Motor and cognitive slowing in multiple sclerosis: An attentional deficit?

A novel tool for characterising upper limb function in progressive multiple sclerosis through kinematic assessment

INTRODUCTION

Current upper limb assessment methods in MS rely on measuring duration in tasks like the nine-hole peg test (9HPT). Kinematic techniques may provide a more useful measure of functional change in clinical and research practice. The aim of this study was to assess upper limb function prospectively in people with progressive MS using a kinematic 3D motion capture system and compare with current measures.

METHODS

42 people with progressive MS (PwPMS) and 15 healthy controls reached-and-grasped different objects whilst recorded by a kinematic assessment system. 9HPT, Expanded Disability Status Scale (EDSS), and patient reported outcome measures (PROs) were collected. All measures were taken at baseline for PwPMS and controls, and again at six months for PwPMS.

RESULTS

Relative to controls, PwPMS had significantly longer reaction (0.11 s, p < 0.05) and reach (0.25 s, p < 0.05) times. PwPMS took longer to pick-up (0.34 s, p < 0.05), move (0.14 s, p < 0.05), and place (0.18 s, p < 0.05) objects. PwPMS had lower peak velocities when reaching (7.4 cm/s, p < 0.05) and moving (7.3 cm/s, p < 0.05) objects. Kinematic assessment demonstrated consistent differences between PwPMS with mild and severe upper limb dysfunction as defined by PROs, which were not captured by 9HPT or EDSS in this group. PwPMS demonstrated altered grip apertures profiles, as measured by their ability to complete individual parts of the reach and grasp task, between the baseline and follow-up timepoints.

CONCLUSIONS

We have created and tested a novel upper limb function assessment tool which has detected changes and characteristics in hand function, not currently captured by the EDSS and 9HPT.

Auditory attention measured by EEG in neurological populations: systematic review of literature and meta-analysis

Sensorimotor synchronization strategies have been frequently used for gait rehabilitation in different neurological populations. Despite these positive effects on gait, attentional processes required to dynamically attend to the auditory stimuli needs elaboration. Here, we investigate auditory attention in neurological populations compared to healthy controls quantified by EEG recordings. Literature was systematically searched in databases PubMed and Web of Science. Inclusion criteria were investigation of auditory attention quantified by EEG recordings in neurological populations in cross-sectional studies. In total, 35 studies were included, including participants with Parkinson's disease (PD), stroke, Traumatic Brain Injury (TBI), Multiple Sclerosis (MS), Amyotrophic Lateral Sclerosis (ALS). A meta-analysis was performed on P3 amplitude and latency separately to look at the differences between neurological populations and healthy controls in terms of P3 amplitude and latency. Overall, neurological populations showed impairments in auditory processing in terms of magnitude and delay compared to healthy controls. Consideration of individual auditory processes and thereafter selecting and/or designing the auditory structure during sensorimotor synchronization paradigms in neurological physical rehabilitation is recommended.

Use of a physiological profile to document upper limb motor impairment in ageing and in neurological conditions

Profiling performance in the physiological domains underpinning upper limb function (such as strength, sensation, coordination) provides insight into an individual's specific impairments. This compliments the traditional medical 'diagnosis' model that is currently used in contemporary medicine. From an initial battery of 13 tests in which data were collected across the adult lifespan (n = 367, 20-95 years) and in those with neurological conditions (specifically, multiple sclerosis (n = 40), Parkinson's disease (n = 34), and stroke (n = 50)), six tests were selected to comprise a core upper limb physiological profile assessment (PPA). This comprised measures of handgrip strength, simple reaction time, finger dexterity, tactile sensation, bimanual coordination, and a functional task. Individual performance in each of these tests can be compared to a reference population score (devised from our database of healthy individuals aged under 60 years), informing the researcher or clinician how to best direct an intervention or treatment for the individual based on their specific impairment(s). Lastly, a composite score calculated from the average performance across the six tests provides a broad overview of an individual's overall upper limb function. Collectively, the upper limb PPA highlights specific impairments that are prevalent within distinct pathologies and reveals the magnitude of upper limb motor impairment specific to each condition.

Original articleQuantifying upper-limb motor impairment in people with multiple sclerosis: a physiological profiling approach

BACKGROUND

. Upper-limb sensory and motor impairments are common in people with multiple sclerosis (MS), yet the current gold standard criteria for documenting functional impairment largely focuses on mobility, balance and postural stability.

