Authors: Cason B Robbins, Dilraj Grewal, James H Powers, Atalie C Thompson, Bryce W Polascik, Rupesh Agrawal, Sharon Fekrat
Published: 2020-12-07
DOI: 10.1002/alz.042040
Source: Full article
AbstractBackgroundThe involvement of the retina and its vasculature has previously been demonstrated in Alzheimer’s disease (AD). Choroidal parameters such as choroidal thickness (CT) and choroidal vascularity index (CVI) as measured on spectral‐domain optical coherence tomography (SD‐OCT) have the potential to be used as non‐invasive biomarkers for Alzheimer’s disease.MethodSD‐OCT imaging of 42 participants with AD, 40 with mild cognitive impairment (MCI), and 139 cognitively healthy controls was obtained in a cross‐sectional study (NCT03233646). Exclusion criteria included diabetes, glaucoma, other non‐AD dementias, and any known vitreoretinal pathology. Subfoveal choroidal thickness (CT) was manually measured by two masked graders, with a third grader used as a tie‐breaker for any measurement discrepancy. Total choroid area and luminal area were calculated by automated image binarization techniques. Choroidal vascularity index (CVI) was measured as the ratio of luminal area to total choroid area. Generalized estimating equations were used to assess the difference in parameters between AD, MCI, and controls in univariable and multivariable analyses.ResultChoroidal thickness (p = 0.009), total choroid area (p = 0.02), and luminal area (p = 0.02) were significantly less in AD versus controls in univariable but not in multivariable analysis after controlling for age, sex, and logMAR visual acuity. Choroidal vascularity index was not significantly different between individuals with AD and controls and was significantly different between individuals with MCI and controls only in univariable analysis (p = 0.04). However, CVI was significantly less in AD versus MCI in both univariable and multivariable analyses (p = 0.01).ConclusionSubfoveal choroidal thickness may not be associated with AD independent of aging. However, the choroidal vascularity index was less in AD compared to MCI, suggesting decreased vascularity of the subfoveal choroid in these patients. CVI may be useful as an adjunctive biomarker for the diagnosis of AD.