The mediating effects of depression in sedentary behavior and the metabolic syndrome with its components

Previous studies have shown a positive association between sedentary behavior (SB) and metabolic syndrome (MetS), but no studies have assessed the mediating effect of depressive symptoms in this process. Participants from the 2007-2018 National Health and Nutrition Examination Survey (NHANES) were included. Multiple logistic regression analyses and restricted cubic splines (RCSs) were adopted to assess the correlations among SB duration, depressed mood and MetS. A mediation effect model was constructed to analyze whether there was a mediating effect of depressed mood on the relationship between SB duration and MetS. This study included 15,944 adults (7,268 patients with MetS in total). We identified high SB duration as an independent risk factor for MetS in a regression model adjusted for relevant confounders (odds ratio (OR) = 1.29, 95% CI [1.08, 1.53]). RCS analysis revealed a nonlinear relationship between SB duration and MetS. The mediation effect analysis revealed that depressive symptoms accounted for 6.70% of the mediation effect between SB duration and MetS. Depressive symptoms were also partially mediated in the analyses with MetS subcomponents. SB is closely associated with MetS, and this association is not only caused by SB itself but also partially mediated by depressive symptoms.