Association of retinal nerve fiber layer thickness with temporal lobe atrophy

AbstractBackgroundThe retinal nerve fiber layer (RNFL) is an extension of the brain that often reflects changes seen in the brain in neurodegenerative diseases. The purpose of this study was to examine the relationship of RNFL thickness measured using optical coherence tomography (OCT) with temporal lobe neurodegeneration in older adults along the Alzheimer’s disease (AD) continuum.MethodParticipants included 26 individuals with subjective cognitive decline (SCD), 21 mild cognitive impairment (MCI/{AD}) and 28 age‐matched cognitively normal (CN) from the Indiana Memory and Aging Study at the Indiana Alzheimer’s Disease Research Center. Participants were excluded from the study if they had significant eye disease determined to interfere with OCT and other ocular measures, non‐AD dementia, or exclusion for MRI. OCT scans were acquired from each eye to measure peripapillary RNFL among other metrics. Structural MRI scans were acquired and processed using Freesurfer version 6 to measure medial and lateral temporal lobe volumes. Finally, the association between the average RNFL thickness and bilateral mean hippocampus, amygdala, and lateral temporal lobe volumes was assessed using a partial Pearson correlation, covaried for age, sex, diagnosis, and total intracranial volume (ICV). A p‐value of p<0.05 was considered significant.ResultPeripapillary RNFL thickness was generally decreased in patients with AD compared to all other groups. In addition, average RNFL thickness across the retina was significantly correlated with brain atrophy, including bilateral mean hippocampal, amygdala, and lateral temporal lobe volumes.ConclusionRNFL thinning measured using OCT is associated with regional atrophy in medial and lateral lobes. Imaging of the eye may represent a useful biomarker to screen patients at risk for AD prior to more invasive and prolonged testing.