Predictors of cognitive impairment in an early stage Parkinson's disease cohort

Authors

  • Michele T. M. Hu MBBS, FRCP, PhD,

    Corresponding author
    1. Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, University of Oxford, Oxford, United Kingdom
    2. Department of Clinical Neurology, John Radcliffe Hospital, Oxford, United Kingdom
    3. Oxford Parkinson's Disease Centre, Oxford, United Kingdom
    • Correspondence to: Dr. Michele T. M. Hu, Department of Clinical Neurology, Level 3, West Wing, John Radcliffe Hospital, Headley Way, Headington, Oxford OX3 9DE United Kingdom; michele.hu@ndcn.ox.ac.uk

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  • Konrad Szewczyk-Królikowski MD, MRCP,

    1. Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, University of Oxford, Oxford, United Kingdom
    2. Oxford Parkinson's Disease Centre, Oxford, United Kingdom
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  • Paul Tomlinson BSc (Hons), PhD, MD, FRACP,

    1. Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, University of Oxford, Oxford, United Kingdom
    2. Oxford Parkinson's Disease Centre, Oxford, United Kingdom
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  • Kannan Nithi MBBS, FRCP,

    1. Department of Clinical Neurology, John Radcliffe Hospital, Oxford, United Kingdom
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  • Michal Rolinski BA(Hons), BM, BCh, MRCP,

    1. Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, University of Oxford, Oxford, United Kingdom
    2. Oxford Parkinson's Disease Centre, Oxford, United Kingdom
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  • Clara Murray BA(Hons), MSc,

    1. Milton Keynes Neuro-Rehabilitation Unit, Milton Keynes, United Kingdom
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  • Kevin Talbot MBBS, DPhil, FRCP,

    1. Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, University of Oxford, Oxford, United Kingdom
    2. Department of Clinical Neurology, John Radcliffe Hospital, Oxford, United Kingdom
    3. Oxford Parkinson's Disease Centre, Oxford, United Kingdom
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  • Klaus P. Ebmeier MD,

    1. Department of Psychiatry, University of Oxford, Oxford, United Kingdom
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  • Clare E. Mackay PhD,

    1. Department of Psychiatry, University of Oxford, Oxford, United Kingdom
    2. Oxford Parkinson's Disease Centre, Oxford, United Kingdom
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  • Yoav Ben-Shlomo MD, PhD

    1. School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom
    2. Oxford Parkinson's Disease Centre, Oxford, United Kingdom
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  • Funding agencies: This study was funded by the Monument Trust Discovery Award from Parkinson's UK, the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre based at Oxford University Hospitals National Health Service (NHS) Trust and University of Oxford, and the Dementias and Neurodegenerative Diseases Research Network (DeNDRoN). The views expressed are those of the author (s) and not necessarily those of the NHS, the NIHR, or the Department of Health.

  • Relevant conflicts of interest/financial disclosures: Nothing to report.

  • Full financial disclosures and author roles may be found in the online version of this article.

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. © 2014 International Parkinson and Movement Disorder Society

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