Task matters: influence of different cognitive tasks on cognitive-motor interference during dual-task walking in chronic stroke survivors.

BACKGROUND: The impact of unilateral brain damage, such as that caused by stroke, on the interaction between higher cognitive functions and walking remains uncertain. We compared cognitive-motor interference (CMI) during dual-task (DT) walking between chronic stroke survivors and young adults performing explicitly different cognitive tasks.

METHODS: Ten community-dwelling chronic stroke survivors and 10 young adults performed 3 cognitive tasks - visuomotor reaction time (VMRT), serial subtraction (SS), and Stroop test (STR) - while sitting and walking. Gait velocity was recorded using an electronic walkway. Cognitive variables included reaction time and number of correct responses. Motor and cognitive costs were computed.

RESULTS: DT walking led to significant declines in motor and cognitive performance. Significant main effect of task (P < .01) and group (P < .01) was observed for motor cost. The stroke group showed highest motor cost for SS task, whereas the young group showed highest motor cost for STR task (Group × Task interaction, P < .05). Although cognitive costs for both groups was highest for VMRT and lowest for STR tasks, cognitive cost for SS task was significantly greater for the stroke group compared with the young group (Group × Task interaction, P < .05).

CONCLUSIONS: CMI pattern in chronic stroke survivors differs significantly with type of cognitive task. Gradual cognitive decline with chronicity of condition might have a role in altering the CMI pattern in this population. Future studies of DT interventions for stroke survivors might benefit from incorporating working memory tasks in their protocols.