Effects of gait and cognitive task difficulty on cognitive-motor interference in aging.

Although gait-related dual-task interference in aging is well established, the effect of gait and cognitive task difficulty on dual-task interference is poorly understood. The purpose of this study was to examine the effect of gait and cognitive task difficulty on cognitive-motor interference in aging. Fifteen older adults (72.1 years, SD 5.2) and 20 young adults (21.7 years, SD 1.6) performed three walking tasks of varying difficulty (self-selected speed, fast speed, and fast speed with obstacle crossing) under single- and dual-task conditions. The cognitive tasks were the auditory Stroop task and the clock task. There was a significant Group × Gait Task × Cognitive Task interaction for the dual-task effect on gait speed. After adjusting for education, there were no significant effects of gait or cognitive task difficulty on the dual-task effects on cognitive task performance. The results of this study provide evidence that gait task difficulty influences dual-task effects on gait speed, especially in older adults. Moreover, the effects of gait task difficulty on dual-task interference appear to be influenced by the difficulty of the cognitive task. Education is an important factor influencing cognitive-motor interference effects on cognition, but not gait.

Training dual-task walking in community-dwelling adults within 1 year of stroke: a protocol for a single-blind randomized controlled trial.

BACKGROUND: Community ambulation is a highly complex skill requiring the ability to adapt to increased environmental complexity and perform multiple tasks simultaneously. After stroke, individuals demonstrate a diminished ability to perform dual-tasks. Current evidence suggests that conventional rehabilitation does not adequately address gait-related dual-task impairments after stroke, which may be contributing to low levels of participation and physical inactivity in community-dwelling stroke survivors. The objective of this study is to investigate the efficacy of dual-task gait training in community-dwelling adults within 1 year of stroke. Specifically, we will compare the effects of dual-task gait training and single-task gait training on cognitive-motor interference during walking at preferred speed and at fastest comfortable speed (Aim 1), locomotor control during obstacle negotiation (Aim 2), and spontaneous physical activity (Aim 3). METHODS/DESIGN: This single-blind randomized controlled trial will involve 44 individuals within 12 months of stroke. Following baseline evaluation, participants will be randomly allocated to single- or dual-task gait training. Both groups will receive 12, 30-minute sessions provided one-on-one over 4-6 weeks in an outpatient therapy setting. Single-task gait training involves practice of gait activities incorporating motor relearning principles. Dual-task gait training involves an identical gait training protocol; the critical difference being that the dual-task gait training group will practice the gait activities while simultaneously performing a cognitive task for 75% of the repetitions. Blinded assessors will measure outcomes at baseline, post-intervention, and 6 months after completion of the intervention. The primary outcome measure will be dual-task effects on gait speed and cognition during unobstructed walking. Secondary outcomes include spatiotemporal and kinetic gait parameters during unobstructed single- and dual-task walking at preferred and fastest comfortable walking speeds, gait parameters during high and low obstacle crossing, spontaneous physical activity, executive function, lower extremity motor function, Timed Up and Go, balance self-efficacy, number of falls, and stroke-related disability. Hypotheses for each aim will be tested using an intention-to-treat analysis with repeated measures ANOVA design. DISCUSSION: This trial will provide evidence to help clinicians make decisions about the types of activities to include in rehabilitation to improve dual-task walking after stroke. TRIAL REGISTRATION: ClinicalTrials.gov NCT01568957.

Effects of once weekly dual-task training in older adults: a pilot randomized controlled trial.

AIM: To compare single-task and dual-task training on obstacle avoidance, gait speed and balance in healthy community-dwelling older adults. METHODS: A total of 17 older adults (65-83 years) participated in a group circuit class, once weekly for 45 min for 4 weeks. The dual-task group carried out cognitive activities simultaneously with gait and balance exercises. The single-task training group carried out identical gait and balance activities without cognitive tasks. We assessed time to complete a 6-m obstacle course under single-task and three different dual-task conditions (spontaneous speech, alphabet recitation and coin transfer), 25-ft gait speed, Timed Up and Go, and the Activities-specific Balance Confidence Scale. RESULTS: Both groups showed significant improvement in gait speed and Timed Up and Go. In addition, the proportion of participants who achieved gait speed >1.0 m/s increased in both groups. There were no within- or between-subjects differences in obstacle course performance under single or dual-task conditions after the intervention. CONCLUSION: Once weekly group circuit training focusing on balance, gait and agility, with or without simultaneous cognitive tasks, resulted in significantly improved walking speed among older adults. Group-format dual-task training once per week did not improve walking time or dual-task cost on an obstacle negotiation task.

Relationships between motor function and gait-related dual-task interference after stroke: a pilot study.

