Global Incidence of All-Cause Dementia
Abstract
Importance Global dementia incidence estimates are limited by underrepresentation 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 analyzed 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-analyzed 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 standardized to the 2023 global age-sex population structure. Results Across 287 632 person-years at risk, 3001 participants developed dementia. Age- and sex-standardized incidence was 9.7 (95% CI, 7.89-11.97) per 1000 person-years at risk. Age-standardized incidence was higher in women than men (10.6; 95% CI, 8.61-13.11 vs 8.6; 95% CI, 6.94-10.72). Standardized 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 24.7 million new cases, assuming constant incidence over time. Conclusions and Relevance The harmonized 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 underrepresented low- and middle-income country settings.
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Authors: Ashleigh S. Vella, Rachel Visontay, Darren M. Lipnicki, Emma L. Nichols, Jaimie D Steinmetz, Theo Vos, Anh Thy H. Nguyen, Juan J. Llibre‐Rodriguez, Jorge J. Llibre‐Guerra, Richard B. Lipton, Mindy Joy Katz, Nikolaos Scarmeas, Maëlenn Guerchet, Pierre‐Marie Preux, Karen A. Ritchie, Maria Skaalum Petersen, Ingmar Gr. Skoog, Elena Rolandi, Annalisa Davin, Michele Rossi, Ki Woong Kim, Ji Won Han, Dae Jong Oh, Steffi Gerlinde Riedel-Heller, Susanne Röhr, Alexander Pabst, Ding Ding, Qianhua Zhao, Xiaowen Zhou, Kaarin Jane Anstey, Moyra E. Mortby, Nicolas Cherbuin, Antonio Lobo, Shifu Xiao, Hugh C. Hendrie, Sujuan Gao, S Köhler, Pascual Sánchez‐Juan, Teodoro del Ser, Meritxell Valentí, Márcia Scazufca, Allison E. Aiello, Jacqueline C. Dominguez, Roger Ho, John D. Crawford, Henry Brodaty, Louise R. Mewton, Perminder Singh Sachdev, Ronald C. Petersen, Richard P Mayeux, Nicole Schupf, Yen-Ching Chen, Jen-Hau Chen, Kenji Narazaki, Michael G. Crowe, Frank Kee, Bernadette McGuinness, Nilton Custodio, Murali Krishna, Mary Ganguli, Suzana Shahar, Jacobijn Gussekloo, kenichi Meguro, Rose Anne Kenny, Ricardo Oliveira Guerra, Cristiano Gomes, liang-kung Chen, Richard Walker, Stella‐Maria Paddick, Oye Gureje, Akin Ojagbemi, Linda Lam, Toshiharu Ninomiya, Rhoda Au, Eleonora d'Orsi, Carol Brayne, Kenneth J. Rockwood, Sabrina Noel, Erico Costa, Óscar H. Del Brutto, Yuda Turana, Aquiles Salas, Ivonne Z. Jiménez‐Velázquez, Mariella G Arteaga, Ana Luisa Sosa, Daisy M Acosta
Institutions: University of Washington, Shanghai Jiao Tong University, University of Hong Kong, Columbia University, The University of Sydney, Fudan University, Albert Einstein College of Medicine, Leipzig University, UNSW Sydney, University of Southern California, Inserm, Universidad de Zaragoza, National University of Singapore, Instituto de Salud Carlos III, Washington University in St. Louis, Sahlgrenska University Hospital, Seoul National University Bundang Hospital, Australian National University, Maastricht University, Indiana University School of Medicine, Centro de Investigación Biomédica en Red de Salud Mental, University of Gothenburg, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Université d'Abomey-Calavi, Hong Kong University of Science and Technology, Seoul National University, National and Kapodistrian University of Athens, Institut de Recherche pour le Développement, Instituto de Investigación Sanitaria Aragón, Huashan Hospital, Region Västra Götaland, Fundacion Centro De Investigacion De Enfermedades Neurologicas, Fondazione Golgi Cenci, St. Luke's Medical Center, Université de Limoges, Neuroscience Research Australia, Indiana University Indianapolis, Institute for Health Metrics and Evaluation, Shanghai Mental Health Center, Centre Hospitalier Universitaire de Limoges, Institute for Neurosciences of Montpellier, University of Havana, Institut d’Epidémiologie et de Neurologie Tropicale, Institute for Health Innovation & Technology