Attention related performance in two cognitively different subgroups of patients with multiple sclerosis

Prospective analyses of alertness, sleep, and fitness to drive one year after de novo multiple sclerosis diagnosis

BACKGROUND

The prevalence and functional burden of the chronic demyelinating disease multiple sclerosis (MS) are well documented; however, little is known about the initial clinical course of alertness, sleep, cognitive, and psychological symptoms.

OBJECTIVES

This exploratory, prospective, longitudinal study multidimensionally investigated the development and progression of alertness, sleep, fitness to drive, and psychological symptoms in the first year after de novo MS diagnosis.

METHODS

Twenty-five people with MS (pwMS) were assessed cognitively, psychologically, and using polysomnography soon after diagnosis and one year later, with outcomes compared to matched healthy controls.

RESULTS

In the early stage of the disease, psychological symptoms of pwMS were comparable with those of controls, and patient conditions did not deteriorate within the first disease year. A small percentage of pwMS experienced increased levels of anxiety and depression after diagnosis. Alertness, sustained attention, and fitness to drive were comparable between both groups, and fatigue levels remained low over the course of the year.

CONCLUSIONS

This study highlights patient experiences within the initial clinical course of MS in a small group of patients. Further research is needed to understand the progression of symptoms and impairments in MS over a longer period and in different stages of the disease.

Longitudinal assessment of neurocognitive function in people with relapsing multiple sclerosis initiating alemtuzumab in routine clinical practice: LEM-COG study results

BACKGROUND

Alemtuzumab is effective in reducing relapse rate and disability, but limited data exist on its effect on cognitive function in relapsing multiple sclerosis (RMS). The present study assessed neurocognitive function and safety associated with alemtuzumab treatment in RMS.

METHODS

This longitudinal, single-arm, prospective study included people with RMS (aged 25-55 years) who were treated with alemtuzumab in clinical practice in the United States of America and Canada. The first participant was enrolled in December 2016. The primary endpoint was the change from baseline to post-baseline (month [M] 12/24) in MS-COGnitive (MS-COG) composite score. Secondary endpoints included Paced Auditory Serial Addition Test (PASAT), Symbol Digit Modalities Test (SDMT), Brief Visuospatial Memory Test-Revised (BVMT-R), Selective Reminding Test (SRT), Controlled Oral Word Association Test (COWAT), and Automated Neuropsychological Assessment Metrics (ANAM) scores. Depression and fatigue were assessed using Hamilton Rating Scale-Depression (HAM-D) and Fatigue Severity Scale (FSS)/Modified Fatigue Impact Scale (MFIS), respectively. Magnetic resonance imaging (MRI) parameters were assessed when available. Safety was assessed throughout the study. Descriptive statistics were used for the pre-specified statistical analyses. Since the study was terminated early (November 2019) because of operational and resource difficulties, post hoc analyses for statistical inference were performed among participants who had a baseline value and at least one complete post-baseline assessment for cognitive parameters, fatigue, or depression.

RESULTS

Of the 112 participants enrolled, 39 were considered as the primary analysis population at M12. At M12, a mean change of 0.25 (95% confidence interval [CI]: 0.04, 0.45; p = 0.0049; effect size [ES]: 0.39) was observed in the MS-COG composite score. Improvements were observed in processing speed (based on PASAT and SDMT; p < 0.0001; ES: 0.62), as well as in individual PASAT, SDMT and COWAT scores. An improvement was also noted in HAM-D (p = 0.0054; ES: -0.44), but not in fatigue scores. Among MRI parameters, decreases in burden of disease volume (BDV; ES: -0.12), new gadolinium-enhancing lesions (ES: -0.41) and newly active lesions (ES: -0.07) were observed at M12. About 92% of participants showed stable or improved cognitive status at M12. There were no new safety signals reported in the study. The most common adverse events (≥10% of participants) were headache, fatigue, nausea, insomnia, urinary tract infection, pain in extremity, chest discomfort, anxiety, dizziness, arthralgia, flushing, and rash. Hypothyroidism (3.7%) was the most frequent adverse event of special interest.

CONCLUSION

The findings from this study suggest that alemtuzumab has a positive impact on cognitive function with significant improvements in processing speed and depression in people with RMS over a period of 12 months. The safety profile of alemtuzumab was consistent with previous studies.

Perceived Fatigue Impact and Cognitive Variability in Multiple Sclerosis

OBJECTIVE

People with Multiple Sclerosis (PwMS) and healthy controls (HCs) were evaluated on cognitive variability indices and we examined the relationship between fatigue and cognitive variability between these groups. Intraindividual variability (IIV) on a neuropsychological test battery was hypothesized to mediate the group differences expected in fatigue.

METHOD

Fifty-nine PwMS and 51 HCs completed a psychosocial interview and battery of neuropsychological tests and questionnaires during a 1-day visit. Fatigue in this study was measured with the Fatigue Impact Scale (FIS), a self-report multidimensional measure of fatigue. IIV was operationalized using two different measures, a maximum discrepancy score (MDS) and intraindividual standard deviation (ISD), in two cognitive domains, memory and attention/processing speed. Two mediation analyses with group (PwMS or HCs) as the independent variable, variability composite (memory or attention/processing speed) measures as the mediators, total residual fatigue (after accounting for age) as the outcome, and depression as a covariate were conducted. The Baron and Kenny approach to testing mediation and the PROCESS macro for testing the strength of the indirect effect were used.

RESULTS

Results of a mediation analysis using 5000 bootstrap samples indicated that IIV in domains of both attention/processing speed and memory significantly mediated the effect of patient status on total residual fatigue.

CONCLUSION

IIV is an objective performance measure that is related to differences in fatigue impact between PwMS and HCs. PwMS experience more variability across tests of attention/processing speed and memory and this experience of variable performance may increase the impact of fatigue.

