Association between grip strength and cognitive function in older adults: results from a cross-sectional study and Mendelian randomization analyses

BACKGROUND: Impaired cognitive function is a known marker of human aging, and the causal relationship between grip strength, as a part of physical activity, and cognitive function is still unclear. METHOD: Data on grip strength and cognitive function were collected in a cross-sectional study conducted in Guangxi Gongcheng 2018-2019. Generalized linear regression models were utilized to assess the relationship between grip strength and cognitive impairment. A two-way two-sample MR study was used to further determine the causal relationship, mainly using Inverse variance weighted (IVW), weighted median, and MR-Egger. Sensitivity analysis was also used to confirm the robustness of the results. Finally, MVMR analysed BMI and CRP as potential confounders. RESULT: A total of 1723 participants were included in the cross-sectional study. Generalized linear regression models showed that low grip strength was a risk factor for cognitive impairment after adjusting for covariates such as age, gender, and ethnicity (OR: 0.965; 95 % CI: 0.947 to 0.984), and the onset of cognitive impairment led to reduced grip strength (OR: 0.251; 95 % CI: 0.113 to 0.559). The results of the two-way two-sample MR also supported the mutual causal relationship between low grip strength (OR = 0.93; 95 % Cl: 0.89-0.97) and cognitive impairment (OR = 0.878; 95 % Cl: 0.794-0.971). The results of the MVMR analysis also proved this relationship. CONCLUSION: Low grip strength increases the risk of cognitive impairment, and conversely, cognitive impairment contributes to an increased risk of reduced grip strength.