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Title: Dual-task balance and mobility in people with stroke
Authors: Yang, Lei
Degree: Ph.D.
Issue Date: 2018
Abstract: Background: Dual-task (DT) ability was shown to be impaired after stroke, which may lead to the further decline in the balance and mobility function. However, the psychometric properties of the DT assessment toolsare yet to be established. In addition, no high-quality clinical trial has investigated the effects of DT training program on individualswith stroke. Purposes: The overall aims of this project were to investigate (1) the psychometric properties of DT balance and mobility assessment tools, (2) the phenomenon of cognitive-motor interference, and (3) the efficacy of a dual-task exercise program in people with chronic stroke. The specific objective of each and inter-related studywas as follows: Study 1: To evaluate the evidence related to the psychometric properties of dual-task balance assessments in older adults; Study 2: to evaluate the evidence related to the psychometric properties of DT balance and walking assessments in individuals with different neurological conditions; Study 3: To evaluate the evidence related to the effects of dual-task balance and mobility training in people with stroke; Study 4: To assess the test-rest reliability, concurrent and known-groups validity of various dual-task walking tests in people with chronic stroke; Study 5: To examine the reliability and validity of the Sensory Organization Test (SOT) under DT conditions(DT-SOT) in individuals with chronic stroke; Study 6: To evaluate how the difficulty level of mobility and cognitive tasks influenced the cognitive-motor interference pattern among individuals with chronic stroke and whether it differed from age-matched control participants; and Study 7: To examine the efficacy of a DT exercise program on cognitive-motor interference in walking performance, balance self-efficacy, participation in everyday activities, and incidence of falls in individuals with chronic stroke. Methods: Study 1: An extensive literature search of electronic databases was conducted. Articles were included if they evaluated the psychometric properties of dual-task balance and walking assessment tools in older adults. The data were extracted by two independent researchers and confirmed with the principal investigator. The methodology quality of each study was rated by using the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) checklist. Study 2: A systematic literature search was conducted to identify articles that studied the psychometric properties of the dual-task balance and walking assessments in individuals with neurological conditions. The methodological quality was rated using the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) checklist. Study 3: An extensive electronic databases literature search was done to identify the randomized controlled studies that assessed the effects of dual-task cognitive-motor exercise training in stroke patients. The methodological quality was evaluated using the Cochrane Collaboration recommendation, and level of evidence was determined according to the criteria described by the Oxford Centre for Evidence-Based Medicine. Study 4: Eighty-eight individuals with chronic stroke participated. The testing protocol involved four walking tasks (walking forward at self-selected and maximal speed, walking backward at self-selected speed, and crossing over obstacles) performed simultaneously with each of the three attention-demanding tasks (verbal fluency, serial 3 subtractions or carrying a cup of water). For each dual-task condition, the time taken to complete the walking task, the correct response rate (CRR) of the cognitive task, and the dual-task effect (DTE) for the walking time and CRR were calculated. Forty-six of the participants were tested twice within 3-4 days to establish test-retest reliability. Study 5: Ninety individuals with chronic stroke were enrolled in the study. Individuals who had experienced at least 1 fall in the previous 12 months were classified as fallers. Standing balance was evaluated in 4 single-task (ST)-SOT conditions: condition 1 (stable surface, eyes open), condition 2 (stable surface, eyes closed), condition 4 (sway-referenced surface, eyes open), and condition 5 (sway-referenced surface, eyes closed). The same balance tasks were then evaluated when performed in conjunction with a verbal fluency (VF) or serial subtraction (SS) task (i.e., DT-SOT). To establish test-retest reliability, 45 participants were assessed again 3-4 days after the initial assessment. Study 6: Sixty-one individuals with chronic stroke and 32 controls performed three mobility tasks (forward walking, obstacle-crossing, backward walking) and two cognitive tasks (serial-3-subtractions, serial-7-subtractions) in single-task and dual-task conditions. CRR and time to complete the walking tasks were recorded. Study 7: A total of 84 individuals with chronic stroke were randomly allocated to DT balance and mobility training group, single-task (ST) balance and mobility training group, and flexibility and upper limb exercise (control) group. Twenty-eight participants in each group received their respective training for three 60-minute session per week for 8 weeks. The degree of DT interference [i.e., DT effect percentage (DTE%)] in walking time (three mobility tasks of different difficulty levels: forward walking, timed-up-and-go test, and obstacle crossing test) and in cognitive performance (correct response rate of verbal fluency task and serial-3-subtraction task), as well as the secondary outcomes, including: Activities-specific balance confidence scale (ABC), Frenchay Activities Index (FAI), and Stroke-specific quality of life (SS-QOL) were measured at baseline, immediately after training, and 8 weeks after training. Data on fall incidence were collected by monthly phone calls for 6 months after the end of the 8-week intervention period.