Validation of Discrete and Regression-Based Performance and Cognitive Fatigability Normative Data for the Paced Auditory Serial Addition Test in Multiple Sclerosis

Cognitive fatigability is an objective performance decrement that occurs over time during a task requiring sustained cognitive effort. Although cognitive fatigability is a common and debilitating symptom in multiple sclerosis (MS), there is currently no standard for its quantification. The objective of this study was to validate the Paced Auditory Serial Addition Test (PASAT) discrete and regression-based normative data for quantifying performance and cognitive fatigability in an Ontario-based sample of individuals with MS. Healthy controls and individuals with MS completed the 3″ and 2″ versions of the PASAT. PASAT performance was measured with total correct, dyad, and percent dyad scores. Cognitive fatigability scores were calculated by comparing performance on the first half (or third) of the task to the last half (or third). The results revealed that the 3″ PASAT was sufficient to detect impaired performance and cognitive fatigability in individuals with MS given the increased difficulty of the 2″ version. In addition, using halves or thirds for calculating cognitive fatigability scores were equally effective methods for detecting impairment. Finally, both the discrete and regression-based norms classified a similar proportion of individuals with MS as having impaired performance and cognitive fatigability. These newly validated discrete and regression-based PASAT norms provide a new tool for clinicians to document statistically significant cognitive fatigability in their patients.

Emerging concepts on bradykinesia in non-parkinsonian conditions

BACKGROUND AND PURPOSE

Bradykinesia is one of the cardinal motor symptoms of Parkinson's disease. However, clinical and experimental studies indicate that bradykinesia may also be observed in various neurological diseases not primarily characterized by parkinsonism. These conditions include hyperkinetic movement disorders, such as dystonia, chorea, and essential tremor. Bradykinesia may also be observed in patients with neurological conditions that are not seen as "movement disorders," including those characterized by the involvement of the cerebellum and corticospinal system, dementia, multiple sclerosis, and psychiatric disorders.

METHODS

We reviewed clinical reports and experimental studies on bradykinesia in non-parkinsonian conditions and discussed the major findings.

RESULTS

Bradykinesia is a common motor abnormality in non-parkinsonian conditions. From a pathophysiological standpoint, bradykinesia in neurological conditions not primarily characterized by parkinsonism may be explained by brain network dysfunction.

CONCLUSION

In addition to the pathophysiological implications, the present paper highlights important terminological issues and the need for a new, more accurate, and more widely used definition of bradykinesia in the context of movement disorders and other neurological conditions.

Postural stability is a valid and meaningful disability metric in progressive MS with potential for use in neuroprotective therapy trials

BACKGROUND

Balance impairment is observed in up to 70% of people with MS (pwMS) and worsens with disease progression. Posturography using a force platform is the current gold standard in the measurement of balance. However, posturography has not been adequately studied or widely accepted for use as a disability outcome measure for pwMS. Importantly, the recent emergence of both successful and failed neuroprotective therapy trials in progressive MS has emphasised the need for new disability outcome measures for people with progressive MS. The main objectives of this study were to evaluate the clinical validity, reliability and feasibility of posturography as a disability metric in progressive MS.

METHODS

This was a prospective cross-sectional study. We recruited 73 people with progressive MS (age 18-65 years, EDSS 3.5-6.0). Participants stood in the centre of a force platform, feet comfortably apart, under various conditions: (i) eyes open (EO), (ii) eyes closed (EC) - a single task, each lasting ninety seconds; and simultaneous EO with a cognitive test: (iii) N-Back, a three-minute test whereby participants were instructed to click the mouse when two identical letters were displayed consecutively on a screen, (iv) Sustained Attention Response Task, a five-minute test whereby participants were instructed to click the mouse for every number "1″ to "9″ except "3″ - i.e., dual-tasks. Additionally, we performed a battery of validated physical and cognitive outcome measures. Posturographic data was processed using Matlab. Statistical analysis was performed using SPSS version 26. We used multiple linear regression modelling to determine whether significant univariate correlations between posturography and clinical metrics were independent of covariates that may influence the associations seen. A two-tailed significance level of 0.05 was used.

RESULTS

Of 73 participants, mean age 52.4 (8.5) years, mean MS disease duration 13.8 (10.3) years, median EDSS 5.0 (IQR 4.0-6.0), 44 (60.4%) were female. EO-Path-Length independently predicted upper extremity function (9-Hole-Peg-Test) with a larger effect size (adjusted R²=20.0%, p = 0.001) than that for walking measures (Timed 25-Foot Walk, adjusted R²=1.6%, p = 0.01; Two-Minute Walk Test, adjusted R²=7.2%, p = 0.002), while controlling for age, disease duration, height, weight, and sex. The addition of EO-Mediolateral-Displacement to the MS Functional Composite (MSFC) created a four-component z-score that increased the variance explained for quality of life (QOL) by 62.1%. Postural stability was significantly lower with mediolateral vs anteroposterior direction of sway, removal of vision, increased body weight, male sex, and fampridine use. Postural stability improved during dual-tasks compared to EO single task. Posturography detected significant worsening of balance over a single prolonged stance.

CONCLUSION

Postural stability independently predicted a wide range of clinical metrics including upper extremity function, walking ability, cognition and QOL, therefore establishing construct and concurrent validity as a disability outcome measure for people with progressive MS. Additionally, posturography is a quantitative, non-invasive, quick-and-easy-to-administer, and highly sensitive device, demonstrating its high feasibility for use as a time- and resource-efficient disability metric in neuroprotective therapy trials for progressive MS.

Attention/Working Memory, Learning and Memory in Adult Cameroonians: Normative Data, Effects of HIV Infection and Viral Genotype

OBJECTIVE

There is lack of Cameroonian adult neuropsychological (NP) norms, limited knowledge concerning HIV-associated neurocognitive disorders in Sub-Saharan Africa, and evidence of differential inflammation and disease progression based on viral subtypes. In this study, we developed demographically corrected norms and assessed HIV and viral genotypes effects on attention/working memory (WM), learning, and memory.

METHOD

We administered two tests of attention/WM [Paced Auditory Serial Addition Test (PASAT)-50, Wechsler Memory Scale (WMS)-III Spatial Span] and two tests of learning and memory [Brief Visuospatial Memory Test-Revised (BVMT-R), Hopkins Verbal Learning Test-Revised (HVLT-R)] to 347 HIV+ and 395 seronegative adult Cameroonians. We assessed the effects of viral factors on neurocognitive performance.

