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

Abstract

Dual-task mobility performance is compromised after stroke. 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. A cross-sectional study. University laboratory. Individuals with chronic stroke and age-matched controls. 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. 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). 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. The study results may provide the basis for establishing assessment tools and creating intervention programs that address dual-task mobility function post-stroke.