Freezing of Gait in Parkinson's Disease: The Impact of Dual-Tasking and Turning

Background: Turning is the most important trigger for freezing of gait (FOG) in Parkinson's disease (PD), and dual-tasking has been suggested to influence FOG as well. Objective: To understand the effects of dual tasking and turning on FOG. Methods: 14 Freezers and 14 non-freezers matched for disease severity and 14 age-matched controls were asked to turn 1808 and 3608 with and without a cognitive dual-task during the off-period of the medication cycle. Total number of steps, duration, cadence, freezing-frequency, and secondary-task performance were measured. Results: Seven freezers froze during the protocol. Freezing occurred in 37.5% of trials during 1808 turning compared to 0% during straight-line walking (X-2 = 10.44, p < 0.01). The occurrence of FOG increased during 3608 when also a dual-task was added (X-2 = 4.23, p = 0.04). Freezers took significantly more steps and were slower than controls in all conditions. The presence of a dual-task increased these differences. Cadence increased significantly for freezers during 3608 and 1808 compared to straight-line walking. In contrast, cadence was decreased during turning in controls and non-freezers. During straight-line walking, only freezers made errors in the secondary task. Controls increased their error-rate during 1808 turning, whereas freezers deteriorated their secondary task performance during 360 degrees. Conclusions: 3608 turning in combination with a dual-task is the most important trigger for freezing. During turning, non-freezers and controls decreased their cadence whereas freezers increased it, which may be related to FOG. Freezers adopted a posture second strategy in contrast to non-freezers when confronted with a dual task. (C) 2010 Movement Disorder Society