Causal associations between sarcopenia and Parkinson's disease ‒ A two-sample Mendelian randomization study.

Introduction

sarcopenia, characterized by the progressive loss of skeletal muscle mass and function, has been observed in individuals with Parkinson's disease (PD), yet the precise causal connection between these two conditions remains unclear.

Objectives

employing a two-sample Mendelian randomization (MR) analysis, this study endeavors to explore the potential causal links between sarcopenia-related traits and the risk of PD.

Methods

genome-wide association study (GWAS) data on PD and sarcopenia traits (low handgrip strength in older adults, appendicular lean mass, and usual walking pace) were extracted. MR analyses were performed with an inverse-variance-weighted approach; an MR-Egger regression, a weighted-mode approach, a weighted-median method, and sensitivity analysis were implemented to evaluate the robustness of results

Results

MR results suggested that that genetically predicted low handgrip strength was correlated with a reduced risk of PD (IVW OR = 0.66; 95 % CI, 0.47-0.92, p = 0.01; MR-Egger OR = 0.29; 95 % CI, 0.12-0.74, p = 0.03; weighted median OR = 0.59; 95 % CI, 0.39-0.91, p = 0.02; weighted mode OR = 0.56; 95 % CI, 0.29-1.1, p = 0.12). However, there were no significant causal associations observed for appendicular lean mass or usual walking pace with PD. Sensitivity analyses suggested that the findings were not influenced by horizontal pleiotropy.

Conclusions

the findings from this MR study suggest that a diminished risk of PD is genetically causally associated with low muscle strength, whereas no such association was observed for muscle mass or walking pace genetically. Further research is needed to clarify the mechanisms underlying the relationship between muscle strength and PD pathogenesis.