Visual dysfunction is a better predictor than retinal thickness for dementia in Parkinson's disease

Area of Science:

• Neuroscience
• Ophthalmology
• Neurology

Background:

• Dementia is a frequent and severe complication of Parkinson's disease (PD).
• Visual function and retinal structure are potential early indicators for PD dementia, but longitudinal data are limited.

Purpose of the Study:

• To investigate if higher-order visual function and retinal thickness predict cognitive decline and dementia onset in Parkinson's disease.
• To assess the longitudinal relationship between baseline visual and retinal measures and cognitive trajectories in PD.

Main Methods:

• Prospective study of 100 PD patients and 29 controls, assessing visual function (skew tolerance, biological motion) and retinal thickness (OCT).
• Longitudinal cognitive assessments at baseline, 18, and 36 months.
• Statistical analysis using linear mixed-effects models and time-to-outcome methods.

Main Results:

• Poorer baseline visual performance in PD was associated with lower cognitive scores (p=0.0005) and faster cognitive decline (p=0.013).
• Impaired visual function predicted increased risk of dementia (p=0.022) and adverse outcomes (p=0.002).
• Retinal ganglion cell-inner plexiform layer thickness did not predict cognitive scores or changes over time.

Conclusions:

• Visual dysfunction, not retinal thickness, is a significant predictor of dementia and poor outcomes in Parkinson's disease.
• Findings support cortical involvement in PD dementia progression.
• Visual tests may aid in stratifying patients for clinical trials in PD dementia.