Visual tests predict dementia risk in Parkinson disease

Area of Science:

• Ophthalmology
• Neurology
• Neuroscience

Background:

• Parkinson disease (PD) is a neurodegenerative disorder with a significant risk of developing dementia.
• Early identification of individuals at risk for PD dementia is crucial for timely intervention.
• Visual dysfunction and retinal changes have been anecdotally linked to PD progression.

Purpose of the Study:

• To investigate the predictive value of visual measures and retinal volume for the risk of dementia in Parkinson disease.
• To explore the association between specific retinal layers and the risk of developing PD dementia.

Main Methods:

• A cohort study involving individuals with PD and age-matched controls.
• Ophthalmic examinations, including visual acuity, contrast sensitivity, skew tolerance, and biological motion perception.
• Retinal imaging using optical coherence tomography (OCT) to measure retinal layer volumes, specifically the ganglion cell layer (GCL) and inner plexiform layer (IPL).
• Assessment of PD dementia risk using a validated algorithm incorporating clinical and demographic factors.

Main Results:

• Poorer performance in visual tests (acuity, contrast sensitivity, skew tolerance, biological motion) was significantly associated with a higher risk of PD dementia.
• Thinner retinal GCL and IPL volumes, layers containing dopaminergic cells, were correlated with an increased risk of PD dementia.
• No significant associations were found in the retinal nerve fiber layer (lacking dopaminergic cells) or in unaffected controls.

Conclusions:

• Visual measures and retinal structure, particularly in dopaminergic cell-containing layers (GCL and IPL), are related to the risk of dementia in Parkinson disease.
• Retinal GCL and IPL volumes, along with visual assessments, show potential as non-invasive biomarkers for predicting dementia risk in PD.