Errors in cognitive performance trigger postural instability in Parkinson's disease.

ABSTRACT

BACKGROUND: Globally, postural stability and cognitive performance are intimately linked in Parkinson's disease (PD). However, a fundamental gap exists in understanding the precise relationship between a disruption in executive function and its impact on postural stability. OBJECTIVE: This project aimed to determine the precise effects of cognitive errors on postural stability under dual-task conditions in participants with PD and controls. METHODS: Twenty-eight individuals with PD and 27 healthy controls completed a series of postural stability tests under single- and dual-tasks. The dual-task required maintenance of balance while performing an audio number discrimination task. RESULTS: In general, postural stability in PD and control subjects was similar across single-task conditions. In controls, an error in the cognitive task during dual-task conditions did not impact measures of postural sway. In contrast, in PD, postural sway increased in epochs surrounding cognitive errors relative to epochs without errors. CONCLUSIONS: Postural task selection plays a critical role when testing for balance deficits in PD compared to healthy controls. Furthermore, time synchronized analysis of cognitive and balance data revealed the greatest episodes of postural instabilities occurred around cognitive errors. The measurement and evaluation of cognitive-motor linkages, relative to postural stability, could provide a patient-specific fingerprint of balance function and provide more sensitive measures for fall risk in PD.