Dual-task mobility among individuals with chronic stroke: Changes in cognitive-motor interference patterns and relationship to difficulty level of mobility and cognitive tasks

BACKGROUND: Dual-task mobility performance is compromised after stroke. AIM: This study evaluated 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. DESIGN: A cross-sectional study. SETTING: University laboratory. POPULATION : Individuals with chronic stroke and age-matched controls. METHODS: Sixty-one individuals with chronic stroke (mean age: 62.9±7.8 years) and 32 controls (mean age: 61.0±7.3 years) 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. time to complete the mobility tasks and correct response rates were recorded. RESULTS: 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 correct response rate 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). CONCLUSIONS: 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. CLINICAL REHABILITATION IMPACT : The study results may provide the basis for establishing assessment tools and creating intervention programs that address dual-task mobility function post-stroke.