Divergent trends in Alzheimer's disease burden: a comparative analysis of the US and G20 nations.

OBJECTIVE: Alzheimer's disease and other dementias (ADOD) impose growing systemic stress. This study compared epidemiological trends and risk factors between the US and G20 to guide resource allocation. METHODS: Using GBD 2023 data, we analyzed incidence, mortality, and DALY rates with Joinpoint regression (1990-2023) and ARIMA forecasting (to 2040). RESULTS: In 2023, US age-standardized incidence rate was 130 (95% CI: 110.5-147.3), mortality rate 30 (7.4-73.2), and DALY rate 510 (224.8-1059.6), all declining from 1990. G20 rates remained lower but showed an upward inflection after 2020. Joinpoint analysis revealed overall downward trends, with a transient US resurgence (1998-2004); projections suggest continued deceleration. Smoking and high fasting plasma glucose burdens in the US were disproportionately elevated compared to G20. CONCLUSION: The US achieved morbidity compression yet faced rising absolute caseloads due to demographic momentum. G20's post-2020 upturn signals an emerging burden. A shift from smoking to metabolic drivers necessitates primary prevention for G20 and targeted metabolic management for the US.