Abstract
BACKGROUND: Given the growing global burden of Alzheimer's Disease and Other Dementias (ADODs) and inequalities in its distribution, it is of great necessity to analyze the trends and cross-country inequalities in the burden of ADODs globally and in China from 1990 to 2021. METHODS: Estimates and 95% uncertainty intervals (UIs) for incidence, prevalence, and disability-adjusted life years (DALYs) of ADODs were obtained from the Global Burden of Diseases Study (GBD) 2021. We described the epidemiology of ADODs at global, regional, and national levels, conducting temporal trend analyses using estimated annual percentage change, joinpoint regression, and age-period-cohort model. Additionally, we performed spatial autocorrelation, decomposition, and cross-country inequality analyses, comparing the burden in China to global trends. RESULTS: The global burden of ADODs increased overall from 1990 to 2021. GBD 2021 estimated 9,837,056 incident cases, 56,856,688 prevalent cases, and 36,332,687 DALYs for ADODs worldwide in 2021, with the highest case number in East Asia and highest age-standardized rate of DALYs in central sub-Saharan Africa. Spatial trends analyses showed hot spots in sub-Saharan Africa, the Middle East and North Africa, Europe, and High-income North America. Decomposition analysis revealed that changes in DALYs were primarily driven by population growth and aging, followed by prevalence, case fatality, and disease severity. Significant increases in absolute and relative sociodemographic index (SDI)-related inequalities in DALYs were observed from 1990 to 2021, with 318.19 to 759.97, and 0.43 to 0.49, respectively. CONCLUSION: The burden of ADODs globally and in China showed overall increasing trends from 1990 to 2021. This increase was primarily driven by population growth and aging. Countries with high SDI values faced a disproportionately large burden of dementia, and SDI-related inequalities among countries exacerbated over time. These findings highlight significant challenges for the prevention and control of ADODs globally and in China.