Evaluating Cognitive-Motor Interference in Multiple Sclerosis: A Technology-Based Approach

BACKGROUND

People with multiple sclerosis (PwMS) frequently present both cognitive and motor impairments, so it is reasonable to assume they may have difficulties in executing dual-tasks (DT). The aim of the present study is to identify novel technology-based parameters to assess cognitive-motor interference (CMI) in PwMS. In particular, we focused on the definition of dual-task cost (DTC) measures using wearable and portable tools such as insoles and mobile apps.

METHODS

All participants underwent a verbal fluency task (cognitive single-task, ST), a motor ST of walking, and a combination of these tasks (DT). Number of words uttered in the cognitive ST and steps recorded by insoles were used to calculate the motor and cognitive DTC.

RESULTS

The number of steps strongly correlated with the walked meters for both single- (r = 0.88, p < 0.05) and dual- (r = 0.91, p < 0.05) tasks. Motor but not cognitive performances significantly worsened during DT. Over the cognitive ST and DT, the number of pronounced words progressively decreased, probably due to the activation of different cognitive processes. Cognitive efforts could be the cause of cognitive task prioritization.

CONCLUSIONS

Our findings promote the use of low-cost devices to assess CMI easily in the clinical context and to detect ecologically valid DT impairments.

Dual-task difficulties as a risk factor for unemployment in people with multiple sclerosis

BACKGROUND

No study has investigated the impact of dual-tasking difficulties as a risk factor for unemployment in people with multiple sclerosis (pwMS). The aim was to examine the influence of dual-task performance on employment status and work difficulties and to identify the predictors of employment status in pwMS.

METHODS

Eighty-four pwMS, including 42 employed and 42 unemployed, participated in the study. Dual-task difficulties were assessed using the Dual-task Impact on Daily-living Activities-Questionnaire (DIDA-Q), while dual-task performance was evaluated through the 30-second Walk Test and Nine-Hole Peg Test, incorporating a cognitive task. Walking and cognitive function were also measured.

RESULTS

Employed pwMS had better scores in walking, cognitive function, single and dual-task performance than unemployed pwMS (p < .05). Lower scores in walking (odds ratio [OR] = 1.81, p < .001) and upper extremity-related (OR = 1.44, p = .019) dual-task performance and higher scores in the cognitive subscale of the DIDA-Q questionnaire (OR = 1.20, p = .037) were significantly associated with higher odds of being unemployed. Among employed pwMS, DIDA-Q subscales showed moderate-to-strong correlations with MSWSDQ-23 scores. The other variables showed weak-to-moderate correlations with subscale and total scores of MSWSDQ-23.

CONCLUSION

Cognitive function, as opposed to motor function, has been found to be a significant predictor of unemployment in pwMS.

Profiling cognitive-motor interference in a large sample of persons with progressive multiple sclerosis and impaired processing speed: results from the CogEx study

BACKGROUND

Performing cognitive-motor dual tasks (DTs) may result in reduced walking speed and cognitive performance. The effect in persons with progressive multiple sclerosis (pwPMS) having cognitive dysfunction is unknown.

OBJECTIVE

To profile DT-performance during walking in cognitively impaired pwPMS and examine DT-performance by disability level.

METHODS

Secondary analyses were conducted on baseline data from the CogEx-study. Participants, enrolled with Symbol Digit Modalities Test 1.282 standard deviations below normative value, performed a cognitive single task ([ST], alternating alphabet), motor ST (walking) and DT (both). Outcomes were number of correct answers on the alternating alphabet task, walking speed, and DT-cost (DTC: decline in performance relative to the ST). Outcomes were compared between EDSS subgroups (≤ 4, 4.5-5.5, ≥ 6). Spearman correlations were conducted between the DTCmotor with clinical measures. Adjusted significance level was 0.01.

RESULTS

Overall, participants (n = 307) walked slower and had fewer correct answers on the DT versus ST (both p < 0.001), with a DTCmotor of 15.8% and DTCcognitive of 2.7%. All three subgroups walked slower during the DT versus ST, with DTCmotor different from zero (p's < 0.001). Only the EDSS ≥ 6 group had fewer correct answers on the DT versus ST (p < 0.001), but the DTCcognitive did not differ from zero for any of the groups (p ≥ 0.039).

