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Purpose: We examined the associations between retinal microvascular density, cognition, and physical fitness in healthy older adults with no reported cognitive decline., Methods: Twenty cognitively normal older adults (age: 70.3 ± 4.6 years) were recruited. Both eyes of each subject were imaged using optical coherence tomography angiography. The vessel densities of the retinal vascular network (RVN), superficial vascular plexus (SVP), and deep vascular plexus (DVP) were measured. Cognitive function was assessed using the Mini-mental state examination (MMSE) and Montreal Cognitive Assessment (MoCA), while physical performance was evaluated using the total work during the YMCA cycle ergometer test (TW-YMCA). Spearman correlations (r s ) were computed between measures of retinal microvascular density, cognitive function, and physical performance., Results: The MoCA was significantly correlated to vessel density of SVD (r s  = 0.53, P = 0.02) but not RVN (r s  = 0.39, P = 0.09) and DVP (r s  = 0.02, P = 0.93). MoCA was not correlated with TW-YMCA (r s  = 0.05, P = 0.83). Retinal microvascular densities were not related to TW-YMCA (r s  = -0.05-0.18, P > 0.05). Additionally, MMSE was not related the retinal vessel densities (r s  = -0.10-0.21, P > 0.05) and TW-YMCA (r s  = -0.19, P = 0.41)., Conclusions: This is the first study to reveal the association between retinal vessel density and cognition as measured with MoCA in healthy older adults with no reported cognitive decline., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Purpose: To determine the retinal tissue perfusion (RTP) and its relation to cognitive function in healthy older people after an 8-week high-speed circuit resistance training program (HSCT)., Methods: Eleven subjects in the HSCT group and seven age-matched non-training controls (CON) were recruited. The HSCT group trained 3 times per week for 8 weeks, while CON performed no formal training. One eye of each subject in both groups was imaged at baseline and at an 8-week follow-up, using a Retinal Function Imager to measure retinal blood flow (RBF). Retinal tissue perfusion (RTP) was calculated as RBF divided by the corresponding tissue volume. Cognitive function was assessed during both visits using the NIH Toolbox Fluid Cognition Battery., Results: RTP was 2.99 ± 0.91 nl·s -1 ·mm -3 (mean ± SD) at baseline and significantly increased to 3.77 ± 0.86 nl·s -1 ·mm -3 after training (P < 0.001) in the HSCT group, reflecting an increase of 26%. In the HSCT group, the Pattern Comparison Processing Speed Test (PAT) and Fluid Cognition Composite Score (FCS) were significantly increased after HSCT (P = 0.01). Furthermore, the changes in Flanker Inhibitory Control and Attention Test (FLNK) were positively correlated to increases in RTP (r = 0.80, P = 0.003)., Conclusions: This is the first prospective study to demonstrate that the increased RTP after HSCT was related to improved cognition in cognitively-normal elders, indicating RTP could be an imaging marker for monitoring cognitive changes due to physical activity in the elderly., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Purpose: To characterize the changes of retinal microvascular density and their relations to cognitive function in the healthy older people without known cognitive impairment after an 8-week high-speed circuit resistance training program (HSCT)., Methods: Twenty cognitively normal older people were recruited and randomly assigned to either the HSCT group or control group (CON). Twelve subjects (age 70.8 ± 5.8 yrs) in the HSCT group trained three times per week for 8 weeks. Eight subjects in the CON group (age 71.8 ± 4.8 yrs) did not perform formal training. Both eyes of each subject were imaged using optical coherence tomography angiography (OCTA) at baseline and at 8-week follow-up. The densities of the retinal vascular network (RVN), superficial vascular plexus (SVP), and deep vascular plexus (DVP) were measured. In addition, their cognitive functions were tested using the NIH toolbox., Results: There were significant increases in pattern comparison processing speed (PAT, P = 0.02) and fluid composite score (FCS, P = 0.005) at the follow-up in the HSCT group. Although the vessel densities did not differ between visits in either group, the variation (i.e., change) in retinal vessel density of SVP was negatively related to the changes of FCS (r = -0.54, P = 0.007) and the List Sorting Working Memory test (r = -0.43, P = 0.039) in the HSCT group., Conclusions: This is the first study to reveal that the individual response of the SVD was related to the improvement in the cognition in cognitively normal older people after HSCT., (Copyright © 2020 Elsevier Inc. All rights reserved.)