Cognitive-motor interference in multiple sclerosis: a systematic review of evidence, correlates, and consequences

The attentional cost of movement in multiple sclerosis

Individuals living with multiple sclerosis frequently have impairments in mobility. These impairments are more pronounced when they engage in a cognitively demanding mobility tasks (i.e., walking and talking, obstacle clearance, etc). Based in part on the attentional capacity model of movement, these impairments are suggested to result from greater attentional demands. Yet, this model has not been directly tested in neurological populations. The objective of the study was to determine whether individuals with multiple sclerosis have greater attentional cost of movement across a range of tasks. This study tested probe reaction times of 20 individuals with multiple sclerosis and 26 healthy controls in five different movement tasks. The tasks were specifically chosen to challenge the perceptual-motor system based on variations in static and dynamic balance requirements. Participants were asked to verbally respond as quickly as possible to randomly presented audio probes during motor performance. Task order was randomized, and average probe reaction time was calculated for each task. The results showed tasks requiring dynamic stability had greater probe reaction times in both healthy controls and individuals with multiple sclerosis. Furthermore, individuals with multiple sclerosis had longer probe reaction times across all tasks compared to healthy controls. Yet, there was no relationship between probe reaction times and performance during a complex walking scenario. The results indicate the attentional capacity model may be inadequate to explain cognitive-motor interaction in people with multiple sclerosis. Future studies should address the theoretical framework of cognitive-motor interaction, which may influence the design of interventions aimed at improving performance in individuals with MS.

Cognitive-motor interference in persons with multiple sclerosis during five upper limb motor tasks with different complexity

BACKGROUND

Cognitive-motor interference in multiple sclerosis has been well examined during walking, but not during upper limb (UL) performance.

OBJECTIVES

To examine the dual-task cost (DTC) in persons with multiple sclerosis (pwMS) and healthy controls (HC) in various type and complexity of UL motor tasks.

METHOD

In total, 30 pwMS without major UL impairment and 30 HC performed five different UL tasks, in single condition and combined with the phonemic word list generation task. The percent change in performances was evaluated by the motor, cognitive, and combined DTC. The motor tasks consisted of four unimanual (sustained hand grip strength, box-and-block test, Purdue pegboard test, finger tapping task) and one bimanual task (Purdue pegboard test). Group and task differences were analyzed with unpaired and paired t-tests, respectively, and overall effect with a multivariate analysis of variance.

RESULTS

The motor DTC ranged between 10% (Purdue pegboard bimanual) and 35% (box-and-block test). The cognitive DTC ranged between -8% (finger tapping test) and +21% (bimanual Purdue pegboard). The magnitude of the combined DTC did not differ significantly between pwMS and HC in any task.

CONCLUSION

DTC is influenced by the complexity of the UL task, but was not significantly different between HC and cognitive intact, but mildly motor disabled pwMS.

An exploration of the experiences and utility of functional electrical stimulation for foot drop in people with multiple sclerosis

Purpose: Functional electrical stimulation (FES) is effective in improving walking in people with multiple sclerosis (MS) with foot drop. There is limited research exploring people's experiences of using this device. This study aims to explore the utility, efficacy, acceptability, and impact on daily life of the device in people with MS.Methods: An interpretative phenomenological approach was employed. Ten participants who had used FES for 12 months were interviewed. Transcripts were analysed, and emergent themes identified.Results: Nine participants continued to use the device. Three relevant super-ordinate themes were identified; impact of functional electrical stimulation, sticking with functional electrical stimulation, and autonomy and control. Participants reported challenges using the device; however, all reported positive physical and psychological benefits. Intrinsic and external influences such as; access to professional help, the influence of others, an individual's ability to adapt, and experiences using the device, influenced their decisions to continue with the device. A thematic model of these factors was developed.Conclusions: This study has contributed to our understanding of people with MS experiences of using the device and will help inform prescribing decisions and support the continued, appropriate use of FES over the longer term.Implications for RehabilitationPeople with multiple sclerosis using functional electrical stimulation report benefits in many aspects of walking, improved psychological well-being and increased engagement in valued activities.A number of challenges impact on functional electrical stimulation use. Factors such as; a positive experience using the device, access to professional help, the influence of others, a strong sense of personal autonomy and an individual's ability to adapt, influence an individual's decision to continue using functional electrical stimulation.Clinicians prescribing functional electrical stimulation should be aware of these factors so that the right support and guidance can be provided to people with multiple sclerosis, thus improving outcomes and compliance over the long term.

Cognitive-motor interference during gait in patients with Multiple Sclerosis: a mixed methods Systematic Review

BACKGROUND

Cognitive-motor interference (CMI) has been proposed as a valid marker of daily life impairment in Multiple Sclerosis (MS). The heterogeneity and scarce number of studies regarding CMI in MS has hampered the synthesis of the existing evidence. The present systematic review employed a mixed methods approach with the aim of identifying and describing variables under which CMI is particularly useful to assess patients with MS.