CONCLUSION

Dual tasking substantially affects walking performance in cognitively impaired pwPMS, to a similar degree for EDSS subgroups.

An EEG-fNIRS neurovascular coupling analysis method to investigate cognitive-motor interference

BACKGROUND AND OBJECTIVE

The simultaneous execution of a motor and cognitive dual task may lead to the deterioration of task performance in one or both tasks due to cognitive-motor interference (CMI). Neuroimaging techniques are promising ways to reveal the underlying neural mechanism of CMI. However, existing studies have only explored CMI from a single neuroimaging modality, which lack built-in validation and comparison of analysis results. This work is aimed to establish an effective analysis framework to comprehensively investigate the CMI by exploring the electrophysiological and hemodynamic activities as well as their neurovascular coupling.

METHODS

Experiments including an upper limb single motor task, single cognitive task, and cognitive-motor dual task were designed and performed with 16 healthy young participants. Bimodal signals of electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) were recorded simultaneously during the experiments. A novel bimodal signal analysis framework was proposed to extract the task-related components for EEG and fNIRS signals respectively and analyze their correlation. Indicators including within-class similarity and between-class distance were utilized to validate the effectiveness of the proposed analysis framework compared to the canonical channel-averaged method. Statistical analysis was performed to investigate the difference in the behavior and neural correlates between the single and dual tasks.

RESULTS

Our results revealed that the extra cognitive interference caused divided attention in the dual task, which led to the decreased neurovascular coupling between fNIRS and EEG in all theta, alpha, and beta rhythms. The proposed framework was demonstrated to have a better ability in characterizing the neural patterns than the canonical channel-averaged method with significantly higher within-class similarity and between-class distance indicators.

CONCLUSIONS

This study proposed a method to investigate CMI by exploring the task-related electrophysiological and hemodynamic activities as well as their neurovascular coupling. Our concurrent EEG-fNIRS study provides new insight into the EEG-fNIRS correlation analysis and novel evidence for the mechanism of neurovascular coupling in the CMI.

How Reliable and Valid are Dual-Task Cost Metrics? A Meta-analysis of Locomotor-Cognitive Dual-Task Paradigms

OBJECTIVE

To assess the retest reliability, predictive validity, and concurrent validity of locomotor and cognitive dual-task cost (DTC) metrics derived from locomotor-cognitive dual-task paradigms.

DATA SOURCES

A literature search of electronic databases (PubMed, PsycINFO, MEDLINE, CINAHL, and Scopus) was conducted on May 29th, 2021, without time restriction.

STUDY SELECTION

For 1559 search results, titles and abstracts were screened by a single reviewer and full text of potentially eligible papers was considered by 2 independent reviewers. 25 studies that evaluated retest reliability, predictive validity, and concurrent validity of locomotor-cognitive DTC in healthy and clinical groups met inclusion criteria.

DATA EXTRACTION

Study quality was assessed using the Consensus-Based Standards for the Selection of Health Measurement Instrument checklist. Data relating to the retest reliability, predictive validity, and concurrent validity of DTC were extracted.

DATA SYNTHESIS

Meta-analysis showed that locomotor DTC metrics (intraclass correlation coefficient [ICC]=0.61, 95% confidence interval [CI; 0.53.0.70]) had better retest reliability than cognitive DTC metrics (ICC=0.27, 95% CI [0.17.0.36]). Larger retest reliability estimates were found for temporal gait outcomes (ICC=0.67-0.72) compared with spatial (ICC=0.34-0.53). Motor DTC metrics showed weak predictive validity for the incidence of future falls (r=0.14, 95% CI [-0.03.0.31]). Motor DTC metrics had weak concurrent validity with other clinical and performance assessments (r=0.11, 95% CI [0.07.0.16]), as did cognitive DTC metrics (r=0.19, 95% CI [0.08.0.30]).

CONCLUSIONS

Gait-related temporal DTC metrics achieve adequate retest reliability, while predictive and concurrent validity of DTC needs to be improved before being used widely in clinical practice and other applied settings. Future research should ensure the reliability and validity of DTC outcomes before being used to assess dual-task interference.

