Childhood and adolescence are vulnerable periods for mental disorders, and the COVID-19 pandemic has exacerbated mental health challenges in this population. We aimed to estimate changes in the global burden of mental disorders among children and adolescents before and during the pandemic.

Using data from the Global Burden of Diseases Study 2021, we analyzed incidence, prevalence, and years lived with disability (YLDs) for mental disorders in individuals aged 5–24. Annual percent changes in age-standardized rates were calculated, and a Bayesian age–period–cohort model estimated the expected and additional burden based on pre-pandemic trends.

In 2021, an estimated 123.0 million new cases of mental disorders were reported among children and adolescents, with an 11.8% average annual increase in the age-standardized incidence rate during the pandemic. Anxiety disorders, which previously ranked third, became the leading cause of nonfatal disability (12.9 million [8.0–19.3] YLDs), while depressive disorders rose to fourth place (10.9 million [6.8–16.5] YLDs). The burden grew in most regions, especially among females, those aged 15–24, and in high sociodemographic index (SDI) areas. Based on pre-pandemic data, we estimated an additional burden of 795.0, 165.9, and 622.8 new cases per 100,000 population for total mental disorders, anxiety disorders, and depressive disorders globally in 2021, respectively. Spearman correlation analysis showed a significant positive correlation between additional burden and SDI levels.

These findings highlight the increased burden of mental disorders among children and adolescents during the pandemic, emphasizing the need for targeted post-pandemic mental health support.