Depression and sarcopenia-related traits: A Mendelian randomization study.

Background: Observational studies have suggested that depression is associated with sarcopenia. However, the causal relationship between depression and sarcopenia remains unclear.

Aim: To investigate the causal relationship between depression and sarcopenia.

Methods: We performed a Mendelian randomization (MR) analysis to identify the bidirectional relationship between depression and sarcopenia-related traits. Summary-level data and independent variants used as instrumental variables came from large genome-wide association studies of depression (414055 cases and 892299 controls), of appendicular lean mass (ALM, 450243 participants), and of hand grip strength (exposure: 360000 participants; outcome: 334925 participants).

Results: We identified a negative association of depression with lower ALM [odds ratio (OR): 0.932, 95% confidence interval (95%CI): 0.889-0.979, = 0.005]. In the reverse MR analysis, we also observed an inverse association of hand grip strength with depression (OR: 0.200, 95%CI: 0.108-0.370, < 0.001). Similar results were obtained in sensitivity analyses.

Conclusion: Depression was causally related to decreased muscle mass, and declined muscle strength might lead to a higher risk of depression.