Cognitive motor interference while walking: A systematic review and meta-analysis

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.

The Performance Index Identifies Changes Across the Dual Task Timed Up and Go Test Phases and Impacts Task-Cost Estimation in the Oldest-Old

Introduction: Dual tasking is common in activities of daily living (ADLs) and the ability to perform them usually declines with age. While cognitive aspects influence dual task (DT) performance, most DT-cost (DT-C) related metrics include only time- or speed- delta without weighting the accuracy of cognitive replies involved in the task.

Objectives: The primary study goal was to weight the accuracy of cognitive replies as a contributing factor when estimating DT-C using a new index of DT-C that considers the accuracy of cognitive replies (P-index) in the instrumented timed up and go test (iTUG). Secondarily, to correlate the novel P-index with domains of the Mini-Mental State Examination (MMSE).

Methods: Sixty-three participants (≥85 years old) took part in this study. The single task (ST) and DT iTUG tests were performed in a semi-random order. Both the time taken to complete the task measured utilizing an inertial measurement unit (IMU), and the accuracy of the cognitive replies were used to create the novel P-index. Clinical and sociodemographic data were collected.

Results: The accuracy of the cognitive replies changed across the iTUG phases, particularly between the walk 1 and walk 2 phases. Moreover, weighting 0.6 for delta-time (W₁) and 0.4 for cognitive replies (W₂) into the P-index enhanced the prediction of the MMSE score. The novel P-index was able to explain 37% of the scores obtained by the fallers in the “spatial orientation” and “attention” domains of the MMSE. The ability of the P-index to predict MMSE scores was not significantly influenced by age, schooling, and number of medicines in use. The Bland-Altman analysis indicated a substantial difference between the time-delta-based DT-C and P-index methods, which was within the limits of agreement.

Conclusions: The P-index incorporates the accuracy of cognitive replies when calculating the DT-C and better reflects the variance of the MMSE in comparison with the traditional time- or speed-delta approaches, thus providing an improved method to estimate the DT-C.

Neuroticism and Extraversion Are Related to Changes in Postural Stability During Anatomically-Related Cognitive Tasks

The relationship between personality and postural stability has received little attention. This study addressed whether neuroticism and extraversion correlate with changes in postural stability while performing cognitive tasks related to brain regions selectively associated with neuroticism and extraversion. Thirty-two adults stood on a foam mat in tandem stance and completed a 2-back task and a weather prediction task (WPT). As predicted, higher neuroticism was related to increased dual task sway during the 2-back task, r = 0.40, p = 0.023, and lower extraversion was related to increased dual task sway during the WPT, r = -0.43, p = 0.013, suggesting that personality is related to postural stability in healthy young adults and that personality could be considered in the prediction and treatment of individuals with balance difficulties.

Urinary urgency acts as a source of divided attention leading to changes in gait in older adults with overactive bladder

AIMS

There is a well-recognised but unexplained association between lower urinary tract symptoms including urgency and urgency incontinence and falls in older people. It has been hypothesised that urinary urgency acts as a source of divided attention, leading to gait changes which increase falls risk. This study aimed to assess whether urinary urgency acts as a source of divided attention in older adults with overactive bladder (OAB).

METHODS

27 community-dwelling adults aged 65 years and over with a clinical diagnosis of OAB underwent 3-Dimensional Instrumented Gait Analysis under three conditions; bladder empty, when experiencing urgency, and when being distracted by the n-back test. Temporal-spatial gait and kinematic gait data were compared between each condition using repeated measures ANOVA.

RESULTS

Gait velocity decreased from 1.1ms-1 in the bladder empty condition to 1.0ms-1 with urgency and 0.9ms-1 with distraction (p = 0.008 and p<0.001 respectively). Stride length also decreased, from 1.2m to 1.1m with urgency and 1.0m with distraction (p<0.001 for both). The presence of detrusor overactivity did not influence these results (p = 0.77).

CONCLUSIONS

In older adults with OAB, urinary urgency induced similar changes in gait to those caused by a distracting task. These gait changes are associated with increased fall risk. This may be part of the explanation for the association between falls and lower urinary tract symptoms in older people. Future research should examine the effect of pharmacological treatment of OAB on gait and on the effect of dual-task training on gait when experiencing urgency.

A Dual-Task Paradigm Using the Oral Trail Making Test While Walking to Study Cognitive-Motor Interactions in Older Adults

Objective: With aging, gait becomes more dependent on executive functions, especially on switching abilities. Therefore, cognitive-motor dual-task (DT) paradigms should study the interferences between gait and switching tasks. This study aimed to test a DT paradigm based on a validated cognitive switching task to determine whether it could distinguish older-old adults (OO) from younger-old adults (YO).

Methods: Sixty-five healthy older participants divided into 29 younger-old (<70 years) and 36 older-old (≥70 years) age groups were evaluated in three single-task (ST) conditions as follows: a cognitive task including a processing speed component [Oral Trail Making Test part A (OTMT-A)], a cognitive task including a switching component [Oral Trail Making Test part B (OTMT-B)], and a gait evaluation at normal speed. They were also evaluated under two DT conditions, i.e., one associating gait with OTMT-A and the other associating gait with OTMT-B. Cognitive and gait performances were measured. The comparison of cognitive and gait performances between condition, logistic regression, and receiver operating characteristic (ROC) analyses were performed.

Results: The cognitive and gait performances were differently affected by the different conditions (i.e., ST, DT, OTMT-A, and OTMT-B). The OTMT-B produced higher interference on gait and cognitive performances. Moreover, a higher number of errors on the OTMT-B performed while walking was associated with the older-old age group.

Conclusion: Using validated cognitive flexibility tasks, this DT paradigm confirms the high interference between switching tasks and gait in older age. It is easily implemented, and its sensitivity to age may highlight its possible usefulness to detect cognitive or motor declines.

The effects of a secondary task on gait in axial spondyloarthritis

Studies on the effects of dual tasking in patients with chronic inflammatory rheumatic diseases are limited. The aim of this study was to assess dual tasking while walking in patients with axial spondyloarthritis (axSpA) in comparison to healthy controls. Thirty patients with axSpA and thirty healthy controls underwent a 10-m walk test at a self-selected comfortable walking speed in single- and dual-task conditions. Foot-worn inertial sensors were used to compute spatiotemporal gait parameters. Analysis of spatiotemporal gait parameters showed that the secondary manual task negatively affected walking performance in terms of significantly decreased mean speed (p < 0.001), stride length (p < 0.001) and swing time (p = 0.008) and increased double support (p = 0.002) and stance time (p = 0.008). No significant interaction of group and condition was observed. Both groups showed lower gait performance in dual task condition by reducing speed, swing time and stride length, and increasing double support and stance time. Patients with axSpA were not more affected by the dual task than matched healthy controls, suggesting that the secondary manual task did not require greater attention in patients with axSpA. Increasing the complexity of the walking and/or secondary task may increase the sensitivity of the dual-task design to axial spondyloarthritis.

Task matters: an investigation on the effect of different secondary tasks on dual-task gait in older adults

Background

Dual-task gait performance declines as humans age, leading to increased fall risk among older adults. It is unclear whether different secondary cognitive tasks mediate age-related decline in dual-task gait. This study aimed to examine how type and difficulty level of the secondary cognitive tasks differentially affect dual-task gait in older adults.

Methods

Twenty young and twenty older adults participated in this single-session study. We employed four different types of secondary tasks and each consisted of two difficulty levels, yielding eight different dual-task conditions. The dual-task conditions included walking and 1) counting backward by 3 s or by 7 s; 2) remembering a 5-item or 7-item lists; 3) responding to a simple or choice reaction time tasks; 4) generating words from single or alternated categories. Gait speed and cognitive task performance under single- and dual-task conditions were used to compute dual-task cost (DTC, %) with a greater DTC indicating a worse performance.

Results

A significant three-way interaction was found for the gait speed DTC (p = .04). Increased difficulty in the reaction time task significantly increased gait speed DTC for older adults (p = .01) but not for young adults (p = .90). In contrast, increased difficulty level in the counting backward task significantly increased gait speed DTC for young adults (p = .03) but not for older adults (p = .85). Both groups responded similarly to the increased task difficulty in the other two tasks.

