Mendelian randomization study on association between grip strength and BMD in different age groups.

Introduction: This study aimed to use the Mendelian randomization study method to verify the causal relationship between grip strength and bone mineral density (BMD) in different ages and different parts of the body.

Materials and methods: The analysis was based on pooled data from genome-wide association studies (GWAS). Hand grip strength (right) was used as the exposure variable and total body bone mineral density (BMD) of different age groups was used as the outcome variable. Single-nucleotide polymorphisms highly correlated with exposure variables were used as instrumental variables. The inverse variance weighted (IVW) method was used as the primary analysis method, and the Mendelian randomization Egger (MR-Egger) regression and weighted median methods were used as supplementary evidence for the IVW results. Horizontal pleiotropy and heterogeneity tests were conducted to ensure the stability of the results.

Results: Analyzing the GWAS data on osteoporosis as the outcome variable, the IVW analysis showed that osteoporosis risk was associated with decreased grip strength in the 45-60 age group and the risk of declining lumbar spine BMD was associated with decreased grip strength. However, there was no significant correlation between the risk of osteoporosis in other age groups and changes in grip strength.

Conclusion: A causal relationship exists between decreased grip strength and osteoporosis risk in people aged 45-60 years. The risk of BMD declining in the lumbar spine was associated with reduced grip strength.