Characterization of retinal microvasculature and its relations to cognitive function in older people after circuit resistance training

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.