Conclusions

Older adults demonstrated a different response to dual-task challenges than young adults. Aging might have different impacts on various cognitive domains and result in distinctive dual-task gait interference patterns.

High Sensory Responsiveness in Older Adults is Associated with Walking Outside but Not Inside: Proof of Concept Study

Background and Purpose

Reduced mobility and a higher risk of falls among older adults are related to aging-associated sensory alteration. Sensory responsiveness (SR) has been found to be strongly correlated with postural control in studies on young adults in stimulating environments; however, SR has not been studied in the context of mobility among older adults, despite its potential to enhance fall risks. The aim of the current study is to characterize the associations between SR and gait under single and dual-task (ST, DT) conditions inside and outside the laboratory.

Methods

Twenty-six community-dwelling older adults (age 70.3 ± 4.6 years, 65.4% women) participated in this cross-sectional study. Gait variables were measured using the APDM system under single and dual task conditions, in a quiet corridor inside and in an ecological (outside) environment. SR was evaluated using the SR questionnaire and cognition was assessed with the Trail-Making Test and the Montreal Cognitive Assessment.

Results

SR was negatively associated with gait speed during ST (r_s = −0.491, p < 0.05) and DT (r_s = −0.528, p < 0.01) outside and with ST gait speed inside (r_s = −0.528, p < 0.01). SR was positively associated with gait variability under DT (r_s = 0.41, p < 0.05) and with DT cost (r_s = 0.44, p < 0.05) only outside.

Conclusion

SR may play an important role in understanding mobility deterioration throughout the aging process, especially outside, illuminating the importance of SR evaluation among older adults during mobility assessment. Therefore, accounting for SR in gait research may contribute to a better understanding of mobility decline throughout the aging process.

Modifications in Prefrontal Cortex Oxygenation in Linear and Curvilinear Dual Task Walking: A Combined fNIRS and IMUs Study

Increased oxygenated hemoglobin concentration of the prefrontal cortex (PFC) has been observed during linear walking, particularly when there is a high attention demand on the task, like in dual-task (DT) paradigms. Despite the knowledge that cognitive and motor demands depend on the complexity of the motor task, most studies have only focused on usual walking, while little is known for more challenging tasks, such as curved paths. To explore the relationship between cortical activation and gait biomechanics, 20 healthy young adults were asked to perform linear and curvilinear walking trajectories in single-task and DT conditions. PFC activation was assessed using functional near-infrared spectroscopy, while gait quality with four inertial measurement units. The Figure-of-8-Walk-Test was adopted as the curvilinear trajectory, with the "Serial 7s" test as concurrent cognitive task. Results show that walking along curvilinear trajectories in DT led to increased PFC activation and decreased motor performance. Under DT walking, the neural correlates of executive function and gait control tend to be modified in response to the cognitive resources imposed by the motor task. Being more representative of real-life situations, this approach to curved walking has the potential to reveal crucial information and to improve people' s balance, safety, and life's quality.

Negative Effects of Embodiment in a Visuo-Spatial Working Memory Task in Children, Young Adults, and Older Adults

Studies examining the effect of embodied cognition have shown that linking one's body movements to a cognitive task can enhance performance. The current study investigated whether concurrent walking while encoding or recalling spatial information improves working memory performance, and whether 10-year-old children, young adults, or older adults (M age = 72 years) are affected differently by embodiment. The goal of the Spatial Memory Task was to encode and recall sequences of increasing length by reproducing positions of target fields in the correct order. The nine targets were positioned in a random configuration on a large square carpet (2.5 m × 2.5 m). During encoding and recall, participants either did not move, or they walked into the target fields. In a within-subjects design, all possible combinations of encoding and recall conditions were tested in counterbalanced order. Contrary to our predictions, moving particularly impaired encoding, but also recall. These negative effects were present in all age groups, but older adults' memory was hampered even more strongly by walking during encoding and recall. Our results indicate that embodiment may not help people to memorize spatial information, but can create a dual-task situation instead.

Influence of Different Dual-Task Conditions During Straight or Curved Walking on Gait Performance of Physically Active Older Women With Cognitive Decline

Real-world walking requires shifting attention from different cognitive demands to adapt gait. This study aims to evaluate the effect of dual tasking on spatiotemporal gait parameters of older adults. Participants were asked to perform a primary complex single-walking task, consisting of a fast-paced linear and a curved gait. Primary task was performed separately and simultaneously with different motor and cognitive secondary tasks. Spatiotemporal gait parameters, walk ratio, and walk stability ratio were measured. Apart from stride length, which stood relatively unchanged, gait speed and cadence were strongly affected by cognitive dual tasking. Cadence seems to be the most impacted by dual tasking during curved gait as it combines challenges of both primary and secondary tasks. Also, during curved phase, walking ratio was significantly lower and stability ratio was greater demonstrating that participants adopted a cautious gait where maintenance of stability took preference over efficiency.

Dual task walking costs in older adults with mild cognitive impairment: a systematic review and meta-analysis

OBJECTIVE

The objective of this systematic review and meta-analysis (PROSPERO registration No CRD42020192121) is to review existing literature focusing on effects of different dual task paradigms on walking speed in older adults with and without Mild Cognitive Impairment.

METHODS

(1) Data Sources: PubMEd, Cumulative Index of Nursing and Allied Health, Cochrane library, and Web of Science. (2) Study Selection: The key terms searched included those associated with dual task, walking speed, executive function, older adults, and MCI. (3) Data Extraction: The search yielded 140 results with 20 studies meeting the inclusion criteria, which were rated by two independent reviewers using the Quality Assessment Tool. Descriptions of each study including the single and dual task protocol, outcome measure, and final outcomes were extracted. Meta-analysis was performed to evaluate the dual task effects on walking costs in older adults with and without MCI.

RESULTS

Meta-analysis revealed that there were significant differences in the dual task walking costs among older adults with or without MCI (p < .05). Pooled effect sizes of the serial subtraction (9.54; 95%CI, 3.93-15.15) and verbal fluency tasks (10.06; 95%CI, 6.26-15.65) showed that there are higher motor dual-task costs in older adults with MCI than age-matched controls. For quality assessment, all studies ranged from 12 to 16 in score, out of 18 (high quality).

CONCLUSIONS

In the studies included in this review, mental tracking tasks, consisting of serial subtraction and verbal fluency, were found to be the most sensitive in detecting MCI-related changes in older adults, and could serve an important role as a target measure for evaluating the efficacy of interventions aimed at improving cognitive and motor function in older adults.

Dual-task treadmill walking at self-paced versus fixed speeds

BACKGROUND

Investigating cognitive-motor interference on the treadmill allows for better examination of motor adaptation to the dual-task challenges through the information of continuous strides. However, one of the major critiques for conducting dual-task investigation on a treadmill is the use of a constant, fixed walking speed, constraining the natural fluctuations of the speed of human walking, which could be addressed by using the self-paced feature of a feedback-controlled treadmill.

RESEARCH QUESTION

Do people use different adaptation and task prioritization strategies during the dual-task treadmill walking at self-paced versus fixed speeds?

METHODS

Eighteen healthy younger participants walked on an instrumented treadmill (1) under two speed conditions: self-paced and fixed-speed, and (2) with and without each of the four different cognitive tasks. Dynamic margins of stability (MOS), step spatiotemporal measures, kinematic variability, and local dynamic stability were computed for each trial.

RESULTS

Participants had significantly more local instability during self-paced than fixed-speed treadmill walking. The often-reported response of reducing stride time variability during dual-task, fixed-speed walking was not observed during dual-task, self-paced walking. In addition, there were significantly greater dual-task interference effects on stride time variability and local dynamic stability as well as the Paced Auditory Serial Addition Test performance during self-paced walking. Reduced variability in the lower-extremity joint angles, trunk motion and position, and MOS measures were observed both in dual-task, self-paced and fixed-speed walking.

SIGNIFICANCE

Healthy younger adults had different task prioritization and greater dual-task effects on gait stability and cognitive performance during self-paced versus fixed-speed walking. However, similar adaptation strategies, in terms of gait adjustments, were used for the two walking conditions. The results suggest that self-paced treadmill walking is more challenging than the fixed-speed walking and can serve as a better alternative to the overground walking than the fixed-speed walking for the dual-task investigation.

