Thicker macula in asymptomatic APOE Ɛ4 middle‐aged adults at high AD risk

INTRODUCTION: We compared retinal layers’ thickness between apolipoprotein E (APOE) Ɛ4 carriers and non‐carriers in a cohort of cognitively normal middle‐aged adults enriched for Alzheimer's disease (AD) risk. METHODS: Participants (N = 245) underwent spectral domain optical coherence tomography. Multivariate analyses of covariance adjusting for age, sex, education, and best corrected vision acuity was used to compare retinal thickness between APOE groups. RESULTS: Participants’ mean age was 59.60 (standard deviation = 6.42) with 66.4% women and 32.2% APOE Ɛ4 carriers. Greater macular full thickness was observed in APOE Ɛ4 carriers compared to non‐carriers (P = .017), reaching statistical significance for the inner and outer nasal (P = .009 and P = .005, respectively), inner superior (P = .041), and inner and outer inferior (P = .013 and P = .033, respectively) sectors. The differences between APOE groups were mainly driven by the ganglion cell layer (P < .05) and the inner plexiform layer (P < .05). DISCUSSION: A thicker macula is observed already in midlife asymptomatic APOE Ɛ4 carriers at high AD risk.