Estimate dementia incidence across populations and project annual new cases worldwide through 2050.
Approach:
Study design: Harmonized meta-analysis of 22 population-based longitudinal cohorts in 18 countries or territories.
Participants: 38,418 adults aged 60 years or older without dementia at baseline; follow-up totaled 287,632 person-years.
Analysis: Researchers estimated standardized incidence rates and examined differences by sex, country income level, and region. Projections applied age- and sex-specific incidence rates to projected populations.
Key Findings:
Among 3,001 incident cases, global age- and sex-standardized dementia incidence was 9.7 per 1,000 person-years.
Age-standardized incidence was higher among women than men (10.6 vs 8.6 per 1,000 person-years); crude rates did not differ significantly by sex.
Standardized incidence was 13.6 per 1,000 person-years in low- and middle-income countries and 8.3 in high-income countries.
Regional estimates ranged from 7.6 per 1,000 person-years in Oceania to 13.1 in Latin America, but regional differences were not statistically significant.
Estimated annual new cases worldwide rose from approximately 11.4 million in 2023 to 24.7 million in 2050, a projected increase of 117%.
Interpretation:
The projected increase reflects population aging under the assumption that age- and sex-specific incidence rates remain constant; it does not demonstrate a change in underlying dementia risk. The authors described the findings as a benchmark for comparing incidence across populations.
Limitations:
Projections assumed constant age- and sex-specific incidence rates over time.
Geographic representation was uneven, with limited data from Africa, Latin America, and Oceania and no cohorts from the Middle East.
Between-study heterogeneity, differences in diagnostic methods, and potentially unrepresentative national samples limit generalizability.
Some regional estimates relied on few cohorts and may not represent entire countries or continents.
Conclusion:
The authors called for targeted equitable prevention strategies and expanded diagnostic and care capacity.
