Task-dependent deterioration of balance underpinning cognitive-postural interference in MS

Effect of Explicit Prioritization on Dual Tasks During Standing and Walking in People With Neurologic and Neurocognitive Disorders: A Systematic Review and Meta-analysis

OBJECTIVES

To examine the effectiveness of explicit task (ie, equal, motor or cognitive) prioritization during dual tasking (DT) in adults with neurologic and neurocognitive disorders (stroke, Parkinson disease [PD], multiple sclerosis, dementia, Alzheimer disease, and mild cognitive impairment).

DATA SOURCE

A systematic search in 4 databases (PubMed, Web of Science, Embase, and Cochrane Central) yielded 1138 unique studies published up to 2023.

STUDY SELECTION

Forty-one experimental studies were selected that assessed the effect of explicit prioritization instructions on both motor and cognitive performance during dual-tasks related to standing and walking in selected populations. Primary outcome measures were walking speed and response accuracy. Availability of data allowed us to perform a meta-analysis on 27 of the 41 articles by using inverse variance with a random effects model.

DATA EXTRACTION

The data including design, subject characteristics, motor and cognitive tasks, prioritization, motor and cognitive outcomes, instructions, and key findings were extracted. Two assessors rated the selected studies for risk of bias and quality using the Quality Assessment Tools of the National Institutes of Health.

DATA SYNTHESIS

This study examined 1535 adults who were asked to perform motor-cognitive DT in standing or walking, including 381 adults with stroke, 526 with PD, 617 with multiple sclerosis, 10 with dementia, 9 with Alzheimer disease, and 8 with mild cognitive impairment. During all prioritization instructions, participants slowed down during DT (standardized mean difference (SMD)equal=0.43; SMDmotor=0.78; SMDcognitive=0.69, P<.03) while maintaining similar response accuracy (SMDequal=0.12; SMDmotor=0.23; SMDcognitive=-.01, P>.05). However, considerable between-group heterogeneity was observed resulting in different motor and cognitive responses between pathologies.

CONCLUSION

Motor prioritization was achieved in adults with PD and stroke, unlike adults with neurocognitive disorders who were negatively affected by any type DT prioritizing. The reported within-group heterogeneity revealed that effects of explicit task prioritization are dependent on motor and cognitive task complexity, and the type of instructions. Recommendations are provided to ensure accurate use of instructions during DT paradigms.

Fatigue may improve equally after balance and endurance training in multiple sclerosis: a randomised, crossover clinical trial

Introduction

Fatigue and poor balance are frequent and severe problems in multiple sclerosis (MS) that may interact. Endurance training is known to be effective on fatigue. This study aims to test if balance training is more effective against MS fatigue.

Methods

A randomised crossover trial was run, recruiting 31 MS people (21 women; median age: 46 years, range: 30-64; median EDSS: 4, range: 2.5-5). Participants received balance and endurance training alternately (15 one-to-one sessions, 5 days/week) and were assessed before (T0), after (T1), and 30 days after treatment ended (T2). The Modified Fatigue Impact Scale (MFIS) with scores linearised through Rasch analysis was the primary outcome (the lower the measure, the better the condition, i.e., the lower the fatigue symptoms). The Equiscale balance scale and posturography (EquiTest) were used to assess balance. Linear mixed-effects models with ANOVA were used for significance testing.

Results

Thirteen participants had no carryover effect and were included in the primary analysis. Fatigue significantly changed across the three time points (F2,58 = 16.0; p < 0.001), but no difference across treatments was found. Altogether, both treatments significantly improved the MFIS measure at T1 (95%CI: -1.24 logits; mean: -1.67 to -0.81 logits) and T2 (95%CI: -1.04; mean: -1.49 to -0.60) compared to T0 (95%CI: -0.51; mean: -0.95 to -0.08; p ≤ 0.001). Equiscale and posturography highlighted balance improvement after balance training but not after endurance training.

Conclusion

Balance and endurance training could similarly reduce fatigue in MS patients in the short term. However, only balance training also improved balance in MS.

Brain and cognitive reserve mitigate balance dysfunction in multiple sclerosis

BACKGROUND

Approximately two-thirds of patients with multiple sclerosis (MS) complain different degrees of balance dysfunction, but some of them are able to withstand considerable disease burden without an overt balance impairment. Here, we tested the hypothesis that brain and cognitive reserve lessen the effect of MS-related tissue damage on balance control.

METHODS

We measured the postural sway of 148 patients and 74 sex- and age-matched healthy controls by force platform under different conditions reflecting diverse neuro-pathological substrates of balance dysfunction: eyes opened (EO), eyes closed (EC), and while performing the Stroop test, i.e., dual-task (DT). Lesion volumes on T2-hyperintense and T1-hypointense sequences, and normalized brain volume provided estimations of MS-related tissue damage in patients with MS. Hierarchical linear regressions explored the protective effect against the MS-related tissue damage of intracranial volume and educational attainment (proxies for brain and cognitive reserve, respectively) on balance.

RESULTS

Larger intracranial volume and high educational attainment mitigated the detrimental effect of MS-related tissue damage on postural sway under EO (adjusted-R2=0.20 and 0.27, respectively, p<0.01) and DT (adjusted-R2=0.22 and 0.30, respectively, p<0.06) conditions. Neither educational level nor brain size was associated with postural sway under EC condition.

CONCLUSION

Our findings suggest a protective role of brain and cognitive reserve even on balance, an outcome that relies on both motor control and higher order processing resources. The lack of a protective effect on postural sway under EC condition confirms that this latter outcome is closer associated with spinal cord rather than brain damage.

Evaluation of mild-to-moderate COVID-19 through dual-task paradigm: a longitudinal case-controlled study

INTRODUCTION

Coronavirus disease (COVID-19) was associated with cognitive alterations affecting everyday life activities. These need input integration of both motor and cognitive systems. The study aim is to evaluate cognitive-motor interference phenomenon in previously independent patients with mild-to-moderate COVID-19 (PwMCOVID-19) compared with healthy controls (HC), through dual-task (DT) paradigm.