OBJECTIVE

. We aimed to determine the validity of the upper-limb Physiological Profile Assessment (PPA) in people with MS by investigating whether the included domains of muscle strength, dexterity, arm stability, position sense, skin sensation and bimanual coordination 1) are sensitive in differentiating people with MS from healthy controls and 2) correlate with a validated measure of upper-limb function and a scale for quantifying disability in MS.

METHODS

. In a cross-sectional study, 40 participants with MS and 80 healthy controls completed all 13 of the upper-limb PPA tests within a single session.

RESULTS

. People with MS were impaired across all physiological domains tested. Performance in 4 of the 13 tests was correlated with a validated measure of self-reported upper-limb function (Pearson's r or Spearman's rho -0.333-0.441), whereas 3 tests were associated with the degree of MS-specific disability (Spearman's rho -0.318; 0.456).

CONCLUSIONS

. The upper-limb PPA offers a valid and clinically suitable assessment of upper-limb function in people with MS. Clinicians should prioritise assessments of motor speed, fine motor control and functional tasks in their assessment of upper-limb function in people with MS because these domains are the most commonly and significantly impaired.

Identifying Perceptual, Motor, and Cognitive Components Contributing to Slowness of Information Processing in Multiple Sclerosis with and without Depressive Symptoms

Increasing findings suggest that different components of the stimulus-response pathway (perceptual, motor or cognitive) may account for slowed performance in Multiple Sclerosis (MS). It has also been reported that depressive symptoms (DS) exacerbate slowness in MS. However, no prior studies have explored the independent and joint impact of MS and DS on each of these components in a comprehensive manner. The objective of this work was to identify perceptual, motor, and cognitive components contributing to slowness in MS patients with and without DS. The study includes 33 Relapsing-Remitting MS patients with DS, 33 without DS, and 26 healthy controls. Five information processing components were isolated by means of ANCOVA analyses applied to five Reaction Time tasks. Perceptual, motor, and visual search components were slowed down in MS, as revealed by ANCOVA comparisons between patients without DS, and controls. Moreover, the compounding effect of MS and DS exacerbated deficits in the motor component, and slowed down the decisional component, as revealed by ANCOVA comparisons between patients with and without DS. DS seem to exacerbate slowness caused by MS in specific processing components. Identifying the effects of having MS and of having both MS and DS may have relevant implications when targeting cognitive and mood interventions.

Dysexecutive disorders and their diagnosis: A position paper

Although executive function disorders are among the most prevalent cognitive impairments a consensus on diagnostic criteria has yet to be reached. With a view to harmonizing these criteria, the present position paper (i) focuses on the main dysexecutive disorders, (ii) examines recent approaches in both the behavioral and cognitive domains, (iii) defines diagnostic boundaries for frontal syndrome, (iv) reports on the frequency and profile of the executive function disorders observed in the main brain diseases, and (v) proposes an operationalization of diagnostic criteria. Future work must define the executive processes involved in human adaptive behavior, characterize their impairment in brain diseases, and improve the management of these conditions (including remediation strategies and rehabilitation).

Interference Effect of Prior Explicit Information on Motor Sequence Learning in Relapsing-Remitting Multiple Sclerosis Patients

BACKGROUND

Multiple sclerosis (MS) is the most widespread disabling neurological condition in young adults around the world. The purpose of this study was to investigate the impact of explicit information (EI) on motor-sequence learning in MS patients.

METHODS

Thirty patients with relapsing-remitting MS (RRMS), age: 29.5 (SD = 5.6) years and 30 healthy gender-, age-, and education-matched control group participants, age: 28.8 (SD = 6.0) years, were recruited for this study. The participants in the healthy group were then randomly assigned into an EI (n = 15) group and a no-EI (n = 15) group. Similarly, the participants in the control group were then randomly assigned into EI (n = 15) and no-EI (n = 15) groups. The participants performed a serial reaction time (SRT) task and reaction times. A retention test was performed after 48 hours.

