Prognosis of mild cognitive impairment in early Parkinson disease: the Norwegian ParkWest study

JAMA Neurol. 2013 May;70(5):580-6. doi: 10.1001/jamaneurol.2013.2110.


Importance: 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.

Design: Prospective longitudinal cohort study.

Setting: The Norwegian ParkWest study, an ongoing population-based study of the incidence, neurobiology, and prognosis of PD in western and southern Norway.

Participants: A population-based cohort of 182 patients with incident PD monitored for 3 years.

Main outcomes and measures: 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 and relevance: 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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Cognitive Dysfunction / diagnosis*
  • Cognitive Dysfunction / etiology
  • Dementia / diagnosis*
  • Dementia / etiology
  • Disease Progression
  • Female
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Neuropsychological Tests
  • Norway
  • Parkinson Disease / complications
  • Parkinson Disease / epidemiology
  • Parkinson Disease / physiopathology*
  • Prognosis
  • Prospective Studies
  • Time Factors