title: Freezing of gait in Parkinson's disease is related to impaired motor switching during stepping.
abstract: BACKGROUND
  Parkinson's disease (PD) has been associated with set switching difficulty in both the motor and the cognitive domain. However, the contribution of these set switching deficits to the primary motor symptoms of the disease is unclear. We investigated whether set switching deficits contribute to gait and stepping problems in PD. By contrasting motor and cognitive set switching within the same paradigm, we investigated the nature of set switching deficits associated with freezing of gait (FOG).
  
  
  METHODS
  We integrated step initiation with set switching within one task and compared patients with and without FOG with healthy subjects. Motor set switching was defined as a change in stepping direction from one trial to the next. Cognitive set switching was defined as a change in task rule (ie, respond according to the shape or color of the presented stimulus).
  
  
  RESULTS
  We found delayed motor switching in PD patients with FOG. We did not observe impaired cognitive switching.
  
  
  CONCLUSIONS
  These findings suggest that motor set switching deficits, commonly reported in tasks using verbal or tapping responses, extend to stepping and can contribute to the occurrence of freezing episodes during gait initiation.
authors: Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour; Department of Neurology, 6500, HB, Nijmegen, The Netherlands.|HAN University of Applied Sciences; Institute for Studies in Sports and Exercise, 6503 GL, Nijmegen, The Netherlands.
authors: Katrijn
authors: K
authors: Smulders
authors: Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour; Department of Neurology, 6500, HB, Nijmegen, The Netherlands.
authors: Rianne A
authors: RA
authors: Esselink
authors: Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour; Department of Neurology, 6500, HB, Nijmegen, The Netherlands.
authors: Bastiaan R
authors: BR
authors: Bloem
authors: Radboud University Medical Center; Donders Institute for Brain, Cognition and Behaviour; Department of Psychiatry, 6500, HB, Nijmegen, The Netherlands.|Radboud University; Donders Institute for Brain, Cognition and Behaviour; Centre for Cognitive Neuroimaging, 6500, HB, Nijmegen, The Netherlands.
authors: Roshan
authors: R
authors: Cools
mesh_terms: D000368:Aged; D056344:Executive Function / Q000502:physiology*; D005260:Female; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology*
keywords: cognitive control; freezing of gait; gait; set shifting; stepping