A secondary motor task exaggerates gait deficits in Parkinson's fallers

INTRODUCTION: People with Parkinson’s disease (PD) who fall demonstrate alterations in temporospatial, segmental and kinematic parameters of gait. Performance of dual tasks while walking results in decreased performance in people with PD. Given that PD fallers have been shown to have poorer segmental control during controlled walking tasks, their risk of falling could be exacerbated under conditions that challenge postural stability.

AIM: The aim of this study was to determine how gait patterns were altered when performing a secondary motor task.

METHODS: 44 PD patients and 34 healthy age-matched controls were assessed using three-dimensional motion analysis while walking at a self-selected pace during normal walking and while carrying a glass of water. Six trials were recorded for each condition. Falls were recorded prospectively over 12 months using daily falls calendars.

RESULTS: Based on the prospective falls data, participants were divided into four groups; PD Fallers (n=29); PD Non-­‐Fallers (n=15); Control Fallers (n=17); and Control Non-­‐Fallers (n=17). PD fallers and non­‐fallers had similar disease severity based on the UPDRS and Hoehn &Yahr scores. PD fallers had significantly greater disease duration, Freezing of Gait score and increased fear of falling than non-­fallers. Average daily Levodopa dose was not different between the PD fallers and non-­fallers. The secondary task resulted in a decrease in walking velocity, cadence, stride length and toe clearance for both groups. Stance and double support time were increased. Trunk flexion, mediolateral pelvis motion and knee flexion/extension range were increased. PD fallers were characterised by slower walking velocity, decreased toe clearance, reduced arm swing, increased trunk flexion and mediolateral motion of the head and pelvis, and increased knee flexion. Performance of the secondary task by PD fallers exaggerated differences in mediolateral pelvis motion and knee flexion angle.

CONCLUSION: Postural control deficits in PD fallers may impair their capacity to adapt to different task constraints. In an everyday activity, carrying a glass of water, PD fallers had increased segmental instability and altered kinematics. The risk of falling for people with PD may be increased when performing secondary tasks.