Relationship of APOE ε4 allele and BDNF Val66Met polymorphism to retinal structural and vascular OCTA parameters in aging cohort: Optic nerve decline and cognitive change study

Abstract

AbstractPurpose: To investigate the relationship between the APOE (Apolipoprotein ε4) allele and brain‐derived neurotrophic factor (BDNF) Val66Met polymorphism on retinal structural and vascular characteristics in healthy aging subjects.Methods: 109 healthy participants (mean age 67.1 (±9.0) years) were recruited. Participants were classified as either APOE carriers or non‐carriers based on the presence or absence of the ε4 allele and cohorts established based on their BDNF genotype (Val/Val, Met/Met and Val/Met). Baseline assessment included ophthalmological examination and retinal imaging including OCT (optical coherence tomography) and OCTA (optical coherence tomography angiography) with 3 T Wide Bore MRI imaging to assess brain volumetric measures. Cognitive function was evaluated using a battery of neuropsychological assessments. The relationship between carriers of APOE ε4 allele and Met carriers between these ocular parameters were analysed using the generalized estimating equation (GEE) models and data adjusted for age, sex and inter‐eye differences as within‐subject variables (p < 0.05).Results: 20 subjects (22%) were identified as APOE ε4 carriers and 44 subjects (41%) were identified as Met Carriers. Temporal RNFL thickness was decreased in APOE ε4 carriers (p < 0.01). Vessel density between carriers and non‐carriers was not significantly different at either the superficial or deep level, however, the FAZ (foveal avascular zone) area was found to be smaller in ε4 carriers in both superficial (p < 0.01) and deep layers (p < 0.003). The BDNF Met allele carriage had significant association with reduction of the entorhinal cortex volume in the healthy aging cohort (p = 0.012). No association was found with cognitive performances.Conclusions: Our results indicate possible associations between reduced FAZ area and reduced temporal RNFL thickness with the APOE ε4 allele, and that carriage of BDNF Val66Met polymorphism may be associated with some specific regions of cortical volume loss. Further studies could further characterize this association.