Trends in Dementia Prevalence Across Latin America and the Caribbean.

Importance

Reliable estimates of dementia prevalence trends are essential for health policy planning. Latin America is undergoing rapid population aging, yet it remains unclear whether dementia prevalence mirrors declining patterns reported in high-income countries.

Objective

To examine 2-decade trends in dementia prevalence across 5 Latin American and Caribbean sites participating in the 10/66 Dementia Research Group.

Design, setting, and participants

This cross-sectional, population-based study included data from 5 population-based catchment areas participating in the 10/66 study: Cuba, the Dominican Republic, Mexico, Peru, and Puerto Rico. Data were collected at 2 time points: 2003 to 2006 and 2016 to 2020. Participants were community-dwelling adults aged 65 years or older, identified through exhaustive door-to-door enumeration across 2 survey waves. Data were analyzed between March 2025 and May 2026.

Exposures

Survey wave (2003-2006 vs 2016-2020) was the primary temporal comparison. Secondary exposures included modifiable dementia risk factors from the Lancet Commission on dementia prevention.

Main outcomes and measures

The main outcome was crude and age- and sex-standardized dementia prevalence using the 10/66 dementia diagnostic algorithm. Adjusted prevalence differences between waves were estimated using Poisson regression with sequential adjustment for education, health behaviors, and health risk factors.

Results

Of 23 709 eligible individuals identified, 5892 declined or could not be traced and 17 817 were assessed. After excluding participants with missing dementia diagnosis or data, the analytic sample included 16 950 participants (wave 1: n = 10 374; wave 3: n = 6576; mean [SD] age, 76.0 [7.5] years; 63.7% women). Pooled crude prevalence increased from 10.6% (95% CI, 10.0%-11.2%) at 2003 to 2006 to 16.9% (95% CI, 15.9%-17.8%) at 2016 to 2020. After age and sex standardization to 2025 United Nations population structures, prevalence remained stable in Cuba and the Dominican Republic but increased substantially in Mexico (4.9 percentage points [pp]; 95% CI, 3.0-6.8 pp), Peru (4.1 pp; 95% CI, 1.9-6.4 pp), and Puerto Rico (5.0 pp; 95% CI, 1.8-8.2 pp). Increasing trends in Mexico (adjusted difference: 6.3%; 95% CI, 4.1%-8.5%) and Puerto Rico (7.2%; 95% CI, 3.8%-10.6%) persisted after full adjustment for health behaviors and risk factors.

Conclusions and relevance

This study found that dementia prevalence has increased over 2 decades across several Latin American 10/66 catchment sites, contrasting with declining trends reported in high-income countries. These findings, while specific to the 5 studied sites, highlight the growing and uneven burden of dementia in the region and underscore the need for strengthened surveillance, risk reduction strategies, and investment in dementia care infrastructure.