RESULTS

Compared to controls, people living with HIV (PLWH) had significantly lower T-scores on PASAT-50 and attention/WM summary scores, on HVLT-R total learning and learning summary scores, on HVLT-R delayed recall, BVMT-R delayed recall and memory summary scores. More PLWH had impairment in attention/WM, learning, and memory. Antiretroviral therapy (ART) and current immune status had no effect on T-scores. Compared to untreated cases with detectable viremia, untreated cases with undetectable viremia had significantly lower (worse) T-scores on BVMT-R total learning, BVMT-R delayed recall, and memory composite scores. Compared to PLWH infected with other subtypes (41.83%), those infected with HIV-1 CRF02_AG (58.17%) had higher (better) attention/WM T-scores.

CONCLUSIONS

PLWH in Cameroon have impaired attention/WM, learning, and memory and those infected with CRF02_AG viruses showed reduced deficits in attention/WM. The first adult normative standards for assessing attention/WM, learning, and memory described, with equations for computing demographically adjusted T-scores, will facilitate future studies of diseases affecting cognitive function in Cameroonians.

Cognitive Fatigability is Independent of Subjective Cognitive Fatigue and Mood in Multiple Sclerosis

BACKGROUND

Sustained cognitive testing is used to detect cognitive fatigability and is often considered a substitute for subjective cognitive fatigue (CF). However, the relationship between cognitive fatigability and subjective CF in people with multiple sclerosis (PwMS) remains undetermined.

OBJECTIVE

To explore potential associations between fatigability induced by sustained cognitive testing and subjective CF in PwMS.

METHODS

We gave 120 PwMS and 60 demographically matched, healthy individuals the Beck Depression Inventory-FastScreen (BDI-FS) to measure mood and the Modified Fatigue Impact Scale to measure CF. In addition, we used the Quotient ADHD Test, a sustained attention test, to measure cognitive fatigability. We also explored potential correlations between the individuals' performance on the sustained attention test and thalamic volume using recent MRI scans.

RESULTS

Forty-one (34.2%) of the PwMS exhibited cognitive fatigability. These 41 were found to be significantly older (P=0.006), had been diagnosed with the disease for longer (P=0.03), had higher scores (P<0.001) on the Expanded Disability Status Scale, and had reduced thalamic volume (P=0.04) compared with the 79 (65.8%) PwMS not exhibiting cognitive fatigability. The PwMS exhibiting cognitive fatigability scored similarly on the BDI-FS (P=0.21) and self-reported similar rates of CF (P=0.62) as the PwMS not exhibiting cognitive fatigability.

CONCLUSION

Cognitive fatigability induced by sustained cognitive testing is not an accurate clinical alternative to subjective CF. This study provides evidence to support cognitive fatigability and CF in PwMS as two distinct concepts.

Auditory mismatch detection, distraction, and attentional reorientation (MMN-P3a-RON) in neurological and psychiatric disorders: A review

Involuntary attention allows for the detection and processing of novel and potentially relevant stimuli that lie outside of cognitive focus. These processes comprise change detection in sensory contexts, automatic orientation toward this change, and the selection of adaptive responses, including reorientation to the original goal in cases when the detected change is not relevant for task demands. These processes have been studied using the Event-Related Potential (ERP) technique and have been associated to the Mismatch Negativity (MMN), the P3a, and the Reorienting Negativity (RON) electrophysiological components, respectively. This has allowed for the objective evaluation of the impact of different neuropsychiatric pathologies on involuntary attention. Additionally, these ERP have been proposed as alternative measures for the early detection of disease and the tracking of its progression. The objective of this review was to integrate the results reported to date about MMN, P3a, and RON in different neurological and psychiatric disorders. We included experimental studies with clinical populations that reported at least two of these three components in the same experimental paradigm. Overall, involuntary attention seems to reflect the state of cognitive integrity in different pathologies in adults. However, if the main goal for these ERP is to consider them as biomarkers, more research about their pathophysiological specificity in each disorder is needed, as well as improvement in the general experimental conditions under which these components are elicited. Nevertheless, these ERP represent a valuable neurophysiological tool for early detection and follow-up of diverse clinical populations.

Cognitive Fatigue in Multiple Sclerosis: An Objective Approach to Diagnosis and Treatment by Transcranial Electrical Stimulation

Cognitive fatigue is one of the most frequent symptoms in multiple sclerosis (MS), associated with significant impairment in daily functioning and quality of life. Despite its clinical significance, progress in understanding and treating fatigue is still limited. This limitation is already caused by an inconsistent and heterogeneous terminology and assessment of fatigue. In this review, we integrate previous literature on fatigue and propose a unified schema aiming to clarify the fatigue taxonomy. With special focus on cognitive fatigue, we survey the significance of objective behavioral and electrophysiological fatigue parameters and discuss the controversial literature on the relationship between subjective and objective fatigue assessment. As MS-related cognitive fatigue drastically affects quality of life, the development of efficient therapeutic approaches for overcoming cognitive fatigue is of high clinical relevance. In this regard, the reliable and valid assessment of the individual fatigue level by objective parameters is essential for systematic treatment evaluation and optimization. Transcranial electrical stimulation (tES) may offer a unique opportunity to manipulate maladaptive neural activity underlying MS fatigue. Therefore, we discuss evidence for the therapeutic potential of tES on cognitive fatigue in people with MS.

Cognitive impairment in multiple sclerosis - a review of current knowledge and recent research

Multiple sclerosis (MS) is a chronic, progressive disease of the central nervous system that is characterised by inflammatory damage to the myelin sheath. Though often neglected, cognitive impairment is a common feature of MS that affects 43-70% of patients. It has a sophisticated neuroanatomic and pathophysiologic background and disturbs such vital cognitive domains as speed of information processing, memory, attention, executive functions and visual perceptual functions. In recent years there has been growing interest in neuroimaging findings with regard to cognitive impairment in MS. The possible options of managing cognitive dysfunction in MS are pharmacologic interventions, cognitive rehabilitation and exercise training; however, not enough evidence has been presented in this field. The aim of our article is to provide current knowledge on cognitive impairment in MS based on the most recent scientific results and conclusions with regard to affected cognitive domains, neuropsychological assessment, underlying mechanisms of this disturbance, neuroimaging findings and therapeutic options.