Patient-Reported Outcome Measures for Assessing Dual-Task Performance in Daily Life: A Review of Current Instruments, Use, and Measurement Properties

The patient perspective of dual-task (DT) impairment in real life is unclear. This review aimed (i) to identify patient-reported outcome measures (PROMs) on DT and evaluate their measurement properties and (ii) to investigate the usage of PROMs for the evaluation of DT difficulties. A systematic literature search was conducted using PubMed and Web of Science from inception to March 2022. Methodological quality was evaluated using the COSMIN checklist. Six studies examined the measurement properties of DT PROMs. Nine studies used DT PROMs as the outcome measure. Five PROMs were identified, including the Divided Attention Questionnaire (DAQ), Dual-Task-Impact on Daily-life Activities Questionnaire (DIDA-Q), a Questionnaire by Cock et al. (QOC), Dual-Tasking Questionnaire (DTQ), and Dual-Task Screening-List (DTSL). Fourteen measurement properties were documented: five (35.7%) rated quality as "sufficient", six (42.8%) "insufficient", and three (21.4%) "indeterminate". The quality of evidence for each measurement property ranged from very low to high. While DT performance is investigated in many populations, the use of PROMs is still limited, although five instruments are available. Currently, due to insufficient data, it is not possible to recommend a specific DT PROM in a specific population. An exception is DIDA-Q, which has the highest quality of measurement properties in people with multiple sclerosis.

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.

The reliability and validity of the Turkish version of the dual-task questionnaire in patients with multiple sclerosis

BACKGROUND

Activities of daily living often require performing dual-task (DT). People with Multiple Sclerosis (PwMS) may have difficulties during dual-task and these difficulties negatively affect their quality of life. However, the number of validated questionnaires to assess DT difficulties in Multiple Sclerosis (MS) is very few. Therefore, the study aimed to translate and adapt the Dual-Task Questionnaire (DTQ) into Turkish, thereafter analyzing the psychometric properties in PwMS.

METHODS

A total of 51 PwMS were recruited in the study. Cronbach's alpha coefficient was used to evaluate internal consistency. The test-retest reliability was determined using the intraclass correlation coefficient (ICC). Correlations of the DTQ with motor-dual task costs (DTCs) and cognitive-DTCs were used to assess construct validity.

RESULTS

The mean age was 36.84±10.47 years. The internal consistency of the DTQ was acceptable (α= 0.780). The test-retest reliability of all items and the total score of the DTQ were excellent (ICC>0.90). The relationships of DTQ-Total between some parameters of motor-DTCs (ρ=-0.409-(-0.495) for walking-DTCs, ρ=-0.313 for manual dexterity-DTC during mental tracking, and ρ=-0.353 for balance-DTC during mental tracking) and cognitive-DTCs (ρ=0.328 for mental tacking-DTC during balance, ρ=0.290-0.342 for all verbal fluency-DTCs) were low to moderately significant.

CONCLUSION

Turkish version of DTQ is a reliable and valid tool to measure DT difficulty in PwMS. Additionally, the questionnaire is a reliable and valid Patient Reported Outcomes Initiative for MS (PROMS) for Turkish-speaking PwMS.

Motor sequence learning in a goal-directed stepping task in persons with multiple sclerosis: a pilot study

Motor sequence learning in persons with multiple sclerosis (pwMS) and healthy controls (HC) under implicit or explicit learning conditions has not yet been investigated in a stepping task. Given the prevalent cognitive and mobility impairments in pwMS, this is important in order to understand motor learning processes and optimize rehabilitation strategies. Nineteen pwMS (the Expanded Disability Status Scale = 3.4 ± 1.2) and 18 HC performed a modified serial reaction time task by stepping as fast as possible on a stepping tile when it lit up, either with (explicit) or without (implicit) knowledge of the presence of a sequence beforehand. Motor sequence learning was studied by examining response time changes and differences between sequence and random blocks during the learning session (acquisition), 24 h later (retention), and in three dual-task (DT) conditions at baseline and retention (automaticity) using subtracting sevens, verbal fluency, and vigilance as concurrent cognitive DTs. Response times improved and were lower for the sequenced compared with the random blocks at the post- and retention tests (P's < 0.001). Response times during DT conditions improved after learning, but DT cost improved only for the subtracting sevens DT condition. No differences in learning were observed between learning conditions or groups. This study showed motor sequence learning, by acquisition and retention, in a stepping task in pwMS with motor impairments, to a similar degree as HC and regardless of learning conditions. Whether automaticity increased remains unclear.

