Global, Regional, and National Burden of Early-Onset Alzheimer's Disease and Other Dementias in Young Adults Aged 40-64 Years, 1990-2021: A Population-Based Study.

BACKGROUND AND PURPOSE: Early-onset Alzheimer's disease and other dementias (EOAD) impose significant burdens on affected individuals and their families. However, the global burden of EOAD has not been fully investigated. We aimed to assess the global, regional, and national burden of EOAD using data from the Global Burden of Diseases, Injuries, and Risk Factors (GBD) study from 1990 to 2021.

METHODS

Data for adults aged 40-64 were extracted within the GBD 2021 framework. Primary outcomes included age-standardized prevalence, incidence, mortality, and disability-adjusted life years (DALYs) for EOAD, as well as average annual percentage change (AAPC) across 21 regions and 204 countries.

RESULTS

In 2021, EOAD cases reached 7.75 million (95% uncertainty interval [UI] 5.82-10.08), up from 3.67 million cases (95% UI 2.75-4.76) in 1990. The age-standardized prevalence rate increased from 341.2 per 100,000 (95% UI 255.89-442.79) in 1990 to 363.5 per 100,000 in 2021, with an AAPC of 0.26% (p < 0.001). EOAD prevalence was higher in women than in men in 2021 (4.28 million, 95% UI 3.24-5.56, vs. 3.46 million, 95% UI 2.57-4.52). EOAD was associated with 0.07 million (95% UI 0.01-0.23) deaths and 3.77 million (95% UI 1.69-8.88) DALYs in 2021. Additionally, 1.06 million (95% UI 0.07-3.03) DALYs were attributable to smoking, elevated fasting plasma glucose, and high body mass index.

CONCLUSIONS

The global number of EOAD cases among adults aged 40-64 years more than doubled from 1990 to 2021. Targeted strategies and interventions are urgently needed to address this growing public health issue.