A meta-analysis spanning participants across diverse populations from 18 countries has suggested women develop dementia at higher age-standardised rates than men, reports Medscape.
The study was led by Ashleigh Vella from the Centre for Healthy Brain Ageing at the University of New South Wales, Sydney, Australia, and published in JAMA Neurology.
The researchers had conducted a meta-analysis of harmonised individual-level data from across 18 countries or territories spanning six continents, with recruitment beginning between 1990 and 2011, and follow-up being conducted until 2021 (median of four assessment waves).
It included 38 418 adults without dementia at baseline (age, 60-102 years; 57.7% women; 30.6% individuals from low- and middle-income countries).
Incidence of all-cause dementia was estimated per 1 000 person-years at risk, with all-cause dementia beings identified using clinically based diagnoses at each wave.
• Over the follow-up period, 3 001 participants developed dementia. Age- and sex-standardised incidence of all-cause dementia was 9.7, equating to 11.4m new cases globally in 2023.
• Age-standardised incidence of all-cause dementia was higher among women than among men (10.6 vs 8.6; P < .001).
• Age- and sex-standardised incidence of all-cause dementia was higher in low- and middle-income countries than in high-income countries (13.6 vs 8.3; P = .02). Age-standardised incidence of all-cause dementia was higher in low- and middle-income countries than in high-income countries (15.3 vs 9.3 among women and 12.6 vs 7.5 among men).
• Age- and sex-standardised incidence of all-cause dementia was the highest in Latin America (13.1) and Asia (13) and the lowest in Oceania (7.6), but the differences were not statistically significant.
Assuming age- and sex-specific incidence rates to be stable and applying them to the projected 2050 population yielded an incidence of 11.7 (12.8 among women vs 10.5 among men), corresponding to 24.7m new cases globally.
“The observed sex- and income-stratified differences, with substantial cross-country variation, highlight the need for targeted equitable prevention strategies and expanded diagnostic and care capacity, particularly for women and in under-resourced settings," the authors wrote.
Limitations
The projections assumed stable age-sex-specific incidence and country-income classifications over time. Diagnostic criteria and assessment methods were varied, and large heterogeneity was observed in pooled estimates.
Additional limitations included potential interval-censoring bias, the under-representation or absence of several regions, and the potential under-representation of institutionalised older adults, people with lower socio-economic status, and certain ethnic or rural groups.
Study details
Global Incidence of All-Cause Dementia: A Meta-Analysis
Ashleigh Vella, Rachel Visontay, Darren Lipnicki et al
Published in JAMA Neurology on 12 October 2026
Key Points
Question What are the 2023 global and regional incidence rates for all-cause dementia, and how do they vary by sex and country income level with projections to 2050?
Findings This meta-analysis estimated 11.4m new cases globally in 2023, with a projected increase to 24.7m in 2050. Incidence was higher in women than in men and among low- and middle-income countries compared with high-income countries.
Meaning The estimates provided in this study offer insights into the present and future global dementia incidence, particularly among women and under-represented low- and middle-income countries.
Abstract
Importance
Global dementia incidence estimates are limited by under-representation of low- and middle-income countries and heterogeneous analytic methods. Due to these limitations, true understanding of the global dementia landscape remains incomplete.
Objective
To identify dementia incidence rates by age and sex in various regions worldwide (high-income countries and low- and middle-income countries) where data on clinically based dementia diagnoses were available.
Data Sources
Retrospective community-based cohorts from the Cohort Studies of Memory in an International Consortium (COSMIC); baseline recruitment commenced between January 1990 and December 2011 and follow-up data were collected through the end of 2021. Data were analysed from June 2024 to June 2025.
Study Selection
Eligible studies included longitudinal COSMIC cohort studies with a clinically based diagnosis of dementia. Individual participant–level data from 22 population-based longitudinal cohorts (N = 38 418) spanning 18 countries or territories across 6 continents were included.
Data Extraction and Synthesis
Data extraction and assessment of study quality and validity were conducted according to Meta-Analyses of Observational Studies in Epidemiology (MOOSE) guidelines. Individual participant–level data were meta-analysed in a 2-step process using random intercepts for country and study at the global and regional levels and by country income level.
Main Outcomes and Measures
For each study with a clinically based diagnosis, incidence rates for all-cause dementia were calculated and a 2-step meta-analysis was conducted. Using a person-years at risk framework with inverse-probability censoring weights and Poisson models, age- and sex-specific incidence were estimated and then standardised to the 2023 global age-sex population structure.
Results
Across 287 632 person-years at risk, 3001 participants developed dementia. Age- and sex-standardised incidence was 9.7 (95% CI, 7.89-11.97) per 1000 person-years at risk. Age-standardised incidence was higher in women than men (10.6; 95% CI, 8.61-13.11 vs 8.6; 95% CI, 6.94-10.72). Standardised incidence was higher in low- and middle-income countries (13.6; 95% CI, 9.67-19.24) than in high-income countries (8.3; 95% CI, 6.57-10.54). Applying age- and sex-specific rates to the projected 2050 population yielded a projected 24.7m new cases, assuming constant incidence over time.
Conclusions and Relevance
The harmonised estimates presented in this study provide a comparable benchmark for global dementia incidence and inform planning for prevention, diagnosis, and memory-care services, particularly in under-represented low- and middle-income country settings.
JAMA Neurology article – Global Incidence of All-Cause Dementia: A Meta-Analysis (Open access)
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