Modulation of Retinal Arteriolar Central Reflection by APOE Genotype

Area of Science:

• Ophthalmology
• Neurology
• Biomarkers

Background:

• The central reflex (CR) in retinal arterioles may reflect micro-vascular health in both the retina and brain.
• A novel semi-automated technique quantifies CR and vessel width, calculating the CR to vessel width ratio (CRR).

Purpose of the Study:

• To investigate the relationship between retinal arteriolar CRR and Alzheimer's disease (AD).
• To explore the utility of CRR as a non-invasive biomarker for cerebrovascular changes.

Main Methods:

• Collected digital retinal photographs from Alzheimer's disease (AD) and cognitively normal (CN) participants in the Australian Imaging, Biomarkers and Lifestyle (AIBL) study.
• Quantified CRR using a novel computer-based semi-automated technique.
• Analyzed CRR in relation to AD diagnosis and APOE ε4 allele status.

Main Results:

• Significantly higher CRR levels were observed in AD participants compared to CN participants (p=0.025).
• CRR was significantly higher in APOE ε4 allele carriers compared to non-carriers (p<0.0001).
• The association between CRR and AD diagnosis was weaker and became non-significant after adjusting for APOE ε4 status.

Conclusions:

• CRR is strongly associated with APOE ε4 status and shows a trend with AD.
• The retina may serve as a valuable model for non-invasive monitoring of APOE ε4 effects on the central nervous system and cerebrovascular disease.