title: The rate of cognitive decline in Parkinson disease.
abstract: OBJECTIVE
  To measure the rate and predictors of change on the Mini-Mental State Examination in patients with Parkinson disease (PD) and to compare that change with the Mini-Mental State Examination changes of patients with Alzheimer disease and nondemented subjects.
  
  
  METHODS
  Patients with PD were drawn from a community-based cohort in Rogaland County, Norway. Those who were without cognitive impairment at disease onset and participated in 1 or more assessments after visit 1 were included and examined after 4 years (visit 2) and 8 years (visit 3). Motor, cognitive, and psychiatric symptoms were rated using standardized scales at visit 1. Two population-based cohorts of patients with Alzheimer disease and nondemented control subjects were included for comparison. Data were analyzed using a mixed-effects model.
  
  
  RESULTS
  One hundred twenty-nine PD patients (57% women) were included. The mean (SD) Mini-Mental State Examination score at visit 1 was 27.3 (5.7). The mean annual decline in score from visit 1 to visit 3 was 1.1 (95% confidence interval, 0.8 to 1.3; 3.9% change from visit 1). Patients with PD and dementia (n = 49) had an annual decline from visit 1 to visit 2 of 2.3 (95% confidence interval, 2.1 to 2.5; 9.1% change from visit 1), compared with 2.6 (95% confidence interval, 2.3 to 2.8; 10.6% change from visit 1) in the patients with Alzheimer disease (n = 34) (mean annual decline among patients with PD and dementia vs patients with Alzheimer disease, not significant). The change in score for nondemented PD patients (n = 80) was small and similar to that for nondemented control subjects (n = 1621). Old age, hallucinations, and more severe motor symptoms (rigidity and motor scores mediated by nondopaminergic lesions) at visit 1 were significantly associated with a more rapid cognitive decline in patients with PD.
  
  
  CONCLUSIONS
  The mean annual decline on the Mini-Mental State Examination for PD patients was 1 point. However, a marked variation was found. In patients with PD and dementia, the mean annual decline was 2.3, which was similar to the decline observed in patients with Alzheimer disease.
authors.affiliation: Section of Geriatric Psychiatry, Central Hospital of Rogaland, Stavanger, N-4095 Hillevåg, Norway. daa@sir.no
authors.forename: Dag
authors.initials: D
authors.lastname: Aarsland
authors.forename: Kjeld
authors.initials: K
authors.lastname: Andersen
authors.forename: Jan Petter
authors.initials: JP
authors.lastname: Larsen
authors.forename: Robert
authors.initials: R
authors.lastname: Perry
authors.forename: Tore
authors.initials: T
authors.lastname: Wentzel-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; D003072:Cognition Disorders / Q000453:epidemiology* / Q000523:psychology*; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000453:epidemiology* / Q000523:psychology*; D011237:Predictive Value of Tests; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data