Obstacle Avoidance and Dual-Tasking During Reaching While Standing in Patients With Mild Chronic Stroke

Background. Poststroke individuals use their paretic arms less often than expected in daily life situations, even when motor recovery is scored highly in clinical tests. Real-world environments are often unpredictable and require the ability to multitask and make decisions about rapid and accurate arm movement adjustments. Objective. To identify whether and to what extent cognitive-motor deficits in well-recovered individuals with stroke affect the ability to rapidly adapt reaching movements in changing cognitive and environmental conditions. Methods. Thirteen individuals with mild stroke and 11 healthy controls performed an obstacle avoidance task in a virtual environment while standing. Subjects reached for a virtual juice bottle with their hemiparetic arm as quickly as possible under single- and dual-task conditions. In the single-task condition, a sliding glass door partially obstructed the reaching path of the paretic arm. A successful trial was counted when the subject touched the bottle without the hand colliding with the door. In the dual-task condition, subjects repeated the same task while performing an auditory-verbal working memory task. Results. Individuals with stroke had significantly lower success rates than controls in avoiding the moving door in single-task (stroke: 51.8 ± 21.2%, control: 70.6 ± 12.7%; P = .018) and dual-task conditions (stroke: 40.0 ± 27.6%, control: 65.3 ± 20.0%; P = .015). Endpoint speed was lower in stroke subjects for successful trials in both conditions. Obstacle avoidance deficits were exacerbated by increased cognitive demands in both groups. Individuals reporting greater confidence using their hemiparetic arm had higher success rates. Conclusion. Clinically well-recovered individuals with stroke may have persistent deficits performing a complex reaching task.

Effect of Dual Task on Step Variability during Stepping in Place without Vision

Stepping in place without vision is a spatial orientation task that is associated with unperceived foot displacements. This study was aimed at determining whether foot displacement variability is modified by a concurrent cognitive task. Fourteen young adults stepped for 50 steps with their vision blocked and performed a continuous mental counting task. 3-D Kinematic data from both feet (heel and big toe) was recorded. The variability of foot displacements was either unchanged or slightly lower in dual task, while the foot displacements were significantly shorter (p < 0.05) in dual task than without the cognitive task. The results suggest that the concurrent cognitive task might have allowed a better control of the repetitive lower limb movements.

Mobile Phone Use during Gait: The Role of Perceived Prioritization and Executive Control

(1) Background: Mobile phone use during gait is associated with adverse health outcomes, namely increased risk of pedestrian injury. Healthy individuals can voluntarily prioritize concurrent task performance, but the factors underlying the impact of phone use during walking remain largely unknown. Thus, the objective of this work was to evaluate the relationship between subjective (perceived) prioritization, cognitive flexibility and dual-task performance when using a mobile phone during walking. (2) Methods: Thirty young participants walked for one minute with and without reading or texting on a mobile phone, as well as reading or texting while sitting. Walking performance (kinematics) was recorded, as well as phone use (text comprehension, text read/written), mental workload, perceived prioritization (visual analog scale), and cognitive flexibility (trail-making test). (3) Results: Texting while walking was associated with larger decreases in gait speed, larger gait variability, higher mental workload, and lower text comprehension compared to reading. Perceived prioritization was associated with walking dual-task costs (DTCs) (r = 0.39–0.42, p < 0.04) when texting, and better cognitive flexibility was associated with lower gait DTCs when texting (r = 0.55, p = 0.002) but not reading. (4) Conclusions: The context-dependent link between perceived prioritization, cognitive flexibility, and walking DTCs promotes our understanding of the factors underlying texting-while-walking performance. This could identify individuals who are more prone to dual-task interference in this increasingly common and dangerous task.

Attentional demands of cane-free walking and cane walking in subacute stroke patients who have just learned to walk without a cane

This study compared the attentional demands between cane-free walking and cane walking in patients with stroke during the transitional period of cane weaning. Patients with stroke who had just learned to walk cane-free were recruited. Cross-sectional measurement was scheduled within 30 days since the patients were able to walk independently without a quad cane. The dual-tasking paradigm required participants to walk with and without a cane, as well as perform continuous subtractions by 1 s (low-demand) or 3 s (high-demand). The cognitive-motor interference (CMI) of walking velocity was calculated as [(low-demand - high-demand)/low-demand]  × 100%. Nine participants (average age, 53.4 ± 6.4 years; stroke onset, 38-131 days) were recruited, and eight showed positive CMI. The paired t-test confirmed a significantly smaller CMI during cane-free walking than during cane walking [t (8) = -3.168; P = 0.013]. The Pearson correlation tests revealed associations between age and CMI of cane walking (r = 0.751; P = 0.010) and CMI of cane-free walking (r = 0.584; P = 0.050). The time since independent cane-free walking was associated with CMI of cane walking (r = 0.699; P = 0.018). In conclusion, experience with cane-free walking leads to increased attentional demand for cane walking. In subacute stroke patients weaning use of a cane, the attentional demand for cane-free walking decreases to less than that of cane walking. During both cane and cane-free walking, the older the participant, the more the walking performance deteriorated due to dual-tasking.

An interrater reliability study of gait analysis systems with the dual task paradigm in healthy young and older adults

Background and aims

One reason for the controversial discussion of whether the dual task (DT) walking paradigm has an added value for diagnosis in clinical conditions might be the use of different gait measurement systems. Therefore, the purpose was 1) to detect DT effects of central gait parameters obtained from five different gait analysis devices in young and old adults, 2) to assess the consistency of the measurement systems, and 3) to determine if the absolut and proportional DT costs (DTC) are greater than the system-measurement error under ST.

Methods

Twelve old (72.2 ± 7.9y) and 14 young adults (28.3 ± 6.2y) walked a 14.7-m distance under ST and DT at a self-selected gait velocity. Interrater reliability, precision of the measurement and sensitivity to change were calculated under ST and DT.

Results

An age effect was observed in almost all gait parameters for the ST condition. For DT only differences for stride length (p < .029, ɳ²_p = .239) as well as single and double limb support (p = .036, ɳ²_p = .227; p = .034, ɳ²_p = .218) remained. The measurement systems showed a lower absolute agreement compared to consistency across all systems.

Conclusions

When reporting DT effects, the real changes in performance and random measurement errors should always be accounted for. These findings have strong implications for interpreting DT effects.

Relating Self-Reported Balance Problems to Sensory Organization and Dual-Tasking in Chronic Traumatic Brain Injury

BACKGROUND

Individuals who have experienced a traumatic brain injury (TBI) often have residual balance problems. It remains unclear whether these balance problems are driven by vestibular dysfunction or gait automaticity deficits, particularly in the chronic stages of TBI recovery, because most studies include only acute/subacute cases.

OBJECTIVES

Compare performance on the Sensory Organization Test vestibular score and Dual-Task test in individuals with and without subjective balance problems at least 1 year after a TBI. Investigate the ability of each test to predict perceived balance problems.

DESIGN

Prospective cohort study.

SETTING

Rehabilitation department within a single institution.

PARTICIPANTS

Fifty adults (21-71 years) with a history of mild, moderate, or severe TBI 1 to 5 years following nonpenetrating TBI.

INTERVENTIONS

N/A.

METHODS

Measures included the Dual-Task test, Sensory Organization Test, Neurobehavioral Symptom Inventory, Dizziness Handicap Inventory, and assessments of four cognitive domains and depression. Participants who endorsed "feeling dizzy" and "loss of balance" on the Neurobehavioral Symptom Inventory were classified as symptomatic (n = 26) and others as asymptomatic (n = 24). T-tests, chi-square, and regression analyses predicting the Dizziness Handicap Inventory total score were performed.

RESULTS

Dual-task gait cost was negatively associated with the Dizziness Handicap Inventory (P = .044), controlling for depression and gender, whereas vestibular scores failed to predict balance-related disability. Symptomatic individuals endorsed more balance problems (P < .001) and depression symptoms (P = .007), had poorer dual-task cognitive output (P = .036), and slower dual-task gait velocity (P = .036) than asymptomatic participants. Groups did not differ on Sensory Organization Test scores.

CONCLUSIONS

The nature of balance problems in chronic TBI may be related to automaticity of gait. These findings suggest that patients in the chronic stages of TBI may benefit from dual-task assessments and interventions. Balance rehabilitation should be tailored to patient needs and assess cognition and affect.

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

OBJECTIVES

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

DESIGN

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

RESULTS AND CONCLUSIONS

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

Effects of cognitive workload on heart and locomotor rhythms coupling

Different physiological signals could be coupled under specific conditions, in some cases related to pathologies or reductions in system complexity. Cardiac-locomotor synchronization (CLS) has been one of the most investigating coupling. The influence of a cognitive task on walking was investigated in dual-task experiments, but how different cognitive tasks may influence CLS has poorly been investigated. Twenty healthy subjects performed a dual-task walking (coupled with verbal fluency vs calculation) on a treadmill at three different speeds (comfortable speed CS; fast-speed: CS + 2 km/h; slow-speed: CS-2 km/h) while cardiac and walking rhythms were recorded using surface electrodes and a triaxial accelerometer, respectively. According to previous studies, we found a cognitive-motor interference for which cognitive performance was affected by motor exercise, but not vice-versa. We found a CLS at the baseline condition, at fast speed in both cognitive tasks, while at comfortable speed only for the verbal fluency task. In conclusion, the cardiac and locomotor rhythms were not coupled at slow speed and at comfortable speed during subtraction task. Cognitive performances generally increased at faster speed, when cardiac locomotor coupling was stronger.

Overload of anxiety on postural control impairments in chronic stroke survivors: The role of external focus and cognitive task on the automaticity of postural control

Background

Despite the high prevalence of anxiety among chronic stroke survivors and evidence of its negative effects on postural control in healthy subjects, it is unclear whether anxiety also affects postural control in these patients. Recent evidence of improved postural control of healthy subjects by distracting the attention using an external focus (EF) or cognitive task, raises the question of whether similar benefits would be observed in stroke survivors. Thus, the current study aimed to investigate the effects of anxiety and distracting the attention on postural control of chronic stroke survivors in terms of both postural sway measures and neuromuscular regulation.

Methods

Postural sway measures and ankle muscle activity of chronic stroke survivors with the high and low level of anxiety (HA-stroke (n = 17), and LA-stroke (n = 17), respectively) and age-, sex-, height-, and weight-matched healthy subjects (n = 17) were assessed while standing on rigid and foam surfaces under following conditions: baseline, internal focus (IF), EF, simple and hard cognitive tasks (SC and HC, respectively).

Results

Stroke survivors, particularly HA-stroke participants, showed greater postural sway measures (i.e. postural instability) and enhanced co-contraction of ankle muscles (i.e. stiffening of the neuromuscular system) compared with healthy subjects. As opposed to baseline and IF conditions, postural instability and neuromuscular stiffening significantly reduced in EF condition and decreased more in cognitive task conditions, particularly HC condition.

Conclusions

The results suggest that anxiety enhances stroke-induced postural instability promoting improper neuromuscular control of posture with stiffening strategy, which can be alleviated by EF and cognitive tasks.

Computerized Dual-Task Testing of Gait Visuomotor and Cognitive Functions in Parkinson's Disease: Test-Retest Reliability and Validity

BACKGROUND

Mobility and cognitive impairments in Parkinson's disease (PD) often coexist and are prognostic of adverse health events. Consequently, assessment and training that simultaneously address both gait function and cognition are important to consider in rehabilitation and promotion of healthy aging. For this purpose, a computer game-based rehabilitation treadmill platform (GRP) was developed for dual-task (DT) assessment and training.

OBJECTIVE

The first objective was to establish the test-retest reliability of the GRP assessment protocol for DT gait, visuomotor and executive cognitive function in PD patients. The second objective was to examine the effect of task condition [single task (ST) vs. DT] and disease severity (stage 2 vs. stage 3) on gait, visuomotor and cognitive function.

METHODS

Thirty individuals aged 55 to 70 years, diagnosed with PD; 15 each at Hoehn and Yahr scale stage 2 (PD-2) and 3 (PD-3) performed a series of computerized visuomotor and cognitive game tasks while sitting (ST) and during treadmill walking (DT). A treadmill instrumented with a pressure mat was used to record center of foot pressure and compute the average and coefficient of variation (COV) of step time, step length, and drift during 1-min, speed-controlled intervals. Visuomotor and cognitive game performance measures were quantified using custom software. Testing was conducted on two occasions, 1 week apart.

RESULTS

With few exceptions, the assessment protocol showed moderate to high intraclass correlation coefficient (ICC) values under both ST and DT conditions for the spatio-temporal gait measures (average and COV), as well as the visuomotor tracking and cognitive game performance measures. A significant decline in gait, visuomotor, and cognitive game performance measures was observed during DT compared to ST conditions, and in the PD-3 compared to PD-2 groups.

CONCLUSION

The high to moderate ICC values along with the lack of systematic errors in the measures indicate that this tool has the ability to repeatedly record reliable DT interference (DTI) effects over time. The use of interactive digital media provides a flexible method to produce and evaluate DTI for a wide range of executive cognitive activities. This also proves to be a sensitive tool for tracking disease progression.

CLINICAL TRIAL REGISTRATION

www.ClinicalTrials.gov, identifier NCT03232996.

Cognitive Load Impairs Time to Initiate and Complete Shooting Tasks in ROTC Members

INTRODUCTION

Multitasking typically requires an individual to simultaneously process cognitive information while performing a motor task. Cognitive motor interference (CMi) is encountered when cognitive challenges negatively impact motor task performance. Military personnel encounter cognitively taxing situations, especially during combat or other tactical performance scenarios, which may lead to injury or motor performance deficits (i.e., shooting inaccuracy, delayed stimulus-response time, and slowed movement speed). The purpose of the current study was to develop four cognitive motor shooting paradigms to determine the effects of cognitive load on shooting performance in healthy Reserve Officers' Training Corps (ROTC) cadets.

METHODS

Thirty-two healthy collegiate ROTC members (24 male and 8 female; 20.47 ± 1.24 years, 174.95 ± 10.58 cm, and 77.99 ± 13.90 kg) were recruited to complete four simulated shooting tasks with additional "motor" challenge (180° turn, gait, weighted, and unweighted landing) and with and without a "cognitive" decision-making challenge requiring response selection and inhibition to both auditory and visual stimuli, totaling eight multi-task cognitive motor shooting conditions. The current study was approved by the university's Institutional Review Board. Task initiation (seconds), task completion (seconds), and number of misses were calculated to determine marksmanship efficiency and accuracy. For each task, a multivariate repeated-measures analysis of variance (ANOVA) was conducted for the combined dependent variables. If the overall multivariate repeated-measures ANOVA was significant, follow-up univariate ANOVAs were conducted for each dependent variable. Alpha was set at α = 0.05 for all analyses.

RESULTS

Task initiation increased for the cognitive condition for the 180° turn (4.29 ± 1.22 seconds baseline, 5.09 ± 1.39 seconds cognitive; P < .05), gait (2.76 ± .60 seconds baseline, 3.93 ± .62 seconds cognitive; P < .05), unweighted (1.27 ± .57 seconds baseline, 3.39 ± .63 seconds cognitive; P < .05), and weighted landing (1.46 ± .72 seconds baseline, 3.35 ± .60 seconds cognitive; P < .05). Task completion time increased for the cognitive condition for the 180° turn (3.48 ± 1.53 seconds baseline, 4.85 ± 1.24 seconds cognitive; P < .05), gait (7.84 ± 2.07 seconds baseline, 9.23 ± 1.76 seconds cognitive; P < .05), unweighted (5.98 ± 1.55 seconds baseline, 7.45 ± 1.51 seconds cognitive; P < .05), and weighted landing (6.09 ± 1.42 seconds baseline, 7.25 ± 1.79 seconds cognitive; P < .05). There were no statistically significant differences in the number of misses for any of the tasks between conditions (P > .05).

CONCLUSIONS

The addition of a cognitive load increased both task initiation and task completion times during cognitive motor simulated shooting. Adding cognitive loads to tactical performance tasks can result in CMi and negatively impact tactical performance. Thus, consideration for additional cognitive challenges into training may be warranted to reduce the potential CMi effect on tactical performance.

