Attentional prioritization in dual-task walking: Effects of stroke, environment, and instructed focus

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

OBJECTIVES

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

DATA SOURCE

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

STUDY SELECTION

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

DATA EXTRACTION

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

DATA SYNTHESIS

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

CONCLUSION

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

How do drivers mitigate the effects of naturalistic visual complexity? : On attentional strategies and their implications under a change blindness protocol

How do the limits of high-level visual processing affect human performance in naturalistic, dynamic settings of (multimodal) interaction where observers can draw on experience to strategically adapt attention to familiar forms of complexity? In this backdrop, we investigate change detection in a driving context to study attentional allocation aimed at overcoming environmental complexity and temporal load. Results indicate that visuospatial complexity substantially increases change blindness but also that participants effectively respond to this load by increasing their focus on safety-relevant events, by adjusting their driving, and by avoiding non-productive forms of attentional elaboration, thereby also controlling "looked-but-failed-to-see" errors. Furthermore, analyses of gaze patterns reveal that drivers occasionally, but effectively, limit attentional monitoring and lingering for irrelevant changes. Overall, the experimental outcomes reveal how drivers exhibit effective attentional compensation in highly complex situations. Our findings uncover implications for driving education and development of driving skill-testing methods, as well as for human-factors guided development of AI-based driving assistance systems.

Language-Specific Dual-Task Effects After Stroke: A Systematic Review

PURPOSE

The dual-task paradigm has been frequently used to examine stroke-related deficits because it samples behavioral performance under conditions of distraction similar to functioning in real-life environments. This original systematic review synthesizes studies that examined dual-task effects involving spoken language production in adults affected by stroke, including transient ischemic attack (TIA) and poststroke aphasia.

METHOD

Five databases were searched (inception to March 2022) for eligible peer-reviewed articles. The 21 included studies reported a total of 561 stroke participants. Thirteen studies focused on single word production, for example, word fluency, and eight on discourse production, for example, storytelling. Most studies included participants who had suffered a major stroke. Six studies focused on aphasia, whereas no study focused on TIA. A meta-analysis was not appropriate because of the heterogeneity of outcome measures.

RESULTS

Some single word production studies found dual-task language effects whereas others did not. This finding was compounded by the lack of appropriate control participants. Most single word and discourse studies utilized motoric tasks in the dual-task condition. Our certainty (or confidence) assessment was based on a methodological appraisal of each study and information about reliability/fidelity. As 10 of the 21 studies included appropriate control groups and limited reliability/fidelity information, the certainty of the findings may be described as weak.

CONCLUSIONS

Language-specific dual-task costs were identified in single word studies, especially those that focused on aphasia as well as half of the nonaphasia studies. Unlike single word studies, nearly all studies of discourse showed dual-task decrements on at least some variables.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.23605311.

Cortical thickness is related to cognitive-motor automaticity and attention allocation in individuals with Alzheimer's disease: a regions of interest study

Alzheimer's disease (AD) is characterized by a distinct pattern of cortical thinning and resultant changes in cognition and function. These result in prominent deficits in cognitive-motor automaticity. The relationship between AD-related cortical thinning and decreased automaticity is not well-understood. We aimed to investigate the relationship between cortical thickness regions-of-interest (ROI) and automaticity and attention allocation in AD using hypothesis-driven and exploratory approaches. We performed an ROI analysis of 46 patients with AD. Data regarding MR images, demographic characteristics, cognitive-motor dual task performance, and cognition were extracted from medical records. Cortical thickness was calculated from MR T1 images using FreeSurfer. Data from the dual task assessment was used to calculate the combined dual task effect (cDTE), a measure of cognitive-motor automaticity, and the modified attention allocation index (mAAI). Four hierarchical multiple linear regression models were conducted regressing cDTE and mAAI separately on (1) hypothesis-generated ROIs and (2) exploratory ROIs. For cDTE, cortical thicknesses explained 20.5% (p = 0.014) and 25.9% (p = 0.002) variability in automaticity in the hypothesized ROI and exploratory models, respectively. The dorsal lateral prefrontal cortex (DLPFC) (β =  - 0.479, p = 0.018) and superior parietal cortex (SPC) (β = 0.467, p = 0.003), and were predictors of automaticity. For mAAI, cortical thicknesses explained 20.7% (p = 0.025) and 28.3% (p = 0.003) variability in attention allocation in the hypothesized ROI and exploratory models, respectively. Thinning of SPC and fusiform gyrus were associated with motor prioritization (β =  - 0.405, p = 0.013 and β =  - 0.632, p = 0.004, respectively), whereas thinning of the DLPFC was associated with cognitive prioritization (β = 0.523, p = 0.022). Cortical thinning in AD was related to cognitive-motor automaticity and task prioritization, particularly in the DLPFC and SPC. This suggests that these regions may play a primary role in automaticity and attentional strategy during dual-tasking.

