infections has been estimated by others to explain approximately 30% of cases, but the underlying pathomechanisms of transition to disease remain in question. LLNI (e.g. from reactivation related to persistent infection) may be involved and other pathomechanisms including dysfunction of the blood-brain barrier or the blood-CSF barrier, CNS-endogenous immunity and the volume transmission mode balancing wiring transmission (the latter represented mainly by synaptic transmission, which is often described as being disturbed in schizophrenia). Volume transmission is linked to CSF signaling; and together could represent a common pathogenetic link for the distributed brain dysfunction, dysconnectivity, and brain structural abnormalities observed in schizophrenia. In addition, CSF signaling may extend into peripheral tissues via the CSF outflow pathway along brain nerves and peripheral nerves, and it may explain the peripheral topology of neuronal dysfunctions found, like in olfactory dysfunction, dysautonomia, and even in peripheral tissues, i.e., the muscle lesions that were found in 50% of cases. Modulating factors in schizophrenia, such as stress, hormones, and diet, are also modulating factors in the immune response. Considering recent investigations of CSF, the ME schizophrenia subgroup may constitute approximately 40% of cases.

Quantitative MRI demonstrates abnormality of the fornix and cingulum in multiple sclerosis

Objective. To characterize MR signal changes associated with tissue damage in the fornix and cingulum in multiple sclerosis (MS) using quantitative MRI measures and to determine associations with cognitive dysfunction. Background. The fornix and cingulum are white-matter bundles that carry information related to cognition. While cognitive dysfunction is reported in 40–60% of MS patients, the neuroanatomical correlates of cognitive impairment remain incompletely understood. Methods. The cingulum, pillars of the fornix, and corticospinal tract were segmented by fiber tracking via diffusion tensor imaging. Average tract-specific fractional anisotropy (FA), mean diffusivity (MD), and magnetization transfer ratio (MTR) were compared in MS cases and healthy volunteers. Associations with clinical measures and neuropsychological tests were derived by multivariate linear regression. Results. Fornix FA (P = 0.004) and MTR (P = 0.005) were decreased, and fornix MD (P < 0.001) and cingulum MD (P < 0.001) increased, in MS cases (n = 101) relative to healthy volunteers (n = 16) after adjustment for age and sex. Lower fornix FA and MTR, and higher fornix MD and λ_||, were correlated with lower PASAT-3 scores, but not with slower 25FTW times. Lower PASAT-3 scores were associated with lower cingulum FA and higher MD and λ_⊥. Conclusions. Cognitive dysfunction in MS may involve damage to a widespread network of brain structures, including white-matter pathways within the limbic system.

No regional gray matter atrophy differences between pediatric- and adult-onset relapsing-remitting multiple sclerosis

OBJECTIVE

To investigate differences in region-specific gray matter (GM) damage between adults with pediatric-onset (PO) multiple sclerosis (MS) and adult-onset (AO) MS.

METHODS

Twenty-four relapsing-remitting (RR) adults with POMS (mean age = 35 years, mean disease duration = 18.4 years) were compared to 23 age-matched (AOA, mean age = 33.9 years, mean disease duration = 2.4 years) and 24 disease-duration matched (AOD, mean age = 45.9 years, mean disease duration = 18.5 years) RRMS adults who developed MS after the age of 18. Three-dimensional-T1-weighted images were acquired on a 1.5 T MRI. Image analysis was conducted using voxel-based morphometry (Statistical Parametric Mapping 8).

RESULTS

There were no regional GM atrophy differences between POMS and AODMS groups. No regional GM atrophy differences were found between POMS and AOAMS patients when disease duration was included as a covariate.

CONCLUSIONS

Regional GM differences were not found between POMS adults and MS controls matched for age or disease duration. Although of limited sample size, these findings suggest that there are no regional GM atrophy differences between RR POMS and AOMS.

Robust perfusion deficits in cognitively impaired patients with secondary-progressive multiple sclerosis

BACKGROUND AND PURPOSE

Cognitive impairment is a common, disabling symptom of MS. We investigated the impact of cerebral perfusion and brain and lesion volumetry on cognitive performance in 45 patients with SPMS by using MR imaging.

