title: Prognosis of mild cognitive impairment in early Parkinson disease: the Norwegian ParkWest study.
abstract: OBJECTIVE
  Mild cognitive impairment (MCI) is common in Parkinson disease (PD), but the prognostic value of MCI in early PD is unknown.
  
  
  OBJECTIVE
  To examine the course of MCI and its progression to dementia in an incident PD cohort.
  
  
  METHODS
  Prospective longitudinal cohort study.
  
  
  METHODS
  The Norwegian ParkWest study, an ongoing population-based study of the incidence, neurobiology, and prognosis of PD in western and southern Norway.
  
  
  METHODS
  A population-based cohort of 182 patients with incident PD monitored for 3 years.
  
  
  METHODS
  Serial neuropsychological tests of attention, executive function, verbal memory, and visuospatial skills were administered at baseline, 1 year, and 3 years. Patients were classified as having MCI and received a diagnosis of dementia according to published consensus criteria.
  
  
  RESULTS
  Significantly more patients with MCI than without MCI at baseline (10 of 37 [27.0%] vs 1 of 145 [0.7%]; relative risk, 39.2 [95% CI, 5.2-296.5]; P < .001) progressed to dementia during follow-up. Of those with MCI at baseline, 8 of 37 (21.6%) had MCI that reverted to normal cognition during follow-up. Mild cognitive impairment at the 1-year visit was associated with a similar progression rate to dementia (10 of 36 patients [27.8%]) and reversion rate to normal cognition (7 of 36 [19.4%]). However, among the 22 patients with persistent MCI at baseline and the 1-year visit, 10 (45.5%) developed dementia and only 2 (9.1%) had MCI that reverted to normal cognition by the end of study.
  
  
  CONCLUSIONS
  Mild cognitive impairment at PD diagnosis predicts a highly increased risk for early dementia. Repeated neuropsychological testing increases the prognostic accuracy of MCI with respect to early dementia development in PD.
authors.affiliation: The Norwegian Centre for Movement Disorders, Stavanger University Hospital, Stavanger, Norway. kenfrp@online.no
authors.forename: Kenn Freddy
authors.initials: KF
authors.lastname: Pedersen
authors.forename: Jan Petter
authors.initials: JP
authors.lastname: Larsen
authors.forename: Ole-Bjorn
authors.initials: OB
authors.lastname: Tysnes
authors.forename: Guido
authors.initials: G
authors.lastname: Alves
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000209:etiology; D003704:Dementia / Q000175:diagnosis* / Q000209:etiology; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D009664:Norway; D010300:Parkinson Disease / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology*; D011379:Prognosis; D011446:Prospective Studies; D013997:Time Factors