FLAIR lesion volume in multiple sclerosis: relation to processing speed and verbal memory

Cognitive phenotypes in multiple sclerosis: mapping the spectrum of impairment

BACKGROUND

Available criteria for cognitive phenotypes in multiple sclerosis (MS) do not consider the severity of impairment.

OBJECTIVES

To identify cognitive phenotypes with varying degrees of impairment in MS patients and describe their demographic, clinical and MRI characteristics.

METHODS

Two hundred and forty-three MS patients and 158 healthy controls underwent neuropsychological tests to assess memory, attention, and executive function. For each domain, mild impairment was defined as performing 1.5 standard deviations below the normative mean on two tests, while the threshold for significant impairment was 2 standard deviations. Patients were classified into cognitive phenotypes based on severity of the impairment (mild/significant) and number of domains affected (one/more).

RESULTS

Five cognitive phenotypes emerged: Preserved cognition (PC; 56%), Mild Single-Domain Impairment (MSD; 15%), Mild Multi-Domain Impairment (MMD; 9%), Significant Single-Domain Impairment (SSD; 12%), Significant Multi-Domain Impairment (SMD; 8%). Compared with PC, MSD patients were older, had longer disease duration (DD) and higher T2-hyperintense lesion volume (LV; all p ≤ 0.02); MMD patients were older, had longer DD, higher disability, higher T2 LV and lower thalamic volume (all p ≤ 0.01); SSD patients had longer DD and lower gray matter cortical volume, thalamic, caudate, putamen and accumbens volumes (all p ≤ 0.04); and SMD patients were older, had longer DD, higher disability and more extensive structural damage in all brain regions explored (all p ≤ 0.03), except white matter and amygdala volumes.

CONCLUSIONS

We identified five cognitive phenotypes with graded levels of impairment. These phenotypes were characterized by distinct demographic, clinical and MRI features, indicating potential variations in the neural substrates of dysfunction throughout disease stages.

Working Memory Training Responsiveness in Parkinson's Disease Is Not Determined by Cortical Thickness or White Matter Lesions

Patients with Parkinson's disease are highly vulnerable for cognitive decline. Thus, early intervention by means of working memory training (WMT) may be effective for the preservation of cognition. However, the influence of structural brain properties, i.e., cortical thickness and volume of white matter lesions on training responsiveness have not been studied. Here, behavioral and neuroimaging data of 46 patients with Parkinson's disease, 21 of whom engaged in home-based, computerized adaptive WMT, was analyzed. While cortical thickness and white matter lesions volume were associated with cognitive performance at baseline, these structural brain properties do not seem to determine WMT responsiveness.

Understanding the health effects of caregiving stress: New directions in molecular aging

Dementia caregiving has been linked to multiple health risks, including infectious illness, depression, anxiety, immune dysregulation, weakened vaccine responses, slow wound healing, hypertension, cardiovascular disease, metabolic syndrome, diabetes, frailty, cognitive decline, and reduced structural and functional integrity of the brain. The sustained overproduction of proinflammatory cytokines is a key pathway behind many of these risks. However, contrasting findings suggest that some forms of caregiving may have beneficial effects, such as maintaining caregivers' health and providing a sense of meaning and purpose which, in turn, may contribute to lower rates of functional decline and mortality. The current review synthesizes these disparate literatures, identifies methodological sources of discrepancy, and integrates caregiver research with work on aging biomarkers to propose a research agenda that traces the mechanistic pathways of caregivers' health trajectories with a focus on the unique stressors facing spousal caregivers as compared to other informal caregivers. Combined with a focus on psychosocial moderators and mechanisms, studies using state-of-the-art molecular aging biomarkers such as telomere length, p16INK4a, and epigenetic age could help to reconcile mixed literature on caregiving's sequelae by determining whether and under what conditions caregiving-related experiences contribute to faster aging, in part through inflammatory biology. The biomarkers predict morbidity and mortality, and each contributes non-redundant information about age-related molecular changes -together painting a more complete picture of biological aging. Indeed, assessing changes in these biopsychosocial mechanisms over time would help to clarify the dynamic relationships between caregiving experiences, psychological states, immune function, and aging.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Supplementary Information

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

The relationship between processing speed and verbal and non-verbal new learning and memory in progressive multiple sclerosis

Objective:

Processing speed (PS) deficits are the most common cognitive deficits in multiple sclerosis (MS), followed by learning and memory deficits, and are often an early cognitive problem. It has been argued that impaired PS is a primary consequence of MS, which in turn decreases learning. The current analysis examined the association between PS and learning in a large cohort of individuals with progressive MS.

