title: Freezing of gait in Parkinson's disease: the impact of dual-tasking and turning.
abstract: 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 180° and 360° 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 180° turning compared to 0% during straight-line walking (X(2) = 10.44, p < 0.01). The occurrence of FOG increased during 360° 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 360° and 180° 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 180° turning, whereas freezers deteriorated their secondary task performance during 360°.
  
  
  CONCLUSIONS
  360° 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.
authors.affiliation: Department of Rehabilitation Sciences, Katholieke Universiteit, Leuven, Belgium. joke.spildooren@faber.kuleuven.be
authors.forename: Joke
authors.initials: J
authors.lastname: Spildooren
authors.forename: Sarah
authors.initials: S
authors.lastname: Vercruysse
authors.forename: Kaat
authors.initials: K
authors.lastname: Desloovere
authors.forename: Wim
authors.initials: W
authors.lastname: Vandenberghe
authors.forename: Eric
authors.initials: E
authors.lastname: Kerckhofs
authors.forename: Alice
authors.initials: A
authors.lastname: Nieuwboer
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D005684:Gait / Q000502:physiology*; D020233:Gait Disorders, Neurologic / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D008875:Middle Aged; D009068:Movement / Q000502:physiology; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology*; D016138:Walking / Q000502:physiology