Differential cognitive impairment for diverse forms of multiple sclerosis

The use of event-related potentials in the investigation of cognitive performance in people with Multiple Sclerosis: Systematic review

A biomarker of cognition in Multiple Sclerosis (MS) that is independent from the response of people with MS (PwMS) to test questions would provide a more holistic assessment of cognitive decline. One suggested method involves event-related potentials (ERPs). This systematic review tried to answer five questions about the use of ERPs in distinguishing PwMS from controls: which stimulus modality, which experimental paradigm, which electrodes, and which ERP components are most discriminatory, and whether amplitude or latency is a better measure. Our results show larger pooled effect sizes for visual stimuli than auditory stimuli, and larger pooled effect sizes for latency measurements than amplitude measurements. We observed great heterogeneity in methods and suggest that future research would benefit from more uniformity in methods and that results should be reported for the individual subtypes of PwMS. With more standardised methods, ERPs have the potential to be developed into a clinical tool in MS.

Patterns of attention deficit in relapsing and progressive phenotypes of multiple sclerosis

Behavioral aspects and underlying pathology of attention deficit in multiple sclerosis (MS) remain unknown. This study aimed to clarify impairment of attention and its relationship with MS-related fatigue. Thirty-four relapse-remitting MS (RRMS), 35 secondary-progressive MS (SPMS) and 45 healthy controls (HC) were included. Results of psychophysics tasks (attention network test (ANT) and Posner spatial cueing test) and fatigue assessments (visual analogue scale and modified fatigue impact scale (MFIS)) were compared between groups. In ANT, attentional network effects were not different between MS phenotypes and HC. In Posner task, RRMS or SPMS patients did not benefit from valid cues unlike HC. RRMS and SPMS patients had less gain in exogenous trials with 62.5 ms cue-target interval time (CTIT) and endogenous trials with 250 ms CTIT, respectively. Total MFIS was the predictor of gain in 250 ms endogenous blocks and cognitive MFIS predicted orienting attentional effect. Executive attentional effect in RRMS patients with shorter disease duration and orienting attentional effect in longer diagnosed SPMS were correlated with MFIS scores. The pattern of attention deficit in MS differs between phenotypes. Exogenous attention is impaired in RRMS patients while SPMS patients have deficit in endogenous attention. Fatigue trait predicts impairment of endogenous and orienting attention in MS.

Grey matter atrophy in patients with benign multiple sclerosis

BACKGROUND

Brain atrophy appears during the progression of multiple sclerosis (MS) and is associated with the disability caused by the disease.

METHODS

We investigated global and regional grey matter (GM) and white matter (WM) volumes, WM lesion load, and corpus callosum index (CCI), in benign relapsing-remitting MS (BRRMS, n = 35) with and without any treatment and compared those to aggressive relapsing-remitting MS (ARRMS, n = 46). Structures were analyzed by using an automated MRI quantification tool (cNeuro®).

RESULTS

The total brain and cerebral WM volumes were larger in BRRMS than in ARRMS (p = .014, p = .017 respectively). In BRRMS, total brain volumes, regional GM volumes, and CCI were found similar whether or not disease-modifying treatment (DMT) was used. The total (p = .033), as well as subcortical (p = .046) and deep WM (p = .041) lesion load volumes were larger in BRRMS patients without DMT. Cortical GM volumes did not differ between BRRMS and ARRMS, but the volumes of total brain tissue (p = .014) and thalami (p = .003) were larger in patients with BRRMS compared to ARRMS. A positive correlation was found between CCI and whole-brain volume in both BRRMS (r = .73, p < .001) and ARRMS (r = .80, p < .01).

CONCLUSIONS

Thalamic volume is the most prominent measure to differentiate BRRMS and ARRMS. Validation of automated quantification of CCI provides an additional applicable MRI biomarker to detect brain atrophy in MS.

Serum GFAP and NfL levels in benign relapsing-remitting multiple sclerosis

OBJECTIVE

We aimed to investigate serum glial fibrillary acidic protein (GFAP) and serum neurofilament light chain (NfL) levels as potential discriminative biomarkers between benign relapsing-remitting multiple sclerosis (BRRMS) and aggressive relapsing-remitting MS (ARRMS).

