title: Predictors of cognitive impairment in an early stage Parkinson's disease cohort.
abstract: The impact of Parkinson's disease (PD) dementia is substantial and has major functional and socioeconomic consequences. Early prediction of future cognitive impairment would help target future interventions. The Montreal Cognitive Assessment (MoCA), the Mini-Mental State Examination (MMSE), and fluency tests were administered to 486 patients with PD within 3.5 years of diagnosis, and the results were compared with those from 141 controls correcting for age, sex, and educational years. Eighteen-month longitudinal assessments were performed in 155 patients with PD. The proportion of patients classified with normal cognition, mild cognitive impairment (MCI), and dementia varied considerably, depending on the MoCA and MMSE thresholds used. With the MoCA total score at screening threshold, 47.7%, 40.5%, and 11.7% of patients with PD were classified with normal cognition, MCI, and dementia, respectively; by comparison, 78.7% and 21.3% of controls had normal cognition and MCI, respectively. Cognitive impairment was predicted by lower education, increased age, male sex, and quantitative motor and non-motor (smell, depression, and anxiety) measures. Longitudinal data from 155 patients with PD over 18 months showed significant reductions in MoCA scores, but not in MMSE scores, with 21.3% of patients moving from normal cognition to MCI and 4.5% moving from MCI to dementia, although 13.5% moved from MCI to normal; however, none of the patients with dementia changed their classification. The MoCA may be more sensitive than the MMSE in detecting early baseline and longitudinal cognitive impairment in PD, because it identified 25.8% of those who experienced significant cognitive decline over 18 months. Cognitive decline was associated with worse motor and non-motor features, suggesting that this reflects a faster progressive phenotype.
authors.affiliation: Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, University of Oxford, Oxford, United Kingdom; Department of Clinical Neurology, John Radcliffe Hospital, Oxford, United Kingdom; Oxford Parkinson's Disease Centre, Oxford, United Kingdom.
authors.forename: Michele T M
authors.initials: MT
authors.lastname: Hu
authors.forename: Konrad
authors.initials: K
authors.lastname: Szewczyk-Królikowski
authors.forename: Paul
authors.initials: P
authors.lastname: Tomlinson
authors.forename: Kannan
authors.initials: K
authors.lastname: Nithi
authors.forename: Michal
authors.initials: M
authors.lastname: Rolinski
authors.forename: Clara
authors.initials: C
authors.lastname: Murray
authors.forename: Kevin
authors.initials: K
authors.lastname: Talbot
authors.forename: Klaus P
authors.initials: KP
authors.lastname: Ebmeier
authors.forename: Clare E
authors.initials: CE
authors.lastname: Mackay
authors.forename: Yoav
authors.initials: Y
authors.lastname: Ben-Shlomo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000150:complications / Q000175:diagnosis; D060825:Cognitive Dysfunction / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D011237:Predictive Value of Tests
keywords: Mini-Mental State Examination; Montreal Cognitive Assessment; Parkinson's disease; dementia; mild cognitive impairment