METHODS

PwMCOVID-19 were included if being independent at home, had no previous referred cognitive impairment, mechanical ventilation or oxygen need. They were assessed at admission and after 6 months with a motor-cognitive DT test (counting backward by twos while walking 2 min). HC were enrolled as control group. Differences between single-task (ST) and DT performance, DT effect (DTE) and task prioritization amongst groups and during time points were analyzed.

RESULTS

One-hundred PwMCOVID-19 [mean age=67.32(12.08) years; 53 M/47 F] and 39 HC [mean age=63.11(9.90) years; 20 M/19 F] were recruited. Upon T0, PwMCOVID-19 showed lower cognitive and motor DT performances than ST and HC. Mutual interference pattern was predominant in PwMCOVID-19. At T1, 41 PwMCOVID-19 were examined [mean age=64.85(10.75); 22 M/19 F]. They had a worse DT performance compared to ST, although DT improved at T1. A stronger cognitive ST-DT difference was present at T0, compared to ST-DT difference at T1, while motor ST-DT difference was unchanged over time in PwCOVID-19.

CONCLUSION

In PwMCOVID-19, there is an impairment of DT counting while walking at baseline and after 6 months from hospitalization, with a more pronounced DT mutual interference pattern at T0. After 6 months, the motor and cognitive ST and DT performances ameliorated, not reaching the HC level.

Fall risk is related to cognitive functioning in ambulatory multiple sclerosis patients

BACKGROUND AND AIMS

Patients with multiple sclerosis (PwMS) may suffer severely from falling and gait disturbance. Cognitive dysfunction, a common condition in MS patients, may also increase falling rates, regardless of physical disability. We planned this study to determine the fall rate and risk factors in MS patients, follow patients for falls, and reveal the relationship between falls and cognitive dysfunction.

METHODS

The study was conducted on 124 patients who have RRMS diagnoses. Patients' gait speed, simultaneous gait speed during other tasks, functions of the upper extremity, balance rating, and fear of falling were evaluated with dual-task Timed-Up-and-Go-3 versions (TUG, TUG-C, TUG-M), Timed 25 Foot Walk (T25WFT), Nine Hole Peg Test (9HPT), Berg Balance Scale (BBS) and Falls Efficacy Scale-International (FES-I) tests. Cognitive functions, fatigue levels, and quality of life were measured with the Symbol Digit Modalities Test (SDMT), Fatigue Severity Scale (FSS), and Multiple Sclerosis Quality of Life (MSQoL) test. Two groups were formed as "fallers" and "non-faller patients". We monitored the patients in six months period.

RESULTS

Forty-six patients fell at least once in the last one year before the study began. Fallers were older, less educated, had lower SDMT scores and higher disability scores. Non-faller patients scored lower in FES-I, TUG, and FSS tests. SDMT scores showed statistically significant, linear, positive, and moderate correlation with BBS and 9HPT scores (r = 0.307, p = 0.038, and r = 0.320, p = 0.030, respectively).

CONCLUSION

We determined that advanced age, lower education level, and cognitive dysfunction adversely affect gait speed and balance. Among the fallers, those with lower SDMT and MoCA scores had higher falling rates. We determined that EDSS and BBS scores are predictive factors for falls in patients with MS. In conclusion, patients with cognitive impairment should be closely monitored for the risk of falling. Consideration of falls during follow-up examinations might be predictive of cognitive deterioration in patients with MS.

Cognitive-motor interference during standing stance across different postural and cognitive tasks in individuals with Down syndrome

BACKGROUND

Individuals with Down syndrome (DS) presented both cognitive and motor impairments that could influence each other. Therefore, exploring cognitive-motor interference during standing stance is relevant in this population.

AIMS

This study explored the dual task (DT) effects on postural balance during diverse cognitive tasks and sensory manipulations in individuals with DS, compared to those with typical development (TD).

METHODS AND PROCEDURES

Fifteen adolescents with DS (age = 14.26 ± 1.27 years; height = 1.50 ± 0.02; weight = 46.46 ± 4.03 kg; BMI =20.54 ± 1.51 kg/m²) and thirteen with TD (age = 14.07 ± 1.11 years; height = 1.50 ± 0.05; weight = 44.92 ± 4.15 kg; BMI =19.77 ± 0.94 kg/m²) participated in this study. Postural and cognitive performances for the selective span task (SST) and the verbal fluency (VF) were recorded during single task (ST) and DT conditions. Postural conditions were: firm eyes open (firm-EO), firm eyes closed (firm-EC) and foam-EO. Motor and cognitive DT costs (DTC) were calculated and analyzed across these different cognitive and postural conditions.

OUTCOMES AND RESULTS

In the DS group, postural performance was significantly (p < 0.001) altered during all DT conditions, compared to the ST situation. Moreover, the motor DTC was significantly (p < 0.001) higher while performing the VF task than the SST. However, in the control group, postural performance was significantly (p < 0.001) impaired only while performing the VF test in the DT-Firm EO condition. For both groups, cognitive performances were significantly (p < 0.05) altered in all DT conditions compared to the ST one.

CONCLUSION

Adolescents with DS are more prone to DT effects on postural balance than those with TD.

The association between cognition and gait disturbance in central nervous system demyelinating disorder with mild disability

INTRODUCTION

Gait disturbance in central nervous system (CNS) demyelinating disorders, including multiple sclerosis (MS) and neuromyelitis optica (NMO) is one of the most troublesome problems that has a direct impact on the quality of life. However, the associations between gait disturbance and other clinical variables of these two diseases have not been fully elucidated.

OBJECTIVE

This study aimed to evaluate gait disturbance using a computerized gait analysis system and its association with various clinical variables in patients with MS and NMO.