RESULTS

All participants reduced their reaction times across acquisition (MS group: 46.4 (SD = 3.3) minutes, P < 0.001, and healthy group: 39.4 (SD = 3.3) minutes, P < 0.001). The findings for the within-participants effect of repeated measures of time were significant (F_{(5.06, 283.7)} = 71.33. P < 0.001). These results indicate that the interaction between group and time was significant (F_{(5.06, 283.7)} = 6.44. P < 0.001), which indicated that the reaction time in both groups was significantly changed between the MS and healthy groups across times (B1 to B10). The main effect of the group (MS and healthy) (F_{(1, 56)} = 22.78. P < 0.001) and also the main effect of no-EI vs EI (F_{(1, 56)} = 4.71. P < 0.001) were significant.

CONCLUSION

This study demonstrated that that RRMS patients are capable of learning new skills, but the provision of EI prior to physical practice is deleterious to implicit learning. It is sufficient to educate MS patients on the aim and general content of the training and only to provide feedback at the end of the rehabilitative session.

The contribution of depressive symptoms to slowness of information processing in relapsing remitting multiple sclerosis

Background:

Slowness of information processing has been suggested as a fundamental factor modulating cognitive impairment in multiple sclerosis (MS). However, the contribution of depressive symptoms (DS) to slowness remains unclear. One of the most accepted hypotheses on the impact of depression on the general population suggests that depression interferes only with tasks requiring high cognitive demands. However, no studies have investigated if the same pattern occurs in MS.

Objective:

The aim of this study was to determine the profile of the contribution of DS to slowness.

Methods:

Four Reaction Time (RT) tasks requiring an increasing level of cognitive demands were administered to 35 relapsing remitting MS patients with DS, 33 MS patients without DS, 17 depressed non-MS patients and 27 controls.

Results:

MS patients without DS obtained longer RTs than controls in all the tasks. On the contrary, depressed non-MS patients were slower than controls only in the most demanding task. Finally, MS patients with DS were slower than MS patients without DS not only in the most demanding task but also in the task requiring a lower level of cognitive demands.

Conclusion:

The contribution of DS to slowness depends on the level of cognitive demands. However, its impact on MS is more deleterious than on the general population.

Effect of dual-task-induced uncertainty on gait biomechanics in patients with multiple sclerosis with 2-6.5 EDSS grade

The goal of this study was to assess the effect that uncertainty induced by dual task conditions has on reaction-response time parameters and gait patterns of patients with multiple sclerosis (MS) with a 2-6.5 EDSS grade. The study involved eleven patients - nine women and two men - diagnosed with multiple sclerosis (age, 48±10years; height, 1.65±0.1m; weight, 72±22kg) with capacity to walk five meters without any aid or assistance. We employed an intra-group repeated measures design. Each participant was asked to walk with and without task-related uncertainty. Reaction-response and gait cycle times, as well as center of mass (CM) dynamics were measured using three force plates synchronized with a video camera through an electronic device that also controlled the system of uncertainty. The results obtained reveal that uncertainty induced by dual tasking is related to a reduction in the mean stride length and mean displacement and horizontal velocity of the CM in patients with MS. The values obtained for CM parameters indicate that uncertainty affects balance, as compared to no-uncertainty situations. These results confirm the necessity of including controlled dual-task-induced uncertainty in physical training programs for MS patients.

Changes in Multidigit Synergies and Their Feed-Forward Adjustments in Multiple Sclerosis

The authors explored the changes in multidigit synergies in patients with multiple sclerosis (MS) within the framework of the uncontrolled manifold hypothesis. The specific hypotheses were that both synergy indices and anticipatory synergy adjustments prior to the initiation of a self-paced quick action would be diminished in the patients compared to age-matched controls. The MS patients and age-matched controls (n = 13 in both groups) performed one-finger and multifinger force production tasks involving both accurate steady-state force production and quick force pulses. The patients showed significantly lower maximal finger forces and a tendency toward slower force pulses. Enslaving was increased in MS, but only in the lateral fingers (index and little). Indices of multifinger synergies during steady-state force production were lower in MS, mainly due to the lower amount of intertrial variance that did not affect total force. Anticipatory synergy adjustments were significantly delayed in MS. The results show that MS leads to significant changes in multidigit synergies and feed-forward adjustments of the synergies prior to a quick action. The authors discuss possible contributions of subcortical structures to the impaired synergic control.

