Relationship between frailty and executive function by age and sex in the Canadian Longitudinal Study on Aging.

ABSTRACT

Frailty reflects age-related damage to multiple physiological systems. Executive dysfunction is often a presenting symptom of diseases characterized by cognitive impairment. A decline in cardiovascular health is associated with worse executive function. We tested the hypothesis that higher frailty would be associated with executive dysfunction and that cardiovascular health would mediate this relationship. Middle- and older-aged adults at baseline (n = 29,591 [51% female]) and 3-year follow-up (n = 25,488 [49% females]) from the Canadian Longitudinal Study on Aging (comprehensive cohort) were included. Frailty was determined at baseline from a 61-item index, a cumulative cardiovascular health score was calculated from 30 variables at baseline, and participants completed a word-color Stroop task as an assessment of executive function. Multiple linear regressions and mediation analyses of cardiovascular health were conducted between frailty, Stroop interference-condition reaction time, and cardiovascular health in groups stratified by both age and sex (middle-aged males [MM], middle-aged females [MF], older-aged males [OM], older-aged females [OF]). Frailty (MM, 0.15 ± 0.05; MF, 0.16 ± 0.06; OM, 0.21 ± 0.06; OF, 0.23 ± 0.06) was negatively associated with cardiovascular health (MM, 0.12 ± 0.08; MF, 0.11 ± 0.07; OM, 0.20 ± 0.10; OF, 0.18 ± 0.09; ß > 0.037, p < 0.001), as well as the Stroop reaction time at 3-year follow-up (MM, 23.7 ± 7.9; MF, 23.1 ± 7.3; OM, 32.9 ± 13.1; OF, 30.9 ± 12.0; ß > 2.57, p < 0.001) across all groups when adjusted for covariates. Cardiovascular health was a partial (~ 10%) mediator between frailty and reaction time, aside from MFs. In conclusion, higher frailty levels are associated with executive dysfunction, which was partially mediated by cardiovascular health. Strategies to improve frailty and better cardiovascular health may be useful for combatting the age-related decline in executive function.