Methods:

Baseline data from a randomized clinical trial on rehabilitation taking place at 11 centers across North America and Europe were analyzed. Participants included 275 individuals with clinically definite progressive MS (primary, secondary) consented into the trial.

Results:

Symbol Digit Modalities Test (SDMT) significantly correlated with California Verbal Learning Test-II (CVLT-II) ( r = 0.21, p = 0.0003) and Brief Visuospatial Memory Test–Revised (BVMT-R) ( r = 0.516, p < 0.0001). Receiver operating characteristic (ROC) analysis of the SDMT z score to distinguish between impaired and non-impaired CVLT-II performance demonstrated an area under the curve (AUC) of 0.61 (95% confidence interval (CI): 0.55–0.68) and a threshold of −1.62. ROC analysis between SDMT and BVMT-R resulted in an AUC of 0.77 (95% CI: 0.71–0.83) and threshold of −1.75 for the SDMT z score to predict impaired BVMT-R.

Conclusion:

Results indicate little ability beyond chance to predict CVLT-II from SDMT (61%), albeit statistically significant. In contrast, there was a 77% chance that the model could distinguish between impaired and non-impaired BVMT-R. Several potential explanations are discussed.

Tract-specific MRI measures explain learning and recall differences in multiple sclerosis

Cognitive difficulties are common and a key concern for people with multiple sclerosis. Advancing knowledge of the role of white matter pathology in multiple sclerosis-related cognitive impairment is essential as both occur early in the disease with implications for early intervention. Consequently, this cross-sectional study asked whether quantifying the relationships between lesions and specific white matter structures could better explain co-existing cognitive differences than whole brain imaging measures. Forty participants with relapse-onset multiple sclerosis underwent cognitive testing and MRI at 3 Tesla. They were classified as cognitively impaired (n = 24) or unimpaired (n = 16) and differed across verbal fluency, learning and recall tasks corrected for intelligence and education (corrected P-values = 0.007-0.04). The relationships between lesions and white matter were characterized across six measures: conventional voxel-based T2 lesion load, whole brain tractogram load (lesioned volume/whole tractogram volume), whole bundle volume, bundle load (lesioned volume/whole bundle volume), Tractometry (diffusion-tensor and high angular resolution diffusion measures sampled from all bundle streamlines) and lesionometry (diffusion measures sampled from streamlines traversing lesions only). The tract-specific measures were extracted from corpus callosum segments (genu and isthmus), striato-prefrontal and -parietal pathways, and the superior longitudinal fasciculi (sections I, II and III). White matter measure-task associations demonstrating at least moderate evidence against the null hypothesis (Bayes Factor threshold < 0.2) were examined using independent t-tests and covariate analyses (significance level P < 0.05). Tract-specific measures were significant predictors (all P-values < 0.05) of task-specific clinical scores and diminished the significant effect of group as a categorical predictor in Story Recall (isthmus bundle load), Figure Recall (right striato-parietal lesionometry) and Design Learning (left superior longitudinal fasciculus III volume). Lesion load explained the difference in List Learning, whereas Letter Fluency was not associated with any of the imaging measures. Overall, tract-specific measures outperformed the global lesion and tractogram load measures. Variation in regional lesion burden translated to group differences in tract-specific measures, which in turn, attenuated differences in individual cognitive tasks. The structural differences converged in temporo-parietal regions with particular influence on tasks requiring visuospatial-constructional processing. We highlight that measures quantifying the relationships between tract-specific structure and multiple sclerosis lesions uncovered associations with cognition masked by overall tract volumes and global lesion and tractogram loads. These tract-specific white matter quantifications show promise for elucidating the relationships between neuropathology and cognition in multiple sclerosis.

A novel in-home digital treatment to improve processing speed in people with multiple sclerosis: A pilot study

OBJECTIVE

To assess whether a videogame-like digital treatment is superior to a control in improving processing speed in adults with multiple sclerosis (MS).

