title: Impaired contrast sensitivity is associated with more severe cognitive impairment in Parkinson disease.
abstract: Dopaminergic degeneration affects both nigrostriatal projection neurons and retinal amacrine cells in Parkinson disease (PD). Parkinsonian retinopathy is associated with impaired color discrimination and contrast sensitivity. Some prior studies described associations between color discrimination deficits and cognitive deficits in PD, suggesting that contrast discrimination deficits are due, at least in part, to cognitive deficits in PD. We investigated the relationship between cognitive deficits and impaired contrast sensitivity in PD.
  
  
  
  PD subjects, n = 43; 15F/28M; mean age 66.5 ± 8.2, Hoehn and Yahr stage 2.6 ± 0.6, and duration of disease of 6.2 ± 5.0 years underwent neuropsychological and Rabin contrast sensitivity testing.
  
  
  
  Mean Rabin contrast sensitivity score was 1.34 ± 0.40. Bivariate analyses showed significant correlation between Rabin contrast sensitivity scores and global cognitive z-scores (R = 0.54, P = 0.0002). Cognitive domain Z-score post hoc analysis demonstrated most robust correlation between Rabin scores and executive functions (R = 0.49, P = 0.0009), followed by verbal learning (R = 0.44, P = 0.0028), visuospatial (R = 0.39, P = 0.001) and attention z-scores (R = 0.32, P = 0.036).
  
  
  
  Impaired contrast sensitivity in PD is robustly associated with cognitive deficits, particularly executive function deficits. These results suggest that contrast sensitivity may be a useful biomarker for cognitive changes in PD and may have implications for driving safety evaluations in PD.
authors.affiliation: Department of Neurology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: A
authors.initials: A
authors.lastname: Ridder
authors.affiliation: Department of Radiology, University of Michigan, Ann Arbor, MI, USA; University of Michigan, Morris K. Udall Center of Excellence for Parkinson's Disease Research, Ann Arbor, MI, USA.
authors.forename: M L T M
authors.initials: ML
authors.lastname: Müller
authors.affiliation: Department of Neurology, University of Michigan, Ann Arbor, MI, USA; Neurology Service and GRECC, VAAAHS, Ann Arbor, MI, USA.
authors.forename: V
authors.initials: V
authors.lastname: Kotagal
authors.affiliation: Department of Neurology, University of Michigan, Ann Arbor, MI, USA; Department of Radiology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Frey
authors.affiliation: Department of Neurology, University of Michigan, Ann Arbor, MI, USA; University of Michigan, Morris K. Udall Center of Excellence for Parkinson's Disease Research, Ann Arbor, MI, USA; Neurology Service and GRECC, VAAAHS, Ann Arbor, MI, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: Albin
authors.affiliation: Department of Neurology, University of Michigan, Ann Arbor, MI, USA; Department of Radiology, University of Michigan, Ann Arbor, MI, USA; University of Michigan, Morris K. Udall Center of Excellence for Parkinson's Disease Research, Ann Arbor, MI, USA; Neurology Service and GRECC, VAAAHS, Ann Arbor, MI, USA. Electronic address: nbohnen@umich.edu.
authors.forename: N I
authors.initials: NI
authors.lastname: Bohnen
mesh_terms: D000368:Aged; D003072:Cognition Disorders / Q000209:etiology*; D015350:Contrast Sensitivity / Q000502:physiology*; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications*; D010775:Photic Stimulation; D012678:Sensation Disorders / Q000209:etiology*; D012720:Severity of Illness Index; D014706:Verbal Learning / Q000502:physiology
keywords: Cognitive impairment; Contrast sensitivity; Parkinson disease; Retina; Visual