Bidirectional associations among handgrip strength, gait speed, and cognitive function in older adults: a longitudinal study in rural China

Accumulating research evidence suggests that handgrip strength (HGS) and gait speed are independently associated with cognitive function in older adults, whereas the magnitude and temporal order of the associations among HGS, gait speed, and cognitive function remain unclear. This study adopted a cohort study design. The participants were from the Guizhou Rural Older Adults’ Health Study (HSRO). Older adults aged 60 years or older were included. Gait speed was measured by asking participants to walk along a 4.6 m walkway, while HGS was measured using an electronic hand dynamometer. Cognitive function was assessed using the Mini-Mental State Examination (MMSE). To explore the associations among HGS, gait speed, and cognitive function, as well as how these variables changed over time in older adults, cross-lagged panel models and linear mixed-effects models were utilized. The results obtained from both of these models were reported with standardized coefficients. A total of 819 participants were included in the analysis (median age 70 years; 60.0% females). The results of the cross-lagged path model showed a significant association between HGS in 2019 and cognitive function in 2022 (β = 0.057, P < 0.05). Meanwhile, an association was observed from 2019 MMSE to 2022 HGS (β = 0.105, P < 0.001). Cognitive function and HGS measured in 2019 were significantly associated with gait speed in 2022, with respective β values of 0.078 and 0.071 (P < 0.05 for both). However, gait speed in 2019 was not significantly associated with either cognitive function or HGS in 2022 (both P > 0.05). The results of the linear mixed effects model showed higher HGS was associated with higher cognitive function (β = 0.090, P < 0.001). Neither gait speed nor the interaction term between HGS and gait speed had a statistically significant association with cognitive function (P > 0.05). In rural older adults, a bidirectional association exists between HGS and cognitive function. The combined effect of gait speed and HGS did not improve the prediction of cognitive function. Future interventions integrating HGS training with cognitive exercises should be developed to further assess the potential synergistic benefits in cognitive and physical function among older adults.