Results: Study 1: Twenty-six articles were included in this systematic review. For dual-task static standing balance assessments, the center of pressure-related parameters (displacement, velocity) and reaction time measurements were reliable but not useful for prediction of falls. For walking balance assessments, the gait outcomes derived generally demonstrated good to excellent reliability [Intraclass correlation coefficient >0.75)], but their ability to predict falls varied. Outcomes derived from the cognitive tasks mostly demonstrated low to fair reliability. The methodological quality of majority of studies was poor to fair, mainly due to small sample size. Study 2: Twenty-three articles involving individuals with stroke, Parkinson's disease, mild cognitive impairment, dementia, Alzheimer's disease, and multiple sclerosis were included. Outcomes derived from the walking tasks under DT condition generally demonstrated good reliability (correlation coefficient ≥0.75) across different neurological disorders, but their usefulness in distinguishing fallers from non-fallers was inconclusive. The reliability of outcomes derived from the cognitive/motor tasks and from the dual-task effect (DTE) (i.e., DT performance minus single-task performance) seemed to be lower but was understudied. The reliability of static or dynamic sitting/standing balance outcomes in DT condition was not assessed in any of the selected studies. Study 3: Fifteen articles were included in this systematic review. All had substantial risk of bias and thus provided level IIb evidence only. DT mobility training was found to cause more improvement in ST and DT walking function when compared with ST mobility training and no-intervention control group. Cognitive-motor balance training was effective in improving ST balance function, but its effect on DT balance ability was uncertain. The effect of DT training on cognitive function was not clear. Training protocols that involved different types of dual tasks tended to yield better outcomes than those that only used one type of task. Study 4: The walking time in various dual-task assessments demonstrated good to excellent reliability [Intraclass correlation coefficient (ICC₂,₁)=0.70-0.93; relative minimal detectable change at 95% confidence level (MDC95%)=29%-45%]. The reliability of the CRR (ICC₂,₁=0.58-0.81) and the DTE in walking time (ICC₂,₁=0.11-0.80) was more varied. The reliability of the DTE in CRR (ICC₂,₁=-0.31-0.40) was poor to fair. The walking time and CRR obtained in various dual-task walking tests were moderately to strongly correlated with those of the dual-task Timed-up-and-Go test, thus demonstrating good concurrent validity. None of the tests could discriminate fallers (those who had sustained at least one fall in the past year) from non-fallers. Study 5: In the DT condition, the reliability of equilibrium scores (ICC₂,₁=0.48-0.81) and correct response rates (CRR; verbal fleuncy: ICC₂,₁=0.59-0.68; serial subtractions: ICC₂,₁=0.64-0.78) was fair-to-moderate. DT-SOT outcomes were insufficient to distinguish fallers from non-fallers. Study 6: Serial subtractions significantly increased the walking time compared to single-task walking (p<0.001) without decreasing the correct response rate (p>0.05) in both groups, indicating cognitive-related motor interference. As the difficulty of the walking task was increased (i.e., obstacle crossing), the dual-task effect on the walking time was similar to that observed during forward walking, but the CRR significantly decreased (p<0.05), indicating that more attentional resources were allocated to the mobility task. When the walking task difficulty level increased further (i.e., backward walking), an exaggerated increase in the walking time (p<0.001) was observed in both groups, but the stroke group also had a decreased correct response rate (p<0.001), indicative of a mutual interference pattern. The control group, however, maintained the correct response rate (p>0.05) despite the slowed walking speed in this condition (p<0.001). Study7: Intention-to-treat analysis showed that only the DT group showed a significant reduction in DTE% of walking time after intervention. This was not accompanied by any significant change in the DTE% of cognitive performance, indicating true improvement in dual-task mobility performance. Furthermore, the training effect was well maintained in the DT group during the follow-up period. For secondary outcomes, the Activities-Specific Balance Confidence score (p=0.001) and Stroke-specific quality of life (p=0.009) score showed significant time effects but the time x group interaction effects were not significant. The DT group had significantly lower incidence of falls (p=0.037) and fall-related injuries (p=0.023) than the control group. Conclusions: Study 1: Among the dual-task balance assessments examined, the reliability and validity varied. The findings of this review should be useful in guiding the selection of dual-task balance measures in future research. Study 2: The reliability of the outcomes derived from walking tasks was good. The psychometric properties of other DT outcomes need to be further investigated. Study 3: The use of DT exercise training to improve ST balance and walking function, and DT walking function is supported by level IIb evidence. The therapeutic effects of DT training on balance and cognitive function require further investigations. Study 4: The walking time derived from the various DT assessments generally demonstrated good to excellent reliability, making them potentially useful in clinical practice and future research endeavors. However, the usefulness of these measurements in predicting falls needs to be further explored. Study 5: The DT-SOT demonstrated low reliability in individuals with chronic stroke and no utility for identifying patients with an increased risk of falling. Study 6: The degree of dual-task interference and task prioritization strategies are highly specific to the combinations of the walking and cognitive tasks used and are affected by the presence of stroke. Study 7: The 8-week DT cognitive-motor exercise training program was effective in improving DT mobility function, and reducing the risk of falls in community-dwelling individuals with chronic stroke. Future study should explore the optimal training protocol that can improve more advanced DT mobility function and the issue of transfer of learning to other novel DT scenarios.
Subjects: Hong Kong Polytechnic University -- Dissertations
Cerebrovascular disease -- Patients
Motor ability -- Testing
Function tests (Medicine)
Pages: 506 pages : color illustrations
Appears in Collections:Thesis

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