Measuring the Performance of Attention Networks with the Dalhousie Computerized Attention Battery (DalCAB): Methodology and Reliability in Healthy Adults

Attention is an important, multifaceted cognitive domain that has been linked to three distinct, yet interacting, networks: alerting, orienting, and executive control. The measurement of attention and deficits of attention within these networks is critical to the assessment of many neurological and psychiatric conditions in both research and clinical settings. The Dalhousie Computerized Attention Battery (DalCAB) was created to assess attentional functions related to the three attention networks using a range of tasks including: simple reaction time, go/no-go, choice reaction time, dual task, flanker, item and location working memory, and visual search. The current study provides preliminary normative data, test-retest reliability (intraclass correlations) and practice effects in DalCAB performance 24-h after baseline for healthy young adults (n = 96, 18-31 years). Performance on the DalCAB tasks demonstrated Good to Very Good test-retest reliability for mean reaction time, while accuracy and difference measures (e.g., switch costs, interference effects, and working memory load effects) were most reliable for tasks that require more extensive cognitive processing (e.g., choice reaction time, flanker, dual task, and conjunction search). Practice effects were common and pronounced at the 24-h interval. In addition, performance related to specific within-task parameters of the DalCAB sub-tests provides preliminary support for future formal assessment of the convergent validity of our interpretation of the DalCAB as a potential clinical and research assessment tool for measuring aspects of attention related to the alerting, orienting, and executive control networks.

Clinical and cognitive implications of cerebrospinal fluid oligoclonal bands in multiple sclerosis patients

The presence of cerebrospinal fluid oligoclonal bands (CSF-OCB) in Caucasian patients with multiple sclerosis (MS) is supportive of diagnosis, though the relation with patients' clinical and specifically cognitive features has never been established or thoroughly examined. Thus, we investigated the clinical and for the first time the cognitive profile of MS patients in relation to CSF-OCB. We studied 108 patients with and without OCB and recorded demographic characteristics and detailed clinical data. A comprehensive neuropsychological battery covering different cognitive domains (attention/processing speed, memory, perception/constructions, reasoning, executive functions) was administered to MS patients and 142 demographically related healthy controls (HC). We did not find any significant differences between patients with and without OCB on demographic and clinical parameters (p > 0.05), including subtype and brain neuroimaging findings. Results revealed significantly higher cognitive scores in HC compared to both OCB subgroups, with more widespread cognitive changes in patients with OCB. Analysis between OCB subgroups showed significantly worse performance in patients with OCB on visual memory (Rey's complex figure test-recall; p = 0.006). Concluding, the presence of CSF-OCB in our MS patients tends to be related to more widespread cognitive changes, specifically worse visual memory. Future longitudinal studies in different populations are warranted to better clarify the clinical and cognitive characteristics related to CSF-OCB which could serve as early biomarker in disease monitoring.

The neurocognitive profile of the cerebellum in multiple sclerosis

In recent years, a high number of studies have demonstrated that neuropsychological functions are altered in multiple sclerosis (MS) patients with cerebellar lesions, mainly including attention, working memory and verbal fluency. Since the present literature is often elusive on this topic, we aim to provide a comprehensive report about the real impact of cerebellar damages (evaluated as volume, lesions or connectivity measures) on cognitive functions. In particular in this review, we report and discuss recent works from 2009 to 2015, which have demonstrated the key role of the cerebellum in cognitive impairment of MS patients.

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.

Reduced Dual-Task Performance in MS Patients Is Further Decreased by Muscle Fatigue

BACKGROUND

Multiple sclerosis (MS) can be accompanied by motor, cognitive, and sensory impairments. Additionally, MS patients often report fatigue as one of their most debilitating symptoms. It is, therefore, expected that MS patients will have difficulties in performing cognitive-motor dual tasks (DTs), especially in a fatiguing condition.

OBJECTIVE

To determine whether MS patients are more challenged by a DT than controls in a fatiguing and less-fatiguing condition and whether DT performance is associated with perceived fatigue.

METHODS

A group of 19 MS patients and 19 age-, sex-, and education-matched controls performed a cognitive task (2-choice reaction time task) separately or concurrent with a low-force or a high-force motor task (index finger abduction at 10% or 30% maximal voluntary contraction).

RESULTS

MS patients performed less well on a cognitive task than controls. Cognitive task performance under DT conditions decreased more for MS patients. Moreover, under high-force DT conditions, cognitive performance declined in both groups but to a larger degree for MS patients. Besides a decline in cognitive task performance, MS patients also showed a stronger decrease in motor performance under high-force DT conditions. DT costs were positively related to perceived fatigue as measured by questionnaires.