Neuropsychological Assessment in Multiple Sclerosis

Abstract. Neuropsychological deficits in multiple sclerosis (MS) are common. Over the past decades, many different procedures have been employed in diagnosing these deficits. Even though certain aspects of cognitive performance such as information processing speed and working memory may be affected more frequently than other cognitive functions, no specific deficit profile has been established in MS. This article provides an overview of the neuropsychological diagnostic procedures in MS and allows the reader to reach an informed decision on the applicability of specific procedures and the availability of study data in the context of MS. Additionally, it makes recommendations on the compilation of both screening procedures and extensive test batteries.

Operationalising cognitive fatigability in multiple sclerosis: A Gordian knot that can be cut?

BACKGROUND

Researchers have attempted to operationalise objective measures of cognitive fatigability in multiple sclerosis (MS) to overcome the perceived subjectivity of patient-reported outcomes of fatigue (PROs). Measures of cognitive fatigability examine decrements in performance during sustained neurocognitive tasks.

OBJECTIVE

This personal viewpoint briefly summarises available evidence for measures of cognitive fatigability in MS and considers their overall utility.

RESULTS

Studies suggest there may be a construct that is distinct from self-reported fatigue, reflecting a new potential intervention target. However, assessments vary and findings across and within measures are inconsistent. Few measures have been guided by a coherent theory, and those identified are likely to be influenced by other confounds, such as cognitive impairment caused more directly by disease processes, depression and assessment biases.

CONCLUSION

Future research may benefit from (a) developing a guiding theory of cognitive fatigability, (b) examining ecological and construct validity of existing assessments and (c) exploring whether the more promising cognitive fatigability measures are correlated with impaired functioning after accounting for possible confounds. Given the issues raised, we caution that our purposes as researchers may be better served by continuing our search for a more objective cognitive fatigability construct that runs in parallel with improving, rather than devaluing, current PROs.

The Berlin Treatment Algorithm: recommendations for tailored innovative therapeutic strategies for multiple sclerosis-related fatigue

More than 80% of multiple sclerosis (MS) patients suffer from fatigue. Despite this, there are few therapeutic options and evidence-based pharmacological treatments are lacking. The associated societal burden is substantial (MS fatigue is a major reason for part-time employment or early retirement), and at least one out of four MS patients view fatigue as the most burdensome symptom of their disease. The mechanisms underlying MS-related fatigue are poorly understood, and objective criteria for distinguishing and evaluating levels of fatigue and tiredness have not yet been developed. A further complication is that both symptoms may also be unspecific indicators of many other diseases (including depression, sleep disorders, anemia, renal failure, liver diseases, chronic obstructive pulmonary disease, drug side effects, recent MS relapses, infections, nocturia, cancer, thyroid hypofunction, lack of physical exercise). This paper reviews current treatment options of MS-related fatigue in order to establish an individualized therapeutic strategy that factors in existing comorbid disorders. To ensure that such a strategy can also be easily and widely implemented, a comprehensive approach is needed, which ideally takes into account all other possible causes and which is moreover cost efficient. Using a diagnostic interview, depressive disorders, sleep disorders and side effects of the medication should be identified and addressed. All MS patients suffering from fatigue should fill out the Modified Fatigue Impact Scale, Epworth Sleepiness Scale, the Beck Depression Inventory (or a similar depression scale), and the Pittsburgh Sleep Quality Index (or the Insomnia Severity Index). In some patients, polygraphic or polysomnographic investigations should be performed. The treatment of underlying sleep disorders, drug therapy with alfacalcidol or fampridine, exercise therapy, and cognitive behavioral therapy-based interventions may be effective against MS-related fatigue. The objectives of this article are to identify the reasons for fatigue in patients suffering from multiple sclerosis and to introduce individually tailored treatment approaches. Moreover, this paper focuses on current knowledge about MS-related fatigue in relation to brain atrophy and lesions, cognition, disease course, and other findings in an attempt to identify future research directions.

The effect of Fampridine-SR on cognitive fatigue in a randomized double-blind crossover trial in patients with MS

BACKGROUND

Cognitive fatigue (CF) is a common complaint in persons with MS (PwMS). Fampridine-SR improves ambulation, fatigue and endurance, due to enhancing action potential formation by blocking potassium channels in demyelinated axons. Thus, through this same mechanism, it is hypothesized that Fampridine-SR could improve CF.

OBJECTIVE

To determine if Fampridine-SR objectively improves CF in PwMS.

METHODS

Sixty PwMS of any type with CF, defined as 3 or less correct responses when comparing the last third to the first third on the Paced Auditory Serial Addition Test (PASAT), were recruited from a tertiary care MS clinic in London (ON) Canada. Subjects also had to be between 18 and 64 years of age, inclusive, not had a relapse in the last 60 days or corticosteroids in the last 30 days, EDSS 0.0-7.0, and no other diagnosis that could cause cognitive impairment. A randomized double blind crossover design was used: subjects were randomized to either placebo or Fampridine-SR for 4 weeks, then after at least a one week washout, received the opposite treatment. Subjects were assessed before and after each treatment block. The primary outcome was the PASAT CF score after treatment with Fampridine-SR compared to placebo. T-tests and chi-square were used to compare demographics between the two groups (placebo-Fampridine-SR vs. Fampridine SR-placebo). Treatment effects were assessed using factorial ANOVA, with treatment (Fampridine-SR vs. placebo) and time (before and after treatment) as within-subject variables.

RESULTS

Of the 60 subjects randomized, 48 completed the study; three were removed due to an adverse event while in the treatment arm (one due to relapse while on placebo, one due to urinary retention and one due to dizziness and headache while on Fampridine-SR). The subjects had a mean age of 46.5±10.0 years, education of 13.6±1.9 years, and were diagnosed with MS 10.6±9.6 years ago. The majority were female (46, 76.7%), had relapsing remitting MS (41, 68.3%) with median EDSS of 3.5 (range 1.0-7.0). There were no significant demographic differences between the two groups. The treatment x time interaction within the factorial ANOVA on PASAT CF scores was statistically significant, F(1, 45)=8.28, p=0.006, suggesting there is a difference between the treatments (placebo vs. Fampridine-SR), over the course of the study. An evaluation of the mean scores suggests, however, that subjects saw a greater improvement when they were given the placebo, than when they were given the active medication. Similarly, individuals showed a greater increase in their information processing speed (as measured by the PASAT) over the course of treatment when they were given the placebo, as compared with the active medication F(1,45)=4.17, p=0.047.