RESULTS

MS patients showed significant CMI. The motor variables that were most sensitive in detecting significant CMI were velocity (m/s), cadence (steps/min), and double support (% gait cycle), which was also specific for MS. Among the cognitive tasks, Alternate Alphabet and Serial Subtracting 7 s were sensitive, whereas Verbal Fluency were both sensitive and specific to CMI in MS.

CONCLUSIONS

CMI should be assessed in MS with a standardised dual task such as the Verbal Fluency task while walking, with measurements of the double support time and the effect on the cognitive task. The clinical usefulness of CMI in the assessment of patients with MS is discussed.

Association between brain atrophy and cognitive motor interference in multiple sclerosis

INTRODUCTION

Cognitive motor interference (CMI) is performance impairment due to simultaneuous task execution and is measured using the dual task cost (DTC). No pathological feature of MS has to date been associated with CMI.

AIM

To assess the relationship between brain volumes and CMI, as measured using the DTC, in a cross-sectional study.

METHODS

A group of persons with MS (pwMS) and an age- and sex-matched healthy control (HC) group underwent 3D gait analysis during using the dual task paradigm. Brain volumes were measured on T1-weighted gradient echo scans using SIENAX software. The relationships between brain volumes and the DTCs of spatial temporal parameters were evaluated using Pearson correlation. A multiple regression model was used to evaluate the ability to predict the DTC of cadence based on brain volume and grey matter (GM) volume.

RESULTS

Forty-four patients and 16 HCs underwent MRI and gait analysis. The mean expanded disability status scale (EDSS) was 2.4 ± 1.5. Significant relationships between brain volumes and DTC were found only in the pwMS group, with higher rho scores for the DTC of mean velocity, DTC of cadence, and DTC of stride time. A statistically significant regression equation with an R² value of 0.684 was found using GM and Z-score on the Stroop test as predictors of the DTC of cadence (p < 0.001).

CONCLUSION

Brain atrophy, especially than in the GM, is a major determinant of DTC, although other pathological markers also contribute to CMI in patients with MS.

ADSTEP: Preliminary Investigation of a Multicomponent Walking Aid Program in People With Multiple Sclerosis

OBJECTIVE

To evaluate the effect of the Assistive Device Selection, Training and Education Program (ADSTEP) on falls and walking and sitting activity in people with multiple sclerosis (PwMS).

DESIGN

Randomized controlled trial.

SETTING

Veterans affairs medical center.

PARTICIPANTS

PwMS (N=40) using a walking aid at baseline who had fallen in the previous year.

INTERVENTIONS

Participants were randomly assigned to ADSTEP or control. ADSTEP had 6 weekly, 40-minute, 1-on-1 sessions with a physical therapist, starting with walking aid selection and fitting, followed by task-oriented progressive gait training. Control was usual medical care with the option of ADSTEP after the study.

MAIN OUTCOME MEASURES

The following were assessed at baseline, intervention completion, and 3 months later: falls, timed Up and Go, timed 25-foot walk, 2-minute walk, Four Square Step Test, International Physical Activity Questionnaire, Quebec User Evaluation of Satisfaction with Assistive Technologies, Multiple Sclerosis Walking Scale-12, Activities-Specific Balance Confidence Scale, and Multiple Sclerosis Impact Scale-29. Effect on these outcomes was estimated by a 2-by-2 repeated measures general linear model.

RESULTS

Fewer ADSTEP than control participants fell (χ²=3.96, P<.05. number needed to treat =3.3). Time spent sitting changed significantly differently with ADSTEP than with control from baseline to intervention completion (F=11.16, P=.002. ADSTEP: reduced 87.00±194.89min/d; control: increased 103.50±142.21min/d; d=0.88) and to 3-month follow-up (F=9.25, P=.004. ADSTEP: reduced 75.79±171.57min/d; control: increased 84.50±149.23min/d; d=0.79). ADSTEP yielded a moderate effect on time spent walking compared to control at 3-month follow-up (P>.05. ADSTEP 117.53±148.40min/d; control 46.43±58.55min/d; d=0.63).

CONCLUSIONS

ADSTEP prevents falls, reduces sitting, and may increase walking in PwMS.

Profiles of Cognitive-Motor Interference During Walking in Children: Does the Motor or the Cognitive Task Matter?

The evidence supporting the effects of age on the ability to coordinate a motor and a cognitive task show inconsistent results in children and adolescents, where the Dual-Task Effects (DTE) – if computed at all – range from either being lower or comparable or higher in younger children than in older children, adolescents and adults. A feasible reason for the variability in such findings is the wide range of cognitive tasks (and to some extend of motor tasks) used to study Cognitive-Motor Interference (CMI). Our study aims at determining the differences in CMI when performing cognitive tasks targeting different cognitive functions at varying walking pathways. 69 children and adolescents (boys, n = 45; girls, n = 24; mean age, 11.5 ± 1.50 years) completed higher-level executive function tasks (2-Back, Serial Subtraction, Auditory Stroop, Clock Task, TMT-B) in comparison to non-executive distracter tasks [Motor Response Task (MRT), TMT-A] to assess relative effects on gait during straight vs. repeated Change of Direction (COD) walking. DT during COD walking was assessed using the Trail-Walking-Test (TWT). The motor and cognitive DTE were calculated for each task. There were significant differences between 5th and 8th graders on single gait speed on the straight (p = 0.016) and the COD pathway (p = 0.023), but not on any of the DT conditions. The calculation of DTEs revealed that motor DTEs were lowest for the MRT and highest for the TWT in the numbers/letters condition (p < 0.05 for all comparisons). In contrast, there were cognitive benefits for the higher-order cognitive tasks on the straight pathways, but cognitive costs for both DT conditions on the COD pathway (p < 0.01 for all comparisons). Our findings demonstrate that DT changes in walking when completing a secondary task that involve higher-level cognition are attributable to more than low-level divided attention or motor response processes. These results specifically show the direct competition for higher-level executive function resources important for walking, and are in agreement with previous studies supporting the cognitive-motor link in relation to gait in children. This might be in line with the idea that younger children may not have adequate cognitive resources.

