Associations between triglyceride glucose-body mass index and depressive symptoms among middle-aged and older adults

Abstract

Depressive symptoms are common among middle-aged and older adults in China and are associated with substantial health burdens. However, the relationship between the triglyceride glucose-body mass index (TyG-BMI), a surrogate marker of insulin resistance, and depressive symptoms remains unclear. This study aimed to investigate the association between TyG-BMI and depressive symptoms among middle-aged and older adults in China. This cross-sectional study used data from the China Health and Retirement Longitudinal Study (CHARLS). Depressive symptoms were assessed using the 10-item Center for Epidemiological Studies Depression Scale (CES-D-10). TyG-BMI was calculated as ln [fasting TG (mg/dL) * fasting glucose (mg/dL)/2] * BMI. Multivariable logistic regression and restricted cubic spline analyses were performed to examine the association between TyG-BMI and depressive symptoms. Subgroup and sensitivity analyses were conducted to evaluate the robustness of the findings. A total of 8397 adults aged 45 years or older were included, of whom 3902 (46.47%) were male and 4495 (53.53%) female, respectively. The mean age was 59.25 ± 9.27 years, and the prevalence rate of depressive symptoms was 28.56%. Restricted cubic spline analysis demonstrated that higher TyG-BMI was linearly associated with lower prevalence odds of depressive symptoms ( P -overall < 0.0001 and P -nonlinearity = 0.3274). Compared with participants in the lowest TyG-BMI quartile (Q1), the adjusted ORs (95%CI) for depressive symptoms were 0.841 (0.730, 0.969), 0.726 (0.623, 0.846), 0.706 (0.598, 0.835) for participants in Q2, Q3, and Q4, respectively. When TyG-BMI was analysed as a continuous variable, each 1-unit increase in TyG-BMI was associated with 0.4% lower odds of depressive symptoms (OR = 0.996, 95% CI: 0.994–0.998). Correspondingly, each 10-unit increase was associated with 3.9% lower odds (OR = 0.961, 95% CI: 0.946–0.976) and each one-standard deviation (SD) increase was associated with 14.4% lower odds of depressive symptoms (OR = 0.856, 95% CI: 0.805–0.910). The inverse association remained consistent across prespecified subgroups, with no significant interactions observed (all P for interaction > 0.05). Higher TyG-BMI was linearly associated with lower prevalence odds of depressive symptoms among Chinese middle-aged and older adults. Given the cross-sectional design, these findings should be considered exploratory and warrant confirmation in prospective studies.