MATERIALS AND METHODS

Cognition was assessed by using a standard battery, the Minimal Assessment of Cognitive Function in Multiple Sclerosis. qCBF and qCBV maps were analyzed by using SPM and PLS. SPM was also used to conduct the GM, WM, and WML volumetric analyses.

RESULTS

Both SPM and PLS demonstrated significantly reduced qCBV in the superior medial frontal cortex of impaired patients. PLS also revealed significantly lower qCBV in the bilateral thalami and caudate nuclei of impaired patients and identified a pattern of significantly attenuated qCBF similar to that of qCBV. Performance on the Symbol Digit Modalities Test, which assesses information-processing speed, correlated most strongly overall with cerebral perfusion. Focal (ie, voxelwise) analyses of GM, WM, and WML volume revealed no significant differences between patients with and without cognitive impairment, though global GM volume was significantly decreased and global WML volume was significantly increased in impaired patients.

CONCLUSIONS

These results suggest that cognitively impaired patients with SPMS exhibit robust perfusion deficits in cortical and subcortical GM and impaired processing speed.

Cognitive impairment and its relation to imaging measures in multiple sclerosis: a study using a computerized battery

BACKGROUND AND PURPOSE

Cognitive impairment (CI) is an important component of multiple sclerosis (MS) disability. A complex biological interplay between white matter (WM) and gray matter (GM) disease likely sustains CI. This study aims to address this issue by exploring the association between the extent of normal WM and GM disease and CI.

METHODS

Cognitive function of 24 MS patients and 24 healthy volunteers (HVs) was studied using the Automated Neuropsychological Assessment Metrics (ANAM) battery. WM focal lesions and normal appearing WM (NAWM) volume in patients, cortical thickness (CTh) and deep GM structure volumes in both patients and HVs were measured by high field strength (3.0-Tesla; 3T) imaging.

RESULTS

An analysis of covariance showed that patients performed worse than HVs on Code Substitution Delayed Memory (P = .04) and Procedural Reaction Time (P = .05) indicative of reduced performance in memory, cognitive flexibility, and processing speed. A summary score (Index of Cognitive Efficiency) indicating global test battery performance was also lower for the patient group (P = .04). Significant associations, as determined by the Spearman rank correlation tests, were noted between each of these 3 cognitive scores and measures of NAWM volume [CDD-TP1(r = .609; P = .0035), PRO-TP1 (r = .456; P = .029) and ICE (r = .489; P = .0129)], CTh (r = .5; P ≤ .05) and volume of subcortical normal appearing GM (NAGM) structures (r = .4; P≤ .04), but not WM lesions.

CONCLUSIONS

Both NAWM and NAGM volumes are related to CI in MS. The results highlight once again the urgent need to develop pharmacological strategies protecting patients from widespread neurodegeneration as possible preventive strategies of CI development.

Shifting imaging targets in multiple sclerosis: from inflammation to neurodegeneration

Classically multiple sclerosis (MS) has been regarded as an auto-immune disease of the white matter in the central nervous system leading to severe disability over the course of several decades. Current therapeutic strategies in MS are mostly based on either immune suppression or immune modulation. Although effective in decreasing relapse frequency and severity as well as delaying disease progression, MS pathology ensues nonetheless. In the last decade it became evident that gray matter pathology plays an important role in disease progression and helps explaining certain aspects of MS-related disability such as cognitive decline. Conventional MRI outcome measures commonly used in clinical trials are sufficient to demonstrate an anti-inflammatory drug-effect but lack pathological specificity and are poor to moderate predictors of disability. In this article, we review new insights in gray matter pathology and functional reorganization in MS and how these novel fields in MS research may validate and establish new MRI outcome measures, aid in the development of new therapeutic strategies for neuroprotection and neurorepair, and may lead to development of novel predictive measures of disability and disease progression in MS.

Relevance of brain lesion location to cognition in relapsing multiple sclerosis

OBJECTIVE

To assess the relationship between cognition and brain white matter (WM) lesion distribution and frequency in patients with relapsing-remitting multiple sclerosis (RR MS).

METHODS

MRI-based T2 lesion probability map (LPM) was used to assess the relevance of brain lesion location for cognitive impairment in a group of 142 consecutive patients with RRMS. Significance of voxelwise analyses was p<0.05, cluster-corrected for multiple comparisons. The Rao Brief Repeatable Battery was administered at the time of brain MRI to categorize the MS population into cognitively preserved (CP) and cognitively impaired (CI).

