title: Severity of mild cognitive impairment in early Parkinson's disease contributes to poorer quality of life.
abstract: BACKGROUND
  Poor quality of life (QoL) is a feature of people with Parkinson's disease (PD) who develop dementia. The relationship between mild cognitive impairment in PD (PD-MCI) and QoL is less clear. To address this, we studied the impact of varying severities of cognitive impairment on QoL in a cohort of non-demented patients with early PD.
  
  
  METHODS
  Patients with newly diagnosed PD (n = 219) and age and sex matched healthy controls (n = 99) completed a schedule of neuropsychological tests, in addition to scales assessing QoL (PDQ-39), depression, sleep, neuropsychiatric symptoms and a clinical examination. The Movement Disorder Society criteria were used to define and classify PD-MCI.
  
  
  RESULTS
  Participants with PD-MCI were significantly older than those with normal cognition, had more severe motor symptoms, scored higher for depression and had poorer quality of life. Logistic regression showed that mild cognitive impairment, independent of other factors, was an indicator of poorer QoL. Using cognitive performance 2.0 standard deviations (SD) below normative data as a cut-off to define PD-MCI, there was a significant difference in QoL scores between patients with PD-MCI and those classified as having normal cognition. Subjects with less severe mild cognitive impairment did not exhibit significant differences in QoL.
  
  
  CONCLUSIONS
  PD-MCI is a significant, independent factor contributing to poorer QoL in patients with newly diagnosed PD. Those classified with greatest impairment (2.0 SD below normal values) have lower QoL. This has implications for clinical practice and future interventions targeting cognitive impairments.
authors: Institute for Ageing and Health, Newcastle University, Newcastle Upon Tyne, UK. Electronic address: rachael.lawson@ncl.ac.uk.
authors: Rachael A
authors: RA
authors: Lawson
authors: Institute for Ageing and Health, Newcastle University, Newcastle Upon Tyne, UK.
authors: Alison J
authors: AJ
authors: Yarnall
authors: Institute for Ageing and Health, Newcastle University, Newcastle Upon Tyne, UK.
authors: Gordon W
authors: GW
authors: Duncan
authors: Griffith Health Institute & School of Medicine, Griffith University, Gold Coast, Australia.
authors: Tien K
authors: TK
authors: Khoo
authors: John van Geest Centre for Brain Repair, University of Cambridge, Cambridge, UK.
authors: David P
authors: DP
authors: Breen
authors: John van Geest Centre for Brain Repair, University of Cambridge, Cambridge, UK.
authors: Roger A
authors: RA
authors: Barker
authors: Institute for Ageing and Health, Newcastle University, Newcastle Upon Tyne, UK.
authors: Daniel
authors: D
authors: Collerton
authors: Institute for Ageing and Health, Newcastle University, Newcastle Upon Tyne, UK.
authors: John-Paul
authors: JP
authors: Taylor
authors: Institute for Ageing and Health, Newcastle University, Newcastle Upon Tyne, UK.
authors: David J
authors: DJ
authors: Burn
mesh_terms: D000368:Aged; D001288:Attention; D060825:Cognitive Dysfunction / Q000209:etiology*; D056344:Executive Function; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications* / Q000523:psychology*; D011237:Predictive Value of Tests; D011788:Quality of Life / Q000523:psychology*; D013028:Space Perception; D018709:Statistics, Nonparametric
keywords: Mild cognitive impairment; Parkinson's disease; Quality of life