METHODS

A total of 33 patients (14 with MS and 19 with NMO) with minor disabilities, who were able to walk independently and had passed their acute phase, were enrolled in the study. Gait analysis were performed using a computer-based instrumented walkway system. (Walk-way MG-1000, Anima, Japan) Clinical variables, such as disease duration, medication, body mass index (BMI), hand grip power, and muscle mass were recorded. The Montreal Cognitive Assessment (MOCA), Beck Depression Inventory score-II (BDI), and fatigue scale were measured using the Functional Assessment of Chronic Illness Therapy-fatigue scale (FACIT-fatigue) scale. A trained neurologist scored the Expanded Disability Status Scale (EDSS).

RESULTS

Gait speed was the single parameter that showed a significant positive correlation with MOCA (p < 0.001). The stance phase time was the single parameter that showed a significant negative correlation with EDSS (p < 0.001). Hand grip strength showed a significant positive correlation with skeletal muscle mass as assessed by bioimpedance analysis (p < 0.05). The FACIT-fatigue scale score showed a significant negative correlation with the BDI (p < 0.001).

CONCLUSION

In our patients with MS/NMO with mild disability, cognitive impairment was significantly correlated with gait speed, and the degree of disability was significantly correlated with stance phase time. Our findings may imply that early detection of a decrease in gait speed and an increase in stance phase time can predict the progression of cognitive impairment in patients with MS/NMO with mild disability.

Cognition and proprioception in persons with multiple sclerosis and healthy controls: Nascent findings

BACKGROUND

Although proprioception and cognitive dysfunction are commonly associated with balance impairment and fall risk in persons with multiple sclerosis (MS), the relationship between cognitive functioning and a quantitative measure of proprioception has not been examined in MS.

OBJECTIVE

The primary goals of this study were to determine differences in vibratory sensation, a proxy measure of proprioception between persons with MS and healthy controls, examine relationships between cognition and vibration sensation, and determine the contribution of cognitive function and demographics to vibratory sensation between persons with MS and healthy controls.

METHODS

One hundred and twenty-two individuals with MS, aged 20-60, with Expanded Disability Status Scale (EDSS) scores ≤5.5 and 48 healthy controls completed reaction time testing, the Stroop test and lower extremity vibratory sensation.

RESULTS

Persons with MS performed significantly worse than controls on measures of vibratory sensation (p = 0.001), two-choice reaction time (p = 0.018), and Stroop Incongruent (p < 0.001) Relative Incongruent Score (RIS) (p = 0.047). In MS, average vibration was significantly related to age (p = 0.002), sex (p = 0.038), disease severity (EDSS; p < 0.001), years since diagnosis (p = 0.016), and Stroop Word (p = 0.041). A model with demographics; including age and disease severity, two-choice reaction time, and RIS explained 33.2% of the variance vibratory sensation in persons with MS.

CONCLUSIONS

These results provide early evidence for the relation between cognitive functioning and proprioception in persons with MS and add to prior work linking cognitive functioning, postural control and falls in persons with MS. This work provides a basis for future studies combining quantitative measures of proprioception and cognitive and postural control assessment to improve fall prediction.

RObotic-Assisted Rehabilitation for balance and gait in Stroke patients (ROAR-S): study protocol for a preliminary randomized controlled trial

Background

Stroke, the incidence of which increases with age, has a negative impact on motor and cognitive performance, quality of life, and the independence of the person and his or her family, leading to a number of direct and indirect costs. Motor recovery is essential, especially in elderly patients, to enable the patient to be independent in activities of daily living and to prevent falls. Several studies have shown how robotic training associated with physical therapy influenced functional and motor outcomes of walking after stroke by improving endurance and walking strategies.

Considering data from previous studies and patients’ needs in gait and balance control, we hypothesized that robot-assisted balance treatment associated with physical therapy may be more effective than usual therapy performed by a physical therapist in terms of improving static, dynamic balance and gait, on fatigue and cognitive performance.

Methods

This is an interventional, single-blinded, preliminary randomized control trial. Twenty-four patients of both sexes will be recruited, evaluated, and treated at the UOC Rehabilitation and Physical Medicine, Fondazione Policlinico Universitario A. Gemelli IRCCS in Rome from January to December 2022. Patients will be randomized into two groups: the experimental group will perform specific rehabilitation for balance disorder using the Hunova® robotic platform (Movendo Technology srl, Genoa, IT) for 3 times a week, for 4 weeks (12 total sessions), and for 45 min of treatment, in addition to conventional treatment, while the conventional group (GC) will perform only conventional treatment as per daily routine. All patients will undergo clinical and instrumental evaluation at the beginning and end of the 4 weeks of treatment.

Conclusions

The study aims to evaluate the improvement in balance, fatigue, quality of life, and motor and cognitive performance after combined conventional and robotic balance treatment with Hunova® (Movendo Technology srl, Genoa, IT) compared with conventional therapy alone. Robotic assessment to identify the most appropriate and individualized rehabilitation treatment may allow reducing disability and improving quality of life in the frail population. This would reduce direct and indirect social costs of care and treatment for the National Health Service and caregivers.

Trial registration

ClinicalTrials.gov NCT05280587. Registered on March 15, 2022.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06812-w.

Cognitive-motor interference in people with mild to moderate multiple sclerosis, in comparison with healthy controls

BACKGROUND

Reduced motor and cognitive dual-task capacity is found to be more common among people with multiple sclerosis (MS), than among healthy populations. However, studies in larger samples of MS conducted using a more stringent methodology, which includes comparisons to healthy controls, are needed. Thus, the primary aim of this study was to explore the effects on motor and cognitive dual-tasking in people with mild to moderate overall MS-disability, in comparison to healthy controls. A second aim was to explore the differences in dual-task performance on a cognitive task between two motor tasks in people with mild to moderate MS and healthy controls.

METHODS

This case-control study evaluated dual-task performance of the motor tasks standing with eyes closed (hereafter standing) and walking and a cognitive task assessing selective executive functions (auditory-Stroop test). Fifty-five people with MS (mild MS, n = 28; moderate MS, n = 27), and 30 healthy controls participated. Standing and walking were assessed using wireless inertial measurement unit sensors (APDM). Standing (three 30 s trials) was measured using sway area and root mean square sway, while walking (2 min) was measured using speed, stride length, and step time. Auditory-Stroop was measured using accuracy and response time. During dual-task assessments, each subject was instructed to pay equal attention to both tasks. Statistical significance was considered if p < .05.

