Objective To examine how a cued change in motor plan influences Parkinson's disease (PD) patients with freezing of gait (FOG) (PD FOG; n=10), compared with those without FOG (PD non-FOG; n=10) and healthy controls (n=10).

Methods Participants walked through a doorway in three experimental conditions: no cue; cue before gait initiation; and cue after gait initiation. The light cue was presented at the end of the pathway and signified that individuals must walk to the cue, turn around and return to starting position.

Results Step-to-step variability (a known precursor to FOG) revealed a significant main effect of group (F2,27=32.83, p<0.001), where PD FOG walked with greater step length variability than PD non-FOG and the control group. A significant interaction (F4,54=3.035, p=0.025) demonstrated that only the PD FOG group was most variable when the cue was present before gait initiation.

Conclusion This study concludes that motor planning deficits affect gait, specifically in individuals who experience FOG. This may have important implications for the design of therapeutic interventions in PD FOG.