METHODS

Adults with MS and baseline Symbol Digit Modalities Test (SDMT) z-scores between -2 and 0 were enrolled in a double-blind randomized controlled clinical trial. After completing a baseline in-clinic evaluation (Visit 1), they were randomized to complete an in-home, tablet-based videogame-like digital treatment (AKL-T03) or control word game (AKL-T09) for up to 25 minutes/day, 5 days/week, for 6 weeks. A repeat in-clinic evaluation occurred at 6 weeks (Visit 2), and again 8 weeks later to determine persistence of effects (Visit 3). The pre-specified primary outcome was change in SDMT score between Visits 1 and 2.

RESULTS

SDMT increased at Visit 2 for participants randomized to both AKL-T03 (p < 0.001) and AKL-T09 (p = 0.024). These respective mean improvements were +6.10 and +3.55 (comparison p = 0.21). At Visit 3, 70% of participants randomized to AKL-T03 maintained a clinically meaningful 4+-point increase in SDMT above their baseline, compared with 37% for AKL-T09 (p = 0.038).

CONCLUSION

This in-home digital intervention resulted in substantial and durable improvements in processing speed. A larger randomized controlled clinical trial is planned.

TRIAL REGISTRATION

This trial is registered on ClinicalTrials.gov under "NCT03569618," https://clinicaltrials.gov/ct2/show/NCT03569618.

Pretreatment Volume of MRI-Determined White Matter Injury Predicts Neurocognitive Decline After Hippocampal Avoidant Whole-Brain Radiation Therapy for Brain Metastases: Secondary Analysis of NRG Oncology Radiation Therapy Oncology Group 0933

Purpose

NRG Oncology's RTOG 0933 demonstrated benefits to memory preservation after hippocampal avoidant whole-brain radiation therapy (HA-WBRT), the avoidance of radiation dose to the hippocampus (using intensity modulated radiation planning and delivery techniques) during WBRT, supporting the hypothesis of hippocampal radiosensitivity and associated memory specificity. However, some patients demonstrated cognitive decline, suggesting mechanisms outside hippocampal radiosensitivity play a role. White matter injury (WMI) has been implicated in radiation therapy–induced neurocognitive decline. This secondary analysis explored the relationship between pretreatment WMI and memory after HA-WBRT.

Methods and Materials

Volumetric analysis of metastatic disease burden and disease-unrelated WMI was conducted on the pretreatment magnetic resonance image. Correlational analyses were performed examining the relationship between pretreatment WMI and Hopkins Verbal Learning Test-Revised (HVLT-R) outcomes at baseline and 4 months after HA-WBRT.

Results

In the study, 113 patients received HA-WBRT. Of 113 patients, 33 underwent pretreatment and 4-month posttreatment HVLT testing and pretreatment postcontrast volumetric T1 and axial T2/fluid-attenuated inversion recovery magnetic resonance imaging. Correlation was found between larger volumes of pretreatment WMI and decline in HVLT-R recognition (r = 0.54, P < .05), and a correlational trend was observed between larger volume of pretreatment WMI and decline in HVLT-R delayed recall (r = 0.31, P = .08). Patients with higher pretreatment disease burden experienced a greater magnitude of stability or positive shift in HVLT-R recall and delayed recall after HA-WBRT (r = –0.36 and r = –0.36, P < .05), compared to the magnitude of stability or positive shift in those with lesser disease burden.

Conclusions

In patients receiving HA-WBRT for brain metastases, extent of pretreatment WMI predicts posttreatment memory decline, suggesting a mechanism for radiation therapy–induced neurocognitive toxicity independent of hippocampal stem cell radiosensitivity. Stability or improvement in HVLT after HA-WBRT for patients with higher pretreatment intracranial metastatic burden supports the importance of WBRT-induced intracranial control on neurocognition.

Temperature sensitivity in multiple sclerosis: An overview of its impact on sensory and cognitive symptoms