A combined stepping and visual tracking task predicts cognitive decline in older adults better than gait or visual tracking tasks alone: a prospective study

BACKGROUND

It is unclear whether motor-cognitive dual tasks predict cognitive decline better than either motor or cognitive tasks alone.

AIMS

To examine the utility of the novel motor-cognitive dual-task test [Stepping Trail Making Test (S-TMT)], as a predictor of cognitive decline, and compare its predictive performance with single motor or cognitive tests.

METHODS

This 2-year population-based prospective study included 626 adults aged ≥ 70 years from Takashimadaira, Itabashi, Tokyo. The S-TMT measured the time taken to step on 16 numbers in order. Gait speed and TMT-A were assessed with standardized methods as single motor and cognitive tasks, respectively. A decline in the Mini-Mental State Examination score by ≥ 3 points over 2 years was defined as a significant cognitive decline.

RESULTS

Over 2 years, 97 (15.5%) experienced cognitive decline. After adjusting for confounders, binary logistic regression models showed no significant associations between gait speed, TMT-A time tertiles, and risk of cognitive decline, but participants in the longest tertile of S-TMT time were more likely to develop cognitive decline than those of the shortest tertile (odds ratio 2.14; 95% confidence interval 1.17-3.90). Only the addition of the S-TMT time to the covariates model significantly improved the reclassification indices for predicting cognitive decline (net reclassification improvement: 0.31, P < 0.01; integrated discrimination improvement: 0.01, P = 0.02).

DISCUSSION AND CONCLUSION

Only the S-TMT was significantly associated with cognitive decline and improved reclassification indices, indicating that it is more useful for predicting cognitive decline than individual gait speed or visual tracking tests alone.

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.

A multimodal approach using TMS and EEG reveals neurophysiological changes in Parkinson's disease

INTRODUCTION

Alterations in large scale neural networks leading to neurophysiological changes have been described in Parkinson's disease (PD). The combination of transcranial magnetic stimulation (TMS) and electroencephalography (EEG) has been suggested as a promising tool to identify and quantify neurophysiological mechanisms. The aim of this study was to investigate specific changes in electrical brain activity in response to stimulation of four brain areas in patients with PD.

METHODS

21 healthy controls and 32 patients with PD underwent a combined TMS-EEG assessment that included stimulation of four brain areas: left M1, right M1, left dorso-lateral prefrontal cortex (DLPFC), and right DLPFC. Six measures were calculated to characterize the TMS evoked potentials (TEP) using EEG: (1) wave form adherence (WFA), (2) late phase deflection (LPD), (3) early phase deflection (EPD), (4) short-term plasticity (STP), (5) inter-trial adherence, and (6) connectivity between right and left M1 and DLPFC. A Linear mixed-model was used to compare these measures between groups and areas stimulated.

RESULTS

Patients with PD showed lower WFA (p = 0.052), lower EPD (p = 0.009), lower inter-trial adherence (p < 0.001), and lower connectivity between homologs areas (p = 0.050), compared to healthy controls. LPD and STP measures were not different between the groups. In addition, lower inter-trial adherence correlated with longer disease duration (r = -0.355, p = 0.050).

CONCLUSIONS

Our findings provide evidence to various alterations in neurophysiological measures in patients with PD. The higher cortical excitability along with increased variability and lower widespread of the evoked potentials in PD can elucidate different aspects related to the pathophysiology of the disease.

Caffeine consumption improves motor and cognitive performances during dual tasking in middle-aged women

The aim of the present study was to explore the effect of caffeine consumption (CC) on cognitive motor interference while walking and maintaining balance in middle-aged women. Twenty middle-aged women (52 ± 2.0 years; height 158 ± 2.0 cm; body mass 77 ± 14.9 kg; body mass index ±3.4 kg/m², mean ± SD) participated in this study. Participants completed measures of a single task (ST) cognitive, a ST motor and a dual task (DT) cognitive-motor tests before and after either caffeine (100 mg) or placebo ingestion. Results showed that before CC, both motor (P < 0.0005) and cognitive (P < 0.05) performances decreased in the DT condition compared to the ST one. After CC, no significant difference in the motor performances between ST and DT conditions was observed. In fact, both standing and walking DT performances were improved as indicated by a significant (P < 0.05) decrease in the dual task cost (DTC) of motor performances. In conclusion, middle-aged women showed difficulties to manage DT situations in which a cognitive and a motor task must be performed concurrently. Caffeine is an effective ergogenic aid to improve both cognitive and motor performances during DT conditions and could be an alternative to nullify the deteriorating effect of DT when maintaining balance and walking in middle-aged women. These enhancements could offer great potential for everyday functioning.

Dual-Motor-Task of Catching and Throwing a Ball During Overground Walking in Virtual Reality

Virtual Reality is a versatile platform to study human behavior in simulated environments and to develop interventions for functional rehabilitation. In this work, we designed a dual-task paradigm in a virtual environment where both tasks demand motor skills. Twenty-one healthy adults (mean age: 24.1 years) participated in this study. The experiment involved three conditions - normal overground walking, catch and throw a ball while standing, and catch and throw a ball while walking overground -all in the virtual environment. We investigated the dual-task gait characteristics and their correlations with outcomes from cognitive assessments. Results show that subjects walk conservatively with smaller stride lengths, larger stride widths and stride time while catching and throwing. However, they are able to throw the balls more accurately at the target and achieve higher scores. During the dual-task throw, we observed that the participants threw more balls during the stance phase of the gait when the foot was in the terminal stance and pre-swing region. During this region, the body has forward momentum. In addition, the changes in gait characteristics during dual-task throw correlate well with outcome measures in standardized cognitive tests. This study provides a new and engaging paradigm to analyze dual-motor-task cost in a virtual reality environment and it can be used as a basis to compare strategies adopted by different population groups with healthy young adults to execute coordinated motor tasks.

How groove in music affects gait

Rhythmic auditory stimulation (RAS) is a gait intervention in which gait-disordered patients synchronise footsteps to music or metronome cues. Musical 'groove', the tendency of music to induce movement, has previously been shown to be associated with faster gait, however, why groove affects gait remains unclear. One mechanism by which groove may affect gait is that of beat salience: music that is higher in groove has more salient musical beats, and higher beat salience might reduce the cognitive demands of perceiving the beat and synchronizing footsteps to it. If groove's effects on gait are driven primarily by the impact of beat salience on cognitive demands, then groove's effects might only be present in contexts in which it is relevant to reduce cognitive demands. Such contexts could include task parameters that increase cognitive demands (such as the requirement to synchronise to the beat), or individual differences that may make synchronisation more cognitively demanding. Here, we examined whether high beat salience can account for the effects of high-groove music on gait. First, we increased the beat salience of low-groove music to be similar to that of high-groove music by embedding metronome beats in low and high-groove music. We examined whether low-groove music with high beat salience elicited similar effects on gait as high-groove music. Second, we examined the effect of removing the requirement to synchronise footsteps to the beat (i.e., allowing participants to walk freely with the music), which is thought to remove the cognitive demand of synchronizing movements to the beat. We tested two populations thought to be sensitive to the cognitive demands of synchronisation, weak beat-perceivers and older adults. We found that increasing the beat salience of low-groove music increased stride velocity, but strides were still slower than with high-groove music. Similarly, removing the requirement to synchronise elicited faster, less variable gait, and reduced bias for stability, but high-groove music still elicited faster strides than low-groove music. These findings suggest that beat salience contributes to groove's effect on gait, but it does not fully account for it. Despite reducing task difficulty by equalizing beat salience and removing the requirement to synchronise, high-groove music still elicited faster, less variable gait. Therefore, other properties of groove also appear to play a role in groove's effect on gait.

Cognitive-motor Interference in Individuals With a Neurologic Disorder: A Systematic Review of Neural Correlates

BACKGROUND

Performing a cognitive task and a motor task simultaneously is an everyday act that can lead to decreased performance on both tasks.

OBJECTIVE

To provide insight into the neural correlates associated with cognitive-motor dual tasking in individuals with a neurologic disorder.