RESULTS

Instanding no significant within-group differences in the standing measures were found between single-task and dual-task performance. However, dual-task performance differed significantly between all groups (moderate MS > mild MS > healthy controls), except between mild and moderate MS in sway area. Inwalking, all groups slowed down speed and shortened stride length during dual-task condition compared to single-task condition. Moderate MS performed significantly poorer than mild MS and healthy controls in dual-task walking, but mild MS did not differ from healthy controls. In thecognitivetask only mild MS increased significantly in auditory-Stroop response time during walking. In healthy controls, the performance of auditory-Stroop was not affected by dual-tasking. Moderate MS had significantly longer response time in dual-task auditory-Stroop compared to the other groups, but no differences were observed between mild MS and healthy controls. Only mild MS had significantly longer response time during walking than during standing.

CONCLUSION

This study showed that cognitive-motor interference in people with MS is present also in the early phases of the disease. This was shown during dual-tasking with slower walking and a longer response time in the cognitive task compared to healthy controls. Moderate MS performed poorer in almost every aspect of the motor and cognitive assessments in dual-task condition, compared to mild MS and healthy controls. Furthermore, during standing, people with MS performed poorer in standing measures compared to healthy controls. Additionally, healthy controls showed no cognitive interference during motor tasks. The results suggest that standardized regular assessment of dual-tasking in MS care might increase the individual's knowledge of dual-task capacity and contribute to understanding of possible related consequences. However, feasible assessment equipment and specific motor-cognitive dual-task training interventions for people with MS need to be developed.

Comparing the effects of cognitive dual tasking on balance and gait motor performance in people with mild multiple sclerosis and healthy individuals

Background/Aims

People with multiple sclerosis show both cognitive and postural impairment, and various static and dynamic postural activities may be affected under conditions of cognitive distraction. The aim of this study was to determine the effects of cognitive dual tasking on the balance and gait motor performance of people with mild multiple sclerosis (Expanded Disability Status Scale score of 2.0 ± 1.3) and healthy people and to compare these two groups in terms of performing single and dual tasks.

Methods

People with mild multiple sclerosis (n=39) and healthy individuals (n=33) performed static balance tests (Romberg's Test, tandem stance test, single-legged stance test) and dynamic balance tests (Functional Reach Test, Four Square Step Test, Timed Up and Go Test, 10-Metre Walk Test), with and without a word list generation test (single and dual tasks). Independent t-tests were used to evaluate differences between the two groups, and paired t-tests were used for single or dual tasks for all static and dynamic tests. The magnitude of differences in tasks between measures was expressed as Cohen's d.

Results

Dual task effects were more evident during dynamic balance tests in participants with multiple sclerosis and healthy participants (specifically the Timed Up and Go Test and 10-Metre Walk Test) (P<0.001). There was a significant difference between both groups only in terms of static balance (P<0.001).

Conclusions

Dynamic balance and gait were shown to be more affected when performing the dual cognitive task than static balance in people with multiple sclerosis. Dual tasks should be included in diagnoses.

2BALANCE: Test-retest reliability of a cognitive-motor dual-task protocol

PURPOSE

Aside from typical symptoms such as dizziness and vertigo, persons with vestibular disorders often have cognitive and motor problems. These symptoms have been assessed in single-task condition. However, dual-tasks assessing cognitive-motor interference might be an added value as they reflect daily life situations better. Therefore, the 2BALANCE protocol was developed. In the current study, the test-retest reliability of this protocol was assessed.

METHODS

The 2BALANCE protocol was performed twice in 20 healthy young adults with an in-between test interval of two weeks. Two motor tasks and five different cognitive tasks were performed in single and dual-task condition. Intraclass correlation coefficients (ICC), the standard error of measurement, and the minimal detectable difference were calculated.

RESULTS

All cognitive tasks, with the exception of the mental rotation task, had favorable reliability results (0.26≤ICC≤0.91). The dynamic motor task indicated overall substantial reliability values in all conditions (0.67≤ICC≤0.98). Similar results were found for the static motor task during dual-tasking (0.50≤ICC≤0.92), but were slightly lower in single-task condition (-0.26≤ICC≤0.75).

CONCLUSIONS

The 2BALANCE protocol was overall consistent across trials. However, the mental rotation task showed lowest reliability values.

The Relationship between Cognitive Dysfunction and Postural Stability in Multiple Sclerosis

Background and Objectives: Multiple Sclerosis (MS) is a demyelinating disease of the central nervous system (CNS), most commonly characterized by balance dysfunction, fatigue syndrome and cognitive impairment. The goal of our study was to determine the association between cognitive functions and static posture control. Materials and Methods: The research group consisted of 76 randomized MS patients (ICDG 35.0) hospitalized at the Neurological Rehabilitation Clinic of the Medical University of Lodz. This group was divided into three subgroups according to the cognitive assessment based on the Mini Mental State Examination (MMSE) for patients over 65 years of age and the Montreal Cognitive Assessment (MoCA) under the age of 65. Fatigue syndrome was assessed using the Fatigue Severity Scale (FSS), and postural stability using a stabilometric platform. Results: The men demonstrated poorer stabilometric platform measurements than the women. Statistically significant differences were observed between patients without dysfunction and severe cognitive impairment. The results of the stabilometric platform were found to correlate with body mass index in all three groups of patients (Spearman’s test). Conclusions: Body mass index and cognition have impact on postural stability in MS patients with moderate disability and fatigue syndrome.

