title: Freezing of gait subtypes have different cognitive correlates in Parkinson's disease.
abstract: BACKGROUND
  Freezing of gait (FOG) is a major concern for Parkinson's disease (PD) patients because it is a leading cause of falls and is associated with poor quality of life. The pathophysiology is unknown but it is hypothesized that it relates to cognitive abnormalities; particularly executive and visuospatial dysfunction. However, prior results have been discrepant. Pharmacologic subtypes of FOG include those that are responsive and unresponsive to levodopa.
  
  
  OBJECTIVE
  To determine whether executive and visuospatial dysfunction are associated specifically with the levodopa unresponsive subtype of FOG.
  
  
  METHODS
  135 PD subjects completed a single assessment included FOG questionnaire, UPDRS motor scale, comprehensive cognitive battery and measure of hallucinations. Analyses compared unresponsive (n = 16), responsive (n = 20) and no FOG (n = 99) subtypes.
  
  
  RESULTS
  The unresponsive subtype had a significantly older age of onset of PD than the responsive group (p = .03) and had worse motor scores (p = .003) than the no FOG group. Longer disease duration was associated with the responsive group compared to the no FOG group (p = .002). The unresponsive FOG group had significantly poorer visuospatial ability (p = .001) and executive functioning (p = .02) than both the no and responsive FOG subgroups. These latter groups were not significantly different. The responsive FOG group was associated with the presence of hallucinations.
  
  
  CONCLUSIONS
  Aside from pharmacological differences, unresponsive FOG is associated with executive and visuospatial dysfunction implicating frontostriatal pathways while responsive FOG is associated with hallucinations suggesting involvement of posterior cortical regions. Further study and treatment of FOG should include appropriate subtype classification.
authors.affiliation: Emory University School of Medicine, Department of Neurology, USA. Electronic address: sfactor@emory.edu.
authors.forename: S A
authors.initials: SA
authors.lastname: Factor
authors.affiliation: Emory University School of Medicine, Department of Neurology, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: Scullin
authors.affiliation: Emory University School of Medicine, Department of Neurology, USA.
authors.forename: A B
authors.initials: AB
authors.lastname: Sollinger
authors.affiliation: Emory University School of Medicine, Department of Neurology, USA.
authors.forename: J O
authors.initials: JO
authors.lastname: Land
authors.affiliation: Emory University School of Medicine, Department of Neurology, USA.
authors.forename: C
authors.initials: C
authors.lastname: Wood-Siverio
authors.affiliation: Emory University School of Medicine, Department of Neurology, USA.
authors.forename: L
authors.initials: L
authors.lastname: Zanders
authors.affiliation: Emory University School of Medicine, Department of Neurology, USA.
authors.forename: A
authors.initials: A
authors.lastname: Freeman
authors.affiliation: Emory University School of Medicine, Department of Neurology, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Bliwise
authors.affiliation: Emory University School of Medicine, Department of Neurology, USA.
authors.forename: F C
authors.initials: FC
authors.lastname: Goldstein
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D003072:Cognition Disorders / Q000175:diagnosis* / Q000209:etiology*; D004185:Disability Evaluation; D056344:Executive Function; D005260:Female; D020233:Gait Disorders, Neurologic / Q000150:complications*; D006212:Hallucinations / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications*; D010468:Perceptual Disorders / Q000209:etiology; D012189:Retrospective Studies; D013028:Space Perception; D011795:Surveys and Questionnaires
keywords: Executive dysfunction; Freezing of gait; Hallucinations; Parkinson's disease; Visuospatial dysfunction