Associations of absolute and relative grip strength with cognitive performance in Chinese middle-aged and older populations

Background Recent meta-analyses indicate that the relationship between grip strength (GS) and cognition is more complex than that was previously assumed. Multiple studies have established a significant correlation between body composition and GS. Objective To assess longitudinal relationships between absolute and relative GS trajectories and cognitive function. Methods The China Health and Retirement Longitudinal Study (CHARLS) data with 2549 participants were analyzed using the Group-Based Trajectory Model (GBTM) to ascertain GS trajectories over time. Absolute GS was defined as the raw force, while relative GS was defined as grip strength adjusted by body weight. Directed Acyclic Graphs (DAGs) were used to identify confounding variables, which were subsequently adjusted for in generalized estimating equation (GEE) models that assessed associations between these trajectories and changes in cognitive function over time. Results We observed that relative GS exhibited three distinct trajectories: The three relative GS trajectories were labeled as Low-decline (n = 823, 32.29%), Medium-decline (n = 1292, 50.69%), and High-decline (n = 434, 17.03%). Absolute GS showed similar downward trends. GEE revealed a uniform five-year decline in cognitive function across all GS trajectory groups (all p time < 0.001). The overall interaction between the timing and patterns of changes in both absolute and relative GS and cognitive function was statistically significant (p < 0.001). Conclusions In middle-aged and older adults, lower grip strength trajectories align with accelerated cognitive decline, while higher grip strength is associated with slower cognitive deterioration. Monitoring grip strength may serve as a practical marker for cognitive health in aging populations.