METHOD

We searched the PubMed and Web of Science databases for studies that had been published up to January 16th, 2019. Studies investigating the neural correlates of cognitive-motor dual task performance in individuals with a variety of neurologic disorders were included, independently from whether the study included healthy controls. Clinical and imaging data were abstracted for the comparison between single tasks and a dual task in the individuals with a neurologic disorder and for the comparison between the healthy controls and the individuals with a neurologic disorder.

RESULTS

Eighteen studies met the inclusion criteria. Study populations included individuals with Parkinson disease, multiple sclerosis, mild cognitive impairment, Alzheimer disease, traumatic brain injury, and stroke. Neuroimaging types used to study the neural correlates of cognitive-motor dual tasking during upper limb or gait tasks included fMRI, functional near-infrared spectroscopy, EEG, and PET.

CONCLUSION

Despite large heterogeneity in study methodologies, some recurrent patterns were noted. Particularly, in neurologic patients, an already higher brain activation during single tasks was seen compared with healthy controls, perhaps compromising the patients' ability to further adapt brain activation with increasing load during dual tasking and resulting in reduced behavioral dual task performance.

Compromised cognition, but not stepping-down performance, when dual-tasking in stroke survivors

Descending stairs is an indicator of independence among stroke survivors, but is demanding in terms of both neuromuscular control and cognitive functioning. Previous studies found a compromised performance when stepping down with a concurrent cognitive task among healthy older adults, but whether stroke survivors react similarly is not known. This cross-sectional study thus investigated how stroke survivors responded to a dual-task that involved stepping down and compared their performance with that of control subjects. Thirty-four healthy individuals and 26 stroke survivors reacted to an auditory Stroop test while stepping off a 19-cm high platform. The auditory Stroop test was evaluated with a composite score (dividing accuracy by averaged reaction time). Stepping down performances were quantified with subjects' sway amplitudes in anteroposterior and mediolateral directions after landing and sway velocities of their center of pressure. Stroke survivors demonstrated significantly lower composite scores when dual-tasking (76.4 ± 31.2) than when single-tasking (90.0 ± 25.6), while no significant change in stepping down performance was observed. Stroke survivors also swayed significantly more and with a higher velocity than controls when dual-tasking. The results suggested that stroke survivors adopted a posture-first strategy to deal with this dual-tasking challenge. This study raised the awareness on dual-tasking ability among stroke survivors.

Spatio-temporal gait parameters obtained from foot-worn inertial sensors are reliable in healthy adults in single- and dual-task conditions

Inertial measurement units (IMUs) are increasingly popular and may be usable in clinical routine to assess gait. However, assessing their intra-session reliability is crucial and has not been tested with foot-worn sensors in healthy participants. The aim of this study was to assess the intra-session reliability of foot-worn IMUs for measuring gait parameters in healthy adults. Twenty healthy participants were enrolled in the study and performed the 10-m walk test in single- and dual-task ('carrying a full cup of water') conditions, three trials per condition. IMUs were used to assess spatiotemporal gait parameters, gait symmetry parameters (symmetry index (SI) and symmetry ratio (SR)), and dual task effects parameters. The relative and the absolute reliability were calculated for each gait parameter. Results showed that spatiotemporal gait parameters measured with foot-worn inertial sensors were reliable; symmetry gait parameters relative reliability was low, and SR showed better absolute reliability than SI; dual task effects were poorly reliable, and taking the mean of the second and the third trials was the most reliable. Foot-worn IMUs are reliable to assess spatiotemporal and symmetry ratio gait parameters but symmetry index and DTE gait parameters reliabilities were low and need to be interpreted with cautious by clinicians and researchers.

The association between white matter hyperintensity volume and gait performance under single and dual task conditions in older people with dementia: A cross-sectional study

BACKGROUND

Understanding the relationship between white matter hyperintensities (WMHs) and gait may assist in understanding the central control of gait and determining treatment modalities. These relationships are yet to be realized in older people with dementia.

OBJECTIVE

To examine the association between WMH volume and gait under single-task and dual task (DT) conditions in people with dementia.

METHODS

Twenty-eight community-dwelling older people with dementia (median age=83 years; [IQR=77-86]; 36% female) had timed gait speed assessed at usual pace. Gait (speed, stride length, cadence) was assessed using the GAITRite® mat under three conditions (n = 18/28): a) single-task, b) functional DT: carrying a glass of water and c) cognitive DT: counting backwards from 30. WMH volumes were quantified using a fully automated segmentation toolbox.

RESULTS

Total, temporal and parietal WMH volumes were negatively correlated with timed and functional DT gait speed, and with stride length under single-task, functional DT and cognitive DT conditions. Frontal WMH volumes were negatively correlated with timed gait speed and stride length under single-task and functional DT conditions. Participants with higher total WMH burden had significantly slower timed and functional DT gait speed and reduced stride length under single-task, functional DT and cognitive DT conditions compared to participants with lower WMH burden.

CONCLUSIONS

WMH volume was associated with slower gait speed and reduced stride length, but not cadence, under single-task and DT conditions in people with dementia. Further research is needed to confirm these findings and determine whether vascular risk management can improve gait in older people with dementia.

Feasibility of a rhythmic auditory stimulation gait training program in community-dwelling adults after TBI: A case report

BACKGROUND

Traumatic brain injury has multiple impacts on gait including decreased speed and increased gait variability. Rhythmic auditory stimulation (RAS) gait training uses the rhythm and timing structure of music to train and ultimately improve slow and variable walking patterns.

OBJECTIVE

To describe the feasibility of RAS gait training in community-dwelling adults with traumatic brain injury (TBI). A secondary objective is to report changes in spatiotemporal gait parameters and clinical measures of balance and walking endurance.

METHODS

Two individuals with a TBI participated in nine sessions of gait training with RAS over a 3-week period. At baseline, post-training and 3-week follow-up, spatiotemporal parameters of walking were analyzed at preferred pace, maximum pace and dual-task walking conditions. Secondary outcomes included the Community Balance and Mobility Scale and the 6-Minute Walk Test. Feasibility was assessed using reports of physical fatigue, adverse event reporting, and perceived satisfaction.

RESULTS

Both participants completed all 9 planned intervention sessions. The sessions were well tolerated with no adverse events. Participant 1 and 2 exhibited different responses to the intervention in line with the therapeutic goals set with the therapist. Participant 1 exhibited improved speed and decreased gait variability. Participant 2 exhibited reduced gait speed but less fatigue during the 6MWT.

CONCLUSIONS

RAS was found to be a safe and feasible gait intervention with the potential to improve some aspects of gait impairments related to gait speed, gait variability, dynamic balance and walking endurance. Further investigation including a pilot randomized controlled trial is warranted.

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.

People with persistent postural-perceptual dizziness demonstrate altered postural strategies in complex visual and cognitive environments

BACKGROUND

People with PPPD report imbalance, increase in symptoms and impaired function within complex visual environments, but understanding of the mechanism for these behaviors is still lacking.

OBJECTIVE

To investigate postural control in PPPD we compared changes in center of pressure (COP) and head kinematics of people with PPPD (N = 22) and healthy controls (N = 20) in response to different combinations of visual and cognitive perturbations during a challenging balance task.

METHODS

Participants stood in a tandem position. Static or moving stars (0.2 Hz, 5 mm or 32 mm amplitude, anterior-posterior direction) were displayed through a head-mounted display (HTC Vive). On half the trials, participants performed a serial-3 subtraction task. We measured medio-lateral and anterior-posterior path and acceleration of COP and head.

RESULTS

Controls significantly increased all COP and head parameters with the cognitive task whereas PPPD increased only COP ML path and acceleration. Only controls significantly increased head anterior-posterior & medio-lateral acceleration with moving visual load. Cognitive task performance was similar between groups.

CONCLUSIONS

We observed altered postural strategies in people with PPPD, in the form of reduced movement with challenge, particularly around the head segment. The potential of this simple and portable head-mounted display setup for differential diagnosis of vestibular disorders should be further explored.