Including cognitive assessments with functional testing predicts capabilities relevant to everyday walking in older adults

BACKGROUND

Dual-task (DT) testing reflects real-world walking demands in older adults but is not always feasible to perform in clinic. Whether clinical measures that predict single-task (ST) performance also predict DT performance or dual-task effects (DTEs) has not been fully explored.

RESEARCH QUESTION

What are the relationships between cognitive performance, functional mobility, and self-reported physical activity and balance confidence and ST and DT Gait Speed and Cognitive Reaction Time, as well as DTEs on Gait Speed (DTE_GS) and Cognitive Reaction Time (DTE_RT), in older adults?

METHODS

Sixty-two older adults (71.5 ± 7.1 years, 17 males) completed cognitive performance, functional mobility, and self-report physical activity and balance confidence assessments. Three 1-min trials were performed: 1) ST Cognition (clock task), 2) ST Gait and 3) DT Cognition + Gait, with Cognitive Reaction Time (recorded during clock task performance via DirectRT) and Gait Speed (measured during walking trial via APDM system) recorded, and DTE_GS and DTE_RT calculated, as the cognitive and gait outcomes. Six multivariate regressions were conducted to test whether cognitive performance, functional mobility, and self-report assessments predicted Gait Speed and Cognitive Reaction Time in ST and DT conditions and DTEs.

RESULTS

The Comprehensive Trail Making Test (CTMT) predicted Reaction Time in ST cognitive (β = - 0.525, p = .003) and DT (β = - 0.510, p = .006) trials. The Physical Activity Scale for the Elderly (PASE) predicted DTE_RT (β = - 0.397, p = .008). The 10-Meter Walk Test (10MWT) predicted Gait Speed in ST gait (β = 0.692, p < .001) and DT (β = 0.715, p < .001) trials. The Four Square Step Test (FSST) predicted ST Gait Speed (β = - 0.233, p = .034). The Montreal Cognitive Assessment (MoCA) (β = 0.293, p = .027), 10MWT (β = 0.322, p = .046), and the FSST (β = 0.378, p = .019) predicted DTE_GS.

SIGNIFICANCE

The 10MWT, CTMT, and MoCA can be easily implemented in the clinic and may be good choices to assess cognitive and functional abilities necessary for ambulation in older adults.

Acute effects of virtual reality treadmill training on gait and cognition in older adults: A randomized controlled trial

INTRODUCTION

Everyday walking often involves walking with divided attention (i.e., dual-tasking). Exercise interventions for older adults should mimic these simultaneous physical and cognitive demands. This proof-of-concept study had a two-fold purpose: 1) identify acute cognitive and gait benefits of a single session of virtual reality treadmill training (VRTT), relative to conventional treadmill training (CTT), and 2) identify differences between those who reduced dual-task costs (i.e., responders) on gait or cognition and those who did not, after the session.

METHODS

Sixty older adults were randomized to complete a single 30-minute session of VRTT (n = 30, 71.2±6.5 years, 22 females) or CTT (n = 30, 72.0±7.7 years, 21 females). Pre- and post-exercise session, participants performed single-task walking, single-task cognitive, and dual-task walking trials while gait and cognition were recorded. Gait variables were gait speed and gait speed variability. Cognition variables were response reaction time, response accuracy, and cognitive throughput. Dual-task effects (DTE) on gait and cognition variables were also calculated.