METHODS

Serum GFAP and NfL levels were analyzed in patients with BRRMS (n = 34), ARRMS (n = 29), and healthy controls (n = 14) by using Single Molecule Array (Simoa). Patients with ARRMS had been treated with highly effective disease-modifying treatments (DMT) (fingolimod or natalizumab).

RESULTS

Serum GFAP levels in both BRRMS (median 210.19 pg/ml, IQR 163.69-287.19) and in ARRMS (median 188.60 pg/ml, IQR39.23-244.93) were significantly higher (p = 0.035 and p = 0.034, respectively) compared to healthy controls (median 117.93 pg/ml, IQR 60.28-183.83). Serum GFAP levels did not differ between BRRMS and ARRMS. There were no statistical differences in NfL levels between BRRMS, ARRMS and healthy controls. GFAP level was significantly higher (p = 0.04) in BRRMS without DMT (median 216.04 pg/ml, IQR 188.60-274.79) than in those BRRMS patients who had used DMT (median 196.26 pg/ml, IQR 133.33-325.54).

CONCLUSIONS

We found elevated levels of serum GFAP in both BRRMS and ARRMS compared to healthy controls, reflecting astrocytic activation. Serum NfL did not differ between BRRMS and ARRMS, probably due to the stable inflammatory phase of the disease and effective DMT use in ARRMS. Single serum NfL and GFAP measurements cannot separate a patient with BRRMS from effectively treated ARRMS after a long history of the disease, thus consecutive samples are needed in the follow-up.

The subtleties of cognitive decline in multiple sclerosis: an exploratory study using hierarchichal cluster analysis of CANTAB results

Background

It is essential to investigate cognitive deficits in multiple sclerosis (MS) to develop evidence-based cognitive rehabilitation strategies. Here we refined cognitive decline assessment using the automated tests of the Cambridge Neuropsychological Test Automated Battery (CANTAB) and hierarchical cluster analysis.

Methods

We searched for groups of distinct cognitive profiles in 35 relapsing-remitting MS outpatients and 32 healthy controls. All individuals participated in an automated assessment (CANTAB) and in a pencil and paper general neuropsychological evaluation.

Results

Hierarchical cluster analysis of the CANTAB results revealed two distinct groups of patients based mainly on the Simple Reaction Time (RTI) and on the Mean Latency of Rapid Visual Processing (RVP). The general neuropsychological assessment did not show any statistically significant differences between the cluster groups. Compared to the healthy control group, all MS outpatients had lower scores for RTI, RVP, paired associate learning, and delayed matching to sample. We also analyzed the associations between CANTAB results and age, education, sex, pharmacological treatment, physical activity, employment status, and the Expanded Disability Status Scale (EDSS). Although limited by the small number of observations, our findings suggest a weak correlation between performance on the CANTAB and age, education, and EDSS scores.

Conclusions

We suggest that the use of selected large-scale automated visuospatial tests from the CANTAB in combination with multivariate statistical analyses may reveal subtle and earlier changes in information processing speed and cognition. This may expand our ability to define the limits between normal and impaired cognition in patients with Multiple Sclerosis.

Electronic supplementary material

The online version of this article (10.1186/s12883-018-1141-1) contains supplementary material, which is available to authorized users.

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.

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.

Resting state fMRI connectivity analysis as a tool for detection of abnormalities in five different cognitive networks of the brain in Multiple Sclerosis patients

Objectives

Cognitive dysfunction is present in at least half of patients with Multiple Sclerosis. The purpose of this study was to examine functional connectivity abnormalities in patients with multiple sclerosis (MS) using resting state fMRI (rsfMRI).

Methods

Conventional MRI, rsfMRI and diffusion tensor imaging (DTI) data was acquired from 10 patients with relapsing-remitting multiple sclerosis (RRMS) and 20 healthy controls. Cross-correlation of the resting state average signal among the voxels in each brain region of the five cognitive networks: default mode network (DMN), attention, verbal memory, memory, and visuospatial working memory network, was calculated. Voxelwise analyses were used to investigate fractional anisotropy (FA) of white matter tracts. The normalized gray matter (GM), white matter and thalamus volumes were calculated.