The Rationale for Monitoring Cognitive Function in Multiple Sclerosis: Practical Issues for Clinicians

About half of patients with multiple sclerosis exhibit cognitive impairment which negatively affects their quality of life. The assessment of cognitive function in routine clinical practice is still undervalued, although various tools have been proposed for this reason. In this article, we describe the potential benefits of implementing cognitive assessment tools in routine follow -ups of MS patients. Early detection of changes in cognitive performance may provide evidence of disease activity, could unmask depression or medication side-effects and provide suitable candidates for cognitive rehabilitation. Since apathy and cognitive deficiencies are common presenting symptoms in Progressive Multifocal Leukoencephalopathy, we discuss the utility of frequent monitoring of mental status in multiple sclerosis patients at increased risk. In addition, we propose a relevant algorithm aiming to incorporate a systematic evaluation of cognitive function in every day clinical practice in multiple sclerosis.

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.

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).

Dual-Tasking in Multiple Sclerosis - Implications for a Cognitive Screening Instrument

The monitoring of cognitive functions is central to the assessment and consecutive management of multiple sclerosis (MS). Though, especially cognitive processes that are central to everyday behavior like dual-tasking are often neglected. We examined dual-task performance using a psychological-refractory period (PRP) task in N = 21 patients and healthy controls and conducted standard neuropsychological tests. In dual-tasking, MS patients committed more erroneous responses when dual-tasking was difficult. In easier conditions, performance of MS patients did not differ to controls. Interestingly, the response times were generally not affected by the difficulty of the dual task, showing that the deficits observed do not reflect simple motor deficits or deficits in information processing speed but point out deficits in executive control functions and response selection in particular. Effect sizes were considerably large with d∼0.80 in mild affected patients and the achieved power was above 99%. There are cognitive control and dual tasking deficits in MS that are not attributable to simple motor speed deficits. Scaling of the difficulty of dual-tasking makes the test applied suitable for a wide variety of MS-patients and may complement neuropsychological assessments in clinical care and research setting.

Effects of cognitive versus motor dual-task on spatiotemporal gait parameters in healthy controls and multiple sclerosis patients with and without fall history

BACKGROUND

The purpose of the current study was to compare the effects of cognitive or motor tasks on gait performance between healthy controls and multiple sclerosis (MS) patients with and without fall history.

METHODS

The investigation included MS patients with fall history (n = 25) and without fall history (n = 25) and matched healthy controls (n = 25). Participants walked at their preferred speed on a motorized treadmill under three walking conditions in a randomized order: walking only, walking while performing a concurrent cognitive task (counting backward aloud by 3s), and walking while performing a concurrent motor task (carrying a tray with glasses).

RESULTS

The findings showed that in patients with MS, regardless of fall history, spatiotemporal gait parameters were different compared to healthy controls. In contrast to average gait parameters, variability in stride length and stride time could discriminate between MS fallers and non-fallers. Simultaneous performance of cognitive task and walking resulted in higher dual-task costs (DTC) in gait performance compared to the motor dual-task. However, the pattern of change was not different among the three groups. All participants responded to the cognitive task challenges by increasing stride length and decreasing cadence and stride length variability while maintaining cognitive task performance.

CONCLUSIONS

The findings may reflect successful adaptation of locomotor system to preserve cognitive task performance under cognitive dual-task condition. Future studies should examine more complex concurrent cognitive and motor tasks to better understand the dual-task-related gait changes and their contribution to falls in patients with MS.

Dual Task of Fine Motor Skill and Problem Solving in Individuals With Multiple Sclerosis: A Pilot Study

OBJECTIVES

To (1) examine and compare dual-task performance in patients with multiple sclerosis (MS) and healthy controls (HCs) using mathematical problem-solving questions that included an everyday competence component while performing an upper extremity fine motor task; and (2) examine whether difficulties in dual-task performance are associated with problems in performing an everyday internet task.

DESIGN

Pilot study, mixed-design with both a within and between subjects' factor.

SETTING

A nonprofit rehabilitation research institution and the community.

PARTICIPANTS

Participants (N=38) included persons with MS (n=19) and HCs (n=19) who were recruited from a nonprofit rehabilitation research institution and from the community.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Participant were presented with 2 testing conditions: (1) solving mathematical everyday problems or placing bolts into divots (single-task condition); and (2) solving problems while putting bolts into divots (dual-task condition). Additionally, participants were required to perform a test of everyday internet competence.

