Retinal microstructure and microvasculature in association with brain amyloid burden

Cortical amyloid burden is associated with neuronal and vascular abnormalities. The retina shares significant structural and physiological similarities with the brain. This study assessed the association of retinal microstructural and microvascular signs with cortical amyloid burden in the prospective Atherosclerosis Risk in Communities-Positron Emission Tomography study. One hundred and twenty-four participants without a diagnosis of dementia underwent florbetapir PET (2011-13) and optical coherence tomography and optical coherence tomography angiography imaging (2017-19). Retinal nerve fibre thickness, total macular thickness and the ganglion cell-inner plexiform layer thickness were derived from the optical coherence tomography scan. Vessel density and the foveal avascular zone were measured on the 3 × 3 mm² optical coherence tomography angiography scan. Amyloid burden, defined by global cortical standardized uptake value ratio, was treated as a dichotomous (standardized uptake value ratio > 1.2) and continuous outcome measure in logistic and robust linear regression models, respectively. Only lower intermediate capillary plexus vessel density [β (95% confidence interval) = -0.05 (-0.12, -0.01)] was significantly associated with increased continuous amyloid standardized uptake value ratio but not elevated dichotomous amyloid burden independently of demographic, genetic and vascular risk factors. No other retinal measure showed a significant association. Microvascular signs may accompany greater amyloid burden in late life in individuals without dementia.