title: Predictors of dementia in Parkinson's disease; findings from a 5-year prospective study using the SCOPA-COG.
abstract: OBJECTIVE
  Aim of this study was to identify risk factors for the development of dementia in patients with Parkinson's disease (PD).
  
  
  METHODS
  A broad range of motor and non-motor features was assessed at baseline and the following five years in 406 PD patients. Cross-sectional analyses of baseline data and longitudinal analyses of follow-up data were performed to identify risk factors for dementia.
  
  
  RESULTS
  Thirty-two percent of patients (n = 129) had dementia at baseline, while 26% of patients (n = 68) without dementia at baseline developed dementia during follow-up. Univariate survival analysis showed that higher age, fewer years of education, longer disease duration, higher age-at-onset, higher levodopa dose, higher Hoehn & Yahr stage, presence of dyskinesias, excessive daytime sleepiness (EDS), presence of hallucinations, and more severe autonomic and depressive symptoms were associated with an increased risk of dementia. Higher baseline Postural-Instability-and-Gait-Difficulty scores were also associated with an increased risk of dementia, whereas no effect of tremor severity was found. These findings largely corresponded with the variables that were associated with the presence of dementia at baseline. In a stepwise regression model, higher age at baseline, fewer years of education, higher daily levodopa dose and excessive daytime sleepiness (EDS) emerged as independent risk factors of future dementia.
  
  
  CONCLUSIONS
  In this large prospective cohort study, we identified a combination of potentially interacting risk factors for dementia in PD that are associated with higher age and more advanced disease.
authors.affiliation: Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Kangdi
authors.initials: K
authors.lastname: Zhu
authors.affiliation: Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Jacobus J
authors.initials: JJ
authors.lastname: van Hilten
authors.affiliation: Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands. Electronic address: j.marinus@lumc.nl.
authors.forename: Johan
authors.initials: J
authors.lastname: Marinus
mesh_terms: D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003704:Dementia / Q000175:diagnosis* / Q000188:drug therapy / Q000209:etiology*; D005260:Female; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications* / Q000188:drug therapy; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D007980:Levodopa
keywords: Cognition; Dementia; Parkinson's disease; Predictors; Risk factors