Global burden of schizophrenia in 204 countries and regions from 1990 to 2021 and machine learning-based projections to 2036: an analysis of the 2021 global burden of disease study

Background: Schizophrenia is a chronic mental disorder and one of the greatest contributors to the global burden of disease. This study aimed to analyze the global burden of schizophrenia from 1990 to 2021 and predict its future trends. Methods: Data from the 2021 Global Burden of Disease (GBD) study were used. Trend analysis was conducted using the estimated annual percentage change (EAPC), Joinpoint regression, and age-period-cohort analysis. Future projections were generated using the Bayesian age-period-cohort (BAPC) model and time-series machine learning (ML) models. Results: 2021, schizophrenia was estimated to affect approximately 23.6 million individuals worldwide, with 1.22 million new cases reported globally. This disorder accounted for 14.82 million disability-adjusted life years (DALYs) lost. From 1990 to 2021, the age-standardized incidence rate (ASIR) exhibited a declining trend with an EAPC of -0.04% (95% UI: -0.04% to -0.03%), whereas the age-standardized prevalence rate (ASPR) and age-standardized disability-adjusted life years rate (ASDR) demonstrated upward trajectories, showing EAPCs of 0.03% (95% UI: 0.02% to 0.04%) and 0.04%(95% UI: -0.03% to -0.05%), respectively. The peak age of onset was 20-24 years, while prevalence and DALYs peaked at 30-34 years, with males exhibiting a higher disease burden. The ARIMA, PROPHET, and Elastic Net models demonstrated superior predictive performance for forecasting future trends of global ASIR, ASPR, and ASDR. Projections suggest a continued global decline in ASIR, while ASPR and ASDR are expected to rise in the future. Conclusion: Our research indicates that the ASIR, ASPR, and ASDR of schizophrenia exhibit significant correlations with gender, socio-demographic index (SDI) and regions. From 2022 to 2036, while the global ASIR of schizophrenia may decline, both the ASPR and ASDR are projected to rise. The escalating disease burden of schizophrenia poses a significant challenge for countries across all development levels.