Abstract
Recent studies have argued that patients with Parkinson's disease (PD) manifesting freezing of gait (FOG) may require greater attentional demand to control gait in more complex situations. Since PD patients with FOG experience more trips and falls, it is important to evaluate how attention might influence foot placements when stepping over an obstacle. As such, the current study evaluated the effects of a dual task on foot placement variability of PD patients with and without freezing of gait when stepping over an obstacle. Participants (PD-FOG=14, PD-nonFOG =13, Healthy controls = 13) were matched in disease severity and age. The obstacle was set at 15% of their height. Foot Placement (FP) variability was calculated using the standard deviation across five trials in each condition for each FP number (N-3, N-2, N-1, N) prior to crossing the obstacle. The dual task was an auditory number monitoring while walking. An interaction between group and step number (P=0.002) revealed that PD-FOG and controls stepped with lower FP variability prior to the obstacle (compared to PD-non FOG). Only PD-FOG increased FP variability during dual task condition in the FP N-3, N-2 and N-1. We conclude that PD-FOG likely develop attention strategies to improve precision of FP allowing them to perform similar to healthy controls. In attention-demanding situations, resources may be overloaded causing freezers to increase variability and be more prone to gait deficits.Acknowledgments: CNPq; CFI; Sun Life Financial