Results

Compared to controls, significant deficit in MS patients at each of five networks, attention (p=0.026), DMN (p=0.004), verbal memory (p<0.001), memory (p=0.001), visuospatial working memory (p=0.003) was found. Significant reduction (p=0.034) in the normalized GM volume and asymmetry in thalamus volume (p=0.041) was detected in MS patients compared to controls.

Conclusion

Wide spread of functional abnormalities are present within different cognitive networks in patients with RRMS, suggesting that DMN may not be sufficient for measurement of MS cognitive impairment. Larger and longitudinal studies should ascertain whether rsfMRI of cognitive networks and changes in GM and thalamus volume can be used as tools for assessment of cognition in clinical trials in MS.

Evaluating Neurocognitive Deficits in Patients With Multiple Sclerosis Via a Brief Neuropsychological Approach

Recent research demonstrates neurocognitive deficits are present early in the sequelae of multiple sclerosis (MS). This is an important consideration given the functional activities of daily living, such as employment, that can be impacted by neurocognitive dysfunction. This study investigated the utility of a brief neuropsychological battery, the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), to evaluate neurocognitive deficits in patients with MS and to examine the relationship between a measure of functional disability (Expanded Disability Status Scale [EDSS]) and the RBANS. Participants were 49 patients with MS (Mage = 45.39 years) who completed the RBANS as part of a neuropsychological assessment and 49 demographically matched healthy controls (Mage = 45.39 years). Multivariate analysis of variance revealed that the two groups differed on the RBANS. Descriptive discriminant analysis indicated the groups differed on domains of attention, language, immediate memory, and delayed memory. EDSS scores were a good predictor of neurocognitive dysfunction in patients with advanced disability but not for patients with mild disability. The RBANS seems to be effective in identifying cognitive dysfunction in patients with MS, and caution should be used in extrapolating cognitive deficits for patients with low EDSS scores.

Disentangling the attention network test: behavioral, event related potentials, and neural source analyses

BACKGROUND

The study of the attentional system remains a challenge for current neuroscience. The "Attention Network Test" (ANT) was designed to study simultaneously three different attentional networks (alerting, orienting, and executive) based in subtraction of different experimental conditions. However, some studies recommend caution with these calculations due to the interactions between the attentional networks. In particular, it is highly relevant that several interpretations about attentional impairment have arisen from these calculations in diverse pathologies. Event related potentials (ERPs) and neural source analysis can be applied to disentangle the relationships between these attentional networks not specifically shown by behavioral measures.

RESULTS

This study shows that there is a basic level of alerting (tonic alerting) in the no cue (NC) condition, represented by a slow negative trend in the ERP trace prior to the onset of the target stimuli. A progressive increase in the CNV amplitude related to the amount of information provided by the cue conditions is also shown. Neural source analysis reveals specific modulations of the CNV related to a task-related expectancy presented in the NC condition; a late modulation triggered by the central cue (CC) condition and probably representing a generic motor preparation; and an early and late modulation for spatial cue (SC) condition suggesting specific motor and sensory preactivation. Finally, the first component in the information processing of the target stimuli modulated by the interaction between orienting network and the executive system can be represented by N1.

CONCLUSIONS

The ANT is useful as a paradigm to study specific attentional mechanisms and their interactions. However, calculation of network effects is based in subtractions with non-comparable experimental conditions, as evidenced by the present data, which can induce misinterpretations in the study of the attentional capacity in human subjects.

Neural correlates of alerting and orienting impairment in multiple sclerosis patients

BACKGROUND

A considerable percentage of multiple sclerosis patients have attentional impairment, but understanding its neurophysiological basis remains a challenge. The Attention Network Test allows 3 attentional networks to be studied. Previous behavioural studies using this test have shown that the alerting network is impaired in multiple sclerosis. The aim of this study was to identify neurophysiological indexes of the attention impairment in relapsing-remitting multiple sclerosis patients using this test.