RESULTS

Out of 142 RRMS, 106 were classified as CP and 36 as CI. Although the CI group had greater WM lesion volume than the CP group (p = 0.001), T2 lesions tended to be less widespread across the WM. The peak of lesion frequency was almost twice higher in CI (61% in the forceps major) than in CP patients (37% in the posterior corona radiata). The voxelwise analysis confirmed that lesion frequency was higher in CI than in CP patients with significant bilateral clusters in the forceps major and in the splenium of the corpus callosum (p<0.05, corrected). Low scores of the Symbol Digit Modalities Test correlated with higher lesion frequency in these WM regions.

CONCLUSIONS

Overall these results suggest that in MS patients, areas relevant for cognition lie mostly in the commissural fiber tracts. This supports the notion of a functional (multiple) disconnection between grey matter structures, secondary to damage located in specific WM areas, as one of the most important mechanisms leading to cognitive impairment in MS.

Grey matter lesions in MS: from histology to clinical implications

Although multiple sclerosis (MS) is a chronic inflammatory-demyelinating disease of the white matter (WM) of the central nervous system, several pathological and magnetic resonance imaging (MRI) studies have shown that a large amount of lesions are located in the cortical and deep gray matter. The histopathological and immunological characteristics of cortical lesions differ significantly from those located in the WM, which suggests a location-dependent expression of the MS immunopathological process. More recently, the availability of not-conventional MRI sequences having higher sensitivity for the gray matter has allowed to depict in vivo a portion of such lesions. The available MRI data obtained on large cohorts of patients, having different clinical forms of the disease, indicate that cortical lesions can be detected early in the disease course, sometimes even before the appearance of WM lesions, and correlate with the severity of physical disability and cognitive impairment, and with the evolution of the disease toward the secondary progressive phase. This review provides a summary of the main histopathological and MRI findings of cortical lesions in MS and discusses their possible clinical implications.

Superior temporal gyrus thickness correlates with cognitive performance in multiple sclerosis

Decreased cortical thickness that signifies gray matter pathology and its impact on cognitive performance is a research field with growing interest in relapsing-remitting multiple sclerosis (RRMS) and needs to be further elucidated. Using high-field 3.0 T MRI, three-dimensional T1-FSPGR (voxel size 1 × 1 × 1 mm) cortical thickness was measured in 82 regions in the left hemisphere (LH) and right hemisphere (RH) in 20 RRMS patients with low disease activity and in 20 age-matched healthy subjects that in parallel underwent comprehensive cognitive evaluation. The correlation between local cortical atrophy and cognitive performance was examined. We identified seven regions with cortical tissue loss that differed between RRMS and age-matched healthy controls. These regions were mainly located in the frontal and temporal lobes, specifically within the gyrus rectus, inferior frontal sulcus, orbital gyrus, parahippocampal gyrus, and superior temporal gyrus, with preferential left asymmetry. Increased cortical thickness was identified in two visual sensory regions, the LH inferior occipital gyrus, and the RH cuneus, implicating adaptive plasticity. Correlation analysis demonstrated that only the LH superior temporal gyrus thickness was associated with cognitive performance and its thickness correlated with motor skills (r = 0.65, p = 0.003), attention (r = 0.45, p = 0.042), and information processing speed (r = 0.50, p = 0.025). Our findings show that restricted cortical thinning occurs in RRMS patients with mild disease and that LH superior temporal gyrus atrophy is associated with cognitive dysfunction.

Comparison of neuropsychological impairment and vocational outcomes in systemic lupus erythematosus and multiple sclerosis patients

Systemic lupus erythematosus (SLE) and multiple sclerosis (MS) are chronic immunologic diseases that can cause cognitive dysfunction. MS is a central nervous system (CNS) disease characterized by demyelination and progressive brain atrophy. SLE is an autoimmune disease capable of damaging multiple organ systems, including the CNS. Cognitive disturbances are seen in both SLE and MS. The present study is concerned with understanding the similarities and differences between the cognitive profiles of SLE and MS as well as the relationship between cognitive impairment and vocational disability in these patients. We examined 47 SLE patients, 47 MS patients, and 44 healthy controls. The groups were well matched on demographics and the patient groups were also matched on disease duration and severity. Group comparisons revealed that generative verbal fluency and visual-spatial memory are more profoundly affected in MS than SLE; whereas depression, fatigue, and working memory deficits are similarly involved in both diseases. Logistic regression analysis revealed that executive function, in particular, was predictive of vocational outcomes in SLE and MS patients.