Slow Walking in Individuals with Chronic Post-Stroke Hemiparesis: Speed Mediated Effects of Gait Kinetics and Ankle Kinematics

Post-stroke rehabilitation often aims to increase walking speeds, as faster walking is associated with improved functional status and quality of life. However, for successful community ambulation, ability to modulate (increase and decrease) walking speeds is more important than walking continuously at constant speeds. Increasing paretic propulsive forces to increase walking speed has been extensively examined; however, little is known about the mechanics of slow walking post-stroke. The primary purpose of this study was to identify the effects of increased and decreased walking speeds on post-stroke kinetics and ankle kinematics. Fifteen individuals with chronic post-stroke hemiparesis and 15 non-neurologically impaired controls walked over an instrumented treadmill under: slow, self-selected, and fast walking speeds. We examined the peak propulsive forces, propulsive impulse, peak braking forces, braking impulse, and ankle kinematics under each condition. When walking at slow walking speeds, paretic limbs were unable to reduce braking impulse and peak propulsive force or modulate ankle kinematics. Impaired modulation of paretic gait kinetics during slow walking places people post-stroke at high risks for slip-related falls. These findings suggest the need for developing gait retraining paradigms for slow walking in individuals chronically post-stroke that target the ability of the paretic limb to modulate braking forces.

Cognitive-Postural Multitasking Training in Older Adults - Effects of Input-Output Modality Mappings on Cognitive Performance and Postural Control

Older adults exhibit impaired cognitive and balance performance, particularly under multi-task conditions, which can be improved through training. Compatibility of modality mappings in cognitive tasks (i.e., match between stimulus modality and anticipated sensory effects of motor responses), modulates physical and cognitive dual-task costs. However, the effects of modality specific training programs have not been evaluated yet. Here, we tested the effects of cognitive-postural multi-tasking training on the ability to coordinate task mappings under high postural demands in healthy older adults. Twenty-one adults aged 65-85 years were assigned to one of two groups. While group 1 performed cognitive-postural triple-task training with compatible modality mappings (i.e., visual-manual and auditory-vocal dual n-back tasks), group 2 performed the same tasks with incompatible modality mappings (i.e., visual-vocal and auditory-manual n-back tasks). Throughout the 6-weeks balance training intervention, working-memory load was gradually increased while base-of-support was reduced. Before training (T0), after a 6-week passive control period (T1), and immediately after the intervention (T2), participants performed spatial dual one-back tasks in semi-tandem stance position. Our results indicate improved working-memory performance and reduced dual-task costs for both groups after the passive control period, but no training-specific performance gains. Furthermore, balance performance did not improve in response to training. Notably, the cohort demonstrated meaningful interindividual variability in training responses. Our findings raise questions about practice effects and age-related heterogeneity of training responses following cognitive-motor training. Following multi-modal balance training, neither compatible nor incompatible modality mappings had an impact on the observed outcomes.

Coordination between motor and cognitive tasks in dual task gait

BACKGROUND

Dual Task (DT) paradigms are frequently used by researchers and clinicians to examine the integrity of motor processes in many movement disorders. However, the mechanism of this interaction is not fully understood. Therefore, the aim of this study was to examine the within-stride interactions between cognitive and motor processes during dual task gait (DT).

RESEARCH QUESTION

Do healthy young adults coordinate gait with secondary task processing? If so, is cognitive task processing capability associated with the coordination observed?

METHODS

Nineteen healthy young adults walked for two minutes on a motorized treadmill whilst counting backwards in sevens from three-digit numbers. The coordination of calculation verbalizations with gait parameters were assessed across six phases of the gait cycle. Mid verbalization time points (VER_Mid) were used as points of high cognitive processing of the dual task and compared with the end of the verbalizations (VER_End) as points of low cognitive processing.

RESULTS

VER_Mid and VER_End did not systematically occur in any phase of the gait cycle. However, 10/19 and 9/19 participants showed non-random distributions of verbalizations for VER_Mid and VER_End time points respectively (p < 0.01), indicating that these walkers coordinated gait with the cognitive task. Analysis of subgroups of Verbalization Coordinators and Non-Coordinators showed slower verbalization response durations (VRD) for VER_Mid Coordinators compared to VER_Mid Non-Coordinators, indicating that VER_Mid Coordinators found the cognitive tasks more demanding. No differences were found in VRD for VER_End Coordinators and VER_End Non-Coordinators.

SIGNIFICANCE

It was found that cognitive processing is coordinated with gait phases in some but not all healthy young adults during DT gait. When demands on cognitive processes are high, healthy young adults coordinate cognitive processing with phases of gait. Analysis of within-stride coordination may be of use for studying clinical conditions where gait and attentional cognition performance breaks down.

Hemodynamic and behavioral changes in older adults during cognitively demanding dual tasks

INTRODUCTION

Executive functions play a fundamental role in walking by integrating information from cognitive-motor pathways. Subtle changes in brain and behavior may help identify older adults who are more susceptible to executive function deficits with advancing age due to prefrontal cortex deterioration. This study aims to examine how older adults mitigate executive demands while walking during cognitively demanding tasks.

METHODS

Twenty healthy older adults (M = 71.8 years, SD = 6.4) performed simple reaction time (SRT), go/no-go (GNG), n-back (NBK), and double number sequence (DNS) cognitive tasks of increasing difficulty while walking (i.e., dual task). Functional near infra-red spectroscopy (fNIRS) was used to measure the hemodynamic response (i.e., oxy- [HbO2] and deoxyhemoglobin [HbR]) changes in the prefrontal cortex (PFC) during dual and single tasks (i.e., walking alone). In addition, performance was measured using gait speed (m/s), response time (s), and accuracy (% correct).

RESULTS

Using repeated measures ANOVAs, neural findings demonstrated a main effect of task such that ∆HbO2 (p = .047) and ∆HbR (p = .040) decreased between single and dual tasks. An interaction between task and cognitive difficulty (p = .014) revealed that gait speed decreased in the DNS between single and dual tasks. A main effect of task in response time indicated that the SRT response time was faster than all other difficulty levels (p < .001). Accuracy performance declined between single and dual tasks (p = .028) and across difficulty levels (p < .001) but was not significantly different between the NBK and DNS.

CONCLUSION

Findings suggest that a healthy older adult sample might mitigate executive demands using an automatic locomotor control strategy such that shifting conscious attention away from walking during the dual tasks resulted in decreased ∆HbO2 and ∆HbR. However, decreased prefrontal activation was inefficient at maintaining response time and accuracy performance and may be differently affected by increasing cognitive demands.

Task specificity impacts dual-task interference in older adults

BACKGROUND

Task prioritization is an important factor determines the magnitude and direction of dual-task interference in older adults. Greater dual-task cost during walking may lead to falling, sometimes causing lasting effects on mobility.

AIMS

We investigated dual-task interference for walking and cognitive performance.

METHODS

Twenty healthy, older adults (71 ± 5 years) completed three cognitive tasks: letter fluency, category fluency, and serial subtraction during seated and walking conditions on a self-paced treadmill for 3 min each, in addition to walking only condition. Walking speed, step length and width were measured during walking and each dual-task condition.

RESULTS

Comparing the percentage of correct answers in cognitive tasks across single and dual-task conditions, there was a main effect of cognitive task (p = 0.021), showing higher scores during letter fluency compared to serial subtraction (p = 0.011). Step width was significantly wider during dual-task letter fluency compared to walking alone (p = 0.003), category fluency (p = 0.001), and serial subtraction (p = 0.007).

DISCUSSION

During both fluency tasks, there was a cost for gait and cognition, with category showing a slightly higher cognitive cost compared to letter fluency. During letter fluency, to maintain cognitive performance, gait was sacrificed by increasing step width. During serial subtraction, there was a cost for gait, yet a benefit for cognitive performance.

CONCLUSION

Differential effect of cognitive task on dual-task performance is critical to be understood in designing future research or interventions to improve dual-task performance of most activities of daily living.

Potentially modifiable risk factors for slow gait in community-dwelling older adults: A systematic review

PURPOSE

Slow gait speed in older adults is associated with increased risk for falls and fractures, functional dependence, multimorbidity, and even mortality. The risk of these adverse outcomes can be reduced by intervening on potentially modifiable risk factors. The purpose of this systematic review was to identify potentially modifiable risk factors associated with slow gait speed and clinically meaningful gait speed decline in older community-dwelling adults.

METHODS

Literature searches were conducted in MEDLINE, EMBASE, and CINAHL, Google Scholar, and in the bibliographies of retrieved articles.