RESULTS

After general slowing had been removed in patients group to isolate the effects of each condition, some behavioral differences between them were obtained. About Contingent Negative Variation, a statistically significant decrement were found in the amplitude for Central and Spatial Cue Conditions for patient group (p<0.05). ANOVAs showed for the patient group a significant latency delay for P1 and N1 components (p<0.05) and a decrease of P3 amplitude for congruent and incongruent stimuli (p<0.01). With regard to correlation analysis, PASAT-3s and SDMT showed significant correlations with behavioral measures of the Attention Network Test (p<0.01) and an ERP parameter (CNV amplitude).

CONCLUSIONS

Behavioral data are highly correlated with the neuropsychological scores and show that the alerting and orienting mechanisms in the patient group were impaired. Reduced amplitude for the Contingent Negative Variation in the patient group suggests that this component could be a physiological marker related to the alerting and orienting impairment in relapsing-remitting multiple sclerosis. P1 and N1 delayed latencies are evidence of the demyelination process that causes impairment in the first steps of the visual sensory processing. Lastly, P3 amplitude shows a general decrease for the pathological group probably indexing a more central impairment. These results suggest that the Attention Network Test give evidence of multiple levels of attention impairment, which could help in the assessment and treatment of relapsing-remitting multiple sclerosis patients.

Clinical neurophysiology of multiple sclerosis

The availability of new treatments able to modify the natural course of multiple sclerosis (MS) has generated interest in paraclinical measures to monitor disease evolution. Among these, neurophysiologic measures, mainly evoked potentials (EPs), are used in the functional assessment of central sensorimotor and cognitive networks affected by MS. EP abnormalities may reveal subclinical lesions, objectivate the involvement of sensory and motor pathways in the presence of vague disturbances, and provide indications of the demyelinating nature of the disease process. However, their diagnostic value is much lower than that of magnetic resonance imaging, and is more sensitive to brain and cervical spinal cord lesions. The application of EPs in assessing disease severity and monitoring the evolution of nervous damage is more promising, thanks to their good correlation with disability in cross-sectional and longitudinal studies, and potential use as paraclinical endpoints in clinical trials. Recent evidence indicates that EPs performed early in the disease may help to predict a worse future progression in the long term. If confirmed, these data suggest the possible usefulness of EPs in the early identification of patients who are more likely to develop future disability, thus requiring more frequent monitoring or being potential candidates for more aggressive disease-modifying treatments.

P300 wave changes in patients with multiple sclerosis

Introduction:

In patients with multiple sclerosis among other symptoms occur cognitive dysfunctions, which can be shown by P300 wave changes.

Goal:

The aim of this study was to demonstrate that patients with multiple sclerosis have reduced amplitude and prolonged latency, longer than 300 ± 10 ms.

Methods:

The study included group of patients with multiple sclerosis and control group. After reviewing the medical records both groups of 14 participants were subjected to the same testing procedures auditory cognitive potentials (P300).

Results:

We have shown that patients with multiple sclerosis don’t have prolonged P300 target stimulus latency, but they have a longer P300 frequent stimulus latency for 18 ms. From 14 patients seven had a pathological P300 target stimulus amplitude, and even 12 patient had pathological P300 frequent stimulus amplitude.

Conclusion:

People with multiple sclerosis have altered P300 which indicates the presence of cognitive dysfunction in these patients.

Can multiple sclerosis as a cognitive disorder influence patients' dreams?

Dream should be considered as a kind of cognitive ability that is formed parallel to other cognitive capabilities like language. On the other hand, multiple sclerosis (MS) is a complex disease that can involve different aspects of our cognition. Therefore, MS may influence patients' dreams. In fact, we do not know what the importance of dream is in MS, but further studies may introduce dream and dreaming as a sign of improvement or progression in MS disease.

Deconstructing spatial working memory and attention deficits in multiple sclerosis

OBJECTIVE

To investigate whether spatial working memory (WM) is impaired in multiple sclerosis (MS), and, if it is, to localize impairment to specific cognitive subprocess(es).

METHOD

In Experiment 1, MS and control participants performed computerized memory-span and visuomotor tasks. WM subprocesses were taxed by manipulating (1) the requirement to remember serial order, (2) delay duration, and (3) the presence of irrelevant stimuli during target presentation. In Experiment 2, recall and recognition tests varied the difficulty of WM retrieval. In Experiment 3, an attention-cueing task tested the ability to voluntarily and rapidly reorient attention.

