Physical Frailty and Cognitive Function among Older Chinese Adults: The Mediating Roles of Activities of Daily Living Limitations and Depression.

BACKGROUND: Physical frailty and cognitive impairment are prevalent globally, particularly in China, which is experiencing an unprecedented aging of its large population.

OBJECTIVES: Examine the association between physical frailty and the level and rate of change of cognitive function, globally and by domain, among community-dwelling Chinese older adults, and quantify the mediation effects from activities of daily living (ADL) limitations and depressive symptoms.

DESIGN: Longitudinal.

SETTING: China Health and Retirement Longitudinal Study (2011-2018).

PARTICIPANTS: 5,431 eligible adults aged ≥ 60 years with valid information on physical frailty.

MEASUREMENTS: Physical frailty, cognitive function, ADL limitations, and depressive symptoms were respectively assessed by frailty phenotypes, the Telephone Interview for Cognitive Status (episodic memory, executive function, and orientation), performance in six daily tasks, and the eight-item Center for Epidemiological Studies Depression Scale. Latent growth curve models were used to address the objectives.

RESULTS: Compared to adults who were non-frail, those who were pre-frail (β = -0.06) and frail (β = -0.13) reported significantly worse global cognitive function and episodic memory (pre-frail: β = -0.05; frail: β = -0.14), executive function (pre-frail: β = -0.04, frail: β = -0.10), and orientation (pre-frail: β = -0.06; frail: β = -0.07) at baseline; those who were frail were more likely to experience faster decline in global cognitive function (β = 0.12) and episodic memory (β = 0.08). ADL limitations (β = -0.07) and depressive symptoms (β = -0.14) significantly mediated the association between physical frailty and the level of cognitive function, but not its rate of decline.

CONCLUSIONS: Intervention strategies that help maintain cognitive function may benefit from early screening and assessment of physical frailty. For pre-frail and frail older Chinese adults, programs designed to help improve or maintain activities of daily living and reduce number of depressive symptoms may contribute to better cognitive performance.