Divergent trajectories of major depressive disorder burden: A comparative analysis of trends in China and worldwide from 1990 to 2021, with projections to 2035

Backgroud Major depressive disorder (MDD) remains a leading contributor to the global health burden. However, its burden exhibits substantial variation across populations and over time. Methods Using data from the global burden of disease study 2021, we analyzed MDD metrics across 204 countries and territories in this study. Joinpoint regression was used to calculate annual percentage changes in MDD trends, and age–period–cohort analysis examined age, period, and cohort effects and local drift in disability‐adjusted life years (DALYs). Bayesian age–period–cohort models projected age‐standardized prevalence, incidence, and DALY rates through 2035 for China and worldwide. Results From 1990 to 2021, the number of MDD cases in China increased by 38.3%, whereas age‐standardized rates declined, reaching levels approximately 49% lower than global averages in 2021. The global burden peaked at ages 20–39 years, whereas in China it peaked at 50–59 years, with widening sex disparities. Joinpoint analyses indicated a decline in the MDD burden in China, with a rebound during 2010–2015. Global trends showed a stable decline until 2010, followed by sustained growth and a sharp rise during 2019–2021. Age–period–cohort analysis showed an age‐related increase and a period effect in China after 2010. The global pattern displayed a plateau in midlife, a decline at older ages, and stronger period effects after 2015. Projections indicated that the MDD burden would continue to decline in China but remain stable or increase worldwide through 2035. Conclusions Intensified efforts are needed to address the growing caregiving burden associated with aging populations and strengthen mental health service systems.