The Association Between Depressive Symptoms and Metabolic Syndrome in Middle-aged Japanese Workers: A longitudinal...

BackgroundDepression has been associated with various chronic conditions, including metabolic syndrome (MetS), but findings from Japanese studies have been inconsistent and are limited to cross-sectional design. We therefore examined the longitudinal association between depressive symptoms and incidence of MetS and its components in middle-aged Japanese workers.MethodsData were analysed from 2969 public servants (aged 35-65, 73.1% male) in the Aichi Workers' Cohort Study who were free of MetS at baseline (2013), with at least one follow-up assessment (between 2014 and 2018). Depressive symptoms were assessed at baseline using the 11-item Centre for Epidemiological Studies Depression scale (CES-D-11) and categorized into tertiles: first tertile (0-4), second tertile (5-7), and third tertile (≥8). MetS was defined by the harmonized criteria for Japanese, based on waist circumference (≥90 cm for men and ≥80 cm for women), triglycerides, HDL cholesterol, blood pressure, and blood glucose levels. Multivariable logistic regression estimated ORs and 95% CIs. Restricted cubic splines and piecewise logistic regression evaluated non-linearity and a threshold.ResultsDuring five years, 391 participants (13.2%) developed MetS, with a cumulative incidence rate of 10.2% in the first tertile, 15.8% in the second tertile, and 14.9% in the third tertile. In the fully adjusted model, participants in the second and third tertile had higher odds of incident MetS (OR: 1.89, 95% CI, 1.44-2.48; OR: 1.92, 95% CI, 1.40-2.64, respectively) and high triglycerides (OR: 1.43, 95% CI, 1.08-1.90; OR: 1.80, 95% CI, 1.31-2.48, respectively) compared with those in the first tertile. Restricted cubic spline suggested non-linearity (p < 0.001) with a threshold at CES-D-11 approximately 10. Below this threshold, each 1-SD increase in CES-D-11 was associated with higher odds of incident MetS (OR 1.59, 95% CI, 1.31-1.92).ConclusionDepressive symptoms were associated with incident MetS among middle-aged Japanese workers, particularly with high triglyceride component. The association appeared non-linear, with risk increasing up to a CES-D-11 score of approximately 10 and then plateauing. This potential threshold may help improve understanding of the relationship between depressive symptoms and MetS risk, although further studies are needed before it can be used for risk stratification and prevention efforts.