Associations between clinical characteristics and dual task performance in Multiple Sclerosis depend on the cognitive and motor dual tasks used

BACKGROUND

In persons with Multiple Sclerosis (pwMS) performing a simultaneous cognitive task while walking often results in slower gait. Clinical characteristics associated with reduced dual task (DT) performance are not yet entirely clear. This multi-centre study aimed to determine the relationship between clinical and demographical characteristics with dual task (DT) walking performance in pwMS during multiple DT conditions.

METHODS

Nine DT conditions were analysed, consisting of combinations of three types of cognitive ('digit span', 'subtraction', 'vigilance') and three types of walking ('walk', 'walk with cup', 'walk over obstacles') conditions. Primary outcomes were DT gait speed (m/s) and motor DT cost of gait speed (DTCmotor, %). Secondary outcomes were clinical tests of physical and cognitive functioning and patient-reported and demographical outcomes. Firstly, univariate analyses and, subsequently, multivariate analyses with backward modelling, were conducted for each type of walking DT condition separately. Cognitive DT conditions were included in the models as main and as interaction effect with the secondary outcomes.

RESULTS

Analysis were performed in 81 pwMS (EDSS 3.3 ± 1.0). In the final models of DTCmotor, the significant main effects were in 'walk' DT-conditions the Symbol Digit Modalities Test (SDMT), in 'cup' conditions the SDMT and Dynamic Gait Index and in 'obstacles' conditions age. For DT gait speed, main effects were found for the 2-Minute Walking Test (2MWT) and the Multiple Sclerosis Walking Scale for all walking conditions. Additionally, interactions between cognitive DT-conditions and SDMT, age and 2MWT were found.

CONCLUSION

Clinical characteristics related to DT walking performance differed according to cognitive-motor DT-condition used. Still, in general, pwMS with a better mobility demonstrated higher DT gait speed, while a faster information processing speed was related to a lower DTCmotor.

Validating the walking while talking test to measure motor, cognitive, and dual-task performance in ambulatory individuals with multiple sclerosis

INTRODUCTION

Multiple Sclerosis (MS) is associated with demyelination of the central nervous system that negatively impacts both motor and cognitive function, resulting in difficulty performing simultaneous motor and cognitive tasks, or dual-tasks. Declines in dual-tasking have been linked with falls in MS; thus, dual-task assessment with the Walking While Talking Test (WWTT) is commonly utilized in the clinical setting. However, the validity and minimal detectable change (MDC) of the WWTT has not been established for persons with MS. The primary objective of the study was to establish the WWTT as a valid measure of dual-task function by examining concurrent validity with other motor, cognitive and dual-task measures, and to establish the MDC for both the simple and complex conditions of the WWTT.

METHODS

In a single visit, 38 adults (34 female, mean (SD) age 49.8(±9.1), Patient Determined Disease Steps (PDDS) mean 3, range 1-6) completed the WWTT simple (walk while reciting the alphabet) and complex (walk while reciting every other letter of the alphabet) conditions as well as a battery of cognitive and motor tests. Spearman correlations were used to examine concurrent validity. The sample was divided into low and high disability groups to determine the impact of disability severity on relationships among WWTT and cognitive and motor function.

RESULTS

Excellent concurrent validity (r ≥ 0.79; p < 0.001) was observed for the WWTT simple and complex with both motor (Timed Up-and-Go, Timed 25-Foot Walk, forward and backward walking velocity, Six-Spot Step Test) and dual-task measures (Timed Up-and-Go Cognitive). The WWTT-simple demonstrated moderate concurrent validity with measures of processing speed (Symbol Digit Modalities Test, p = 0.041) and was related to all motor and dual-task measures across disability levels. The WWTT complex was only related to complex motor tasks in the low disability group. Within the low disability group, WWTT was associated with processing speed (p = 0.045) and working memory (California Verbal Learning Test, p = 0.012). The MDC values were established for WWTT simple (6.9 s) and complex (8 s) conditions.

DISCUSSION

The WWTT is a quick, easy-to-administer clinical measure that captures both motor and cognitive aspects of performance for persons with MS. Clinicians should consider adding the WWTT to the evaluation of persons with MS to examine dual-task performance.

Dual-Task Performance in Multiple Sclerosis' Patients: Cerebellum Matters?