RESULTS

As expected, dual-task performance was significantly worse than either of the single-task tasks (ie, number of bolts into divots or correct answers, and time to answer the questions). Cognitive but not motor dual-task cost was associated with worse performance in activities of everyday internet tasks.

CONCLUSIONS

Cognitive dual-task cost is significantly associated with worse performance of everyday technology. This was not observed in the motor dual-task cost. The implications of dual-task costs on everyday activity are discussed.

Dual task training in persons with Multiple Sclerosis: a feasability randomized controlled trial

OBJECTIVE

To determine the feasibility of dual task training in persons with Multiple Sclerosis.

DESIGN

Randomized, single-blinded controlled trial.

SETTING

University research laboratory.

PARTICIPANTS

A total of 234 individuals inquired about the investigation. After screening, 20 individuals with multiple sclerosis who self-reported problems with multitasking and were ambulatory volunteered for the investigation. 14 participants completed the post-assessment following the 12-week intervention.

INTERVENTION

Participants were randomly assigned to either single task training program which focused on balance and walking function ( n=6) or dual task training program that incorporated cognitive tasks in balance and walking training ( n=8).

MEASURES

Before and after the 12-week interventions participants underwent assessments of walking; dual task walking; balance (Berg Balance Scale and balance confidence) and cognition as indexed by the Brief International Cognitive Assessment for MS.

RESULTS

There was an 8.5% recruitment rate, a 70% retention rate, and a 100% adherence rate. There was a trend for dual task gait speed to improve in the dual task training group following the intervention (Pre: task 1: 109.8±39, task 2: 104.2±34.1; Post: task 1:127.6±40.1, task 2: 122.8±37.4; P=0.14; η2 = 0.24). There was also a trend for the dual task training group (28.1) to have greater performance than the control group (24.7) on visuospatial memory ( P=0.10; η2= 0.23). There were no changes in cognitive performance during walking trials.

CONCLUSIONS

The study procedures were found to be feasible and improvements should be made in recruitment efforts going forward. Further examination of dual task training programs in individuals with multiple sclerosis is warranted.

Cognitive-motor interference in multiple sclerosis: What happens when the gait speed is fixed?

During the last decade, numerous studies have confirmed a coupling between walking performance and cognition in people with multiple sclerosis (PwMS). Our aim was to provide new insights into a walking-cognitive dual-task (DT) in PwMS. We tested the DT phenomenon by controlling the walking speed using an instrumented treadmill. Thirty PwMS (20 women) with a mean age 40.1 (SD=12.0) participated in the study. Twenty-one healthy subjects served as controls. Each subject completed a sequence of tests: a) Normal walking (ST) - the participant walked on the instrumented treadmill at a comfortable walking speed for 1min; b) Cognitive evaluation (ST) - subjects performed two cognitive tests while seated; c) DT cognitive tests performed while walking on the treadmill at the identical speed performed during normal walking. Outcome measures were spatio-temporal parameters of gait (mean and variability), the Word List Generation Test (WLG) and the Serial-3 Subtraction Test. MS participants significantly decreased their cadence while increasing their stride length during the DT condition compared to the ST condition. Non-significant differences were observed for the WLG and Serial-3 Subtraction Cognitive Tests between the ST condition and the DT condition in both the MS and healthy groups. In terms of gait variability parameters, MS subjects demonstrated a 2 to 3-fold greater gait variability compared to the healthy controls. Non-significant differences in gait variability parameters were observed between the ST and DT conditions in both the MS and control groups. This study provides new insights into the DT phenomenon in the MS population.

Does the radiologically isolated syndrome exist? A dual-task cost pilot study

Simultaneous performance of motor and cognitive tasks may compete for common brain network resources in aging or patients with some neurological diseases, suggesting the occurrence of a cognitive-motor interference. While this phenomenon has been well described for multiple sclerosis (MS) patients, it never has been tested on asymptomatic subject with magnetic resonance imaging (MRI) findings suggestive of demyelinating disease (i.e., radiologically isolated syndrome: RIS). In this pilot study, 10 RIS subjects and 10 sex/age-matched healthy controls were tested by means of static posturography under eyes opened (single-task trial) and while performing two different cognitive tasks (semantic modified word list generation for first dual-task trial and phonemic semantic modified word list generation for second dual-task trial), to estimate the dual-task cost (DTC) of standing balance. In our sample, under cognitive interference (without any substantial differences between semantic and phonemic modified word list generation), the RIS group showed significance differences in CoP (center of pressure) total sway area, ellipse eccentricity, CoP sway path length, CoP median sway velocity along the AP (anteroposterior) axis and along the ML (mediolateral) axis, reflecting a higher negative DTC respect to healthy subjects (which have simply shown a statistical trend, failing to reach a significance, in some trials). The phenomenon of cognitive-motor interference might be unmasked by a dual-task posturography in RIS subjects, too. We hypothesize that this approach could be useful to early reveal the presence of a demyelinating disease and to reach a MS diagnosis in subjects otherwise classified as RIS.

