Measurement and training of dual-task of gait in persons with multiple sclerosis

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Individuals with multiple sclerosis (MS) present with a wide variability of motor, sensory, and cognitive symptoms that affect their ability to engage in and perform their daily activities. Walking is a motor task that is known to be widely affected by the symptoms of MS and individuals with MS demonstrate difficulties with their ability to ambulate even early on in their disease process. Although it is broadly accepted that walking is heavily influenced by motor and sensory symptoms, recent studies in the area of cognitive-motor interference have identified a relationship between cognitive functioning and motor performance in individuals with MS. The concurrent performance of a motor and cognitive task (dual-task) has been found to adversely affect the gait mechanics of individuals with MS, effectually increasing their risk for falling.

Physical therapists often rely on outcome measures to help quantify an individual’s physical performance; however, there is a lack of a standardized dual-task outcome measure that not only measures overall dual-task performance but also measures the single-task performance of the motor and cognitive task. The modified Walking and Remembering Test (mWART) is one such dual-task outcome measure that quantifies dual-task performance relative to the single-task performance of the motor and the cognitive task. Additionally, the mWART adjusts the difficulty of the dual-task cognitive task relative to the individual’s single-task cognitive performance.

As we continue to improve our understanding of the underlying mechanisms of cognitive-motor interference and the anatomical correlates of dual-task performance, studies have emerged to study methods by which we can improve dual-task ability. Although there has been a substantial growth of research in individuals with Parkinson disease, stroke, or dementia, more studies are needed, especially in individuals with MS.

Three studies comprise this dissertation. The first study determined the test-retest reliability and discriminant validity of the mWART. The second study assessed the feasibility and effects of a six-week gait-specific dual-task training intervention on gait velocity, cadence, and step length. Finally, the third study evaluated the effects of the training intervention on walking capacity, self-perceived walking ability, and subjective fatigue. The participants were tested on two separate days to collect the average baseline data for studies one and two. Participants were randomly allocated to a six-week dual-task training group or a six-week single-task training group for studies two and three.

Study one results revealed good to excellent test-retest reliability of the mWART for single-task gait velocity (ICC2,k = .961, p<.001), dual-task gait velocity (ICC2,k = .968, p<.001), and single-task digit span recall (ICC2,k = .829, p=.004) for individuals with MS. The mWART was also able to discriminate based on single-task gait velocity (p=.001) and dual-task gait velocity (p=.002) between individuals with MS and without MS. To assess spatiotemporal gait parameters, the Protokinetics ZenoWalkway was used to quantify gait velocity, cadence, and step length in response to the gait-specific dual-task training intervention. Results from the second study revealed that the dual-task training intervention elicited clinically significant improvements in single-task (18.6% improvement) and dual-task gait velocity (13.0% improvement) at post intervention. The dual-task group was the only group able to demonstrate significantly different changes in single-task gait velocity at both post-intervention (p=.018) and follow-up (p=.042). Observationally, the results also suggest that dual-task training supports more robust changes in dual-task performance (3.5% or less change at follow-up compared to post-intervention). The results from the final study revealed clinically meaningful improvements in walking capacity (p=.007, partial η2=.505) and self-perceived walking ability (p=.009, partial η2=.345) following the dual-task training intervention despite there being no significant changes in subjective fatigue.

The overall results indicate the mWART is a valid and reliable clinical measure of dual-task performance in individuals with MS. Additionally, the gait-specific dual-task training intervention detailed within is effective in improve single-task and dual-task performance in individuals with MS and can serve as a framework from which clinicians may initiate dual-task training for their patients with MS.

Dual-task training, multiple sclerosis, Cognitive-motor interference, Physical therapy, Rehabilitation, Gait training