OBJECTIVE

Gait, cognitive impairments, and their mutual influence in dual tasking (cognitive-motor dual tasking, CM-DT) are important to address therapeutic approaches in patients with multiple sclerosis (PMS). CM-DT correlates have been widely investigated with variable and dissimilar results, due to differences in methods. However, although the cerebellum has recently shown to be involved in both motor and cognitive functions, few studies have explored its role in the integration of the concurrent execution of gait and cognition. This case-control study aims to explore the effects of adding a cognitive task to walking in PMS and to investigate the role of the cerebellum in the interfering process.

METHODS

In total, 20 patients and 18 healthy controls (HC) underwent clinical assessments, dual task (DT), and 3 T magnetic resonance imaging (MRI). DT was composed by three 2-min trials requiring fast walking. In 2 of them 2 different cognitive tasks were added.

RESULTS

Both groups evidenced the presence of cognitive-motor interference (CMI) for both cognitive conditions with a greater effect of word list generation task in PMS. Analysis of variance between HC and patients with high or low performances showed a significantly increased volume in Vermis lobules VIIIa and IX of high performers compared with HC.

CONCLUSION

Our results show that CMI is also present in healthy individuals but is significantly more disabling in PMS. Furthermore, MRI data point to the existence of an initial mechanism of cerebellar reorganization in PMS with lower interference. Subsequently, the failure of this mechanism due to the progression of disability leads to a more evident expression of symptoms.

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.

The patients' perspective on the perceived difficulties of dual-tasking: development and validation of the Dual-task Impact on Daily-living Activities Questionnaire (DIDA-Q)

BACKGROUND

Everyday-life activities often require performing dual tasks (DT), with consequent possible occurrence of motor-cognitive or motor-motor interference. This could reduce quality of life, in particular in people with neurological diseases. However, there is lack of validated tools to assess the patients' perspective on DT difficulties in this population. Therefore, we developed the Dual-task Impact on Daily-living Activities-Questionnaire (DIDA-Q) and tested its psychometric properties in people with multiple sclerosis (PwMS).

METHODS

Items were generated based on existing scales, DT paradigms used in previous studies and the opinion of a multi-stakeholder group, including both experts and PwMS. Twenty DT constituted the preliminary version of the DIDA-Q which was administered to 230 PwMS. The psychometric properties of the scale were evaluated including internal consistency, validity and reliability.

RESULTS

Nineteen items survived after exploratory factor analysis, showing a three-factor solution which identifies the components mostly contributing to DT perceived difficulty (i.e., balance and mobility, cognition and upper-limb ability). The DIDA-Q appropriately fits the graded response model, with first evaluations supporting internal consistency (Cronbach's alpha=0.95), validity (70% of the hypotheses for convergent and discriminant constructs confirmed) and reliability (intraclass correlation coefficients=0.95) of this tool.

CONCLUSION

The DIDA-Q could be used in research and clinical settings to discriminate individuals with low vs. high cognitive-motor or motor-motor interference, and to develop and evaluate the efficacy of personalized DT rehabilitative treatments in PwMS.

Foot-Worn Inertial Sensors Are Reliable to Assess Spatiotemporal Gait Parameters in Axial Spondyloarthritis under Single and Dual Task Walking in Axial Spondyloarthritis

The aim of this study was (1) to evaluate the relative and absolute reliability of gait parameters during walking in single- and dual-task conditions in patients with axial spondyloarthritis (axSpA), (2) to evaluate the absolute and relative reliability of dual task effects (DTE) parameters, and (3) to determine the number of trials required to ensure reliable gait assessment, in patients with axSpA. Twenty patients with axSpa performed a 10-m walk test in single- and dual-task conditions, three times for each condition. Spatiotemporal, symmetry, and DTE gait parameters were calculated from foot-worn inertial sensors. The relative reliability (intraclass correlation coefficients-ICC) and absolute reliability (standard error of measurement-SEM and minimum detectable change-MDC) were calculated for these parameters in each condition. Spatiotemporal gait parameters showed good to excellent reliability in both conditions (0.59 < ICC < 0.90). The reliability of symmetry and DTE parameters was low. ICC, SEM, and MDC were better when using the mean of the second and the third trials. Spatiotemporal gait parameters obtained from foot-worn inertial sensors assessed in patients with axSpA in single- and dual-task conditions are reliable. However, symmetry and DTE parameters seem less reliable and need to be interpreted with caution. Finally, better reliability of gait parameters was found when using the mean of the 2nd and the 3rd trials.