CONCLUSION

Although this small pilot study does not suggest that Fampridine-SR results in a statistically significant improvement of CF in MS patients, as compared to placebo, individuals demonstrated an improvement in both information processing speed and CF, suggesting further studies are warranted.

Does the Modified Fatigue Impact Scale offer a more comprehensive assessment of fatigue in MS?

Background: As a symptom of multiple sclerosis (MS), fatigue is difficult to manage because of its unknown etiology, the lack of efficacy of the drugs tested to date and the absence of consensus about which would be the ideal measure to assess fatigue. Objective: Our aim was to assess the frequency of fatigue in a sample of MS patients and healthy controls (HC) using two fatigue scales, the Fatigue Severity Scale (FSS) and the Modified Fatigue Impact Scale (MFIS) with physical, cognitive and psychosocial subscales. We also studied the relationship fatigue has with depression, disability and interferon beta. Methods: Three hundred and fifty-four individuals (231 MS patients and 123 HC) were included in this cross-sectional study. Fatigue was assessed using the FSS and MFIS. Depression was measured by the Beck Depression Inventory (BDI), and disability by the Expanded Disability Status Scale (EDSS). A status of fatigue was considered when the FSS≥ 5, of non-fatigue when the FSS≤4, and scores between 4.1 and 4.9 were considered doubtful fatigue cases. Results: Fifty-five percent of MS patients and 13% of HC were fatigued. The global MFIS score positively correlated with the FSS in MS and HC (r=0.68 for MS and r=0.59 for HC, p<0.0001). Nonetheless, the MFIS physical subscale showed the strongest correlation score with the FSS (r=0.75, p<0.0001). In addition, a prediction analysis showed the physical MFIS subscale to be the only independent predictor of FSS score (p<0.0001), suggesting other aspects of fatigue, as cognition and psychosocial functions, may be explored by the FSS to a lesser extent. Depression also correlated with fatigue (r=0.48 for the FSS and r=0.7 for the MFIS, p<0.0001) and, although EDSS correlated with fatigue as well, the scores decreased after correcting for depression. Interferon beta showed no relationship with fatigue. Conclusions: Fatigue is a frequent symptom found in MS patients and clearly related with depression. Each fatigue scale correlates with one another, indicating that they are measuring similar constructs. Nevertheless, spheres of fatigue as cognition and psychosocial functions are probably better measured by the MFIS, although this hypothesis will need to be confirmed with appropriate psychometrical testing.

The PASAT performance among patients with multiple sclerosis: analyses of responding patterns using different scoring methods

The Paced Auditory Serial Addition Test (PASAT) is widely used in the evaluation of multiple sclerosis (MS) patients’ cognitive performance, and also used as the sole measure of cognition in a recently developed assessment tool for MS clinical trials, the Multiple Sclerosis Functional Composite (MSFC). We analysed if MS patients and healthy controls have different patterns of responding in the PASAT, and whether different scoring methods influence the PASAT’s sensitivity and specificity in detecting disease-associated cognitive impairment. Forty-five relapsing-remitting MS patients and 48 healthy controls were evaluated using the PASAT and a comprehensive neuropsychological examination. Cognitively deteriorated MS patients compensated for their difficulties in PASAT by omitting rather than guessing answers. They skipped items intermittently, which reduces the difficulty of the task. Furthermore, towards the end of the PASAT’s 60-item series MS patients’ performance had a trend to fade whereas controls’ performance was more even throughout the task. The dyad score or the percent dyad score did not essentially improve the sensitivity or the specificity, but the accuracy improved when the answers at the end of the PASAT series were specifically emphasized. Using the combined score, 73% of the patients were correctly classified as cognitively impaired or unimpaired.

Cognitive fatigue during a test requiring sustained attention: a pilot study

Background: Fatigue is common in multiple sclerosis (MS), but difficulty quantifying fatigue severity has impeded studies of its characteristics, mechanisms, and therapeutics. Motor fatigue can be objectively measured as the decline in strength occurring during sustained contractio ns. A nalogous declines in cognitive performance occur during tasks requiring sustained attentio n. Objective: To objectively measure cognitive fatigue as a decline in performance during tests requiring sustained attentio n. Design/Methods: Patients with clinically stable MS (n=20) and healthy controls (n=21) with comparable age, gender, and education completed the Paced A uditory Serial A ddition Test (PA SAT) and the Digit O rdering Test (DOT) at two identical test sessions separated by 4-10 days, within a month after two practice sessions. C ognitive fatigue was quantified with two pre-specified methods for each test. The reliability of cognitive fatigue assessments was evaluated with intraclass correlation coefficients (ICC s) and construct validity was evaluated using correlations with measures of self-reported fatigue, cognition, and overall impairment/disability. Results: MS patients had an average of 18.7 items correct on the first 20 items of the PA SAT and 17.8 correct on the last 20 items, quantified as 5.3-5.8% declines in performance using the different measurement methods (P =0.01, rejecting the null hypothesis of zero mean decline). A lthough MS patients as a group demonstrated a similar decline at both sessions, IC C s were relatively low. C ontrol patients did not demonstrate significant declines in performance during PA SAT administration, but tests comparing declines in MS patients and controls did not demonstrate significant differences. Fatigue was not demonstrated using the DOT, and test-retest reliability was very poor. Conclusions: MS patients have objectively measurable cognitive fatigue during administration of the PASAT.

Information processing speed and attention in multiple sclerosis: Reconsidering the Attention Network Test (ANT)

OBJECTIVE

The Attention Network Test (ANT) assesses attention in terms of discrepancies between response times to items that differ in the burden they place on some facet of attention. However, simple arithmetic difference scores commonly used to capture these discrepancies fail to provide adequate control for information processing speed, leading to distorted findings when patient and control groups differ markedly in the speed with which they process and respond to stimulus information. This study examined attention networks in patients with multiple sclerosis (MS) using simple difference scores, proportional scores, and residualized scores that control for processing speed through statistical regression.

METHOD

Patients with relapsing-remitting (N = 20) or secondary progressive (N = 20) MS and healthy controls (N = 40) of similar age, education, and gender completed the ANT.

RESULTS

Substantial differences between patients and controls were found on all measures of processing speed. Patients exhibited difficulties in the executive control network, but only when difference scores were considered. When deficits in information processing speed were adequately controlled using proportional or residualized score, deficits in the alerting network emerged. The effect sizes for these deficits were notably smaller than those for overall information processing speed and were also limited to patients with secondary progressive MS.