RESULTS

Forty studies met the inclusion criteria for qualitative review. Study designs were cross-sectional and longitudinal. Operational definitions of 'slow gait' and 'meaningful gait speed decline' were variable and based on sample distributions (e.g. quartiles), external criteria (e.g. < 0.8 m/s), and dynamic changes over time (e.g. ≥ 0.05 m/s decline per year). Twenty-six potentially modifiable risk factors were assessed in at least two studies. The risk factors most commonly investigated and that showed significant associations with slow gait and/or meaningful gait speed decline include physical activity, education, body mass index-obesity, pain, and depression/depressive symptoms.

CONCLUSION

Our results suggest that there are modifiable targets to maintain gait speed that are amenable to potential treatment.

Effects of Nonelastic Taping and Dual Task on Kinematics and Kinetics of the Ankle Joint

Objectives

The purpose of this experimental study was to investigate the effects of nonelastic taping and dual task on ankle kinematics and kinetics in gait analysis of healthy adults.

Methods

A total of 21 healthy adults completed trials of gait analysis using a Vicon system combining ground walking with different cognitive task conditions (none, modified Stroop color/character naming, and serial-7 subtraction), with or without nonelastic taping. Ankle kinematics and kinetics including speed, ankle plantarflexion and inversion angle, ground reaction force (GRF), and stride time variability (STV) under all conditions of taping (YES or NO) and cognitive task (none, naming, and subtraction) were characterized and analyzed with repeated-measures ANOVA.

Results

As regards cognitive performance, the serial-7 subtraction performance under walking conditions with and without taping was significantly poorer than simple sitting condition (P < 0.001). For kinematics and kinetics, STV showed statistically significant decrease (P=0.02) when subjects underwent taping application. Vertical GRF was significantly greater under taping than barefoot (P=0.001). Ankle plantarflexion at initial contact (IC) under the dual-task walking was significantly more than under simple walking (P=0.008).

Conclusions

Applications of nonelastic taping and dual task may lead to the STV, vertical GRF, ankle plantarflexion, and speed alterations because of restricted joint range of motion and changed sensorimotor neural circuit. When healthy adults performed dual-task walking, central neural resources allocation was disturbed, leading to weakened performance in both motor and cognitive tasks.

EEG in motion: Using an oddball task to explore motor interference in active skateboarding

Recent advancements in portable computer devices have opened new avenues in the study of human cognition outside research laboratories. This flexibility in methodology has led to the publication of several electroencephalography studies recording brain responses in real-world scenarios such as cycling and walking outside. In the present study, we tested the classic auditory oddball task while participants moved around an indoor running track using an electric skateboard. This novel approach allows for the study of attention in motion while virtually removing body movement. Using the skateboard auditory oddball paradigm, we found reliable and expected standard-target differences in the P3 and MMN/N2b event-related potentials. We also recorded baseline electroencephalography activity and found that, compared to this baseline, alpha power is attenuated in frontal and parietal regions during skateboarding. In order to explore the influence of motor interference in cognitive resources during skateboarding, we compared participants' preferred riding stance (baseline level of riding difficulty) versus their non-preferred stance (increased level of riding difficulty). We found that an increase in riding difficulty did not modulate the P3 and tonic alpha amplitude during skateboard motion. These results suggest that increases in motor demands might not lead to reductions in cognitive resources as shown in previous literature.

Age-related changes in children's cognitive-motor dual tasking: Evidence from a large cross-sectional sample

Children coordinate two tasks simultaneously at several occasions throughout the day; however, this dual-task ability and its development across childhood are poorly understood. Therefore, the current study investigated age-related changes in children's dual-task ability using a large cross-sectional sample of 8- to 13-year-old children (N = 135). In our dual-task methodology, children were asked to walk across an electronic pathway while performing three concurrent cognitive tasks. These tasks targeted at children's executive function components: inhibition, switching, and updating skills. Our findings indicate associations between age and children's stride time variability but not with normalized velocity. Younger children showed higher stride time variability in the dual-task situation as compared with older children after accounting for their single-task performance, intelligence, anthropometric variables, and sex, indicating a more regular gait pattern in older children. Furthermore, age was differently related to children's accuracy in solving the concurrent cognitive tasks. Whereas age was associated with children's performance in the updating and switching task, there was no relation between age and children's inhibitory skills. In addition, our data imply that children's dual-task ability was associated with a number of individual variables. In particular, children with higher intelligence scores showed fewer errors and girls showed lower stride time variability in the dual tasks. Our results suggest a considerable developmental progression in children's ability to coordinate two simultaneous tasks across middle childhood. Furthermore, our study qualifies previous dual-task research and implies that heterogeneous findings may be related to a differential involvement of executive function components in the dual task.

Cross-Sectional Study Using Virtual Reality to Measure Cognition

Dual-task research is limited in its transferability to authentic contexts because laboratory conditions do not replicate real-world physical activity and decision-making scenarios. Creating valid, reliable methodologies to assess physiological and behavioral responses under varying physical and cognitive demands using virtual reality (VR) environment addresses this limitation. This study determined the feasibility of using VR to investigate the effects of dual-tasking on healthy young adults' cognitive performance. Three dual-tasking conditions (i.e., standing, preferred-paced walking, and fast-paced walking, each with blocked congruent and incongruent tasks) were developed. Using a within-subjects, randomized design, thirty-two young adults (17 female, mean age = 21.03 ± 2.86) were randomly assigned to a starting condition but experienced all three conditions. Physiological responses of heart rate (HR) and accelerometry data measured energy expenditure as the physical demand. Behavioral responses of reaction time and error rate quantified cognitive performance. Results indicated that (a) each condition verified independent physiological and behavioral responses; (b) reaction time and error rate during preferred walking or fast-paced walking dual-tasking conditions was significantly lower than standing condition; and surprisingly, (c) congruent tasks showed lower reaction time than the incongruent tasks. These findings suggest that it is feasible to use VR to assess the effects of dual-task conditions. Specifically, walking can optimize the motor-cognitive dual-task performance, compared to standing. These findings may be attributed to the dose-response effects of exercise intensity. Future studies should incorporate advanced technology such as the VR exercise.

Performance in complex life situations: effects of age, cognition, and walking speed in virtual versus real life environments

Background

Virtual reality (VR) enables objective and accurate measurement of behavior in ecologically valid and safe environments, while controlling the delivery of stimuli and maintaining standardized measurement protocols. Despite this potential, studies that compare virtual and real-world performance of complex daily activities are scarce. This study aimed to compare cognitive strategies and gait characteristics of young and older healthy adults as they engaged in a complex task while navigating in a real shopping mall and a high-fidelity virtual replica of the mall.

Methods

Seventeen older adults (mean (SD) age = 71.2 (5.6) years, 64% males) and 17 young adults (26.7 (3.7) years, 35% males) participated. In two separate sessions they performed the Multiple Errands Test (MET) in a real-world mall or the Virtual MET (VMET) in the virtual environment. The real-world environment was a small shopping area and the virtual environment was created within the CAREN™ (Computer Assisted Rehabilitation Environment) Integrated Reality System. The performance of the task was assessed using motor and physiological measures (gait parameters and heart rate), MET or VMET time and score, and navigation efficiency (cognitive performance and strategy). Between (age groups) and within (environment) differences were analyzed with ANOVA repeated measures.

Results

There were no significant age effects for any of the gait parameters but there were significant environment effects such that both age groups walked faster (F_(1,32) = 154.96, p < 0.0001) with higher step lengths (F_(1,32) = 86.36, p < 0.0001), had lower spatial and temporal gait variability (F_(1,32) = 95.71–36.06, p < 0.0001) and lower heart rate (F_(1,32) = 13.40, p < 0.01) in the real-world. There were significant age effects for MET/VMET scores (F_(1,32) = 19.77, p < 0.0001) and total time (F_(1,32) = 11.74, p < 0.05) indicating better performance of the younger group, and a significant environment effect for navigation efficiency (F_(1,32) = 7.6, p < 0.01) that was more efficient in the virtual environment.

Conclusions

This comprehensive, ecological approach in the measurement of performance during tasks reminiscent of complex life situations showed the strengths of using virtual environments in assessing cognitive aspects and limitations of assessing motor aspects of performance. Difficulties by older adults were apparent mainly in the cognitive aspects indicating a need to evaluate them during complex task performance.