Longitudinal Analysis of Macular Thickness, Brain Volume, and Cognition in Alzheimer’s Disease and Mild Cognitive Impairment

Theme: Retina*
What: Retina
Part of: Retina II: Stamping out Blindness and Restoring Sight / Rétine II: Lutter contre la cécité et redonner la vue
When: 6/1/2024, 04:15 PM - 05:45 PM
Where: Room | Salle 713 AB

Abstract

Purpose: To investigate the utility of macular retinal thickness (mRT), measured by Spectral Domain Optical Coherence Tomography (SDOCT), as a potential biomarker for Alzheimer’s disease (AD) and mild cognitive impairment (MCI) by exploring temporal relationships between mRT, brain volumes, and cognition.

Study Design: Longitudinal observational cohort study.

Methods: 47 participants enrolled in the Ontario Neurodegenerative Research Initiative (ONDRI) with two annual study visits and diagnosed with either MCI or AD were included in the analysis. They underwent assessments at each visit including Montreal Cognitive Assessment (MoCA) testing, mRT measurements, and neuroimaging using established neurodegenerative markers including total cerebrospinal fluid (CSF) and normal-appearing grey matter (NAGM) volumes. Overall mRT was calculated by averaging all Early Treatment Diabetic Retinopathy Study (ETDRS) grids composing the inner (1-3mm diameter) and outer (3-6mm diameter) macular rings (superior, temporal, inferior, nasal), followed by taking the mean of both eyes. Time-adjusted changes in each of these measures (mRT, MoCA, CSF, and NAGM) were calculated by dividing the difference in values between visits (first minus last) by the time in days. Spearman's correlation (ρ), Wilcoxon tests, and multivariable linear regression models were used to investigate relationships between time-adjusted changes in mRT, CSF, NAGM, and MoCA scores, along with various demographic covariates.

Results: Our analysis revealed significant correlations between time-adjusted changes in mRT and CSF (ρ=-0.32, 95% CI -0.56 to -0.04, p<0.05) as well as NAGM (ρ=0.36, 95% CI 0.08 to 0.59, p<0.05). No significant correlation was identified with changes in MoCA scores (ρ=0.02, 95% CI -0.27 to 0.31, p=0.89). Time-adjusted change in overall mRT was a significant predictor for the time-adjusted changes in CSF (parameter estimate: -928.87 mm³, 95% CI: -1836.09 to -21.66, p<0.05), NAGM (parameter estimate: 934.16 mm³, 95% CI: 292.99 to 1575.34, p<0.01), and MoCA scores (parameter estimate: 0.37 points, 95% CI: 0.07 to 0.71, p<0.05). There was no statistically significant difference in time-adjusted mRT change between the MCI and AD groups.

Conclusion: Our study identified time-adjusted mRT change as a significant predictor of CSF volume alterations as well as cognitive decline in patients with AD and MCI. Specifically, an increase in time-adjusted mRT (macular thinning) was significantly linked to CSF volume expansion, NAGM reduction, and decreasing MoCA scores (ie worsening cognition). These findings underscore the potential utility of SDOCT as a non-invasive, cost-effective biomarker for cognitive decline. However, further validation is required with larger studies and longer follow-up time, as well as sublayer analyses to fully explore the role of SDOCT in diagnosing, monitoring, and prognosticating neurodegenerative disorders.

Presenter(s)

Presenting Author: Michael Balas

Additional Author(s):

Tina Felfeli, Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada

M. Amin Banahashemi, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Canada

Brian Tan, Rotman Research Institute, Baycrest Health Sciences, Toronto, Canada

Chris Hudson, Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada

Wendy Hatch, Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada

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