title: Cognitive characteristics associated with mild cognitive impairment in Parkinson's disease.
abstract: BACKGROUND
  Cognitive deficits are common in Parkinson's disease (PD), but the range of deficits is variable. The aim of this study was to identify different cognitive subgroups associated with PD.
  
  
  METHODS
  A broad range of neuropsychological measures and cognitive domains were used in a cluster analysis to identify subgroups of patients.
  
  
  RESULTS
  Three subgroups of patients were identified. Compared to controls, one PD subgroup showed no or minimal cognitive impairment (PD-NCI), a second group showed a variable or uncertain pattern of mild to severe cognitive impairments (PD-UCI), and a third group had evidence of severe cognitive impairment across most cognitive domains (mild cognitive impairment; PD-MCI). The subgroups did not differ with regard to age, motor impairment, or disease duration.
  
  
  CONCLUSIONS
  Patients with PD are heterogeneous with regard to cognitive presentation and it may be possible to identify patients in the preclinical stage of dementia. The identification of preclinical dementia in PD patients (PD-MCI) provides an opportunity to understand cognitive decline in PD and its progression to dementia.
authors.affiliation: Psychology Department, University of Canterbury, Christchurch, New Zealand. audrey.mckinlay@canterbury.ac.nz
authors.forename: A
authors.initials: A
authors.lastname: McKinlay
authors.forename: R C
authors.initials: RC
authors.lastname: Grace
authors.forename: J C
authors.initials: JC
authors.lastname: Dalrymple-Alford
authors.forename: D
authors.initials: D
authors.lastname: Roger
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D016000:Cluster Analysis; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000209:etiology / Q000523:psychology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications / Q000523:psychology*; D011597:Psychomotor Performance / Q000502:physiology; D014888:Wechsler Scales