CONCLUSIONS

Compared with controls, MS patients performed less well on DTs as demonstrated by a reduction in both cognitive and motor performances. This performance decrease was stronger under fatiguing conditions and was related to the sense of fatigue of MS patients. These data illustrate problems that MS patients may encounter in daily life because of their fatigue.

Walking execution is not affected by divided attention in patients with multiple sclerosis with no disability, but there is a motor planning impairment

Purpose: We analysed the cognitive influence on walking in multiple sclerosis (MS) patients, in the absence of clinical disability. Method: A case-control study was conducted with 12 MS patients with no disability and 12 matched healthy controls. Subjects were referred for completion a timed walk test of 10 m and a 3D-kinematic analysis. Participants were instructed to walk at a comfortable speed in a dual-task (arithmetic task) condition, and motor planning was measured by mental chronometry. Results: Scores of walking speed and cadence showed no statistically significant differences between the groups in the three conditions. The dual-task condition showed an increase in the double support duration in both groups. Motor imagery analysis showed statistically significant differences between real and imagined walking in patients. Conclusion: MS patients with no disability did not show any influence of divided attention on walking execution. However, motor planning was overestimated as compared with real walking.

Compromised motor imagery ability in individuals with multiple sclerosis and mild physical disability: an ERP study

BACKGROUND

Motor imagery (MI) impairment has been reported in individuals with multiple sclerosis (MS). The present study was designed to investigate neural evidence for MI impairment and its relationship to working memory in MS patients.

METHODS

The study participants included 24 early stage MS patients (age: 22-40/mean=32.7 years; M/F=4/20; years since duration: 1-10/mean=5.8) and 24 age-, gender-, and education-matched controls (age: 21-40/mean=31.8 years; M/F=5/19). Event-related potentials were recorded during a mental hand rotation task, in which participants were instructed to judge the laterality of hands displayed in different orientations. Furthermore, the Paced Auditory Serial Addition Test (PASAT) was used for assessment of working memory.

RESULTS

At the behavioral level, MS patients were significantly less accurate and much slower (accuracy: 83.80 ± 7.72%; reaction time: 1665.95 ± 269.82 ms) than controls (accuracy: 88.35 ± 7.68%; reaction time: 1505.16 ± 225.11 ms). At the neural level, MS patients showed a significantly reduced amplitude (MS: 0.99 ± 0.89 μv, controls: 1.46 ± 1.00 μv) and delayed peak latency (MS: 458.45 ± 67.60 ms, controls: 417.91 ± 62.47 ms) at P3 for mental rotation effect. Moreover, there were significant correlations between individuals' PASAT scores and performance of the hand rotation task.

CONCLUSION

The results of the present study demonstrate MI impairment in patients with MS at both the behavioral and neural level. Neuronal activity dysfunction (decreased and delayed activity) in patients with MS provides new insights into MI impairment. Furthermore, our findings suggest the contribution of working memory dysfunction to compromised MI ability in patients with MS.

Cognitive rehabilitation in multiple sclerosis

Cognitive impairments are frequent in multiple sclerosis (MS). However, most studies about efficacy of cognitive rehabilitation interventions have been criticized in terms of methods and/or design. The aim of this study is to evaluate the efficacy of cognitive rehabilitation in MS patients with a cognitive intervention (ProCogSEP* program), compared to a control intervention (discussion program). Twenty MS patients have completed this simple blind study: 10 patients followed 13 sessions (2 hours) of the ProCog-SEP(1) program. Ten other patients followed 13 sessions (2 hours) of a discussion program (Control Group). All patients underwent neuropsychological assessment, before and after their program, in order to evaluate cognitive functions. Two neuropsychologists respectively assessed the patients and conducted the group sessions. Compared to its own baseline, ProCog-SEP Group show improvements in verbal memory [free recall (p = .02), learning (p = .002)], in visual memory [free (p = .05) and delayed recall (p = .007)], in working-memory (p = .03), in verbal fluency (p = .05) and in language (p = .01). Inter group analysis show a benefit of cognitive program mainly in verbal and visual memory, and in verbal fluencies. These results support the interest of a cognitive therapeutic management of MS patients.