Impaired contrast sensitivity is associated with more severe cognitive impairment in Parkinson disease

Parkinsonism Relat Disord. 2017 Jan:34:15-19. doi: 10.1016/j.parkreldis.2016.10.006. Epub 2016 Oct 7.


Objectives: 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.

Methods: 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.

Results: 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).

Conclusions: 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.

Keywords: Cognitive impairment; Contrast sensitivity; Parkinson disease; Retina; Visual.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aged
  • Cognition Disorders / etiology*
  • Contrast Sensitivity / physiology*
  • Executive Function / physiology*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Neuropsychological Tests
  • Parkinson Disease / complications*
  • Photic Stimulation
  • Sensation Disorders / etiology*
  • Severity of Illness Index
  • Verbal Learning / physiology