Falls in Parkinson's disease: A proprioceptive or cognitive deficit?


Falls are one of the most debilitating occurrences of Parkinson's disease (PD), resulting in injury, hospitalizations, and reduced quality of life. As PD progresses, balance impairments worsen, making falls almost inevitable. Unfortunately, balance impairments are unaffected by dopaminergic-medication, leading researchers to investigate the causes of these balance impairments. Cognitive impairment and proprioceptive decline have the potential to underlie balance impairment and falls. Therefore, the purpose of this study was to determine whether cognitive impairment or proprioceptive decline are more indicative of balance impairment in PD, and to determine how anti-Parkinsonian medications influence balance impairment. 15 participants were categorized as "fallers" or "non-fallers" based on a 6-month fall history. They were then randomized into "same-day" or "next-day" testing to assess effects of anti-Parkinsonian medication (utilizing the motor symptom assessment of the UPDRS-III). Each participant completed the MoCA, a proprioceptive limb-matching task, and subsequently a balance assessment using Biodex (CTSIB). OFF-medication, passive proprioception significantly predicted balance impairment(b=5.152,t(5)=3.512 p=.006), and explained a significant amount of variance in balance impairment( R2=.784, F(1,5)=11.901,p=.001). ON-medication, active proprioception significantly predicted balance impairment(b=1.768,t(5)=9.678,p<.001), and explained a significant amount of variance in balance impairment(R2=.801, F(1,5)=13.059,p<.001), whereas cognitive assessment revealed much lower predictability(b=-0.128,t(5)=-4.316). These results suggest that proprioception is a better predictor of balance impairment (likely fall risk) than cognitive impairment. Further, these results suggest that balance deteriorates as proprioception gets worse and when in the ON-medication state. Practically, proprioception may be important to assess as a predictor of PD participants that may be at risk of balance impairment.

Acknowledgments: Movement Disorders Research and Rehabilitation Centre and Wilfrid Laurier University