Patterns of cognitive-motor dual-task interference post stroke: an observational inpatient study at hospital discharge

BACKGROUND

Many ambulatory stroke survivors are discharged to community settings where they will confront highly attention-demanding mobility situations. Very little is known about cognitive-motor interference during walking in acutely rehabilitating stroke survivors.

AIM

To examine the magnitude and patterns of cognitive-motor dual-task interference at hospital discharge post stroke and explore the characteristics associated with distinct interference patterns.

DESIGN

Observational study.

SETTING

Acute care and inpatient rehabilitation centers.

POPULATION

Forty-seven adults with hospital admission for stroke who were being discharged to home. Mean age was 59.5 years (SD=11.7) and median days post stroke was 14 (IQR=7-21).

METHODS

Gait and cognitive (category naming task) performance were assessed under single- and dual-task conditions at hospital discharge. Dependent variables were gait speed, stride duration, stride duration variability, stride length, cadence, and correct response rate. Single and dual-task values were compared to assess the effects of dual-tasking on gait and category naming. Relative dual-task effects on gait speed and cognitive performance were plotted to identify patterns of dual-task interference. Exploratory analysis compared clinical characteristics between subgroups defined by pattern of interference.

RESULTS

There were significant dual-task declines in gait speed, with corresponding dual-task effects on stride length, cadence, and stride duration, but no dual-task effects on stride duration variability or correct response rate. Dual-task effects on the category naming task were not significant due to large between-subject variability. Three predominant patterns of cognitive-motor interference were evident: mutual interference (37% of participants), gait interference (30% of participants), and cognitive-priority trade-off (22% of participants) - these patterns reflect the consistently observed negative dual-task effect on gait speed with positive, negative, or null effects on category naming. Participants who demonstrated cognitive-priority trade-off pattern of interference had significantly worse single-task category-naming performance, while those with mutual interference had greater overall stroke severity.

CONCLUSIONS

Cognitive-motor dual-task interference on gait speed is highly prevalent in ambulatory stroke survivors with mild cognitive-linguistic impairments at hospital discharge. Variability in cognitive-task performance under dual-task conditions has implications for the reliability of dual-task assessment after stroke.

CLINICAL REHABILITATION IMPACT

Assessment of dual-task walking is feasible as a predischarge evaluation of attention-demanding mobility function after stroke.

Reliability of gait and dual-task measures in multiple sclerosis

BACKGROUND

Single-task (ST) and dual-task (DT) assessments are commonly used to evaluate motor and cognitive impairment in people with multiple sclerosis (MS). Although variability can influence repeated DT testing measures, the reliability of several DT variables over time has not been adequately explored. For instance, a third testing session has never been included to observe whether DT has a learning effect. DT cognition rate reliability has not yet been examined and dual-task cost (DTC), a widely used calculation for DT interpretation, has not been proven reliable.

RESEARCH QUESTION

To evaluate the reliability of ST and DT measures of gait and cognition over three test sessions.

METHODS

This was a cross-sectional study involving 18 people with MS and 12 controls. Participants attended three test sessions, each one week apart. ST and DT (serial seven subtraction) gait variables, DTC, coefficient of variability (CV), and cognition rate were extracted and calculated using an instrumented walkway. Reliability was assessed using intraclass correlation coefficients (ICC) or Kendall's coefficient of concordance (KCC; nonparametric test) and minimum detectable change (MDC); between-session learning effect was assessed using repeated measures ANOVA.

RESULTS

ICC/KCC values for ST and DT gait variables ranged from moderate to excellent (0.50-0.99). However, reliability for DT stride width and cognition rate was lower in controls. In general, DTC and CV variables had poor ICCs and high MDC values (49.19-1478.67 %), although some DTC variables had moderate or higher reliability in controls. Cognition rate was reliable in both MS (ICC 0.91) and controls (ICC 0.84). A learning effect between sessions was observed for DT velocity in both groups and for DTC cadence in people with MS.

SIGNIFICANCE

ST and DT gait measures as well as DT cognition rate are reliable outcomes for repeated testing, while DTC and CV variables may not be suitable for long-term monitoring.