RESULTS

Post-exercise, there were no group differences (all p>0.05). During single- and dual-task trials, both groups walked faster (single-task: F(1, 58) = 9.560, p = 0.003; dual-task: F(1, 58) = 19.228, p<0.001), responded more quickly (single-task: F(1, 58) = 5.054, p = 0.028; dual-task: F(1, 58) = 8.543, p = 0.005), and reduced cognitive throughput (single-task: F(1, 58) = 6.425, p = 0.014; dual-task: F(1, 58) = 28.152, p<0.001). Both groups also exhibited reduced DTE on gait speed (F(1, 58) = 8.066, p = 0.006), response accuracy (F(1, 58) = 4.123, p = 0.047), and cognitive throughput (F(1, 58) = 6.807, p = 0.012). Gait responders and non-responders did not differ (all p>0.05), but cognitive responders completed fewer years of education (t(58) = 2.114, p = 0.039) and better information processing speed (t(58) = -2.265, p = 0.027) than cognitive non-responders.

CONCLUSIONS

The results indicate that both VRTT and CTT may acutely improve gait and cognition. Therefore, older adults will likely benefit from participating in either type of exercise. The study also provides evidence that baseline cognition can impact training effects on DTE on cognition.

Pilates and Cognitive Stimulation in Dual Task an Intervention Protocol to Improve Functional Abilities and Minimize the Rate of Age-Related Cognitive Decline in Postmenopausal Women

It is already known the effectiveness of Pilates training on cognitive and functional abilities. It is also known that dual-task exercise and cognitive stimuli improve cognition and functional capacity. However, no previous report combined cognitive stimuli and Pilates in dual task and measured its effects on the cognitive and physical performances of postmenopausal women.

OBJECTIVE

To apply an interventional dual-task (PILATES-COG) protocol and to evaluate its influence on memory, language, and functional physical performances on healthy, community-dwelling postmenopausal older women.

METHODS

47 women with amenorrhea for at least 12 months participated in this study. Those allocated on the PILATES-COG group underwent a 12-week, twice a week regimen of 50 min sessions of simultaneous mat Pilates exercise program and cognitive tasks. Cognitive and physical functional performance were assessed. Two-way mixed ANOVA was used for data analysis, and Bonferroni post hoc tests were used for within- and between-group comparisons.

RESULTS

The PILATES-COG group showed significant improvement after the intervention in semantic verbal fluency (p < 0.001; ηρ² = 0.268), phonological verbal fluency (p < 0.019; ηρ² = 0.143), immediate memory (p < 0.001; ηρ² = 0.258), evocation memory (p < 0.001 ηρ² = 0.282), lower-limb muscle strength (p < 0.001; ηρ² = 0.447), balance (p < 0.001; ηρ² = 0.398), and dual-ask cost (p < 0.05; ηρ² = 0.111) assessments on healthy, community-dwelling postmenopausal older women.

CONCLUSION

This is the first report of a feasible and effective approach using Pilates and cognitive stimulation in dual task for the reduction of age-related cognitive decline and the improvement of physical functional performance in healthy postmenopausal women.

Dual-task interference as a function of varying motor and cognitive demands

Multitasking is a critical feature of our daily lives. Using a dual-task paradigm, this experiment explored adults’ abilities to simultaneously engage in everyday motor and cognitive activities, counting while walking, under conditions varying the difficulty of each of these tasks. Motor difficulty was manipulated by having participants walk forward versus backward, and cognitive difficulty was manipulated by having participants count forward versus backward, employing either a serial 2 s or serial 3 s task. All of these manipulations were performed in single-task conditions (walk only, count only) and dual-task conditions (walk and count simultaneously). Both motor performance variables (cycle time, stride length, walking velocity) and cognitive variables (counting fluency, counting accuracy) were assessed in these conditions. Analyses of single-task conditions revealed that both motor and cognitive manipulations predictably influenced performance. Analyses of dual-task performance revealed influences of motor and cognitive factors on both motor and cognitive performance. Most centrally, dual-task costs (normalized difference between single- and dual-task conditions) for motor variables revealed that such costs occurred primarily for temporal or spatiotemporal gait parameters (cycle time, walking velocity) and were driven by cognitive manipulations. Dual-task cost analyses for cognitive measures revealed negative dual-task costs, or dual-task benefits, for cognitive performance. Finally, the effects of dual-task manipulations were correlated for motor and cognitive measures, indicating dual-task performance as a significant individual difference variable. These findings are discussed with reference to theories of attentional allocation, as well as the possible role of auditory–motor entrainment in dual-task conditions.

