Association of socioeconomic status and depressive symptom trajectories among Chinese middle-aged and older adults: a nationwide cohort study from CHARLS

Extensive research has established a relationship between socioeconomic status (SES) and depressive symptoms. However, the longitudinal association between SES and depressive symptom trajectories among middle-aged and older adults in China remains underexplored, particularly regarding its independent effects. To address this gap, the present study investigated this association using data from a nationally representative longitudinal survey. This study leveraged longitudinal data from the China Health and Retirement Longitudinal Study (CHARLS) covering the period from 2011 to 2020. Depressive symptoms were measured using the validated 10-item Center for Epidemiologic Studies Depression Scale (CESD-10). SES was determined via latent class analysis (LCA) incorporating education level, health insurance, household consumption, and occupational data. Group-based trajectory modeling (GBTM) was applied to account for heterogeneous progression of symptoms. Multivariable logistic regression analyses were then conducted to evaluate the association between SES and trajectories of depressive symptoms. Additionally, stratified and sensitivity analyses were performed to confirm the robustness of the findings. This analysis included 12,554 CHARLS participants. LCA identified three SES groups: low (56.97%), medium (29.45%), and high (13.58%). GBTM revealed two distinct trajectories of depressive symptoms: stable low (52.84%) and persistent elevated (47.16%). After adjusting for potential confounders, the ORs for medium and high SES were 0.70 (95% CI: 0.64–0.77, P < 0.001) and 0.55 (95% CI: 0.47–0.66, P < 0.001), respectively, compared to low SES. Stratified and sensitivity analyses confirmed these results. These findings demonstrated that higher SES was associated with improved depressive symptom trajectories among Chinese middle-aged and older adults, indicating that SES has a notable association with depressive symptom burden in the population.