CONCLUSIONS

Deficits in processing speed are more prominent in MS than those involving attention, and when the former are properly accounted for, differences in the latter are confined to the alerting network.

Defective sensorimotor integration in preparation for reaction time tasks in patients with multiple sclerosis

Slowness of voluntary movements in patients with multiple sclerosis (MS) may be due to various factors, including attentional and cognitive deficits, delays in motor conduction time, and impairment of specific central nervous system circuits. In 13 healthy volunteers and 20 mildly disabled, relapsing-remitting MS patients, we examined simple reaction time (SRT) tasks requiring sensorimotor integration in circuits involving the corpus callosum and the brain stem. A somatosensory stimulus was used as the imperative signal (IS), and subjects were requested to react with either the ipsilateral or the contralateral hand (uncrossed vs. crossed SRT). In 33% of trials, a startling auditory stimulus was presented together with the IS, and the percentage reaction time change with respect to baseline SRT trials was measured (StartReact effect). The difference between crossed and uncrossed SRT, which requires interhemispheric conduction, was significantly larger in patients than in healthy subjects ( P = 0.021). The StartReact effect, which involves activation of brain stem motor pathways, was reduced significantly in patients with respect to healthy subjects (uncrossed trials: P = 0.015; crossed trials: P = 0.005). In patients, a barely significant correlation was found between SRT delay and conduction abnormalities in motor and sensory pathways ( P = 0.02 and P = 0.04, respectively). The abnormalities found specifically in trials reflecting interhemispheric transfer of information, as well as the evidence for reduced subcortical motor preparation, indicate that a delay in reaction time execution in MS patients cannot be explained solely by conduction slowing in motor and sensory pathways but suggest, instead, defective sensorimotor integration mechanisms in at least the two circuits examined.

The progress of cognitive decline in newly diagnosed MS patients

OBJECTIVES

Cognitive impairment occurs in multiple sclerosis already in the early stages of the disease. Less is known about the evolution of cognitive decline, especially in newly diagnosed MS patients. The results of existing studies are contradictory in that both cognitive preservation and progressive deterioration have been reported. The purpose of this study was to examine how cognitive impairment evolves over time in the early stages of MS.

MATERIAL AND METHODS

At baseline, the participants were 36 newly diagnosed MS patients and 37 controls. A group of 30 patients were followed longitudinally at a mean test-retest interval of 6.1 years. The test battery covered attention, information processing, memory and learning, verbal and motor functions and reasoning.

RESULTS

There was a significant decline in divided attention (dual task) and information-processing speed (SDMT) at follow-up, but no significant deterioration in overall cognitive performance.

CONCLUSIONS

Overall cognitive functioning remained quite stable during the 6-year follow-up, whereas divided attention and processing speed deteriorated. However, deterioration in performance on the SDMT and the dual task does not seem to indicate more extensive cognitive deterioration. Given the impact of cognitive impairment on patients' quality of life, early detection of its occurrence in MS is extremely important.

Effect of withdrawal from long-term use of temazepam, zopiclone or zolpidem as hypnotic agents on cognition in older adults

PURPOSE

The aim of this study was to assess the effect of withdrawal from the long-term use of temazepam, zopiclone or zolpidem as hypnotics drugs (here referred to as BZD) on cognitive performance.

METHODS

Ninety-two adults (age ≥55 years) with primary insomnia and who were long-term daily users of BZD volunteered to participate in a 1-month medically supported withdrawal attempt from BZD use, with a subsequent 5-month follow-up. Withdrawal was based on plasma BZD measurements at baseline, at 1 month and during subsequent regular clinical appointments. Attention and psychomotor performance were measured using the CogniSpeed® at baseline and at 1, 2 and 6 months. Reaction times were determined in the Simple Reaction Time (SRT), Two-Choice Reaction Time (2-CRT) and Vigilance tests, and errors were measured by the 2-CRT and Vigilance tests. The cognition data of the withdrawal group were also compared with a cohort of BZD non-users.

RESULTS

Eighty-nine (97 %) participants (59 women, 30 men) were followed-up for a maximum of 6 months. During the follow-up period, changes in reaction times and errors did not differ between short-term withdrawers (no residual BZD at 1 month; N = 69), non-withdrawers (residual BZD at 1 month; N = 20) or long-term withdrawers (N = 34). Compared to the reaction times of the BZD-free cohort, those of BZD users were slower at baseline. The reaction times of BZD withdrawers based on the results of the SRT or 2-CRT tests during follow-up did not reach those of the BZD-free cohort, but there was no difference between these groups in the Vigilance test.

CONCLUSIONS

Long-term use of BDZ as hypnotic drugs by older adults is related to prolonged impairment of attentional and psychomotor cognitive functioning that persists for at least 6 months after withdrawal.

The effects of heat stress on cognition in persons with multiple sclerosis

Background: Heat sensitivity and cognitive deficits are typical manifestations of multiple sclerosis (MS). Although cognitive deficits are quite well characterized, practically no data exist on the effects of heat on cognitive performances in MS.

Objective: To assess the effects of short-term heat stress on cognitive functioning in subjects with MS.

Methods: A total of 23 heat-sensitive MS and 19 healthy control (HC) subjects participated. Moderate heat exposure took place in a Finnish sauna. Cognitive functioning was measured with tests of sustained attention and processing speed, the Paced Auditory Serial Addition Test (PASAT 3” and 2”) and the computerized visual vigilance test, before, during and after heat exposure.

Results: During the heat exposure, the core body temperature of the MS group rose significantly more ( p = 0.002) than that of the HC group. The heat stress worsened the performance of the MS group in the PASAT 3” ( p = 0.025) but not in the other cognitive measures. The performance in the PASAT 3” was reversed almost to the baseline level only 1- h after the heat exposure.

Conclusions: A significant increase in core body temperature during heat stress is associated with a mild and reversible worsening of the PASAT 3” performance, while visual vigilance performance seems to remain almost unaffected.

The effects of rivastigmine on processing speed and brain activation in patients with multiple sclerosis and subjective cognitive fatigue

Background: Cognitive decline and fatigue are typical in multiple sclerosis (MS). However, there is no official medication for either of these symptoms.

