Objective:
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.
Sources:
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