Cannabis Use Disorders in China from 1990 to 2040: Incidence Trends and Future Projections

BACKGROUND: Examining the incidence trends of cannabis use disorders (CUDs) in China over recent decades offers a unique opportunity to observe the evolving trajectories of CUDs under different regulatory frameworks worldwide. METHODS: Leveraging data from the Global Burden of Disease (GBD) 2021 study, a comprehensive international comparative assessment that estimates disease burden across countries by age, sex, and time, this study examined CUD incidence in China from 1990 to 2021 using joinpoint regression and age-period-cohort analysis, and projected future trends through 2040 using Bayesian age-period-cohort modeling. RESULTS: Across the entire population of China, the age-standardized incidence rate (ASIR) of CUDs increased from 29.55 per 100,000 in 1990 to 36.29 per 100,000 in 2021. Projection analysis indicates that this upward trend is expected to persist over time, with the ASIR of CUDs expected to reach 68.48 per 100,000 by 2040. Males demonstrated higher ASIRs than females across all age groups. Age-specific patterns revealed that CUD incidence increased from adolescence to young adulthood, peaked in the 20-29 age group, and then declined gradually with advancing age. Period rate ratios for CUD incidence remained stable from 1990 to 2014 before sharply increasing through 2021. Cohort effects suggest that, in China, younger generations face higher risks of developing CUDs than older generations. CONCLUSIONS: The observed increases in CUD incidence and cohort-specific vulnerabilities in China suggest that prohibition alone may not fully prevent the emergence of cannabis-related disorders.