Objective: The purpose of this study was to estimate the effects of a single dose of rivastigmine on processing speed and associated brain activity in patients with MS and subjective cognitive fatigue.

Methods: Fifteen patients with MS and subjective cognitive fatigue and 13 healthy controls (HCs) matched for age, gender and education performed a neuropsychological assessment and functional (f)MRI. A modified version of the Paced Visual Serial Addition Test (mPVSAT) was used as the behavioural task during fMRIs. After the first scanning session, both groups were randomly divided into two subgroups receiving either rivastigmine or placebo. A single dose of rivastigmine or placebo was administrated double-blindly and 2.5 hours later the scanning was repeated.

Results: At baseline, the patients with MS showed slower processing speed in mPVSAT compared with the HCs. They also demonstrated stronger bilateral frontal activation after sustained cognitive effort than the HCs. Performance improvement and a further activation increase in the left anterior frontal cortex and additional activation in the right cerebellum were observed in patients who received rivastigmine but not in patients on placebo, or in HCs with placebo or rivastigmine.

Conclusion: These preliminary findings suggest that rivastigmine may improve cognitive processing speed by enhancing compensatory brain activation in patients with MS.

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.

Correlation of self-assessed fatigue and alertness in multiple sclerosis

Background: Fatigue is the most common symptom in multiple sclerosis patients, but is difficult to measure; quantification thus relies on self-assessed questionnaires.

Objective: To evaluate a battery of neuropsychological tests regarding their capacity to objectify self-reported fatigue.

Methods: We assessed the correlation between age, gender, education, Kurtzke’s Expanded Disability Status Scale, depression, fatigue and neuropsychological testing using a cross-sectional approach in 110 multiple sclerosis patients. Fatigue was measured with the Fatigue Severity Scale. Cognition was measured using a series of neuropsychological tests including three subtests of the Test of Attentional Performance, the Brief Repeatable Battery of Neuropsychological Tests and the Faces Symbol Test.

Results: According to the Fatigue Severity Scale 51.4% of the cohort were fatigued (scores ≥4). Age, education and depression showed a significant correlation with the Fatigue Severity Scale. Only 5.5% of the cohort exhibited cognitive impairment in the Brief Repeatable Battery of Neuropsychological Tests scores. After correction for age, education, Expanded Disability Status Scale and depression, Fatigue Severity Scale scores were an independent predictor of performance in the alertness subtest of the Test of Attentional Performance (standardized coefficient beta = 0.298, p = 0.014).

Conclusion: The alertness subtest of the Test of Attentional Performance may offer an objective method of evaluating self-reported fatigue, and may therefore — in addition to the Fatigue Severity Scale — be a suitable tool for the assessment of multiple sclerosis patients complaining of fatigue.

The impact of multiple sclerosis on patients' performance on the Stroop Test: processing speed versus interference

Deficits in multiple sclerosis (MS) patients' performance on the Stroop Test have been attributed to problems with processing speed and selective attention. Data for 248 MS patients and 178 controls on all three trials of the Stroop were combined using various scoring formulas proposed for assessing processing speed, color difficulty, and interference. The greatest differences between patients and controls involved processing speed. Formulas purporting to measure interference yielded highly inconsistent results: Significant differences between groups were found on two of the most common measures but were in opposite directions. This contradiction stems from the failure of both measures to effectively control for processing speed when assessing interference. Three alternative measures, using relative, ratio, and residualized scores, offer much better indices of interference. When assessed with these alternative measures, interference increased with age, but no differences between patients and controls were found. Difficulties that MS patients have with the Stroop Test are confined to processing speed.

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 impairment in multiple sclerosis

Multiple sclerosis (MS) is a progressive disease of the CNS that is characterised by widespread lesions in the brain and spinal cord. MS results in motor, cognitive, and neuropsychiatric symptoms, all of which can occur independently of one another. The common cognitive symptoms include deficits in complex attention, efficiency of information processing, executive functioning, processing speed, and long-term memory. These deficits detrimentally affect many aspects of daily life, such as the ability to run a household, participate fully in society, and maintain employment--factors that can all affect the overall quality of life of the patient. The increased use of neuroimaging techniques in patients with MS has advanced our understanding of structural and functional changes in the brain that are characteristic of this disease, although much remains to be learned. Moreover, examination of efforts to treat the cognitive deficits in MS is still in the early stages.

The psychology of fatigue in patients with multiple sclerosis: a review

Fatigue is a frequent and disabling symptom in patients with multiple sclerosis (MS), but it is difficult to define and measure. Today, MS-related fatigue is not fully understood, and evidence related to explanatory pathophysiological factors are conflicting. Here, we evaluate the contribution of psychological factors to MS-related fatigue. Insight into the possible underlying psychological mechanisms might help us to develop adequate psychological interventions and to improve the overall management of fatigue. Conceptual issues and the relationships between MS-related fatigue and mood, anxiety, cognition, personality, and cognitive-behavioral factors are discussed, and the implications for clinical practice and research are presented.

A brief neuropsychological screening test battery for cognitive dysfunction in Brazilian multiple sclerosis patients

PRIMARY OBJECTIVE

The cognitive profile of patients with Multiple Sclerosis in the Brazilian population is relatively unknown and no cognitive screening instruments have been developed for this population. The purpose of the present study was to develop a neuropsychological screening instrument battery to identify cognitive impairment in epidemiological research protocols in this country.

METHODS AND PROCEDURES

Fifty-four patients with Relapsing-Remitting Multiple Sclerosis (RRMS) and 54 controls matched by sex, age and educational level were evaluated through a long and comprehensive neuropsychological test battery.

MAIN OUTCOMES AND RESULTS

In comparison to the control group, 51.8% of the patients with RRMS presented some form of cognitive impairment. Three neuropsychological tests - Verbal Fluency, Rey Auditory Verbal Learning and Enhanced Cued Recall - presented an 80.6% sensitivity and 97.2% specificity in differentiating RRMS patients with cognitive deficits from paired control subjects.

CONCLUSIONS

These three tests constitute a Brief Battery that represents a first Brazilian MS cognitive screening instrument. However, further validation study is necessary to achieve better normative scores in a larger sample and to establish feasibility of this battery.

