title: Dopaminergic modulation of arm swing during gait among Parkinson's disease patients.
abstract: BACKGROUND
  Reduced arm swing amplitude, symmetry, and coordination during gait have been reported in Parkinson's disease (PD), but the relationship between dopaminergic depletion and these upper limb gait changes remains unclear.
  
  
  OBJECTIVE
  We aimed to investigate the effects of dopaminergic drugs on arm swing velocity, symmetry, and coordination in PD.
  
  
  METHODS
  Forearm angular velocity was recorded in 16 PD and 17 control subjects (Controls) during free walking trials. Angular velocity amplitude of each arm, arm swing asymmetry, and maximum cross-correlation were compared between control and PD groups, and between OFF- and ON-medication states among PD subjects.
  
  
  RESULTS
  Compared to Controls, PD subjects in the OFF-medication state exhibited lower angular velocity amplitude of the slower- (p = 0.0018), but not faster- (p = 0.2801) swinging arm. In addition, PD subjects demonstrated increased arm swing asymmetry (p = 0.0046) and lower maximum cross-correlation (p = 0.0026). Following dopaminergic treatment, angular velocity amplitude increased in the slower- (p = 0.0182), but not faster- (p = 0.2312) swinging arm among PD subjects. Furthermore, arm swing asymmetry decreased (p = 0.0386), whereas maximum cross-correlation showed no change (p = 0.7436). Pre-drug angular velocity amplitude of the slower-swinging arm was correlated inversely with the change in arm swing asymmetry (R = -0.73824, p = 0.0011).
  
  
  CONCLUSIONS
  This study provides quantitative evidence that reduced arm swing and symmetry in PD can be modulated by dopaminergic replacement. The lack of modulations of bilateral arm coordination suggests that additional neurotransmitters may also be involved in arm swing changes in PD. Further studies are warranted to investigate the longitudinal trajectory of arm swing dynamics throughout PD progression.
authors.affiliation: Department of Neurology, The Pennsylvania State University - Milton S. Hershey Medical Center, Hershey, PA, USA Department of Public Health Sciences, The Pennsylvania State University - Milton S. Hershey Medical Center, Hershey, PA, USA.
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Sterling
authors.affiliation: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Cusumano
authors.affiliation: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Noam
authors.initials: N
authors.lastname: Shaham
authors.affiliation: Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Piazza
authors.affiliation: Department of Public Health Sciences, The Pennsylvania State University - Milton S. Hershey Medical Center, Hershey, PA, USA.
authors.forename: Guodong
authors.initials: G
authors.lastname: Liu
authors.affiliation: Department of Public Health Sciences, The Pennsylvania State University - Milton S. Hershey Medical Center, Hershey, PA, USA.
authors.forename: Lan
authors.initials: L
authors.lastname: Kong
authors.affiliation: Department of Neurology, The Pennsylvania State University - Milton S. Hershey Medical Center, Hershey, PA, USA.
authors.forename: Guangwei
authors.initials: G
authors.lastname: Du
authors.affiliation: Department of Neurology, The Pennsylvania State University - Milton S. Hershey Medical Center, Hershey, PA, USA Department of Pharmacology, The Pennsylvania State University - Milton S. Hershey Medical Center, Hershey, PA, USA.
authors.forename: Mechelle M
authors.initials: MM
authors.lastname: Lewis
authors.affiliation: Department of Neurology, The Pennsylvania State University - Milton S. Hershey Medical Center, Hershey, PA, USA Department of Kinesiology, The Pennsylvania State University, University Park, PA, USA Department of Pharmacology, The Pennsylvania State University - Milton S. Hershey Medical Center, Hershey, PA, USA Department of Radiology, The Pennsylvania State University - Milton S. Hershey Medical Center, Hershey, PA, USA Department of Neurosurgery, The Pennsylvania State University - Milton S. Hershey Medical Center, Hershey, PA, USA.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Huang
mesh_terms: D000368:Aged; D001132:Arm / Q000503:physiopathology*; D015259:Dopamine Agents / Q000494:pharmacology / Q000627:therapeutic use; D005260:Female; D020233:Gait Disorders, Neurologic / Q000188:drug therapy* / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000187:drug effects* / Q000502:physiology; D010300:Parkinson Disease / Q000150:complications* / Q000188:drug therapy; D011597:Psychomotor Performance / Q000187:drug effects; D016138:Walking
chemical_list: D015259:Dopamine Agents
keywords: Arm swing; Parkinson's disease; asymmetry; dopamine; gait; locomotion