Cognitive deficits in multiple sclerosis: correlations with T2 changes in normal appearing brain tissue

OBJECTIVES

Although disease load in multiple sclerosis (MS) often is based on T2 lesion volumes, the changes in T2 of normal appearing brain tissue (NABT) are rarely considered. By means of magnetic resonance, (MR) we retrospectively investigated whether T2 changes in NABT explain part of the cognitive impairment seen in MS and constitute a supplement to traditional measurement of T2 lesion volume.

MATERIALS AND METHODS

Fifty patients with clinically definite MS were included (38 women, 12 men). Patients were MR scanned, neuropsychologically tested, and evaluated clinically with the Kurtzke Expanded Disability Status Scale (EDSS) and the Multiple Sclerosis Impairment Scale (MSIS). Voxel-wise T2 estimates and total T2 lesion volume were tested for correlations with eight cognitive domains, a general cognitive dysfunction factor (CDF), and the two clinical scales.

RESULTS

We found distinct clusters of voxels with T2 estimates correlating with CDF, mental processing speed, complex motor speed, verbal fluency, and MSIS. A significant negative correlation was found between total lesion volume and CDF (r = -0.34, P = 0.02), verbal intelligence (r = -0.40, P = 0.005), mental processing speed (r = -0.34, P = 0.03), visual problem solving (r = -0.40, P = 0.01), and complex motor speed (r = -0.39, P = 0.01). No significant correlation was detected between total lesion load and the clinical measures EDSS and MSIS.

CONCLUSION

Our results suggest that even in the NABT MR detects changes likely to be associated with an underlying pathology and possibly contributes to the cognitive impairment in MS.

Spatiotemporal distribution of white matter lesions in relapsing-remitting and secondary progressive multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system. MS lesions show a typical distribution pattern and primarily affect the white matter (WM) in the periventricular zone and in the centrum semiovale.

OBJECTIVE

To track lesion development during disease progression, we compared the spatiotemporal distribution patterns of lesions in relapsing-remitting MS (RRMS) and secondary progressive MS (SPMS).

METHODS

We used T1 and T2 weighted MR images of 209 RRMS and 62 SPMS patients acquired on two different 1.5 Tesla MR scanners in two clinical centers followed up for 25 (± 1.7) months. Both cross-sectional and longitudinal differences in lesion distribution between RRMS and SPMS patients were analyzed with lesion probability maps (LPMs) and permutation-based inference.

RESULTS

MS lesions clustered around the lateral ventricles and in the centrum semiovale. Cross-sectionally, compared to RRMS patients, the SPMS patients showed a significantly higher regional probability of T1 hypointense lesions (p ≤ 0.03) in the callosal body, the corticospinal tract, and other tracts adjacent to the lateral ventricles, but not of T2 lesions (peak probabilities were RRMS: T1 9%, T2 18%; SPMS: T1 21%, T2 27%). No longitudinal changes of regional T1 and T2 lesion volumes between baseline and follow-up scan were found.

CONCLUSION

The results suggest a particular vulnerability to neurodegeneration during disease progression in a number of WM tracts.

Clinical correlates of grey matter pathology in multiple sclerosis

Traditionally, multiple sclerosis has been viewed as a disease predominantly affecting white matter. However, this view has lately been subject to numerous changes, as new evidence of anatomical and histological changes as well as of molecular targets within the grey matter has arisen. This advance was driven mainly by novel imaging techniques, however, these have not yet been implemented in routine clinical practice. The changes in the grey matter are related to physical and cognitive disability seen in individuals with multiple sclerosis. Furthermore, damage to several grey matter structures can be associated with impairment of specific functions. Therefore, we conclude that grey matter damage - global and regional - has the potential to become a marker of disease activity, complementary to the currently used magnetic resonance markers (global brain atrophy and T2 hyperintense lesions). Furthermore, it may improve the prediction of the future disease course and response to therapy in individual patients and may also become a reliable additional surrogate marker of treatment effect.