Effect of Cognitive Demand on Functional Mobility in Ambulatory Individuals with Multiple Sclerosis

BACKGROUND

As disease progresses, cognitive demands may affect functional mobility in individuals with multiple sclerosis (MS). The Timed Up and Go (TUG) test assesses functional mobilityin populationssuch as MS. A cognitive-demanding task can be added to the TUG test to assess its effect on functional mobility.

METHODS

People with MS (n = 52) and controls (n = 57) performed three versions of the TUG test: TUG alone (TUG-alone), TUG plus reciting the alphabet (TUG-alpha), and TUG plus subtracting numbers by 3s (TUG-3s). Times to complete the TUG tests were compared among controls and three groups of participants with MS created using Expanded Disability Status Scale (EDSS) scores 0 to 3.5, 4.0 to 5.5, and 6. Differences among groups were analyzed using split-plot analysis of variance.

RESULTS

Group and TUG type were significant (P < .001 for both), with no interaction effect of group × TUG type (P = .21). Mean times were 8.7, 9.4, and 11.1 seconds to perform the TUG-alone, TUG-alpha, and TUG-3s, respectively. Mean times for groups were 8.0, 8.2, 11.1, and 11.6 seconds for controls and individuals with MS and EDSS 0 to 3.5, 4.0 to 5.5, and 6, respectively.

CONCLUSIONS

People with MS with an EDSS score greater than 3.5 had a statistically significant reduction in performance of the TUG test even with the addition of a simple cognitive task, which might have implications for a person's more complex everyday activities.

Reliability and Concurrent Validity of the Narrow Path Walking Test in Persons With Multiple Sclerosis

BACKGROUND AND PURPOSE

About 90% of people with multiple sclerosis (PwMS) have gait instability and 50% fall. Reliable and clinically feasible methods of gait instability assessment are needed. The study investigated the reliability and validity of the Narrow Path Walking Test (NPWT) under single-task (ST) and dual-task (DT) conditions for PwMS.

METHODS

Thirty PwMS performed the NPWT on 2 different occasions, a week apart. Number of Steps, Trial Time, Trial Velocity, Step Length, Number of Step Errors, Number of Cognitive Task Errors, and Number of Balance Losses were measured. Intraclass correlation coefficients (ICC2,1) were calculated from the average values of NPWT parameters. Absolute reliability was quantified from standard error of measurement (SEM) and smallest real difference (SRD). Concurrent validity of NPWT with Functional Reach Test, Four Square Step Test (FSST), 12-item Multiple Sclerosis Walking Scale (MSWS-12), and 2 Minute Walking Test (2MWT) was determined using partial correlations.

RESULTS

Intraclass correlation coefficients (ICCs) for most NPWT parameters during ST and DT ranged from 0.46-0.94 and 0.55-0.95, respectively. The highest relative reliability was found for Number of Step Errors (ICC = 0.94 and 0.93, for ST and DT, respectively) and Trial Velocity (ICC = 0.83 and 0.86, for ST and DT, respectively). Absolute reliability was high for Number of Step Errors in ST (SEM % = 19.53%) and DT (SEM % = 18.14%) and low for Trial Velocity in ST (SEM % = 6.88%) and DT (SEM % = 7.29%). Significant correlations for Number of Step Errors and Trial Velocity were found with FSST, MSWS-12, and 2MWT.

DISCUSSION AND CONCLUSIONS

In persons with PwMS performing the NPWT, Number of Step Errors and Trial Velocity were highly reliable parameters. Based on correlations with other measures of gait instability, Number of Step Errors was the most valid parameter of dynamic balance under the conditions of our test.Video Abstract available for more insights from the authors (see Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A159).

Neuroimaging of Human Balance Control: A Systematic Review

This review examined 83 articles using neuroimaging modalities to investigate the neural correlates underlying static and dynamic human balance control, with aims to support future mobile neuroimaging research in the balance control domain. Furthermore, this review analyzed the mobility of the neuroimaging hardware and research paradigms as well as the analytical methodology to identify and remove movement artifact in the acquired brain signal. We found that the majority of static balance control tasks utilized mechanical perturbations to invoke feet-in-place responses (27 out of 38 studies), while cognitive dual-task conditions were commonly used to challenge balance in dynamic balance control tasks (20 out of 32 studies). While frequency analysis and event related potential characteristics supported enhanced brain activation during static balance control, that in dynamic balance control studies was supported by spatial and frequency analysis. Twenty-three of the 50 studies utilizing EEG utilized independent component analysis to remove movement artifacts from the acquired brain signals. Lastly, only eight studies used truly mobile neuroimaging hardware systems. This review provides evidence to support an increase in brain activation in balance control tasks, regardless of mechanical, cognitive, or sensory challenges. Furthermore, the current body of literature demonstrates the use of advanced signal processing methodologies to analyze brain activity during movement. However, the static nature of neuroimaging hardware and conventional balance control paradigms prevent full mobility and limit our knowledge of neural mechanisms underlying balance control.

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.