The purpose of this pilot study was to examine the relationships between motor performance measures and dual-task interference in gait among community-dwelling adults with stroke. Dual-task costs on gait were correlated with Fugl-Meyer lower extremity score and usual gait speed in 13 community-dwelling adults with stroke. Individuals with greater lower extremity motor impairment and slower gait speed experienced greater cognitive-motor interference in gait. Paretic single limb stance was particularly susceptible to dual-task interference. Gait speed was only vulnerable to dual-task interference in the most complex dual-task. Thus, global characteristics of gait were vulnerable in the most difficult cognitive tasks, but even easy tasks impaired discrete components of dynamic balance.

Dual-task effects of spontaneous speech and executive function on gait in aging: exaggerated effects in slow walkers.

This study compared the effects of spontaneous speech and executive function on gait and investigated the effects of single-task gait speed on dual-task costs. Twenty-one older adults (74.7 years, SD 5.9) and 23 younger adults (22 years, SD 1.2) walked for 60s while performing an auditory Stroop task and a spontaneous speech task; they also performed each task in isolation. Walking while talking significantly reduced gait speed in both groups; however, only older adults experienced significant cognitive-motor interference during the Stroop task. Stride duration variability and gait symmetry were also affected by the speech task in older but not younger adults. Dual-task costs on gait speed were greater in slow-walking older adults than fast walkers. These results demonstrate that spontaneous speech is a highly demanding task that has a profound impact on gait in older adults, especially those with gait speed <1 m/s.

Interference between cognition, double-limb support, and swing during gait in community-dwelling individuals poststroke.

BACKGROUND: Dual tasking can interfere with activity after stroke. OBJECTIVE: The authors examined the interactions between 3 different cognitive tasks and the swing and double-limb support (DLS) components of the gait cycle in community-dwelling individuals poststroke. METHODS: Acquisition of cognitive and gait data were synchronized to study the cognitive-motor interference effects during the different phases of the gait cycle. Participants performed 3 different cognitive tasks in isolation and in combination with walking as well as a single walking task. Tasks were performed continuously for 3 minutes, generating 131 +/- 39 gait cycles per person for analysis for each walking trial. Data were analyzed for 8 participants 7.6 +/- 4.2 months poststroke. RESULTS: A significant increase was found in the proportion of the gait cycle spent in DLS in dual-task walking because of an increased duration of the DLS phase associated with paretic weight acceptance. There was a significant dual-task effect on nonparetic swing duration: participants reduced the amount of time in paretic single-limb stance in the 3 dual-task conditions. Temporal asymmetry of gait did not increase significantly under dual-task conditions. Reaction times were not affected by whether the stimuli were present during the swing or DLS phase of the gait cycle. CONCLUSIONS: The findings from this pilot study provide evidence that cognitive-motor interference during gait may be influenced by the phase of the gait cycle, especially DLS involving paretic weight acceptance, which may affect community ambulators with hemiparetic stroke.

Discourse coherence and cognition after stroke: a dual task study.

UNLABELLED: Several researchers have suggested that the maintenance of global coherence (topic maintenance) and local coherence (maintenance between utterances) in discourse requires cognitive resources. This study directly tests this hypothesis by examining the relationship between cognitive variables and coherence in narrative discourse produced by mobility-impaired stroke survivors under single (talking) and dual (talking and walking) task conditions. Although there were no effects of the dual task on coherence, global coherence was significantly disrupted regardless of the single or dual task condition. Moreover, global coherence strongly correlated with cognitive function measures, whereas local coherence did not. Findings are consistent with two interpretations: (1) that global and local coherence may be subserved by different cognitive processes or (2) that maintaining global coherence is a more difficult task and thus will show effects of cognitive impairment before local coherence is impaired. These are both testable hypotheses for future research. LEARNING OUTCOMES: After reading the manuscript, the reader will be able to: (1) understand and differentiate between local and global measures of coherence; (2) discuss the effects of a dual task, walking and talking, on global coherence in a gait-impaired group of stroke survivors; (3) understand why the maintenance of global coherence in discourse might be more cognitively demanding than the maintenance of local coherence.

International randomized clinical trial, stroke inpatient rehabilitation with reinforcement of walking speed (SIRROWS), improves outcomes.

BACKGROUND: Feedback about performance may optimize motor relearning after stroke. OBJECTIVES: Develop an international collaboration to rapidly test the potential efficacy of daily verbal feedback about walking speed during inpatient rehabilitation after stroke, using a protocol that requires no research funds. METHODS: This phase 2, single-blinded, multicenter trial randomized inpatients to either feedback about self-selected fast walking speed (daily reinforcement of speed, DRS) immediately after a single, daily 10-m walk or to no reinforcement of speed (NRS) after the walk, performed within the context of routine physical therapy. The primary outcome was velocity for a 15.2-m (50-foot) timed walk at discharge. Secondary outcomes were walking distance in 3 minutes, length of stay (LOS), and level of independence (Functional Ambulation Classification, FAC). RESULTS: Within 18 months, 179 participants were randomized. The groups were balanced for age, gender, time from onset of stroke to entry, initial velocity, and level of walking-related disability. The walking speed at discharge for DRS (0.91 m/s) was greater (P = .01) than that for NRS (0.72 m/s). No difference was found for LOS. LOS for both DRS and NRS was significantly shorter, however, for those who had mean walking speeds >0.4 m/s at entry. The DRS group did not have a higher proportion of FAC independent walkers (P = .1) and did not walk longer distances ( P = .09). CONCLUSIONS: An Internet-based collaboration of 18 centers found that feedback about performance once a day produced gains in walking speed large enough to permit unlimited, slow community ambulation at discharge from inpatient rehabilitation.