Stroop performance in multiple sclerosis: information processing, selective attention, or executive functioning?

Cognitive impairments in information processing speed, attention and executive functioning are widely reported in patients with multiple sclerosis (MS). Several studies have identified impaired performance on the Stroop test in people with MS, yet uncertainty remains over the cause of this phenomenon. In this study, 25 patients with MS were assessed with a neuropsychological test battery including a computerized Stroop test and a computerized test of information processing speed, the Graded Conditional Discrimination Tasks (GCDT). The patient group was compared with an individually age, sex and estimated premorbid IQ-matched healthy control group. The patients' reaction times (RTs) were significantly longer than those of the controls on all Stroop test trials and there was a significantly enhanced absolute (RT(incongruent)-RT(neutral)) and relative (100 x [RT(incongruent)-RT(neutral)]/RT(neutral)) Stroop interference effect for the MS group. The linear function relating RT to stimulus complexity in the GCDT was significantly steeper in the patient group, indicating slowed information processing. The results are discussed with reference to the difference engine model, a theory of diversity in speeded cognition. It is concluded that, in the assessment of people with MS, great caution must be used in the interpretation of performance on neuropsychological tests which rely on RT as the primary measure.

Rapid serial processing in patients with multiple sclerosis: the role of peripheral deficits

This study compared speed of information processing in patients with relapsing-remitting or secondary progressive multiple sclerosis (MS) and healthy controls using the Stroop Test and a Picture Naming Test (PNT). While both tests evaluated processing speed within a format calling for rapid serial processing of stimulus information, the PNT included trials designed to impose greater verbal-motor and ocular-motor challenges by using novel rather than repeated pictures and by presenting the pictures in distributed locations rather than always centered on the screen. The results confirmed that a decrease in the speed of information processing is a key feature of the cognitive impairment occurring in conjunction with MS. When this feature is evaluated with tests requiring rapid serial processing of stimulus information, the contribution of peripheral motor deficits appears to be modest.

The reliability of the MSFC and its components

BACKGROUND

The Multiple Sclerosis Functional Composite (MSFC) is a multidimensional measurement tool for multiple sclerosis (MS) including a measure of ambulation (Timed 25-foot Walk [TWT]), arm function (Nine-Hole Peg Test [9HPT]) and cognition (Paced Auditory Serial Addition Test [PASAT]).

OBJECTIVES

To assess the reliability and practice effects in the Finnish version of the MSFC and its components.

MATERIALS AND METHODS

Ten relapsing-remitting MS patients and 10 healthy controls underwent five testing sessions with the MSFC over a 4-week period.

RESULTS

The MSFC showed excellent intra- (0.99) and inter-rater (1.0) reliability. The MSFC, especially the 9HPT and the PASAT showed significant practice effects. On the 9HPT the controls remained stable whereas the patients improved their performance; on the PASAT both groups improved.

CONCLUSIONS

The MSFC showed excellent intra- and inter-rater reliability although the 9HPT and the PASAT were prone to considerable practice effects.

Qualitative and quantitative assessment of fatigue in multiple sclerosis (MS)

It was the aim of the present study to develop a synoptic multidimensional test system for assessment of fatigue in multiple sclerosis (MS) patients objectifying physical and mental fatigue as well as the subjective and objective standpoint in these two fatigue forms. Seventy nine patients with relapsing remitting multiple sclerosis (RRMS) and 51 age-matched healthy controls (H) were analysed by means of the physical fatigue test (hand dynamometer) and an objective mental fatigue test (vigilance test from the computerised Test Battery for Attentional Performance). Furthermore, subjective tiredness caused by test procedures, subjective persisting tiredness (Modified Fatigue Impact Scale; MFIS: physical and cognitive scale) and mood (Beck Depression Inventory; BDI-18) were analysed.MS patients differed significantly from the controls in their objective physical and mental performance under fatigue, as well as in their subjective estimation of tiredness. MS patients showed an inverse relationship between below-average objective performance and high subjective feeling of tiredness when compared to controls. Subjectively severely tired MS patients achieved clearly poorer performances on the hand dynamometer test and slightly poorer performances on the vigilance test when compared to subjectively rarely tired MS patients. Depressed MS patients estimated their subjective tiredness in the MFIS significantly higher than non-depressed MS patients, but attained the same objective performance. This set of standardised tests enables meaningful comparisons between objective fatigue performance and subjective fatigue estimations in the physical and mental sphere and considers the influence of depression. Depression affects the subjective tiredness but not the objective fatigue performance.

Cognitive impairment in multiple sclerosis

Cognitive dysfunctions are frequent symptoms of multiple sclerosis (MS) and occur in up to 65% of patients. Especially memory, attention, executive and visual constructive functions are impaired. These problems strongly affect patients' ability to work, social relationships, and quality of life. Symptoms of physical disabilities can arise independently. Cognitive dysfunctions are clear indicators of MS progression, because they represent highly complex functions that depend on the integrity of the neuronal networks. Once manifested after a relapse, they remain stable . Given a differentiating diagnosis, it is possible to treat these dysfunctions by cognitive training and with pharmaceutical drugs, for example by immunomodulating drugs. However, treatment options are limited at present. This report provides a detailed description of cognitive functions and performance in MS patients, their comorbidities such as fatigue and depression and therapeutic options.

One-year follow-up study of relapsing-remitting MS patients' cognitive performances: Paced Auditory Serial Addition Test's susceptibility to change

To evaluate the progression of cognitive decline in multiple sclerosis (MS) patients and the susceptibility of the Multiple Sclerosis Functional Composite (MSFC) Paced Auditory Serial Addition Test (PASAT) to change, we conducted a 1-year follow-up with a comprehensive neuropsychological examination to 19 initially cognitively impaired and 26 cognitively intact relapsing-remitting MS patients, and to 48 healthy controls. The results indicated that the cognitive performance of MS patients remained relatively stable. Healthy controls tended to perform better on most neuropsychological measures at follow-up, the same was not observed in the MS groups. PASAT showed a significant difference between the groups: the cognitively impaired group tended to deteriorate, whereas the control group and the cognitively intact group improved. The change in PASAT could not be explained by the background variables, for example, mood, quality of life, or nervousness. Therefore, the MSFC-PASAT seems to be a sensitive measure to show clinical change in the cognitive status.