Objectives
Frailty is not an end state of aging, but rather represents physiological vulnerability across multiple systems that unfolds across adulthood. However, examinations of frailty at the midlife transition, and how frailty may impact other age-sensitive traits, such as processing speed (PS) remain scarce. Our research aims were to examine frailty and frailty-speed associations before midlife, a ripe developmental period for healthy aging interventions.
Method
Using data from the Colorado Adoption/Twin Study of Lifespan behavioral development and cognitive aging (CATSLife1; N=1215; Mage=33.23 years; SD=4.98), we constructed 25-item (FI25) and 30-item (FI30) frailty indices. PS was measured using the Colorado Perceptual Speed (CPS) task and WAIS-III Digit Symbol (DS) subtest. Multilevel models accounted for clustering among siblings and adjusted for sex, race, ethnicity, adoption status, educational attainment, and age.
Results
Reliability of FI measures was apparent from strong intraclass correlations (ICCs) among identical twin siblings, while ICC patterns across all siblings suggested that FI variability may include non-additive genetic contributions. Higher FI was associated with poorer PS performance but was significant for DS only (BFI25=-1.17, p=.001, d=-0.12; BFI30=-1.23, p=.0007, d=-0.12). Furthermore, the negative frailty-DS association was moderated by age (BFI25xAge=-0.14, p=.042; BFI30xAge=-0.19, p=.008) where increasingly worse performance with higher frailty emerged at older ages.
Discussion
Frailty is evident before midlife and associated with poorer PS, an association that magnifies with age. These findings help elucidate the interrelationship between indicators of frailty and cognitive performance for adults approaching midlife, an understudied period within lifespan development.