Evaluation of inner retinal layers as biomarkers in mild cognitive impairment to moderate Alzheimer’s disease

Abstract

Inner retina in Alzheimer's Disease (AD) may experience neuroinflammation resulting in atrophy. The objective of our study was to determine whether retinal GCIPL (ganglion cell-inner plexiform layer) or nerve fiber layer (NFL) thickness may serve as noninvasive biomarkers to diagnose AD. This cross-sectional case-control study enrolled 15 mild cognitive impairment (MCI) patients, 15 mild-moderate AD patients, and 18 cognitively normal adults. NFL and GCIPL thicknesses on optical coherence tomography (OCT) were measured using Duke Optical Coherence Tomography Retinal Analysis Program (DOCTRAP) and Spectralis software. We demonstrated that regional thicknesses of NFL or GCIPL on macular or nerve OCTs did not differ between groups. However, a multi-variate regression analysis identified macular areas with a significant thickening or thinning in NFL and GCIPL in MCI and AD patients. Our primary findings controvert previous reports of thinner NFL in moderate-to-severe AD. The areas of thickening of GCIPL and NFL in the macula adjacent to areas of thinning, as revealed by a more complex statistical model, suggest that NFL and GCIPL may undergo dynamic changes during AD progression.

Correlation between cognitive impairment and retinal neural loss assessed by swept‐source optical coherence tomography in patients with mild cognitive impairment

“…It may be argued that this anatomic fact makes neuronal loss in MCI and AD easier to detect with OCT. Matching our findings, Lad et al [36] found a reduction in GC-IPL thickness in the inner sector of patients with MCI. In a previous study on patients with AD conducted by our group [25], full macular thickness was preferentially affected in a 3-mm circle around the fovea, suggesting that MCI and AD have similar patterns of ganglion cell impairment and, consequently, supporting the notion that MCI and AD are part of the same spectrum of neurodegeneration.…”

Ganglion cell layer thinning in prodromal Alzheimer's disease defined by amyloid PET

“…Our results reflect these findings, as we found significant GCL thinning in the four sectors. On the contrary, some in vivo studies displayed controversial GCL measurements using SD-OCT, reporting that RNFL and GCL thickness were unable to distinguish AD dementia from MCI and normal controls in clinically well-characterized series [37,38]. The authors themselves hypothesized that a larger series would be necessary to delineate significant differences between the groups studied.…”

Updated Information on Some Cognitive Disorders

“…Recent study made by Correa-Jaraba and colleagues confirmed that the event-related potential technique is useful for evaluating changes in brain electrical activity and increased amplitude of the P3a component is a novel neurocognitive marker for differentiating amnestic MCI [35].…”