Repository logo

Stability of mild cognitive impairment in newly diagnosed Parkinson's disease.

Published version



Change log


Lawson, Rachael A 
Yarnall, Alison J 
Duncan, Gordon W 
Breen, David P 
Khoo, Tien K 


BACKGROUND: Mild cognitive impairment (MCI) is common in early Parkinson's disease (PD). We evaluated the stability of PD-MCI over time to determine its clinical utility as a marker of disease. METHODS: 212 newly diagnosed participants with PD were recruited into a longitudinal study and reassessed after 18 and 36 months. Participants completed a range of clinical and neuropsychological assessments. PD-MCI was classified using Movement Disorders Society Task Force level I (Montreal Cognitive Assessment <26) and level II (using cut-offs of 1, 1.5 and 2SD) criteria. RESULTS: After 36 months, 75% of participants returned; 8% of patients had developed a dementia all of which were previously PD-MCI. Applying level I criteria, 70% were cognitively stable, 19% cognitively declined and 11% improved over 36 months. Applying level II criteria (1, 1.5 and 2SD), 25% were cognitively stable, 41% cognitively declined, 15% improved and 19% fluctuated over 36 months. 18% of participants reverted to normal cognition from PD-MCI. DISCUSSION: Cognitive impairment in PD is complex, with some individuals' function fluctuating over time and some reverting to normal cognition. PD-MCI level I criteria may have greater clinical convenience, but more comprehensive level II criteria with 2SD cut-offs may offer greater diagnostic certainty.



COGNITION, DEMENTIA, PARKINSON'S DISEASE, Aged, Cognitive Dysfunction, Cohort Studies, Dementia, Disease Progression, England, Female, Humans, Longitudinal Studies, Male, Middle Aged, Neuropsychological Tests, Parkinson Disease

Journal Title

J Neurol Neurosurg Psychiatry

Conference Name

Journal ISSN


Volume Title



Parkinson's UK (via Newcastle University) (RES/0211/7258)
Cambridge University Hospitals NHS Foundation Trust (CUH) (unknown)
Wellcome Trust (103838/Z/14/Z)
Medical Research Council (MC_U105597119)
Medical Research Council (MC_UU_00005/12)