Longitudinal Retinal Findings in Individuals with Mild Cognitive Impairment over a Two Year Period

Abstract

AbstractBackgroundChanges in the retina, an embryologically brain‐derived structure, are exemplar of measurable pre‐clinical findings in neurodegenerative disease. However, limited data exists on the utility of retinal imaging in mild cognitive impairment (MCI). Changes in the retina over time may act as a quantitative measure of disease progression.MethodThis was a longitudinal study consisting of MCI patients and cognitively normal controls over the age of 50. Exclusion criteria included diabetes, uncontrolled hypertension, glaucoma, and retinal pathology. Zeiss Cirrus HD‐5000 AngioPlex optical coherence tomography (OCT) and OCT angiography (OCTA) and Mini Mental State Exam were performed at study entry and year 2.ResultEighty‐seven eyes of 42 MCI patients and 83 eyes of 42 controls were analyzed. Controls were matched by age (range 58‐84 years) and sex (51% male, 49% female). Average MMSE at baseline was 26.3 in MCI and 29.3 in controls (p < 0.01). There were no significant differences in rate of change (ROC) of OCT/OCTA data between controls and MCI patients at baseline. The ROC of MMSE at year 2 was ‐0.33 in controls vs ‐1.78 in MCI (p = 0.12). The ROC of OCTA perfusion density (PD) was significantly different (p < 0.04) in year 2, with an ROC of 0%/year in controls and ‐0.1%/year in MCI for both 3×3 ETDRS circle and ring as well as 6×6 ETDRS circle, inner ring, and outer ring. Changes in vessel density (VD) at year 2 were significant (p <0.04) in 3×3 ETDRS circle and ring as well as the 6×6 ETDRS circle, inner ring, and outer ring.ConclusionAt baseline, there was no significant difference in OCT and OCTA metrics between MCI patients and controls, which is consistent with previous work. However, after 2 years of follow‐up, there is a significantly greater velocity of decline in OCTA PD and VD in MCI patients compared to controls prior to a significant change in MMSE scores. Longitudinal assessment of these retinal microvascular differences in MCI may be a strong marker of progressive disease preceding measurable cognitive changes.