Frailty Progression Moderates the Association Between Sensory and Cognitive Trajectories Over 6 Years: Evidence From the Canadian Longitudinal Study on Aging

Objectives: Sensory loss is associated with cognitive decline in later life, but little is known about how biological factors such as frailty alter this relationship. This study examined whether trajectories of hearing, vision, and frailty progression independently predicted cognitive trajectories over 6 years, and whether frailty progression moderated the associations between sensory and cognitive trajectories. Design: Data came from three waves of the Canadian Longitudinal Study on Aging, including 19,378 participants aged 45 to 86 years at baseline. Latent growth curve modeling was used to estimate trajectories of sensory performance, frailty, and cognitive function (executive function and memory), examining the main and moderating effects of frailty. All analyses were adjusted for key baseline covariates, including age, sex, education, household income, ethnicity, and lifestyle factors, and were stratified by sex. Frailty was measured using a modified 40-item Canadian Longitudinal Study on Aging frailty index. Hearing loss was assessed using pure-tone threshold averages, and vision was assessed via binocular visual acuity. Memory function was assessed using the Rey Auditory Verbal Learning Test (delayed recall), and executive function was derived from verbal and animal fluency, mental alternation, and Stroop interference tasks. Results: Lower baseline sensory performance and frailty were associated with lower baseline cognitive performance. Frailty progression was associated with declines in both executive function and memory over time. Declines in hearing were specifically linked to declines in memory, whereas declines in vision were more strongly associated with declines in executive function over time. Participants with both declining vision and increasing frailty exhibited the steepest declines in executive function ( β = −0.066, 95% confidence interval [CI] = −0.121, −0.011) over 6 years. In addition, baseline poor hearing was associated with lower baseline executive function among individuals with higher baseline frailty ( β = −0.032, 95% CI = −0.062, −0.002). Frailty progression moderated the association between worsening hearing and executive function trajectories over 6 years ( β = −0.039, 95% CI = −0.073, −0.004); however, simple slope analyses were not statistically significant across levels of frailty progression. Among females, baseline frailty significantly moderated the association between poor baseline hearing and executive function ( β = –0.052, 95% CI = −0.095, −0.009), indicating stronger effects in females with higher frailty. Conclusions: This longitudinal study suggests that frailty progression may play a role in the association between sensory decline and executive function over 6 years, particularly in the context of vision decline. Public health policies targeting (pre)frailty among individuals experiencing sensory decline could promote healthy cognitive aging.