RESULTS

Performance was worse for MS than for control participants in both spatial recall (Exp. 1 span: 95% CIMS = [5.11, 5.57], 95% CIControls = [5.58, 6.03], p = .003, 1-tailed; Exp. 2 span: 95% CIMS = [4.44, 5.54], 95% CIControls = [5.47, 6.57], p = .006, 1-tailed) and recognition (accuracy: 95% CIMS = [0.71, 0.81], 95% CIControls = [0.79, 0.88], p = .01, 1-tailed) tests. However, there was no evidence for deficits in spatiotemporal binding, maintenance, retrieval, distractor suppression, or visuomotor processing. In contrast, MS participants were abnormally slow to reorient attention (cueing effect (ms): 95% CIMS: [90, 169], 95% CIControls: [29, 107], p = .015, 1-tailed).

CONCLUSIONS

Results suggest that, whereas spatial WM is impaired in MS, once spatial information has been adequately encoded into WM, individuals with MS are, on average, able to maintain and retrieve this information. Impoverished encoding of spatial information, however, may be due to inefficient voluntary orienting of attention.

Subcutaneous Interferon Beta-1a Has a Positive Effect on Cognitive Performance in Mildly Disabled Patients with Relapsing-Remitting Multiple Sclerosis: 2-Year Results from the COGIMUS Study

The effect of interferon (IFN) beta-1a (44 and 22 μg subcutaneously [sc] three times weekly [tiw]) on cognition in mildly disabled patients with relapsing-remitting multiple sclerosis (McDonald criteria; Expanded Disability Status Scale =4.0) was assessed by validated neuropsychological testing at baseline and at regular intervals for up to 2 years in this ongoing open-label, 3-year study. Year-2 data were available for 356 patients (22 μg, n = 175; 44μg, n = 181). The proportion of patients with impaired cognitive function was stable during the study: 21.4% at baseline and 21.6% at 2 years. At 2 years, the proportion of patients with =3 impaired cognitive tests was significantly lower in the 44 μg treatment group (17.0%) compared with the 22 μg group (26.5%; p = 0.034), although there was already a trend towards a higher proportion of patients with cognitive impairment in the 22 μg group at baseline. Factors associated with impairment in = three cognitive tests after 2 years were age (odds ratio [OR]: 1.05; 95% confidence interval [CI]: 1.00-1.09), verbal intelligence quotient (OR: 0.95; 95% CI: 0.92-0.98), and having = three impaired cognitive tests at baseline (OR: 11.60; 95% CI: 5.94-22.64). These interim results show that IFN beta-1a sc tiw may have beneficial effects on cognitive function as early as 2 years after treatment initiation, but the final 3-year data of the study are required to confirm these results.

Cluster analysis of behavioural and event-related potentials during a contingent negative variation paradigm in remitting-relapsing and benign forms of multiple sclerosis

Background

Event-related potentials (ERPs) may be used as a highly sensitive way of detecting subtle degrees of cognitive dysfunction. On the other hand, impairment of cognitive skills is increasingly recognised as a hallmark of patients suffering from multiple sclerosis (MS). We sought to determine the psychophysiological pattern of information processing among MS patients with the relapsing-remitting form of the disease and low physical disability considered as two subtypes: 'typical relapsing-remitting' (RRMS) and 'benign MS' (BMS). Furthermore, we subjected our data to a cluster analysis to determine whether MS patients and healthy controls could be differentiated in terms of their psychophysiological profile.

Methods

We investigated MS patients with RRMS and BMS subtypes using event-related potentials (ERPs) acquired in the context of a Posner visual-spatial cueing paradigm. Specifically, our study aimed to assess ERP brain activity in response preparation (contingent negative variation -CNV) and stimuli processing in MS patients. Latency and amplitude of different ERP components (P1, eN1, N1, P2, N2, P3 and late negativity -LN) as well as behavioural responses (reaction time -RT; correct responses -CRs; and number of errors) were analyzed and then subjected to cluster analysis.

