Retinal layer thickness in preclinical Alzheimer's disease

Abstract

Abstract Purpose There is urgent need for non‐invasive diagnostic biomarkers in the preclinical phase of Alzheimer's Disease ( AD ). Several studies suggest that retinal thickness is reduced in AD . Here, we aim to test the diagnostic value of retinal thickness in preclinical AD , as defined by cognitively normal individuals with amyloid pathology on PET . Methods One hundred and sixty five cognitively healthy monozygotic twins aged ≥ 60 were included from the Netherlands Twin Register taking part in the European Medical Information Framework for Alzheimer's Disease Preclin AD study. Participants underwent [ 18 F] flutemetamol PET that was visually rated for presence or absence of cortical amyloid beta (A β ). Binding potential ( BP ND ) was calculated as continuous measure for A β . Spectral Domain OCT was used to asses total and individual inner retinal layer thickness in the macular region ( ETDRS circles) as well as peripapillary retinal nerve fibre layer ( pRNFL ) thickness. Differences between A β + and A β − individuals and associations between BP ND and retinal thickness were analyzed. Results No differences were found in retinal layer thickness in the macula or pRNFL between A β + and A β − individuals. A positive associations between BP ND and macular total retinal thickness was observed in the inner ring (p = 0.018), but this was not statistically significant after correction for multiple testing (p = 0.144). Brain/eye parameters had moderate to high intra‐twin correlations (p < 0.001) except visual rating score of A β , which did not correlate ( r = 0.21, p = 0.068). Conclusion Variation in retinal thickness likely reflects genetic differences between individuals, but cannot discriminate between healthy and preclinical AD cases, making its use as biomarker in these early stages limited.