Hemispatial neglect and rehabilitation in acute stroke.

OBJECTIVES: To compare 2 methods for determining neglect in patients within 2 days of stroke, and to investigate whether early neglect was related to rehabilitation practice, and whether this relationship was affected by an early, intensive mobilization intervention. DESIGN: Data were collected from patients participating in a phase II randomized controlled trial of early rehabilitation after stroke. SETTING: Acute hospital stroke unit. PARTICIPANTS: Stroke patients (N=71). INTERVENTION: The 2 arms of the trial were very early mobilization (VEM) and standard care (SC). MAIN OUTCOME MEASURES: Neglect was assessed using the Star Cancellation Test and the National Institutes of Health Stroke Scale (NIHSS) inattention item within 48 hours of stroke onset, and therapy details were recorded during the hospital stay. RESULTS: Assessing neglect so acutely after stroke was difficult: 29 of the 71 patients were unable to complete the Star Cancellation Test, and agreement between this test and the NIHSS measure was only .42. Presence of neglect did not preclude early mobilization. SC group patients with neglect had longer hospital stays (median, 11d) than those without neglect (median, 4d); there was no difference in length of stay between patients with and without neglect in the VEM group (median, 6d in both). CONCLUSION: Early mobilization of patients with neglect was feasible and may contribute to a shorter acute hospital stay.

Managing gait disorders in older persons residing in nursing homes: a review of literature.

Managing gait disorders in the nursing home setting is a challenge. Nursing home residents can present with a variety of factors that may contribute to the presentation of gait abnormalities. The development of an individualized intervention program can be effective in improving a resident's ability to ambulate. This article reviews the research pertaining to the management of gait disorders including deconditioning, therapeutic exercise intervention, dementia, and cardiovascular and cardiopulmonary systems. The review provides the reader with strategies to help improve and understand gait performance in older persons residing in nursing homes.

Reliable assessment of lower limb motor representations with fMRI: use of a novel MR compatible device for real-time monitoring of ankle, knee and hip torques.

This study describes the use of a novel magnetic resonance imaging (MRI) compatible system capable of measuring isometric ankle, knee and hip joint torques in real-time during functional MRI (fMRI) testing in healthy volunteers. The motor representations of three isometric torques--ankle dorsiflexion, ankle plantarflexion and knee extension--were studied at two time points. The reliability of motor performance and fMRI-derived measures of brain activity across sessions was examined. Reproducible motor performance was observed for each of the tasks; torques of the requested amplitude, assisted by visual feedback, were generated at the relevant joint with good accuracy, both within and across the two sessions. Significant blood oxygen level dependent (BOLD) signal increases were observed in the left primary sensorimotor cortex (SM1) in the paracentral lobule and in secondary motor areas for all tasks. Within these areas there was substantial overlap of the motor representations though differential activation was observed in SM1, with greater activation of inferior paracentral lobule during knee extension than for either ankle task. Also, BOLD signal decreases were observed bilaterally within SM1 in the hand knob region for all tasks. No major session-related effects were identified at the group level. High intraclass correlation coefficients were observed for t-values of voxels in cortical motor areas for each contraction type for individuals, suggesting that fMRI-derived activity across time points was reliable. These findings support the use of this apparatus in serial studies of lower limb function.

Interactions between cognitive tasks and gait after stroke: a dual task study.

This study investigated the interactions between gait and three different cognitive tasks in people after stroke. Thirteen people post-stroke who were living in the community, were able to walk 10 m without physical assistance, and could respond verbally to auditory stimuli participated. Participants performed a walking task alone, three different cognitive tasks while seated, and each cognitive task in combination with walking. Gait data were acquired continuously for approximately 3 min. Reaction time and accuracy were recorded for two of the cognitive tasks (visuospatial task, working memory task). Speech samples from the spontaneous speech task were analyzed on several dimensions of language. Significant dual task effects were observed for gait speed, stride time, average stride length, and cadence, but not for stride time variability. Speech produced more gait interference than memory and visuospatial tasks. Interference effects on cognition were minimal; only speech was significantly affected by concurrent walking. Narratives in the dual task condition had more pauses, shorter sentences, but more utterances with new information. Even though participants in this study were mobility-impaired, they prioritized the cognitive tasks. Future research should determine whether dual task training can reduce gait decrements in dual task situations in people after stroke.