title: Prevalence and characteristics of dementia in Parkinson disease: an 8-year prospective study.
abstract: BACKGROUND
  Few longitudinal studies of dementia in Parkinson disease (PD) have been reported, and the proportion of patients with PD who eventually develop dementia is unknown.
  
  
  OBJECTIVE
  To examine the 8-year prevalence, characteristics, and risk factors of dementia in patients with PD.
  
  
  METHODS
  Patients were recruited from an epidemiological study of PD in the county of Rogaland, Norway, using explicit criteria for PD. Subjects with cognitive impairment at disease onset were excluded. A semistructured caregiver-based interview, cognitive rating scales, and neuropsychological tests were used to diagnose dementia according to criteria from the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition at baseline and 4 and 8 years later. A population-based sample of 3295 subjects in the municipality of Odense, Denmark, was used as a comparison group and examined at baseline and after 2 and 5 years.
  
  
  RESULTS
  We included 224 patients with PD (116 women). At baseline, 51 patients (26%) had dementia. Fifty-five patients died, and 10 refused follow-up without their dementia status known. Forty-three and 28 new cases of dementia were identified at the 4- and 8-year evaluations, respectively. The 4-year prevalence of dementia in PD was nearly 3 times higher than in the non-PD group. The 8-year prevalence in PD was 78.2% (95% confidence interval [CI], 71.1-84.0). Risk factors for dementia were hallucinations before baseline (odds ratio [OR] = 3.1; 95% CI, 1.6-6.2) and akinetic-dominant or mixed tremor/akinetic PD (OR = 3.3; 95% CI, 1.2-8.5).
  
  
  CONCLUSIONS
  More than three quarters of this representative PD cohort developed dementia during the 8-year study period. Early hallucinations and akinetic-dominant PD were associated with an increased risk of dementia.
authors.affiliation: Section of Geriatric Psychiatry, Psychiatric Clinic, Central Hospital of Rogaland, PO 1163, Hillevag, N-4095 Stavanger, Norway. daa@post.rps.no
authors.forename: Dag
authors.initials: D
authors.lastname: Aarsland
authors.forename: Kjeld
authors.initials: K
authors.lastname: Andersen
authors.forename: Jan P
authors.initials: JP
authors.lastname: Larsen
authors.forename: Anette
authors.initials: A
authors.lastname: Lolk
authors.forename: Per
authors.initials: P
authors.lastname: Kragh-Sørensen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003704:Dementia / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000453:epidemiology*; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors