Assessment of retinal microvascular alterations in individuals with amnestic and non‐amnestic mild cognitive impairment using optical coherence tomography angiography

Abstract

AbstractBackgroundIndividuals with mild cognitive impairment (MCI) can be categorized into amnestic and non‐amnestic subgroups based on the absence or presence of intact working memory. Patients with amnestic MCI have increased likelihood of progressing to Alzheimer’s disease (AD); however, identification of predictive biomarkers distinguishing amnestic and non‐amnestic MCI remains ambiguous. This prospective, cross‐sectional study utilizes optical coherence tomography angiography (OCT‐A) to assess how retinal microvascular density and structure might differ among amnestic and non‐amnestic MCI patients.MethodOne hundred and twelve eyes of 59 amnestic MCI participants, 32 eyes of 17 non‐amnestic MCI participants, and 111 eyes of 56 cognitively healthy controls were included in our study. All participants were imaged using the Zeiss Cirrus HD‐5000 AngioPlex. OCT‐A vessel density (VD) and perfusion density (PD) in Early Treatment Diabetic Retinopathy Study (ETDRS) 3mm and 6mm circles and rings were assessed. Retinal thickness parameters on OCT including retinal nerve fiber layer thickness (RNFL), ganglion cell‐inner plexiform layer (GC‐IPL), and central subfield thickness (CST) were also analyzed. Generalized estimating equations accounting for correlation between two eyes of the same subject were utilized for statistical analysis.ResultAssessment of PD in the 3x3mm inner ETDRS ring revealed a significant decrease in amnestic MCI when compared to non‐amnestic MCI (0.29 ± 0.03 vs 0.34 ± 0.09, p = 0.025), and was significantly lower in amnestic MCI when compared to healthy controls (0.29 ± 0.03 vs 0.39 ± 0.02, p < 0.001), after adjustment for age and sex. Vessel density, subfoveal choroidal thickness, and other retinal thickness parameters (GC‐IPL, RNFL, CST) showed no statistically significant difference among or between diagnostic groups.ConclusionAfter adjusting for age and sex, OCT‐A perfusion density significantly differed among controls, non‐amnestic MCI, and amnestic MCI. Other retinal parameters did not differ between groups after adjusting for covariates. Non‐invasive retinal imaging deserves further study as a potential biomarker for diagnosing and classifying subtypes of MCI.