Effects of dual tasks and dual-task training on postural stability: a systematic review and meta-analysis

The use of dual-task training paradigm to enhance postural stability in patients with balance impairments is an emerging area of interest. The differential effects of dual tasks and dual-task training on postural stability still remain unclear. A systematic review and meta-analysis were conducted to analyze the effects of dual task and training application on static and dynamic postural stability among various population groups. Systematic identification of published literature was performed adhering to Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines, from inception until June 2016, on the online databases Scopus, PEDro, MEDLINE, EMBASE, and SportDiscus. Experimental studies analyzing the effects of dual task and dual-task training on postural stability were extracted, critically appraised using PEDro scale, and then summarized according to modified PEDro level of evidence. Of 1,284 records, 42 studies involving 1,480 participants met the review’s inclusion criteria. Of the studies evaluating the effects of dual-task training on postural stability, 87.5% of the studies reported significant enhancements, whereas 30% of the studies evaluating acute effects of dual tasks on posture reported significant enhancements, 50% reported significant decrements, and 20% reported no effects. Meta-analysis of the pooled studies revealed moderate but significant enhancements of dual-task training in elderly participants (95% CI: 1.16–2.10) and in patients suffering from chronic stroke (−0.22 to 0.86). The adverse effects of complexity of dual tasks on postural stability were also revealed among patients with multiple sclerosis (−0.74 to 0.05). The review also discusses the significance of verbalization in a dual-task setting for increasing cognitive–motor interference. Clinical implications are discussed with respect to practical applications in rehabilitation settings.

Intervention modalities for targeting cognitive-motor interference in individuals with neurodegenerative disease: a systematic review

INTRODUCTION

Individuals with neurodegenerative disease (NDD) commonly have elevated cognitive-motor interference, change in either cognitive or motor performance (or both) when tasks are performed simultaneously, compared to healthy controls. Given that cognitive-motor interference is related to reduced community ambulation and elevated fall risk, it is a target of rehabilitation interventions. Areas covered: This review details the collective findings of previous dual task interventions in individuals with NDD. A total of 21 investigations focusing on 4 different neurodegenerative diseases and one NDD precursor (Parkinson's disease, multiple sclerosis, Alzheimer's disease (AD), dementia other than AD, and mild cognitive impairment) consisting of 721 participants were reviewed. Expert commentary: Preliminary evidence from interventions targeting cognitive-motor interference, both directly and indirectly, show promising results for improving CMI in individuals with neurodegenerative diseases. Methodological limitations, common to pilot investigations preclude firm conclusions. Well-designed randomized control trials targeting cognitive motor interference are warranted.

Unplanned gait termination in individuals with multiple sclerosis

Despite the pervasive nature of gait impairment in multiple sclerosis (MS), there is limited information concerning the control of gait termination in individuals with MS. The purpose of this investigation was to examine unplanned gait termination with and without cognitive distractors in individuals with MS compared to healthy controls. Thirty-one individuals with MS and 14 healthy controls completed a series of unplanned gait termination tasks over a pressure sensitive walkway under distracting and non-distracting conditions. Individuals with MS were further broken down into groups based on assistive device use: (no assistive device (MS_noAD) n=18; and assistive device (MS_AD) n=13). Individuals with MS who walked with an assistive device (MS_AD: 67.8±15.1cm/s) walked slower than individuals without an assistive device (MS_noAD: 110.4±32.3cm/s, p<0.01) and controls (120.0±30.0cm/s; p<0.01). There was a significant reduction in velocity in the cognitively distracting condition (93.4±32.1cm/s) compared to the normal condition [108.8±36.2cm/s; F(1,43)=3.4, p=0.04]. All participants took longer to stop during the distracting condition (1.7±0.6s) than the non-distracting condition (1.4±0.4s; U=673.0 p<0.01). After controlling for gait velocity, post-hoc analysis revealed the MS_AD group took significantly longer to stop compared to the control group (p=0.05). Further research investigating the control of unplanned gait termination in MS is warranted.

Gait pattern in patients with different multiple sclerosis phenotypes

BACKGROUND

Gait pattern is frequently impaired in multiple sclerosis (MS), however gait characteristics in patients with different MS phenotypes have not been fully elucidated.

METHODS

We analyzed spatio-temporal gait pattern characteristics in patients with relapsing-remitting (RR, n=52) and primary-progressive (PP, n=18) MS in comparison with age-matched healthy controls (HC, n=40). All subjects performed a standardized simple walking task, a dual motor- motor task, a dual motor-mental task, and a triple combined motor-mental task at a GAITRite electronic walkway of 5.5m active area. We measured: cycle time (CT), stride length (SL), swing time (ST), double support time (DST), gait velocity (GV) and calculated symmetry index (SI) for CT, SL and ST.

RESULTS

With each task performed, CT and DST in the total MS group were significantly longer while SL was significantly shorter and GV significantly lower than in HC. ST was similar in the total MS patient group and HC. In both MS patients and HC, CT and DST increased and SL and GV decreased over repeated assessments. Dual and triple tasks while walking influenced walking performance in both MS patients and HC. Although patients with PPMS differed significantly from those with RRMS in the majority of gait parameters, the subgroup analysis in patients matched for age and disability (Expanded Disability Status Scale Score -EDSS, 3.0-5.0) showed similar gait performance in RRMS and PPMS patients having the same level of disability, except for CT and ST- symmetry parameters that were more impaired in the PPMS group. The EDSS score correlated significantly with CT, DST, SL and GV, but no significant correlation was found with ST except at the triple combined motor-mental task.

