Global burden of depressive disorders from 1990 to 2021: temporal trends, COVID-19 Impact, and projections to 2050

Depressive disorders constitute a leading global cause of disability, yet comprehensive evidence regarding their long-term trends, socioeconomic disparities, and the impact of the COVID-19 pandemic remains limited. This study aimed to investigate the global burden, epidemiological patterns, and risk factors of depressive disorders from 1990 to 2021, and to project future trends to 2050. Using Global Burden of Disease 2021 data, we analyzed spatial-temporal patterns, demographic disparities, and socioeconomic gradients with joinpoint regression, cross-lagged modeling, and SHAP analysis. We further forecasted disease burden through 2050 using time-series projection. The global burden of depressive disorders exhibited substantial geographic heterogeneity and increased continuously over the study period, with a marked acceleration after 2019. COVID-19 incidence predicts subsequent increases in depressive disorder burden at the population level. Females and individuals aged 15-49 years carried the highest disease burden, and the contribution of older adults gradually increased. Drug use, smoking, and intimate partner violence represented the leading modifiable risk factors. Burden projections indicated continuous growth through 2050 without effective public health intervention. These findings highlight persistent global inequalities in depressive disorder burden and confirm the adverse impact of COVID-19 on mental health. Targeted, cross-sectoral, and equity-oriented mental health strategies are urgently needed to alleviate the growing global burden of depressive disorders.