Psychometric Properties of Cognitive-Motor Dual-Task Studies With the Aim of Developing a Test Protocol for Persons With Vestibular Disorders: A Systematic Review

OBJECTIVES

Patients suffering from vestibular disorders (VD) often present with impairments in cognitive domains such as visuospatial ability, memory, executive function, attention, and processing speed. These symptoms can be attributed to extensive vestibular projections throughout the cerebral cortex and subcortex on the one hand, and to increased cognitive-motor interference (CMI) on the other hand. CMI can be assessed by performing cognitive-motor dual-tasks (DTs). The existing literature on this topic is scarce and varies greatly when it comes to test protocol, type and degree of vestibular impairment, and outcome. To develop a reliable and sensitive test protocol for VD patients, an overview of the existing reliability and validity studies on DT paradigms will be given in a variety of populations, such as dementia, multiple sclerosis, Parkinson's disease, stroke, and elderly.

DESIGN

The systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. An extensive literature search on psychometric properties of cognitive-motor DTs was run on MEDLINE, Embase, and Cochrane Databases. The studies were assessed for eligibility by two independent researchers, and their methodological quality was subsequently evaluated using the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN).

RESULTS AND CONCLUSIONS

Thirty-three studies were included in the current review. Based on the reliability and validity calculations, including a static as well as dynamic motor task seems valuable in a DT protocol for VD patients. To evoke CMI maximally in this population, both motor tasks should be performed while challenging the vestibular cognitive domains. Out of the large amount of cognitive tasks employed in DT studies, a clear selection for each of these domains, except for visuospatial abilities, could be made based on this review. The use of the suggested DTs will give a more accurate and daily life representation of cognitive and motor deficiencies and their interaction in the VD population.

Characteristics of improvements in balance control using vibro-tactile biofeedback of trunk sway for multiple sclerosis patients

BACKGROUND AND AIMS

Previously, we determined that training with vibrotactile feedback (VTfb) of trunk sway improves MS patients' balance impairment. Here, we posed 5 questions: 1) How many weeks of VTfb training are required to obtain the best short-term carry over effect (CoE) with VTfb? 2) How long does the CoE last once VTfb training terminates? 3) Is the benefit similar for stance and gait? 4) Is position or velocity based VTfb more effective in reducing trunk sway? 5) Do patients' subjective assessments of balance control improve?

METHODS

Balance control of 16 MS patients was measured with gyroscopes at the lower trunk. The gyroscopes drove directionally active VTfb in a head-band. Patients trained twice per week with VTfb for 4 weeks to determine when balance control with and without VTfb stopped improving. Thereafter, weekly assessments without VTfb over 4 weeks and at 6 months determined when CoEs ended.

RESULTS

A 20% improvement in balance to normal levels occurred with VTfb. Short term CoEs improved from 15 to 20% (p ≤ 0.001). Medium term (1-4 weeks) CoEs were constant at 19% (p ≤ 0.001). At 6 months improvement was not significant, 9%. Most improvement was for lateral sway. Equal improvement occurred when angle position or velocity drove VTfb. Subjectively, balance improvements peaked after 3 weeks of training (32%, p ≤ 0.05).

CONCLUSIONS

3-4 weeks VTfb training yields clinically relevant sway reductions and subjective improvements for MS patients during stance and gait. The CoEs lasted at least 1 month. Velocity-based VTfb was equally effective as position-based VTfb.

Compensatory image of the stability of people with multiple sclerosis and atrial vertigo based on posturography examination

Pathophysiology of balance disorders due to multiple sclerosis (MS) and atrial vertigo (AV) is different. We evaluated posture stability when maintaining balance in people with MS presenting symptoms of ataxia and those with AV. We included 45 women (15 with MS; 15 with AV; 15 controls). A posturography platform was used to measure balance parameters. To characterize the image of stability and the compensation of balance disorders, the surface area of the stabilogram (SAS), vision control index (VCI) and the vision-motion control index (VMCI) were used. The stability image of people with MS and AV with eyes open (p = 0.002), with eyes closed (p = 0.080) and with visual biofeedback (p = 0.0008) differed significantly. SAS depended on visual biofeedback regardless of the occurrence of balance disorders and was the basis for determining the compensatory share of vision-motor coordination. Differences in VCI between groups were insignificant. VMCI was significantly higher in people with balance disorders than in those without, but similar in the MS and AV groups. The image of stability is different in people with MS and AV. Thanks to visual biofeedback, it becomes possible to launch effective vision-motor coordination when compensating balance disorders. VCI may become the measure of compensation for balance disorders.

Differential effects and discriminative validity of motor and cognitive tasks varying in difficulty on cognitive-motor interference in persons with multiple sclerosis

BACKGROUND

Cognitive-motor interference (CMI) has been well recognized in persons with multiple sclerosis (pwMS); however, there are limited data on effects of task difficulty.

OBJECTIVE

Examine (1) the effects of motor and cognitive tasks varying in difficulty on the magnitude of CMI and (2) the discriminative validity of CMI between pwMS and healthy controls (HC).

METHODS

Nine cognitive-motor dual-task (DT) conditions (combinations of three cognitive and three walking tasks) were examined. Outcome measures were DT-performance and dual-task cost (DTC) of gait parameters and correct answers. Task differences and overall group-effects were analysed by mixed model analysis, plus the Wilcoxon signed-rank tests or multivariate analysis of variances (MANOVAs), respectively.

RESULTS

Task effects were examined in 82 pwMS (Expanded Disability Status Scale (EDSS): 3.3 ± 1.0) and discriminative validity in a subsample (35 pwMS and 33 HC). Motor-DTC and DT-performance were affected by difficulty of both the cognitive task (p < 0.001) and the walking condition (p ⩽ 0.002), while cognitive-DTC only varied between cognitive tasks with a large difference in difficulty (p ⩽ 0.005) and not between walking conditions (p ⩾ 0.125). None of the DTCs differed between groups.

CONCLUSION

CMI, and especially motor performance, is affected by difficulty of the DT. Although pwMS performed worse on the tasks than HC, none of the DT-conditions showed a discriminative DTC.