CONCLUSION

A disturbed gait pattern in MS patients with different MS phenotypes depends on disability and reflects a cognitive-motor interference.

Adverse working events in patients with multiple sclerosis

Multiple sclerosis (MS) and working status have recently arisen great interest. Fatigue, physical disability, cognition, and psychological disturbances have been linked to unemployment, as well to accidents during daily activities. The aim of our study was to determine frequency of different types of accidents at workplace (AWE) and possible clinical differences among employed (MSe) and unemployed (MSu) MS patients. Sixty MS patients (31 employed, 29 unemployed) and twenty healthy control subjects were recruited. All employed participants were requested to complete an ad-hoc questionnaire to collect AWE and related risks occurring at workplace in the past 2 months. Physical, cognitive, mood, and fatigue evaluations were also assessed. Illness and bumps along with risk of bumps and near falls resulted the most frequent AWE and risks occurring in MSe. Interestingly, those AWE were mostly observed among subjects with anxiety, depression, and cognitive fatigue rather than depending on severity of physical impairment. Moreover, psychological aspects, like anxiety and anger, seemed to play a crucial role in determining AWE. This study provides data on AWE occurrence and suggests possible mechanisms underlying negative events at workplace in MS. This might be important for planning strategies of AWE prevention in MS patients.

Cognitive Motor Interference in Multiple Sclerosis: Insights From a Systematic Quantitative Review

OBJECTIVE

To synthesize the evidence for differences in cognitive motor interference (CMI) between persons with multiple sclerosis (MS) and those without MS by using systematic review and meta-analysis.

DATA SOURCES

EMBASE, PubMed, ScienceDirect, Scopus, SPORTDiscus, and Web of Science. Our focused literature search was informed by past systematic reviews of CMI during walking in MS.

STUDY SELECTION

The key terms searched included Multiple sclerosis and synonyms of motor function (eg, Gait disorders, Gait, Walking, Balance, or Fall) and motor and cognitive functions (eg, Cognitive motor interference or Thinking).

DATA EXTRACTION

From the 116 abstract-identified articles, 13 experimental studies were selected for the final analysis and were rated using the Quality Assessment of Diagnostic Accuracy Studies tool. A meta-analysis was performed for all considered outcomes.

DATA SYNTHESIS

The results yielded a small overall effect size (ES) of .08 (SE=.17; 95% confidence interval, -.25 to .40; z=.49; P>.05), which indicated a nonsignificant minimal difference in CMI between persons with MS and those without MS. The moderator analysis for motor task (mobility task: ES, .22; postural task: ES, -.11) was not significantly different between persons with MS and those without MS. The moderator analysis for cognitive task (verbal fluency task: ES, .66; mental tracking task: ES, .04; discrimination and decision-making task: ES, -.30) resulted in a significant difference in CMI between persons with MS and those without MS (P<.05).

CONCLUSIONS

We provide evidence that overall there is a minimal difference in CMI between persons with MS and those without MS.

Effects of dual-task balance training on postural performance in patients with Multiple Sclerosis: a double-blind, randomized controlled pilot trial

Objective:

To investigate the effects of dual-task balance training on postural performance in patients with multiple sclerosis as compared with single-task balance training.

Design:

Double-blind, pretest-posttest, randomized controlled pilot trial.

Setting:

Local Multiple Sclerosis Society.

Subjects:

A total of 47 patients were randomly assigned to two equal groups labeled as single-task training and dual-task training groups.

Interventions:

All patients received supervised balance training sessions, 3 times per week for 4 weeks. The patients in the single-task group performed balance activities, alone. However, patients in dual-task group practiced balance activities while simultaneously performing cognitive tasks.

Main measures:

The 10-Meter Walk Test and Timed Up-and-Go under single-task and dual-task conditions, in addition to Activities-specific Balance Confidence, Berg Balance Scale, and Functional Gait Assessment were assessed pre-, and post intervention and also 6-weeks after the end of intervention.

Results:

Only 38 patients completed the treatment plan. There was no difference in the amount of improvement seen between the two study groups. In both groups there was a significant effect of time for dual-10 Meter Walk Test (F1, 36=11.33, p=0.002) and dual-Timed Up-and-Go (F1, 36=14.27, p=0.001) but not for their single-tasks. Moreover, there was a significant effect of time for Activities-specific Balance Confidence, Berg Balance Scale, and Functional Gait Assessment ( P<0.01).

Conclusions:

This pilot study did not show more benefits from undertaking dual-task training than single-task training. A power analysis showed 71 patients per group would be needed to determine whether there was a clinically relevant difference for dual-task gait speed between the groups.

Dual task cost of cognition is related to fall risk in patients with multiple sclerosis: a prospective study

OBJECTIVE

To examine whether change in cognitive performance during dual task condition compared with a task in isolation, known as dual task cost, is related to fall risk of patients with multiple sclerosis.