Results

Both MS groups showed delayed behavioural responses and enhanced latency for long-latency ERP components (P2, N2, P3) as well as relatively preserved ERP amplitude, but BMS patients obtained more important performance deficits (lower CRs and higher RTs) and abnormalities related to the latency (N1, P3) and amplitude of ERPs (eCNV, eN1, LN). However, RRMS patients also demonstrated abnormally high amplitudes related to the preparation performance period of CNV (cCNV) and post-processing phase (LN). Cluster analyses revealed that RRMS patients appear to make up a relatively homogeneous group with moderate deficits mainly related to ERP latencies, whereas BMS patients appear to make up a rather more heterogeneous group with more severe information processing and attentional deficits.

Conclusions

Our findings are suggestive of a slowing of information processing for MS patients that may be a consequence of demyelination and axonal degeneration, which also seems to occur in MS patients that show little or no progression in the physical severity of the disease over time.

Impaired information processing speed and attention allocation in multiple sclerosis patients versus controls: a high-density EEG study

BACKGROUND

The no-go P3a is a variant of the P300 event-related potential (ERP) that indexes speed of information processing and attention allocation. The aim of this study was to compare ERP findings with results from the paced auditory serial addition test (PASAT) and to quantify latency, amplitude and topographical differences in P3a ERP components between multiple sclerosis (MS) patients and controls.

PATIENTS AND METHODS

Seventy-four subjects (20 relapsing remitting (RRMS) patients, 20 secondary progressive (SPMS) patients and 34 controls) completed a three-stimulus oddball paradigm (target, standard, and non-target). Subjects participated in separate visual and auditory tasks while data were recorded from 134 EEG channels. Latency differences were tested using an ANCOVA. Topographical differences were tested using statistical parametric mapping.

RESULTS

Visual P3a amplitude correlated with PASAT score in all MS patients over frontal and parietal areas. There were significant differences in latency, amplitude, and topography between MS patients and controls in the visual condition. RRMS and SPMS patients differed in visual P3a latency and amplitude at frontal and parietal scalp regions. In the auditory condition, there were latency differences between MS patients and controls only over the parietal region.

CONCLUSION

The present results demonstrate that information processing speed and attention allocation are impaired in MS.

Matrix metalloproteinases, synaptic injury, and multiple sclerosis

Multiple sclerosis (MS) is a disease of the central nervous system in which immune mediated damage to myelin is characteristic. For an overview of this condition and its pathophysiology, please refer to one of many excellent published reviews (Sorensen and Ransohoff, 1998; Weiner, 2009). To follow, is a discussion focused on the possibility that synaptic injury occurs in at least a subset of patients, and that matrix metalloproteinases (MMPs) play a role in such.

Psychiatric disorders in multiple sclerosis patients

Multiple sclerosis (MS) is a demyelinating disease showing variable clinical presentation. Optic neuritis is the most common symptom, followed by motor and sensitive manifestations. It is known that this disease may be related to several psychiatric disorders, especially depression. In this study we will discribe 5 cases of MS patients harboring psychiatric disorder related or unchained by the disease itself.

Control of visually guided saccades in multiple sclerosis: Disruption to higher-order processes

Ocular motor abnormalities are a common feature of multiple sclerosis (MS), with more salient deficits reflecting tissue damage within brainstem and cerebellar circuits. However, MS may also result in disruption to higher level or cognitive control processes governing eye movement, including attentional processes that enhance the neural processing of behaviourally relevant information. The attentional control of eye movement was investigated in 25 individuals with MS and a comparable number of neurologically healthy individuals matched for age and IQ. This entailed an evaluation of distractor-related effects on the generation of both unpredictable and predictable visually guided saccades, as well as an evaluation of the effects of presenting endogenous cues prior to target onset. For unpredictable saccades, we revealed an exaggerated distractor effect in MS, with saccade latencies prolonged and endpoints less accurate in the presence of a visual distractor. Predictable saccades tended to be hypometric for MS patients, although we found no significant distractor effects. For endogenously cued saccades, we found no group differences in latency following a valid cue, but an exaggerated increase in latency following invalid cues for MS patients. MS patients also generated a significantly greater proportion of erroneous responses to cue stimuli. These ocular motor characteristics demonstrate considerable sensitivity with respect to evaluating attentional deficits in MS, evident even in the absence of clinical signs of disease.