Multiple sclerosis (MS) is an autoimmune neurodegenerative disease characterized by demyelination of the central nervous system (CNS). The exact cause of MS is still unknown; yet its incidence and prevalence rates are growing worldwide, making MS a significant public health challenge. The heterogeneous distribution of demyelination within and between MS patients translates in a complex and varied array of autonomic, motor, sensory and cognitive symptoms. Yet a unique aspect of MS is the highly prevalent (60-80%) temperature sensitivity of its sufferers, where neurological symptoms are temporarily exacerbated by environmental- or exercise-induced increases (or decreases) in body temperature. MS temperature sensitivity is primarily driven by temperature-dependent slowing or blocking of neural conduction within the CNS due to changes in internal (core) temperature; yet changes in skin temperature could also contribute to symptom exacerbation (e.g. during sunlight and warm ambient exposure). The impact of temperature sensitivity, and particularly of increases in core temperature, on autonomic (e.g. thermoregulatory/cardiovascular function) and motor symptoms (e.g. fatigue) is well described. However, less attention has been given to how increases (and decreases) in core and skin temperature affect sensory and cognitive symptoms. Furthermore, it remains uncertain whether changes in skin temperature alone could also trigger worsening of symptoms. Here we review the impact of temperature sensitivity on MS sensory and cognitive function and discuss additional factors (e.g. changes in skin temperature) that potentially contribute to temperature-induced worsening of symptoms in the absence of alteration in core temperature.

Information processing speed in multiple sclerosis: Relevance of default mode network dynamics

Objective

To explore the added value of dynamic functional connectivity (dFC) of the default mode network (DMN) during resting-state (RS), during an information processing speed (IPS) task, and the within-subject difference between these conditions, on top of conventional brain measures in explaining IPS in people with multiple sclerosis (pwMS).

Methods

In 29 pwMS and 18 healthy controls, IPS was assessed with the Letter Digit Substitution Test and Stroop Card I and combined into an IPS-composite score. White matter (WM), grey matter (GM) and lesion volume were measured using 3 T MRI. WM integrity was assessed with diffusion tensor imaging. During RS and task-state fMRI (i.e. symbol digit modalities task, IPS), stationary functional connectivity (sFC; average connectivity over the entire time series) and dFC (variation in connectivity using a sliding window approach) of the DMN was calculated, as well as the difference between both conditions (i.e. task-state minus RS; ΔsFC-DMN and ΔdFC-DMN). Regression analysis was performed to determine the most important predictors for IPS.

Results

Compared to controls, pwMS performed worse on IPS-composite (p = 0.022), had lower GM volume (p < 0.05) and WM integrity (p < 0.001), but no alterations in sFC and dFC at the group level. In pwMS, 52% of variance in IPS-composite could be predicted by cortical volume (β = 0.49, p = 0.01) and ΔdFC-DMN (β = 0.52, p < 0.01). After adding dFC of the DMN to the model, the explained variance in IPS increased with 26% (p < 0.01).

Conclusion

On top of conventional brain measures, dFC from RS to task-state explains additional variance in IPS. This highlights the potential importance of the DMN to adapt upon cognitive demands to maintain intact IPS in pwMS.

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Problems with information processing speed occur often in multiple sclerosis (MS)

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Dynamics in brain communication can reflect information transfer within the brain

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With fMRI, dynamic communication can be measured, which increases upon task demands

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This increase in dynamics explains information processing speed in MS

Neuropsychological assessment without upper limb involvement: a systematic review of oral versions of the Trail Making Test and Symbol-Digit Modalities Test

The Trail Making Test (TMT) and written version of the Symbol Digit Modalities Test (SDMT) assess attention, processing speed, and executive functions but their utility is limited in populations with upper limb dysfunction. Oral versions of the TMT and SDMT exist, but a systematic review of their psychometric properties and clinical utility has not been conducted, which was the goal of this study. Searches were conducted in PubMed and PsycINFO, test manuals, and the reference lists of included articles. Four measures were identified: the SDMT-oral, oral TMT-A, oral TMT-B, and the Mental Alternation Test (MAT). Two investigators independently reviewed abstracts to identify peer-reviewed articles that reported on these measures in adult populations. From each article, one investigator extracted information on reliability, validity, responsiveness, minimum detectable change, normative data, and demographic influences. A second investigator verified the accuracy of the data in a random selection of 10% of papers. The quality of the evidence for each psychometric property was rated on a 4-point scale (unknown, poor, adequate, excellent). Results showed excellent evidence for the SDMT-oral, adequate evidence for the oral TMT-B and MAT, and adequate to poor evidence for the oral TMT-A. These findings inform the clinical assessment of attention, processing speed, and executive functions in individuals with upper limb disability.

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.