Dual-Task Cost and Related Clinical Features in Patients With Multiple Sclerosis

This study aimed to investigate the dual-task cost of both motor and cognitive performances in patients with multiple sclerosis (PwMS) and in healthy controls and to determine their relationships with clinical features in PwMS. The participants performed motor tasks (postural stability, walking, and manual dexterity) and cognitive tasks (mental tracking and verbal fluency) under single- and dual-task conditions. The results showed that postural stability under dual-task conditions did not change, whereas walking and manual dexterity deteriorated, regardless of the concurrent cognitive task, in PwMS (median Expanded Disability Status Scale score: 1) and the healthy controls. Verbal fluency decreased during postural stability, whereas it increased during walking, and it was maintained during manual dexterity in both groups. Mental tracking did not change during walking; it declined during manual dexterity in both groups. Mental tracking during postural stability deteriorated in PwMS, while it did not change in the healthy controls. In general, dual-task costs were associated with baseline performances of tasks rather than clinical features. Therefore, baseline performances of both tasks should be increased for improving dual-task performance in PwMS.

'Posture second' strategy predicts disability progression in multiple sclerosis

We assessed 168 patients with multiple sclerosis (MS) by force platform to obtain the dual-task cost (DTC) of balance, that is, the change in postural sway from quiet standing to dual-task condition (Stroop test). After a median follow-up time of 3.5 years from this assessment, disability progression occurred in 45 (27%) patients. Disability progression was predicted by the adoption of a 'posture second' strategy, that is, values of DTC of balance exceeding those obtained from 62 healthy controls, even after controlling by demographic and clinical characteristics. The DTC of balance may potentially represent a novel and easy tool to predict MS progression.

Dual tasking impairments are associated with striatal pathology in Huntington's disease

BACKGROUND

Recent findings suggest that individuals with Huntington's disease (HD) have an impaired capacity to execute cognitive and motor tasks simultaneously, or dual task, which gradually worsens as the disease advances. The onset and neuropathological changes mediating impairments in dual tasking in individuals with HD are unclear. The reliability of dual tasking assessments for individuals with HD is also unclear.

OBJECTIVES

To evaluate differences in dual tasking performance between individuals with HD (presymptomatic and prodromal) and matched controls, to investigate associations between striatal volume and dual tasking performance, and to determine the reliability of dual tasking assessments.

METHODS

Twenty individuals with HD (10 presymptomatic and 10 prodromal) and 20 healthy controls were recruited for the study. Individuals undertook four single and dual task assessments, comprising motor (postural stability or force steadiness) and cognitive (simple or complex mental arithmetic) components, with single and dual tasks performed three times each. Participants also undertook a magnetic resonance imaging assessment.

RESULTS

Compared to healthy controls, individuals with presymptomatic and prodromal HD displayed significant deficits in dual tasking, particularly cognitive task performance when concurrently undertaking motor tasks (P < 0.05). The observed deficits in dual tasking were associated with reduced volume in caudate and putamen structures (P < 0.05),however, not with clinical measures of disease burden. An analysis of the reliability of dual tasking assessments revealed moderate to high test-retest reliability [ICC: 0.61-0.99] for individuals with presymptomatic and prodromal HD and healthy controls.

CONCLUSIONS

Individuals with presymptomatic and prodromal HD have significant deficits in dual tasking that are associated with striatal degeneration. Findings also indicate that dual tasking assessments are reliable in individuals presymptomatic and prodromal HD and healthy controls.

2BALANCE: a cognitive-motor dual-task protocol for individuals with vestibular dysfunction

INTRODUCTION

Aside from primary vestibular symptoms such as vertigo and dizziness, persons with vestibular dysfunction frequently express cognitive and motor problems. These symptoms have mainly been assessed in single-task setting, which might not represent activities of daily living accurately. Therefore, a dual-task protocol, consisting of the simultaneous performance of cognitive and motor tasks, was developed. This protocol assesses cognitive and motor performance in general, as well as cognitive-motor interference in specific.

METHODS AND ANALYSIS

The motor component of the 2BALANCE protocol consists of a static and dynamic postural task. These motor tasks are combined with different cognitive tasks assessing visuospatial cognition, processing speed, working memory and response inhibition. First, test-retest reliability will be assessed with an interval of 2 weeks in a group of young adults. Second, the 2BALANCE protocol will be validated in persons with bilateral vestibulopathy. Finally, the protocol will be implemented in persons with unilateral vestibular loss.

DISCUSSION AND CONCLUSIONS

The 2BALANCE project aims to elucidate the impact of vestibular dysfunction on cognitive and motor performance in dual-task setting. This protocol represents everyday situations better than single-task protocols, as dual-tasks such as reading street signs while walking are often encountered during daily activities. Ultimately, this project could enable individualised and holistic clinical care in these patients, taking into account single as well as dual-task performance.

ETHICS AND DISSEMINATION

The current study was approved by the ethics committee of Ghent University Hospital on 5 July 2019 with registration number B670201940465. All research findings will be disseminated in peer-reviewed journals and presented at vestibular as well as multidisciplinary international conferences and meetings.

TRIALS REGISTRATION NUMBER

NCT04126798, pre-results phase.

Structural Neural Correlates of Impaired Postural Control in People with Secondary Progressive Multiple Sclerosis

BACKGROUND

Secondary progressive multiple sclerosis (SPMS) is characterized by worsening of postural control and brain atrophy. However, little is known about postural deficits and their neuroanatomical correlates in this population. We aimed to determine the neuroanatomical correlates of postural deficits in people with SPMS and whether posture control deteriorates concomitantly with the brain and spinal cord atrophy in 2 years in SPMS.

METHODS

This study is a post hoc analysis of data from 27 people with SPMS (mean ± SE age, 58.6 ± 1.1 years). Participants had magnetic resonance imaging (MRI) of the brain and cervical spinal cord followed by sway testing using inertial sensors during standing with eyes open (EO) and eyes closed without (EC) and with (ECC) a cognitive task. Partial correlations investigated relationships between postural control and MRI measures at baseline and 2 years.