Design, Development, and Testing of an App for Dual-Task Assessment and Training Regarding Cognitive-Motor Interference (CMI-APP) in People With Multiple Sclerosis: Multicenter Pilot Study

Background

Dual tasking constitutes a large portion of most activities of daily living; in real-life situations, people need to not only maintain balance and mobility skills, but also perform other cognitive or motor tasks at the same time. Interest toward dual-task training (DTT) is increasing as traditional interventions may not prepare patients to adequately face the challenges of most activities of daily living. These usually involve simultaneous cognitive and motor tasks, and they often show a decline in performance. Cognitive-motor interference (CMI) has been investigated in different neurological populations, but limited evidence is present for people with multiple sclerosis (MS). The use of computerized tools is mandatory to allow the application of more standardized assessment and rehabilitation intervention protocols and easier implementation of multicenter and multilanguage studies.

Objective

To describe the design and development of CMI-APP, an adaptive and interactive technology tablet-based app, and to present the preliminary results of a multicenter pilot study involving people with MS performed in several European centers for evaluating the feasibility of and adherence to a rehabilitation program based on CMI-APP.

Methods

CMI-APP includes user-friendly interfaces for personal data input and management, assessment of CMI, and DTT. A dedicated team developed CMI-APP for Android tablets above API level 14 (version 4.0), using C# as the programming language and Unity and Visual Studio as development tools. Three cognitive assessment tests for working memory, information processing speed, and sustained attention and four motor assessment tests for walking at different difficulty levels were implemented. Dual cognitive-motor tasks were performed by combining single cognitive and motor tasks. CMI-APP implements exercises for DTT involving the following 12 cognitive functions: sustained attention, text comprehension, verbal fluency, auditory discrimination, visual discrimination, working memory, information processing speed, auditory memory, visual memory, verbal analog reasoning, visual analog reasoning, and visual spatial planning, which can be performed during walking or stepping on the spot. Fifteen people with MS (mean age 52.6, SD 8.6 years; mean disease duration 9.4, SD 8.4 years; mean Expanded Disability Status Scale score 3.6, SD 1.1) underwent DTT (20 sessions). Adherence to the rehabilitation program was evaluated according to the percentage of performed sessions, perceived exertion during the training (Borg 15-point Ratings of Perceived Exertion [RPE] Scale), and subjective experience of the training (Intrinsic Motivation Inventory [IMI]).

Results

The adherence rate was 91%. DTT was perceived as “somewhat difficult” (mean RPE Scale score 12.6, SD 1.9). IMI revealed that participants enjoyed the training and felt that it was valuable and, to some extent, important, without feelings of pressure. They felt competent, although they did not always feel they could choose the exercises, probably because the therapist chose the exercises and many exercises had few difficulty levels.

Conclusions

CMI-APP is safe, highly usable, motivating, and well accepted for DTT by people with MS. The findings are fundamental for the preparation of future large-sample studies examining CMI and the effectiveness of DTT interventions with CMI-APP in people with MS.

Structured Cognitive-Motor Dual Task Training Compared to Single Mobility Training in Persons with Multiple Sclerosis, a Multicenter RCT

The aim was to compare the effectiveness of dual-task training (DTT) compared to single mobility training (SMT) on dual-task walking, mobility and cognition, in persons with Multiple Sclerosis (pwMS). Forty pwMS were randomly assigned to the DTT or SMT groups. The DTT-group performed dual-task exercises using an interactive tablet-based application, while the SMT-group received conventional walking and balance exercises. Both interventions were supervised and identical in weeks (8) and sessions (20). Nine cognitive-motor dual-task conditions were assessed at baseline, after intervention and at 4-weeks follow-up (FU). The dual-task cost (DTC), percentage change of dual-task performance compared to single-task performance, was the primary outcome. Mobility and cognition were secondarily assessed. Mixed model analyses were done with group, time and the interaction between group and time as fixed factors and participants as random factors. Significant time by group interactions were found for the digit-span walk and subtraction walk dual-task conditions, with a reduction in DTC (gait speed) for the DTT maintained at FU. Further, absolute dual-task gait speed during walking over obstacles only improved after the DTT. Significant improvements were found for both groups in various motor and cognitive measures. However, the DTT led to better dual-task walking compared to the SMT.