Balancing Early Aggression Against Risk of Progression in Multiple Sclerosis

Multiple sclerosis is a chronic demyelinating disease characterized by focal and diffuse inflammation of the central nervous system resulting in significant physical and cognitive disabilities. Disease-modifying therapies targeting the dysfunctional immune response are most effective in the first few years after disease onset, indicating that there is a limited time window for therapy to influence the disease course. No evidence of disease activity is emerging as a new standard for treatment response and may be associated with improved long-term disability outcomes. An aggressive management strategy, including earlier use of more potent immunomodulatory agents and close monitoring of the clinical and radiologic response to treatment, is recommended to minimize early brain volume loss and slow the progression of physical and cognitive impairments in patients with relapsing-remitting multiple sclerosis.

The nature of verbal memory impairment in multiple sclerosis: a list-learning and meta-analytic study

The primary purpose of this study was to test the hypothesis that multiple sclerosis (MS) patients have impaired acquisition rather than a retrieval deficit. Verbal memory impairment in MS was examined in 53 relapsing-remitting MS patients and 31 healthy controls (HC), and in a meta-analysis of studies that examined memory functioning in MS with list-learning tasks. The MS group demonstrated significantly lower acquisition and delayed recall performance than the HC group, and the meta-analysis revealed that the largest effect sizes were obtained for acquisition measures relative to delayed recall and recognition. Our data argue against a retrieval deficit as the sole explanation for verbal memory impairment in MS, and make a consistent case for the position that deficient acquisition contributes to the memory dysfunction of MS patients. Deficient acquisition may result from demyelination in relevant white matter tracts that reduces encoding efficiency as a result of impaired speed of information processing.

The role of speed versus working memory in predicting learning new information in multiple sclerosis

The most common cognitive impairments in multiple sclerosis (MS) have been documented in specific domains, including new learning and memory, working memory, and information processing speed. However, little attempt has been made to increase our understanding of their relationship to one another. While recent studies have shown that processing speed impacts new learning and memory abilities in MS, the role of working memory in this relationship has received less attention. The present study examines the relative contribution of impaired working memory versus processing speed in new learning and memory functions in MS. Participants consisted of 51 individuals with clinically definite MS. Participants completed two measures of processing speed, two measures of working memory, and two measures of episodic memory. Data were analyzed via correlational and multiple regression analysis. Results indicate that the variance in new learning abilities in this sample was primarily associated with processing speed, with working memory exerting much less of an influence. Results are discussed in terms of the role of cognitive rehabilitation of new learning and memory abilities in persons with MS.

Cognitive deficits in multiple sclerosis: a systematic review

OBJECTIVE: To present the results of prospective and retrospective studies on multiple sclerosis patients cognitive dysfunctions, as well as to discuss the batteries of neuropsy- chological tests used in these investigations. METHOD: A systematic review was performed involving 40 studies published from 1997 to 2009, in PubMed, Scopus, Ovid, ISI Web of Knowledge, Scientific Electronic Library on line (Scielo) and Latin-American and Caribbean Center of Health Sciences Informations database. Clear description of multiple sclerosis patients cognitive deficits evaluation, study design, sample size; inclusion-exclusion and discontinuation criteria; instruments for neuropsychological evaluation, diagnostic methods, evaluated functions and detailed statistical analysis had been the inclusion criteria. RESULTS: There is consensus on cognitive impairment of multiple sclerosis patients, especially on memory, speed processing, executive function, attention and concentration domains. One has identified use of 23 batteries and 74 neuropsychological tests, despite the recommendation of Consortium of Multiple Sclerosis Centers to the application of MACFIMS battery. CONSIDERATIONS: The absence of the uniformization for multiple sclerosis patients cognitive evaluation battery has precluded to achieve evidences to recommend its incorporation on diagnostic routine. Nevertheless this tendency is already outlined.

Cognitive decline in multiple sclerosis: impact of topographic lesion distribution on differential cognitive deficit patterns

Background: Multiple sclerosis (MS) is often accompanied by cognitive dysfunction. A negative correlation between cerebral lesion load and atrophy and cognitive performance has been pointed out almost consistently. Further, the distribution of lesions might be critical for the emergence of specific patterns of cognitive deficits.

Objective: The current study evaluated the significance of total lesion area (TLA) and central atrophy for the prediction of general cognitive dysfunction and tested for a correspondence between lesion topography and specific cognitive deficit patterns.

