Association between frailty and cognitive function: a pooled analysis of three ageing cohorts

Cross-sectional evidence suggested that frailty was an important risk factor for cognitive impairment. However, previous studies only focused on baseline frailty status, not taking into consideration the dynamic changes in frailty status during follow-up. This study aimed to investigate the associations between changes in frailty status and cognitive impairment. This study used data from three prospective cohorts: China Health and Retirement Longitudinal Study (CHARLS), Health and Retirement Study (HRS) and English Longitudinal Study of Ageing (ELSA). Frailty status was evaluated by the frailty index and classified as robust, pre-frailty, or frailty. Cognitive function was assessed by memory, orientation and executive function. Linear mixed regression model was used to evaluate the longitudinal relationship between frailty statuses with cognitive impairment. A total of 49,864 participants with a mean of 2.70 follow-up times were included in the analysis. The median follow-up periods were 2.89 years in the CHARLS, 3.32 years in the ELSA, and 8.40 years in the HRS. Compared with robust participants, both pre-frailty and frailty were significantly associated with declined global cognitive function (beta -0.11, 95% CI: [-0.12, -0.09] for pre-frailty and beta -0.29 [95% CI: -0.30, -0.27] for frailty). Significant associations were also observed for memory (beta -0.27, 95% CI: [-0.29, -0.26] for frailty), orientation (beta -0.15 [95% CI: -0.17, -0.13] for frailty), and executive function (beta -0.21 [95% CI: -0.23, -0.19] for frailty). The subgroup analysis revealed that the CHARLS cohort had the greatest effect, and it was the main source of heterogeneity. Pre-frailty and frailty are associated with an increased risk of cognitive impairment, highlighting the need for early assessment and monitoring of frailty in at-risk populations.