Arterial Stiffness and Age Moderate the Association Between Physical Activity and Global Cognition in Older Adults

Background: Evidence supports that time spent on physical activity has beneficial effects on cognition in older adults. Nevertheless, whether these beneficial effects are still present at the intersection of different levels of arterial stiffness and age is uncertain. Methods: One hundred ten healthy older adults aged 60 to 75 years old were examined for arterial stiffness (carotid-femoral Pulse Wave Velocity [cf-PWV]), global cognition (composite score of Montreal Cognitive Assessment, and Mini-Mental State Examination), and self-reported physical activity (PACED diary). Using PROCESS macro for SPSS, we evaluated if cf-PWV (moderator 1), and age (moderator 2) moderate the relationship between physical activity (X) and global cognition (Y). The threshold for high stiffness was set at 8.5 m/s based on previous studies that reported this cut-off as more appropriate for classifying cerebrovascular risk groups. Results: Physical activity had a positive effect on cognition in younger-older adults ( 8.5 m/s (β=.57, SE=.222, p=.011, 95% CI=.133 to 1.014) and in older-older adults (>68.5 years) with cf-PWV 8.5 m/s (β=.00, SE=.180, p=.990, 95% CI=-.355 to 359), or in younger-older adults with cf-PWV<8.5 m/s (β=.17, SE=.245, p=.487, 95% CI=-.315 to 657). Conclusions: The interaction of arterial stiffness and age moderated the effect of physical activity on global cognition. Time spent on physical activity alone might not be sufficient to achieve cognitive benefit over a specific threshold of arterial stiffness and age.