Influence of Speech and Cognitive Load on Balance and Timed Up and Go

The interaction between oral and/or mental cognitive tasks and postural control and mobility remains unclear. The aim of this study was to analyse the influence of speech production and cognitive load levels on static balance and timed up and go (TUG) during dual-task activities. Thirty healthy young subjects (25 ± 4 years old, 17 women) participated in this study. A control situation and two different cognitive arithmetic tasks were tested: counting backward in increments of 3 and 7 under oral (O) and mental (M) conditions during static balance and the TUG. We evaluated the dual-task cost (DTC) and the effect of speech production (SP) and the level of cognitive load (CL) on these variables. There was a significant increase in the centre of pressure oscillation velocity in static balance when the dual task was performed orally compared to the control situation The DTC was more pronounced for the O than for the M. The SP, but not the CL, had a significant effect on oscillation velocity. There was an increase in TUG associated with the cognitive load, but the mental or oral aspect did not seem to have an influence. Mobility is more affected by SP when the cognitive task is complex. This may be particularly important for the choice of the test and understanding postural control disorders.

Dual-Task Abilities During Activities Representative of Daily Life in Community-Dwelling Stroke Survivors: A Pilot Study

Background

In addition to several physical skills, being able to walk in the community, walking independently and safely in the community requires the ability to divide attention between walking and other tasks performed simultaneously. The aims of the present pilot study were to measure cognitive-locomotor dual-task (DT) abilities during activities representative of daily living in stroke survivors and to compare them with age- and gender-matched healthy individuals.

Methods

To assess DT abilities, all participants walked along a virtual shopping mall corridor and memorized a 5-item shopping list. Two levels of task complexity were used for the walking task (with or without virtual agents to avoid) and the cognitive task to recall a list of items (with or without a modification at mid-course). The assessment was conducted using an omnidirectional platform and a virtual reality (VR) headset. Locomotor and cognitive DT costs (DTC) were calculated as the percent change from single-task (ST) performance. Walking speed and minimal distance between the participant and the virtual agents were used to characterize locomotor performance. Cognitive performance was assessed by the number of correctly recalled items. One-sample Wilcoxon tests were used to determine the presence of DTCs and Mann-Whitney tests were performed to compare DTCs between the 2 groups.

Results

Twelve community-dwelling stroke survivors [60.50 years old (25-75^th percentiles: 53.50–65.75); 5 women; 13.41 months post-stroke (5.34–48.90)] and 12 age- and gender- matched healthy individuals were recruited. Significant cognitive or mutual (cognitive and locomotor) interferences were observed in participants with stroke in all DT conditions, except the simplest (no virtual agents, no modifications to the list). For the control group, significant mutual interferences were only observed during the most complex DT condition. A group difference was detected in cognitive DTCs during the most complex DT condition (virtual agents and list modifications; p = 0.02). Stroke survivors had greater cognitive DTCs than the control group.

Conclusions

Using an ecological perspective contributes to understanding behavior of stroke survivors in daily activities. Virtual scenarios appear to be an interesting avenue for a more comprehensive understanding of DT abilities during activities representative of daily living in stroke survivors. The usability and feasibility of such an approach will have to be studied before considering implementation in rehabilitation settings.

A Novel Way of Measuring Dual-Task Interference: The Reliability and Construct Validity of the Dual-Task Effect Battery in Neurodegenerative Disease

BACKGROUND

Decreased automaticity is common among individuals with neurodegenerative disease and is often assessed using dual-task (DT) paradigms. However, the best methods for assessing performance changes related to DT demands remain inconclusive.

OBJECTIVE

To investigate the reliability and validity of a novel battery of DT measures (DT Effect-Battery (DTE-B)) encompassing three domains: task-specific interference, task prioritization, and automaticity.

