The Effects of Task Prioritization on Dual-Tasking Postural Control in Patients With Parkinson Disease Who Have Different Postural Impairments.

OBJECTIVE: To investigate the effect of task prioritization on dual-task control in Parkinson disease (PD) associated with different postural impairments. DESIGN: Cross-sectional study. Participants were instructed to keep 2 interlocking rings apart and maintain balance in a tandem stance. Attention was focused on either stance stability (posture-focus strategy) or the interlocking rings (supraposture-focus strategy). SETTING: University research laboratory. PARTICIPANTS: Fifteen patients with PD and less postural impairment and 15 patients with PD and more postural impairment (N=30). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Postural sway, postural determinism (%DET), ankle co-contraction, and ring-touching time. RESULTS: In the less-impairment group, the supraposture-focus strategy provided smaller postural sway and postural %DET compared with the posture-focus strategy. In the more-impairment group, task prioritization showed lower effect on both postural sway and postural %DET. The supraposture-focus strategy led to less ankle co-contraction than the posture-focus strategy in the more-impairment group, but task prioritization did not affect ankle co-contraction in the less-impairment group. In both groups, the supraposture-focus strategy led to less ring-touching time than the posture-focus strategy. CONCLUSIONS: The supraposture-focus strategy provided better dual-task control than the posture-focus strategy in both PD groups. In the less-impairment group, the supraposture-focus strategy enhanced postural automaticity and postural stability. In the more-impairment group, the supraposture-focus strategy reduced ankle stiffness, owing to reduced muscle co-contraction.