Association Between Body Mass Index and Depressive Symptom Trajectories Among Chinese Middle and Old Aged Adults: A...

The prevalence of depressive symptoms among middle-aged and older adults persists at concerning levels. Despite this high prevalence, limited research has investigated the association between body mass index (BMI) and longitudinal trajectories of depressive symptoms. We aimed to examine this understudied association in a nationally representative population-based longitudinal study.

The data were obtained from the China Health and Retirement Longitudinal Study (CHARLS), covering the period from 2011 (Wave 1) to 2020 (Wave 5). Depressive symptoms were assessed using the 10-item Center for Epidemiologic Studies Depression Scale (CESD-10). We employed group-based trajectory modeling (GBTM) to analyze depressive symptom trajectories over time, followed by multivariable logistic regressions to examine the association between BMI and depressive symptom trajectories. Gender-stratified analysis was performed to elucidate differential associations between BMI and trajectories of depressive symptoms across sexes. Additionally, sensitivity analyses were performed to evaluate the stability of the results.

A total of 10,521 participants were included in the final analysis. Two depressive symptom trajectory groups were identified: a stable low-symptom trajectory group (N = 5467, 51.96%) and a consistently high-symptom trajectory group (N = 5054, 48.04%). Compared with normal-weight, participants with underweight were more likely to suffer from depressive symptoms (OR = 1.29, 95% CI: 1.07-1.56, p = 0.009) after adjusting for potential confounding covariates. However, no statistically significant associations were observed in participants with overweight (OR = 0.94, 95% CI: 0.85-1.04, p = 0.248) or obesity (OR = 0.89, 95% CI: 0.77-1.02, p = 0.100). Gender-stratified analysis revealed a significant positive association between underweight status and consistently high-symptom trajectory in males (adjusted OR = 1.32, 95% CI: 1.01-1.72, p = 0.041), whereas no statistically significant association was observed in females (adjusted OR = 1.23, 95% CI: 0.94-1.62, p = 0.134). The sensitivity analyses yielded results consistent with our primary findings, thereby reinforcing the robustness of our outcomes.

Underweight was more likely to be associated with depressive symptoms in males than in females. Future investigations are needed to elucidate the underlying biological mechanisms connecting underweight and depressive symptoms, as well as evaluate the potential role of regulating underweight in the prevention and treatment of depressive symptoms.