METHODS

Data for this retrospective cross-sectional study included 125 participants with Parkinson's disease (PD), 127 participants with Alzheimer's disease (AD), and 84 healthy older adults. Reliability analyses were conducted using a subset of each population. DTE-B measures were calculated from single and DT performance on the Timed Up and Go test and a serial subtraction task. Construct validity was evaluated via associations within the DTE-B and with theoretically supported measures as well as known-groups validity analyses.

RESULTS

Good to excellent reliability was found for DTE-B measures of task interference (motor and cognitive DT effects) (ICCs≥.658) and automaticity (combined DT effect (cDTE)) (ICCs≥.938). Evidence for convergent validity was found with associations within the hypothesized constructs. Known-groups validity analyses revealed differences in the DTE-B among the healthy group and PD and AD groups (ps≤.001), excepting task prioritization (ps≥.061).

CONCLUSIONS

This study provides evidence to support the DTE-B as a reliable measure of multiple constructs pertinent to DT performance. The cDTE demonstrated evidence to support its validity as a measure of automaticity. Further investigation of the utility of the DTE-B in both PD and AD, as well as other populations, is warranted.

Speech-Language Pathology Incorporating Horses

Incorporating horses into speech-language pathology services is a valid treatment strategy that can be used to help the client achieve their communication and/or swallowing goals. The purpose of this article is to discuss the history and terminology of incorporating horses into rehabilitation, explain theories for why incorporating horses works, and provide clinical applications to the American Speech-Language-Hearing Association's nine areas of practice with clinical reports.

Greater Cognitive-Motor Interference in Individuals Post-Stroke During More Complex Motor Tasks

BACKGROUND AND PURPOSE

Dual-task (DT) walking assessments allow for the simultaneous evaluation of cognitive and motor performance. During DT walking, individuals may experience interference in one or both tasks, known as cognitive-motor interference (CMI). The primary purpose of this study was to compare CMI between individuals post-stroke and healthy persons group during single- and dual-motor and cognitive tasks, using 2 distinct walking tasks.

METHODS

Motor performance was quantified as the total time for the Timed Up and Go (TUG) and gait speed for the 90-second walk (90W). Cognitive performance was measured as the correct response rate (CRR) during serial 7 subtractions. Participants performed the motor and cognitive tasks in isolation for the single-task (ST) and simultaneously for DT conditions, TUG-DT and 90W-DT. A repeated-measures analysis of variance assessed group (poststroke and healthy) by condition (ST and DT) interactions for the TUG, 90W, and CRR.

RESULTS

There were significant main effects of group and condition for both the TUG and the 90W (P < 0.05). There was also an interaction effect for the TUG, with individuals post-stroke demonstrating a larger decrement in TUG-DT performance compared with healthy persons (P < 0.05). Furthermore, a significant interaction effect was observed for the CRR, in which healthy individuals exhibited a greater decrement in performance from the ST to the 90W-DT (P < 0.05).

DISCUSSION AND CONCLUSIONS

Individuals post-stroke were susceptible to greater motor interference during the more complex motor task, the TUG-DT. However, the only decrements observed in cognitive performance from the ST to DT occurred in healthy individuals during the 90W-DT.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A367).

The influence of cognitive load on balance control during steady-state walking

For an individual to successfully walk, they must maintain control of their dynamic balance. However, situations that require increased cognitive attention may impair an individual's ability to actively control their balance. While dual-task studies have analyzed walking-while-talking conditions, few studies have focused specifically on the influence of cognitive load on balance control. The purpose of this study was to assess how individuals prioritize their cognitive resources and control dynamic balance during dual-task conditions of varying difficulty. Young healthy adults (n = 15) performed two single-task conditions (spelling-while-standing and treadmill walking with no cognitive load) and three dual-task conditions (treadmill walking with increasing cognitive load: attentive listening and spelling short and long words backwards). Cognitive performance did not change between the single- and dual-task as measured by spelling percent error and response rate (p = 0.300). Balance control, assessed using the range of whole-body angular momentum, did not change between the no load and listening conditions, but decreased during the short and long spelling conditions (p < 0.001). These results highlight that in young adults balance control decreases during dual-task treadmill walking with increased cognitive loads, but their cognitive performance does not change. The decrease in balance control suggests that participants prioritized cognitive performance over balance control during these dual-task walking conditions. This work offers additional insight into the automaticity of walking and task-prioritization in healthy young individuals and provides the basis for future studies to determine differences in neurologically impaired populations.

