Life course central depressive symptoms among the depressed Chinese: From adolescence to old age

This study investigates how the network metrics of Major Depressive Disorder (MDD) vary across different developmental life stages in Chinese residents. Utilizing cross-sectional data from two nationally representative samples collected in 2022 and 2023 (total N=51,970), MDD was identified using the PHQ-9 scale (cut-off ≥ 10). Participants were categorized into 13 age groups and five developmental stages. A Gaussian graphical model examined the depressive network structure, global network strength, and central symptoms, with network comparison tests performed to identify significant differences. 10,181 residents (5,167 males; age range 11.63-94.48 years) were finally included. The prevalence of MDD varied between 16.57% and 25.12% across age groups. Significant differences in network structure were found in 28 of 78 pair comparisons (P.s < .04). Global network strength exhibited a distinctive trajectory: increasing from under 18 to 30-34 years (significantly higher at 30-34 compared to 18-24 years, P = .014), decreasing at 60-64 years (lower than younger groups, P.s < .002), increasing again at 65-69 years, and finally decreasing at 75+ years. Sadness emerged as the central symptom in almost all stages, most central symptoms significantly varied across life stages (P.s < .047). Unique central symptoms were identified in different developmental stages: sadness and fatigue in adolescence/emerging adulthood, failure and sadness in young adulthood, suicidality and sadness in middle adulthood, and disturbed appetite in older adulthood. These findings underscore the importance of considering a life course perspective when developing interventions for depression, as central symptoms and network metrics of MDD vary significantly across different life stages.