Abstract

Background: The purpose of this study was to examine the cognitive-motor interference pattern while concurrently performing a higher cognitive task with three dynamic postural tasks – limits of stability (intentional balance), compensatory stepping during (reactive balance -RB) and walking tasks across younger adults (YA), older adults (OA) and older chronic stroke survivors.
Methods: Thirty-six individuals in each group performed either of the three postural tasks – forward limits of stability (LOS, intentional balance), forward compensatory stepping (reactive balance - RB) and walking task (gait) with (dual-task) and without (single-task) performing a serial subtraction (SS) task. The SS tasks was also performed in isolation. Maximum center of pressure excursion (MXE) for LOS, center of mass position relative to base of support at step touchdown for RB, gait velocity and number of correct responses for SS task were measured. Motor and cognitive costs were calculated.
Results: The healthy adults showed higher motor cost for more dynamic gait and RB tasks compared with the LOS task however, motor costs were similar for all the tasks in the stroke group. Although the motor cost for OA and stroke groups were more than YAs for all postural tasks, motor cost was significantly greater in stroke group than OA group only for the LOS task.
Conclusion: The attentional demands are higher for postural task that are biomechanically unstable in healthy adults. Chronic stroke survivors show disproportionate ability to divide attention seen by higher motor cost during LOS task. Nevertheless, in chronic phase of recovery, stroke survivors may regain some dual-task function displaying similar strategies as healthy counterparts.