Virtual reality-based assessment of cognitive-locomotor interference in healthy young adults

BACKGROUND

A recent literature review emphasized the importance of assessing dual-task (DT) abilities with tasks that are representative of community ambulation. Assessing DT ability in real-life activities using standardized protocols remains difficult. Virtual reality (VR) may represent an interesting alternative enabling the exposure to different scenarios simulating community walking. To better understand dual-task abilities in everyday life activities, the aims of this study were (1) to assess locomotor and cognitive dual-task cost (DTC) during representative daily living activities, using VR, in healthy adults; and 2) to explore the influence of the nature and complexity of locomotor and cognitive tasks on DTC.

METHODS

Fifteen healthy young adults (24.9 ± 2.7 years old, 8 women) were recruited to walk in a virtual 100 m shopping mall corridor, while remembering a 5-item list (DT condition), using an omnidirectional platform and a VR headset. Two levels of difficulty were proposed for the locomotor task (with vs. without virtual agent avoidance) and for the cognitive task (with vs. without items modification). These tasks were also performed in single task (ST) condition. Locomotor and cognitive DTC were measured by comparing performances in ST and DT conditions. Locomotor performance was characterized using walking speed, walking fluidity, and minimal distance between the participant and the virtual agent during avoidance. Cognitive performance was assessed with the number of items correctly recalled. Presence of DTC were determined with one-sample Wilcoxon signed-rank tests. To explore the influence of the tasks' complexity and nature on DTC, a nonparametric two-way repeated measure ANOVA was performed.

RESULTS

No locomotor interference was measured for any of the outcomes. A cognitive DTC of 6.67% was measured (p = .017) while participants performed simultaneously both complex locomotor and cognitive tasks. A significant interaction between locomotor task complexity and cognitive task nature (p = .002) was identified on cognitive DTC.

CONCLUSIONS

In challenging locomotor and cognitive conditions, healthy young adults present DTC in cognitive accuracy, which was influenced by the locomotor task complexity task and the cognitive task nature. A similar VR-based protocol might be used to investigate DT abilities in older adults and individuals with a stroke.

Influence of the environment on cognitive-motor interaction during walking in people living with and without multiple sclerosis

BACKGROUND

Motor and cognitive impairments are highly prevalent in people with multiple sclerosis (pwMS). The current theoretical frameworks of cognitive-motor interaction (CMI) suggest that the environment can influence both motor and cognitive performance during walking. However, the relationship between increasing environmental demands and CMI in pwMS remains to be elucidated.

RESEARCH QUESTION

What is the impact of increased environmental demands on CMI during walking in people living with and without MS?

METHODS

Twenty pwMS and 20 age-matched healthy adults (HA) participated in this cross-sectional study. Participants (age = 57.6 ± 7.8 years) performed four walks (baseline walking (BW), obstacle walking (OW), narrow walking (NW), and narrow with obstacles (NO)) in single-task and dual-task (serial-7 subtraction test) conditions. The dual-task costs (DTC) of gait (% change in walking time) and cognition (% change in correctly verbalized utterances) were calculated to quantify CMI. Secondary outcomes included physiological profile assessment (PPA), measures of cognition and falls efficacy scale international (FES-I).

RESULTS

Mixed-factor ANOVAs revealed no main effect of task (F = 1.71, p = 0.196) and group (F = 0.71, p = 0.406) on DTC of gait, while there were significant main effects of both task (F = 23.75, p < 0.001) and group (F = 6.53, p = 0.015) on DTC of cognition. Simple main effects revealed that pwMS had a significantly higher DTC of cognition during BW (+37.6 %, p=0.013), NW (+34.2 %, p=0.014) and NO (+49 %, p=0.016) compared to HA. Additionally, DTC of cognition increased during the more environmentally demanding conditions compared to BW (range: +28.4 % to +54.2 %, all p-values<0.01) in both pwMS and HA. Only DTCs of cognition were significantly correlated with PPA and FES-I.

SIGNIFICANCE

The study findings suggest that CMI may be influenced by the individual/environment at levels above those described by the more mechanistic theories of attention.