Methods: Thirty-seven patients with MS underwent neuropsychological assessment and magnetic resonance imaging. Lesion burden and central atrophy were quantified. Patients were classified into three groups by means of individual lesion topography (punctiform lesions/periventricular lesions/confluencing lesions in both periventricular and extra-periventricular regions).

Results: TLA was significantly related to 7 cognitive variables, whereas third ventricle width was significantly associated with 20 cognitive parameters. The three groups differed significantly in their performances on tasks concerning alertness, mental speed, and memory function.

Conclusion: Third ventricle width as a straight-forward measure of central atrophy proved to be of substantial predictive value for cognitive dysfunction, whereas total lesion load played only a minor role. Periventricular located lesions were significantly related to decreased psychomotor speed, whereas equally distributed cerebral lesion load did not. These findings support the idea that periventricular lesions have a determinant impact on cognition in patients with MS.

Transverse diffusivity of cerebral parenchyma predicts visual tracking performance in relapsing-remitting multiple sclerosis

This study investigated the relation between cerebral damage related to multiple sclerosis (MS) and cognitive decline as determined by two classical mental tracking tests. Cerebral damage in 15 relapsing-remitting MS patients was measured by diffusion tensor imaging (DTI). Fractional anisotropy, longitudinal and transverse diffusivity were defined in the cerebral parenchyma. Cognitive performance of the MS patients was assessed with the oral response format of the Symbol Digit Modalities Test (SDMT) and the Paced Auditory Serial Addition Test (PASAT). A significant correlation was found between performance on the SDMT and the fractional anisotropy in the brain. This correlation was predominantly induced by transverse diffusivity. Transverse diffusivity refers to the diffusion across fibers rather than along the fibers and is believed to be a specific marker for axonal loss and demyelination associated with MS. No significant association between DTI-measures and PASAT performance was found and this negative finding was mainly attributed to psychometric qualities. These results indicate that diffusivity along the non-principal diffusion direction, a possible signature of MS-related white matter pathology, contributes to information processing speed as measured with the SDMT, a task that requires close visual tracking and a widely used clinical marker for cognitive decline in MS.

Examining the link between information processing speed and executive functioning in multiple sclerosis

Slowed information processing speed (IPS) is frequently reported in those with multiple sclerosis (MS), and at least 20% are compromised on some aspect of executive functioning also. However, any relationship between these two processes has not been examined. The Sternberg Memory Scanning Test, Processing Speed Index (WAIS-III), Delis Kaplan Executive Function System (D.KEFS), and Working Memory Index (WMS-III) were administered to 90 participants with MS. Their performance on the PSI was significantly below the normative scores but no deficits in memory scanning speed were evident. The initial response speed of the Sternberg and the PSI were more closely related to D.KEFS performance, particularly in timed tasks with a high cognitive demand (switching tasks). In contrast, memory scanning speed was related to working memory. This study reinforces the link between IPS and working memory in MS, and supports the suggestion that IPS is not a unitary construct.

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.

Magnetic Resonance Imaging of Diffuse Axonal Injury: Quantitative Assessment of White Matter Lesion Volume

Diffuse axonal injury (DAI) is a common mechanism of traumatic brain injury (TBI) for which there is no well-accepted anatomic measures of injury severity. The present study aims to quantitatively assess DAI by measuring white matter lesion volume visible in fluid-attenuated inversion recovery (FLAIR) weighted images and to determine whether higher lesion volumes are associated with unfavorable functional outcome 6 months after injury. Twenty-four patients who experienced moderate to severe TBI without extra-axial or major cortical contusions were included in this study. Lesion volume was assessed by quantifying areas of hyperintensities in the white matter utilizing digitized FLAIR images. Two independent raters processed the magnetic resonance (MR) images and determined the total DAI volume. Functional outcome was assessed at 6 months after injury using the Glasgow Outcome Scale-Extended (GOSE). Interclass correlation analyses showed very high interrater reliability for each measure between the two raters (Interclass Correlation Coefficient = 0.95, p <or= 0.001). Total DAI volume was significantly, although modestly, correlated to GOSE (r = -0.453, p = 0.034). White matter lesion volume resulting from DAI can be quantitatively and reliably assessed from standard FLAIR-weighted MRIs. Patients with greater DAI volume have poorer functional outcomes. These methods may be useful in stratifying injury severity and for the assessment of DAI-directed therapies.