RESULTS

At baseline, sway measures were inversely related to cortical thickness and cord cross-sectional area (CSA) during the EO task but only to cord CSA with EC (P < .05). After 2 years, the percentage change in sway amplitude and dispersion during EO tasks significantly related to the percentage decline in cord CSA (P < .01).

CONCLUSIONS

Cortical and spinal cord inputs are essential for regulation of postural control during standing with EO in SPMS. Without visual input, people with SPMS preferentially rely on somatosensory inputs from the spinal cord for maintaining postural control. Postural deficits related to cord atrophy over 2 years, suggesting that postural control may be a surrogate marker of disease progression in people with SPMS.

Dalfampridine to Improve Balance in Multiple Sclerosis: Substudy from a Randomized Placebo-Controlled Trial

This was a substudy of a randomized, double-blind, placebo-controlled trial originally designed to explore the effect of dalfampridine on information processing speed (2013-002558-64 EU Clinical Trials Register) in patients with multiple sclerosis (MS). A total of 120 patients were originally randomized in a 2:1 ratio to receive dalfampridine 10 mg or placebo twice daily for 12 weeks. Here, we sought to explore the effect of dalfampridine on static balance in single-task and dual-task conditions in a subgroup of 41 patients. They underwent static posturography in quiet standing (single-task) and while performing the Stroop test (dual-task) at randomization (baseline), after 12 weeks and after a 4-week wash-out period. Baseline characteristics of active group (n = 27) did not differ from those of placebo group (n = 14). Dalfampridine treatment was associated with better balance control than placebo in both single-task (F = 4.80, p = 0.034) and dual-task (F = 6.42, p = 0.015) conditions, with small-to-moderate effect sizes (Cohen's f2 = 0.122-0.162). The beneficial effect of dalfampridine was not retained 4 weeks after its discontinuation. The rate of accidental falls per month did not differ between the two groups (p = 0.12). Our preliminary findings suggest that dalfampridine can be considered a potential option to treat balance impairment due to MS. Larger sample sizes are needed to verify if the beneficial effect of dalfampridine on balance can be translated into a reduced risk of accidental falls.

Cognitive-Postural Interference in Multiple Sclerosis

Multiple Sclerosis (MS) is a neurodegenerative disease associated with cognition and balance impairments, which can lead to accidental falls. Postural control requires cognitive resources. This interaction is quantifiable by using the dual-task paradigm. The cognitive-postural interference (CPI) is commonly evaluated through an assessment of the dual-task cost (DTC). The aim of this review was to summarize literature related to process, results and effects of CPI in MS patients. The Prisma statement was used to guide this systematic review. Eligible articles had to include participants with MS for whom CPI was assessed using the DTC. A total of 14 articles meeting inclusion criteria were retained. All studies used the double stance with eyes open for the postural task component. Three types of cognitive tasks were used: Stroop Color–Word Test (SCWT), Word List Generation and Backward Counting. However, cognitive task scores in single or dual task were unavailable in 11 studies, which prevented calculating the DTC for that task. Prioritization instructions were provided in seven studies. Mutual interference was shown in three studies, postural interference in nine and postural facilitation in two. This review highlights the presence of CPI among MS patients. Postural interference usually occurred during dual task while cognitive performance during dual task was rarely reported. Postural task performance does not appear to vary based on EDSS level. We advise authors of future studies to use the SCWT in combination with postural task measure (sway area and postural sway) for DT assessment, with explicit prioritization instructions. Further, the cognitive and postural tasks should be performed in ST and DT and all results should be presented.

Test-Retest Reliability of Cognitive-Motor Interference Assessments in Walking With Various Task Complexities in Persons With Multiple Sclerosis

Background. Simultaneous execution of motor and cognitive tasks can result in worsened performance on one or both tasks, indicating cognitive-motor interference (CMI). A growing amount of research on CMI in persons with multiple sclerosis (pwMS) is observed. However, psychometric properties of dual-task outcomes have been scarcely reported. Objective. To investigate the between-day test-retest reliability of the motor and cognitive dual-task costs (DTCs) during multiple CMI test conditions with various task complexities in pwMS and matched healthy controls (HCs). Methods. A total of 34 pwMS (Expanded Disability Status Scale score 3.0 ± 0.8) and 31 HCs were tested and retested on 3 single cognitive, 4 single motor, and 12 cognitive-motor dual tasks. Cognitive tasks included serial subtraction by 7, titrated digit span backward, and auditory vigilance. Motor tasks were walking at self-selected speed, over obstacles, crisscross, and while carrying a water-filled cup. Outcome measures were cognitive and motor DTC, calculated as percentage change of dual-task performance compared with single-task performance. Intraclass correlations (ICCs) and Spearman correlation coefficients were calculated as appropriate. Results. For DTCmotor of gait speed, ICCs ranged from 0.45 to 0.81 and Spearman correlations from 0.74 to 0.82. For DTCcognitive, ICCs ranged from −0.18 to 0.49 and Spearman correlations from −0.28 to 0.26. Reliability depended on the type of motor and cognitive task. Conclusion. Reliability of the DTCmotor was, overall, good, whereas that of the DTCcognitive was poor. The “walking” and “cup” dual-task conditions were the most reliable regardless of the integrated cognitive task.

Spotlight on postural control in patients with multiple sclerosis

Multiple sclerosis (MS) is a disease that heavily affects postural control, predisposing patients to accidental falls and fall-related injuries, with a relevant burden on their families, health care systems and themselves. Clinical scales aimed to assess balance are easy to administer in daily clinical setting, but suffer from several limitations including their variable execution, subjective judgment in the scoring system, poor performance in identifying patients at higher risk of falls, and statistical concerns mainly related to distribution of their scores. Today we are able to objectively and reliably assess postural control not only with laboratory-grade standard force platform, but also with low-cost systems based on commercial devices that provide acceptable comparability to gold-standard equipment. The sensitivity of measurements derived from force platforms is such that we can detect balance abnormalities even in minimally impaired patients and predict the risk of future accidental falls accurately. By manipulating sensory inputs (dynamic posturography) or by adding a concurrent cognitive task (dual-task paradigm) to the standard postural assessment, we can unmask postural control deficit even in patients at first demyelinating event or in those with a radiologic isolated syndrome. Studies on neuroanatomical correlates support the multifactorial etiology of postural control deficit in MS, with the association with balance impairment being correlated with cerebellum, spinal cord, and highly ordered processing network according to different studies. Postural control deficit can be managed by means of rehabilitation, which is the most important way to improve balance in patients with MS, but there are also suggestions of a beneficial effect of some pharmacologic interventions. On the other hand, it would be useful to pay attention to some drugs that are currently used to manage other symptoms in daily clinical setting because they can further impair postural controls of patients with MS.

