Color discrimination deficits in Parkinson's disease are related to cognitive impairment and white-matter alterations§

Authors

  • Josie-Anne Bertrand MPs,

    1. Center for Advanced Research in Sleep Medicine, Sacré-Coeur Hospital, Montreal, Québec, Canada
    2. Department of Psychology, Université de Montréal, Montreal, Québec, Canada
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  • Christophe Bedetti MSc,

    1. Center for Advanced Research in Sleep Medicine, Sacré-Coeur Hospital, Montreal, Québec, Canada
    2. Unité de Neuroimagerie Fonctionelle, Institut universitaire de gériatrie de Montréal, Montreal, Québec, Canada
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  • Ronald B. Postuma MD, MSc,

    1. Center for Advanced Research in Sleep Medicine, Sacré-Coeur Hospital, Montreal, Québec, Canada
    2. Department of Neurology, Montreal General Hospital, Montreal, Québec, Canada
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  • Oury Monchi PhD,

    1. Unité de Neuroimagerie Fonctionelle, Institut universitaire de gériatrie de Montréal, Montreal, Québec, Canada
    2. Department of Radiology, Université de Montréal, Montreal, Québec, Canada
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  • Daphné Génier Marchand BSc,

    1. Center for Advanced Research in Sleep Medicine, Sacré-Coeur Hospital, Montreal, Québec, Canada
    2. Department of Psychology, Université du Québec à Montréal, Montreal, Québec, Canada
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  • Thomas Jubault PhD,

    1. Unité de Neuroimagerie Fonctionelle, Institut universitaire de gériatrie de Montréal, Montreal, Québec, Canada
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  • Jean-François Gagnon PhD

    Corresponding author
    1. Center for Advanced Research in Sleep Medicine, Sacré-Coeur Hospital, Montreal, Québec, Canada
    2. Department of Psychology, Université du Québec à Montréal, Montreal, Québec, Canada
    • Centre d'Études Avancées en Médecine du Sommeil, Hôpital du Sacré-Coeur de Montréal, 5400 Boul. Gouin Ouest, Montréal, Québec, Canada H4J 1C5

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  • Funding agencies: This study was supported by the Canadian Institutes of Health Research (CIHR MOP-84482, to J. F. Gagnon) and the Fonds de la Recherche en Santé du Québec (FRSQ 11834, to J. F. Gagnon).

  • 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

Color discrimination deficit is a common nonmotor manifestation of Parkinson's disease (PD). However, the pathophysiology of this dysfunction remains poorly understood. Although retinal structure changes found in PD have been suggested to cause color discrimination deficits, the impact of cognitive impairment and cortical alterations remains to be determined. We investigated the contribution of cognitive impairment to color discrimination deficits in PD and correlated them with cortical anomalies. Sixty-six PD patients without dementia and 20 healthy controls performed the Farnsworth–Munsell 100 hue test and underwent a comprehensive neuropsychological assessment for mild cognitive impairment diagnosis. In a subgroup of 26 PD patients, we also used high-definition neuroanatomical magnetic resonance imaging for cortical thickness and diffusion tensor analysis. PD patients with mild cognitive impairment performed poorly on the Farnsworth–Munsell 100 hue test compared with PD patients without mild cognitive impairment and controls. In PD patients, performance on the Farnsworth–Munsell 100 hue test was correlated with measures of visuospatial abilities and executive functions. Neuroimaging analysis revealed higher mean and radial diffusivity values in right posterior white-matter structures that correlated with poor performance on the Farnsworth–Munsell 100 hue test. No cortical thickness correlation reached significance. This study showed that cognitive impairment makes a major contribution to the color discrimination deficits reported in PD. Thus, performance on the Farnsworth–Munsell 100 hue test may reflect cognitive impairment more than color discrimination deficits in PD. Poor performance on the Farnsworth–Munsell 100 hue test was also associated with white-matter alterations in right posterior brain regions. © 2012 Movement Disorder Society

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