Quantitative electroencephalography reveals different physiological profiles between benign and remitting-relapsing multiple sclerosis patients

BACKGROUND

A possible method of finding physiological markers of multiple sclerosis (MS) is the application of EEG quantification (QEEG) of brain activity when the subject is stressed by the demands of a cognitive task. In particular, modulations of the spectral content that take place in the EEG of patients with multiple sclerosis remitting-relapsing (RRMS) and benign multiple sclerosis (BMS) during a visuo-spatial task need to be observed.

METHODS

The sample consisted of 19 patients with RRMS, 10 with BMS, and 21 control subjects. All patients were free of medication and had not relapsed within the last month. The power spectral density (PSD) of different EEG bands was calculated by Fast-Fourier-Transformation (FFT), those analysed being delta, theta, alpha, beta and gamma. Z-transformation was performed to observe individual profiles in each experimental group for spectral modulations. Lastly, correlation analyses was performed between QEEG values and other variables from participants in the study (age, EDSS, years of evolution and cognitive performance).

RESULTS

Nearly half (42%) the RRMS patients showed a statistically significant increase of two or more standard deviations (SD) compared to the control mean value for the beta-2 and gamma bands (F = 2.074, p = 0.004). These alterations were localized to the anterior regions of the right hemisphere, and bilaterally to the posterior areas of the scalp. None of the BMS patients or control subjects had values outside the range of +/- 2 SD. There were no significant correlations between these values and the other variables analysed (age, EDSS, years of evolution or behavioural performance).

CONCLUSION

During the attentional processing, changes in the high EEG spectrum (beta-2 and gamma) in MS patients exhibit physiological alterations that are not normally detected by spontaneous EEG analysis. The different spectral pattern between pathological and controls groups could represent specific changes for the RRMS patients, indicative of compensatory mechanisms or cortical excitatory states representative of some phases during the RRMS course that are not present in the BMS group.

Cognitive impairments in relapsing-remitting multiple sclerosis: a meta-analysis

There is debate in the literature regarding the magnitude, nature, and influence of cognitive impairment in individuals with relapsing-remitting multiple sclerosis (RRMS). Therefore, we conducted a meta-analysis that quantified the overall magnitude of cognitive impairment in individuals with RRMS and identified the domains of cognition and clinical/demographic variables that were moderators of the overall effect. We included 57 studies with 3891 participants that yielded a total of 755 effect sizes. Overall, there was a moderate decline in cognitive functioning in individuals with RRMS compared with healthy controls. Larger effects were observed in cognitive domains of motor functioning, mood status and memory and learning. Regarding demographic and clinical variables, age and gender were moderators of cognitive impairment in all cognitive domains, whereas neurological disability and disease duration primarily moderated performance on tasks assessing memory and learning.

Cognitive dysfunction 24–31 years after isolated optic neuritis

Objective

Cognitive dysfunction is common in multiple sclerosis (MS), but long-term data on cognition in patients with clinically isolated syndromes are sparse.

Methods

We determined cognitive functions in 22 patients 44–75 years old diagnosed with optic neuritis 24–31 years earlier but had no further clinical bouts and had not progressed clinically to MS. We used a neuropsychological test battery covering nine cognitive domains. Magnetic resonance imaging (MRI) of the brain had been performed earlier and was normal in six patients and showed two or more white matter abnormalities compatible with demyelinating lesions in 16 patients.

Results

On neuropsychological testing, one patient was within normal range on all tests, six subjects showed borderline results, and 15 patients (68%) showed significantly impaired performance in at least one cognitive domain. Seven patients showed significant impairment in two or more domains. Executive function, visuo-spatial ability, and information processing speed were the most frequently affected domains. There was no apparent correlation between MRI findings and cognitive function.

Conclusions

We conclude that cognitive dysfunction is common in patients many years after clinically isolated optic neuritis. Cognitive dysfunction was found even in patients who had no apparent demyelinating lesions on follow-up MRI.