Sarcopenia as a mediator: Bridging basal metabolic rate and depression in middle-aged and older populations

Depression greatly affects global health. Although the link between basal metabolic rate (BMR) and depression risk is established, the role of sarcopenia is uncertain. This study explored if sarcopenia mediates the BMR-depression risk relationship.

This investigation utilized cross-sectional data obtained from the 2015 China Health and Retirement Longitudinal Study (CHARLS), focusing on participants aged 45 years and above. Depression was evaluated using the abbreviated 10-item version of the Center for Epidemiological Studies Depression Scale (CESD-10). Statistical analyses employing logistic regression assessed associations between BMR, sarcopenia, and depression, with adjustments made for potential confounders. Mediation analysis assessed sarcopenia's role in the BMR-depression link. Nonlinear relationships were explored with restricted cubic splines, and subgroup analysis evaluated effect variations across groups.

The study comprised 9948 participants with a mean age of 60.4 ± 9.6 years, of whom 6847 were without depression and 3101 were diagnosed with depression. The average BMR was 1248.1 ± 220.9 for the non-depression group and 1169.0 ± 211.7 for the depression group. In the non-depression group, 989 (14.4 %) participants had sarcopenia, while in the depression group, 723 (23.3 %) participants had it. Intergroup comparisons demonstrated marked divergence in both BMR and sarcopenia status (P < 0.001). Covariate-adjusted analyses revealed an inverse relationship between elevated BMR and depression severity. An increase of one unit in BMR was associated with an 11 % reduction in the risk of depression (OR = 0.89, 95 % CI: 0.84-0.94, p < 0.001). Conversely, sarcopenia exhibited a positive association with depression, whereby each unit increase in sarcopenia corresponded to a 25 % elevation in depression risk (OR = 1.25, 95 % CI: 1.08-1.45, p = 0.003). Sarcopenia indirectly affected the BMR-depression relationship, accounting for 14.20 % of the total effect variation (-2.18e-05, p < 0.001).

The study found that BMR is inversely associated with depression, whereas sarcopenia is positively associated with depression and mediates the BMR-depression association.