Longitudinal retinal changes in mild cognitive impairment and Alzheimer’s Disease

Abstract

AbstractBackgroundPrevious studies have shown retinal thickness and vascular alterations in Alzheimer’s disease (AD), even in patients with mild cognitive impairment (MCI), suggesting that retinal parameters are potential biomarkers for AD. However, the prospective observation of retinal markers is still insufficient. In this study, we aimed to observe longitudinal retinal thickness and vascular changes in patients with AD and MCI, and to identify critical retinal markers that significantly change over time.MethodPatients with AD (N = 22) and MCI (N = 21) were recruited from the Shanghai Memory Study. Age‐ and gender‐matched cognitively normal (NC) participants (N = 26) were included from the Shanghai Aging Study. Optical coherence tomography (OCT) and OCT angiography were performed in all participants at baseline and after an average 19.2 months follow‐up to assess changes in peripapillary retinal nerve fiber layer thickness (p‐RNFL), ganglion cell layer thickness (GCC), macular thickness and volume divided by the Early Treatment Diabetic Retinopathy Study grid, retinal vessel density, and fovea avascular zone (FAZ). Differences of monthly variation rate of retinal parameters between NC, MCI, and AD individuals were evaluated.ResultThe monthly variation rates among groups showed significant differences in thickness and volume of full temporal para‐fovea sector, inner temporal peri‐fovea sector, outer temporal para‐fovea sector, and thickness of outer superior hemisphere para‐fovea sector (all P<0.05). There was no difference in the rate of change of p‐RNFL, GCC, retinal vessel density, and FAZ among all groups. Post hoc analysis revealed that the monthly change in thickness and volume of the full‐temporal and outer sectors were significantly faster in AD than in NC, whereas the inner‐temporal sectors changed faster in MCI than in NC groups (all P<0.05). Furthermore, the monthly changes in inner temporal peri‐fovea thickness were faster in MCI than in NC and AD participants (all P<0.05).ConclusionDuring follow‐up, retinal temporal thinning was faster in patients with AD, whilst inner retina‐temporal sector thinning was faster in participants with MCI. Accelerated thinning of temporal sectors of the retina, especially the inner‐temporal sector may be an early marker of AD disease progression.