title: Predictors of mild cognitive impairment in early-stage Parkinson's disease.
abstract: OBJECTIVE
  The aim of this study was to identify mild cognitive deficits in Parkinson's disease (PD) prior to extensive neurodegeneration and to evaluate the extent to which dopamine depletion and other disease-related predictors can explain cognitive profiles.
  
  
  METHODS
  Neuropsychological performances of 40 nondemented early-stage PD patients and 42 healthy controls were compared across on or off dopaminergic medications. Stepwise regression evaluated cognitive predictors of early-stage PD and disease-related predictors of PD cognition (levodopa dose, disease duration, Unified Parkinson's Disease Rating Scale score, sleep, quality of life, and mood) across on and off states.
  
  
  RESULTS
  Neuropsychological performance was lower in PD patients across cognitive domains with significant memory, naming, visuomotor, and complex attention/executive deficits, but with intact visuospatial, simple attention, and phonemic fluency functions. However, medication effects were absent except for simple attention. Regression analyses revealed age, working memory, and memory recall to be the best cognitive predictors of PD, while age, quality of life, disease duration, and anxiety predicted PD cognition in the off state.
  
  
  CONCLUSIONS
  Nondemented early-stage PD patients presented with extensive mild cognitive deficits including prominent memory impairment. The profile was inconsistent with expected isolated frontostriatal dysfunction previously attributed to dopamine depletion and this highlights the need to further characterize extranigral sources of mild cognitive impairment in PD.
authors.affiliation: Division of Neuropsychology, Department of Neurology, Emory University School of Medicine, Atlanta, Ga. ; Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Ga.
authors.forename: Brenda
authors.initials: B
authors.lastname: Hanna-Pladdy
authors.forename: Katherine
authors.initials: K
authors.lastname: Jones
authors.forename: Romeo
authors.initials: R
authors.lastname: Cabanban
authors.forename: Rajesh
authors.initials: R
authors.lastname: Pahwa
authors.forename: Kelly E
authors.initials: KE
authors.lastname: Lyons
keywords: Dopaminergic medication; Mild cognitive impairment; Neuropsychological performance; Parkinson's disease; Predictors