DESIGN

Prospective cohort. During baseline assessment, data about balance, walking and cognitive performance of patients with multiple sclerosis were collected under a single and dual task condition. The dual task cost was calculated as a percentage of change in parameters from single to dual task conditions. Falls were recorded prospectively for six months and participants were classified as none/one time fallers and recurrent fallers (⩾2 falls). The association between dual task costs and fall status was evaluated by logistic regression.

SETTING

Balance research lab of university hospital.

PARTICIPANTS

A total of 60 patients with relapsing-remitting multiple sclerosis.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The dual task cost of the center of pressure sway area, walking velocity and correct response rate were outcome measures for balance, walking and cognitive performance, respectively.

RESULTS

A total of 79 falls were reported by 38 of the participants who experienced one or more falls; 26 (43.3%) of them had recurrent falls. Dual tasking resulted in increased sway area and decreased walking velocity and correct response rate during walking (all p values <0.05). Logistic regressions showed that the dual task cost of the correct response rate during walking and walking velocity were associated with increased risk of recurrent falls ( P = 0.02, odds ratio = 1.34; confidence interval (CI) 1.04-3.74; P =  0.05, odds ratio = 1.23, CI = 1.02-4.45, respectively).

CONCLUSIONS

The dual task cost of cognition was related to fall, which should be considered as a target for falls evaluation and prevention strategies.

Walking impairs cognitive performance among people with multiple sclerosis but not controls

People with multiple sclerosis (MS) complain of problems completing two tasks simultaneously; sometimes called 'dual-tasking' (DT). Previous research in DT among people with MS has focused on how adding a cognitive task interferes with gait and few have measured how adding a motor task could interfere with cognition. We aimed to determine the extent to which walking affects a concurrent working memory task in people with MS compared to healthy controls. We recruited MS participants (n=13) and controls (n=10) matched by age (±3years), education (±3years) and gender. Participants first completed the cognitive task (subtracting 7's from the previous number) and then again while walking on an instrumented walkway. Although there were no baseline differences in cognition or walking between MS participants and controls, MS participants demonstrated a 52% decrease in number of correct answers during DT (p<0.001). Mental Tracking Rate (% correct answers/min) correlated strongly with MS-related disability measured using the Expanded Disability Status Scale (EDSS; r(11)=-0.68, p<0.01). We propose that compromised mental tracking during walking could be related to limited neural resource capacity and could be a potentially useful outcome measure to detect ecologically valid dual tasking impairments.

The Effect of Two Different Cognitive Tests on Gait Parameters during Dual Tasks in Healthy Postmenopausal Women

INTRODUCTION

The paper aims to evaluate the influence of two different demanding cognitive tasks on gait parameters using BTS SMART system analysis.

PATIENTS AND METHODS

The study comprised 53 postmenopausal women aged 64.5 ± 6.7 years (range: 47-79). For every subject, gait analysis using a BTS SMART system was performed in a dual-task study design under three conditions: (I) while walking only (single task), (II) walking while performing a simultaneous simple cognitive task (SCT) (dual task), and (III) walking while performing a simultaneous complex cognitive task (CCT) (dual task). Time-space parameters of gait pertaining to the length of a single support phase, double support phase, gait speed, step length, step width, and leg swing speed were analyzed.

RESULTS

Performance of cognitive tests during gait resulted in a statistically significant prolongation of the left (by 7%) and right (by 7%) foot gait cycle, shortening of the length of steps made with the right extremity (by 4%), reduction of speed of swings made with the left (by 11%) and right (by 8%) extremity, and reduction in gait speed (by 6%).

CONCLUSIONS

Performance of cognitive tests during gait changes its individual pattern in relation to the level of the difficulty of the task.

The dual task-cost of standing balance affects quality of life in mildly disabled MS people

The aim of this study was to explore the correlations between the dual-task cost (DTC) of standing balance and quality of life (QoL) in mildly disabled patients with multiple sclerosis (MS). In this cross-sectional study, patients affected by MS with an expanded disability status scale (EDSS) score of 3.0 or less and without an overt balance impairment were tested by means of static posturography under eyes-opened (single-task condition) and while performing the Stroop word-color test (dual-task condition), to estimate the DTC of standing balance. The self-reported 54-item MS quality of life questionnaire (MSQoL-54) was also administered to obtain a MS-specific assessment of health-related QoL. Among the 120 screened patients, 75 (53 women, 22 men) were tested. Although there was no impact of the DTC of standing balance on the physical and mental composite scores of MSQoL-54, patients who had a greater DTC of standing balance scored worse on role limitations due to physical problems (p = 0.007) and social function (p < 0.001), irrespective of demographic and other clinical characteristics including walking performance and cognitive status. However, the EDSS step and fatigue also contributed to reduced scores in these two QoL domains (p-values < 0.01). In conclusion, the phenomenon of cognitive-motor interference, investigated as DTC of standing balance, may affect specific QoL domains even in mildly disabled patients with MS and in the absence of an overt balance dysfunction.