Balance worsening associated with nabiximols in multiple sclerosis

We performed a dual-task experiment to explore the effect of nabiximols on postural control in 22 patients with multiple sclerosis. They were assessed with static posturography and Stroop test in single- and dual-task conditions at treatment start and after 1, 3 and 12 months. At follow-up, we found more impaired postural control in single-task ( F = 3.07, p = 0.044) and dual-task ( F = 4.90, p = 0.005) conditions in patients who continued treatment (continuers, n = 11) compared with those who discontinued (quitters, n = 11). Continuers were more impaired at Stroop test only in dual-task condition ( F = 3.17, p = 0.038). Our findings suggest that nabiximols had a detrimental effect on postural control, especially in multi-tasking conditions.

Balancing the Demands of Two Tasks: An Investigation of Cognitive-Motor Dual-Tasking in Relapsing Remitting Multiple Sclerosis

BACKGROUND

People with relapsing remitting multiple sclerosis (PwRRMS) suffer disproportionate decrements in gait under dual-task conditions, when walking and a cognitive task are combined. There has been much less investigation of the impact of cognitive demands on balance.

OBJECTIVES

This study investigated whether: (1) PwRRMS show disproportionate decrements in postural stability under dual-task conditions compared to healthy controls, and (2) dual-task decrements are associated with everyday dual-tasking difficulties. The impact of mood, fatigue, and disease severity on dual-tasking was also examined.

METHODS

A total of 34 PwRRMS and 34 matched controls completed cognitive (digit span) and balance (movement of center of pressure on Biosway on stable and unstable surfaces) tasks under single- and dual-task conditions. Everyday dual-tasking was measured using the Dual-Tasking Questionnaire. Mood was measured by the Hospital Anxiety & Depression Scale. Fatigue was measured via the Modified Fatigue Index Scale.

RESULTS

No differences in age, gender, years of education, estimated pre-morbid IQ, or baseline digit span between groups. Compared with controls, PwRRMS showed significantly greater decrement in postural stability under dual-task conditions on an unstable surface (p=.007), but not a stable surface (p=.679). Balance decrement scores were not correlated with everyday dual-tasking difficulties or fatigue. Stable surface balance decrement scores were significantly associated with levels of anxiety (rho=0.527; p=.001) and depression (rho=0.451; p=.007).

CONCLUSIONS

RRMS causes dual-tasking difficulties, impacting balance under challenging conditions, which may contribute to increased risk of gait difficulties and falls. The relationship between anxiety/depression and dual-task decrement suggests that emotional factors may be contributing to dual-task difficulties. (JINS, 2018, 24, 247-258).

Balance, gait, and falls in multiple sclerosis

Multiple sclerosis (MS) is a chronic disease of the central nervous system (CNS) and the most widespread nontraumatic cause of disability in young adults around the world. MS occurs in people of all ages, races, and ethnicities. MS is characterized by clinical symptoms resulting from lesions in the brain, spinal cord, or optic nerves that can affect balance, gait, and fall risk. Lesions accumulate over time and occur in different areas of the CNS causing symptoms that include weakness, spasticity, and fatigue, as well as changes in sensation, coordination, vision, cognition, and bladder function. Thus, it is not surprising that imbalance, gait dysfunction, and falls are common in people with MS. The overwhelming majority have abnormalities of postural control and gait even early in the disease course. In all, 50-80% have balance and gait dysfunction and over 50% fall at least once each year. Balance dysfunction in MS is conceptualized as three interrelated problems: decreased ability to maintain position, limited and slowed movement towards limits of stability, and delayed responses to postural displacements and perturbations. In addition, functional balance performance may be affected by impaired dual-task integration. Walking changes in MS include reduced gait speed, impaired walking balance, and reduced walking-related physical activity. Falls in people with MS are associated with injuries, reduced participation, and increased fear of falling. A wide and growing range of rehabilitation and medical interventions are available to address the changes in balance, gait, and fall risk associated with MS.

Lesion symptom map of cognitive-postural interference in multiple sclerosis

Objective:

To investigate the disease-altered structure–function relationship underlying the cognitive–postural interference (CPI) phenomenon in multiple sclerosis (MS).

Methods:

We measured postural sway of 96 patients and 48 sex-/age-matched healthy controls by force platform in quiet standing (single-task (ST)) while performing the Stroop test (dual-task (DT)) to estimate the dual-task cost (DTC) of balance. In patient group, binary T2 and T1 lesion masks and their corresponding lesion volumes were obtained from magnetic resonance imaging (MRI) of brain. Normalized brain volume (NBV) was also estimated by SIENAX. Correlations between DTC and lesion location were determined by voxel-based lesion symptom mapping (VLSM) analyses.

Results:

Patients had greater DTC than controls (p < 0.001). Among whole brain MRI metrics, only T1 lesion volume correlated with DTC (r = −0.27; p < 0.01). However, VLSM analysis did not reveal any association with DTC using T1 lesion masks. By contrast, we found clusters of T2 lesions in distinct anatomical regions (anterior and superior corona radiata, bilaterally) to be correlated with DTC (p < 0.01 false discovery rate (FDR)-corrected). A multivariable stepwise regression model confirmed findings from VLSM analysis. NBV did not contribute to fit the model.

Conclusion:

Our findings suggest that the CPI phenomenon in MS can be explained by disconnection along specific areas implicated in task-switching abilities and divided attention.