The association between retinal vascular fractal dimension and cognitive function in the community-dwelling older adults cohort TIGER

Background/Purpose: The small retinal vessels reflect cerebral microcirculation and its fractal dimension (Df), representing the complexity of the retinal microcirculation. However, the connection between retinal circulation and cognitive function lacked consistent and longitudi-nal evidence. This study aimed to explore the association between retinal vascular complexity and cognitive impairment over time in non-demented community-dwelling older adults. Methods: This four-year prospective cohort study (2015-2019) is part of the ongoing Taiwan Initiative for Geriatric Epidemiological Research (TIGER, 2011 to present). Of the 434 older adults (age >65) recruited, 207 participants were included for analysis. The retinal vascular Df was assessed by baseline images from fundus photography (2015-2017). Global (Montreal Cognitive Assessment-Taiwanese version, MoCA-T) and domain-specific cognition were as-sessed at the baseline and 2-year follow-up (2017-2019). The multivariable linear regression models and generalized linear mixed models were used to evaluate the association of Df with cognitive decline/impairment over time. Results: Decreased left retinal vascular complexity was associated with poor attention perfor-mance (5 =-0.40). As follow-up time increased, decreased vascular complexity was associ-ated with poor memory performance (right: 5 =-0.25; left: 5 =-0.19), and decreased right vascular complexity was associated with poor attention performance (5 =-0.18).Conclusion: Low retinal vascular complexity of the right or left eye may be differentially asso-ciated with cognitive domains in community-dwelling older adults over two years. The retinal vascular Df of either eye may be served as a screening tool for detecting cognitive impairment in the preclinical phase of dementia.Copyright 2023, Formosan Medical Association. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).