Public Health

Vella AS 1 , Visontay R 2 , Lipnicki DM 3 , Nichols E 4 , Steinmetz J 5 , Lipton RB 6 Show all authors , Llibre-Rodriguez JJ 7 , Katz MJ 8 , Scarmeas N 9 , Guerchet M 10 , Preux PM 10 , Ritchie K 11 , Carriere I 12 , Petersen MS 13 , Skoog I 14 , Rolandi E 15 , Kim KW 16 , Riedel-Heller SG 17 , Shahar S 18 , Ganguli M 19 , Anstey KJ 20 , Lobo A 21 , Crawford JD 22 , Mewton L 2 , Sachdev PS 23 , other COSMIC authors

Affiliations 

  • 1 Centre for Healthy Brain Ageing, University of New South Wales, Sydney, NSW, Australia
  • 2 The Matilda Centre for Research in Mental Health and Substance Use, The University of Sydney, Sydney, NSW, Australia
  • 3 Centre for Healthy Brain Ageing, Discipline of Psychiatry & Mental Health, School of Clinical Medicine, University of New South Wales, Sydney, NSW, Australia
  • 4 Institute for Health Metrics and Evaluation, Seattle, WA, USA
  • 5 Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, USA
  • 6 Department of Neurology, Albert Einstein College of Medicine, Bronx, NY, USA
  • 7 Dementia Research Unit/Medical University of Havana, Havana, Havana, Cuba
  • 8 Albert Einstein College of Medicine, Bronx, NY, USA
  • 9 Columbia University, New York, NY, USA
  • 10 National Institute for Health and Medical Research U1094, Institut de Recherche pour le Developpement UMR270, Epidemiology of Chronic Diseases in Tropical Zone, Institute of Epidemiology and Tropical Neurology, OmegaHealth, University Limoges, Centre Hosp, Limoges, France
  • 11 Institut du Cerveau Trocadéro, Paris, France
  • 12 Institute for Neurosciences of Montpellier, University of Montpellier, INSERM, Montpellier, France
  • 13 The National Hospital of Faroe Island, Tórshavn, Faroe Islands
  • 14 Psychiatry, Cognition and Old Age Psychiatry, Sahlgrenska University Hospital, Gothenburg, Sweden
  • 15 Golgi Cenci Foundation, Abbiategrasso, Italy
  • 16 Seoul National University College of Medicine, Seoul, Korea, Republic of (South)
  • 17 Institute of Social Medicine, Occupational Health and Public Health (ISAP), Medical Faculty, University of Leipzig, Leipzig, Germany
  • 18 Community Rehabilitation and Aging Research Centre, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kajang Selangor, Malaysia
  • 19 Division of Geriatrics & Neuropsychiatry, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
  • 20 University of New South Wales, Sydney, NSW, Australia
  • 21 University of Zaragoza, Zaragoza, Spain
  • 22 Centre for Healthy Brain Ageing (CHeBA), UNSW Sydney, Sydney, NSW, Australia
  • 23 Neuropsychiatric Institute, Prince of Wales Hospital, Randwick, NSW, Australia
Alzheimers Dement, 2024 Dec;20 Suppl 7(Suppl 7):e087341.
PMID: 39785197 DOI: 10.1002/alz.087341

Abstract

BACKGROUND: High-income countries (HICs) are over-represented in current global dementia incidence rates, skewing estimates. Variance in diagnostic methods between HICs and low- and middle-income countries (LMICs) is speculated to contribute to the regional differences in rates. Cohort Studies of Memory in an International Consortium (COSMIC) offers a unique opportunity to address these research inequalities by harmonising data from international studies, including representation from LMICs. This study aimed to identify dementia incidence rates by age and sex in various regions worldwide, where data for dementia diagnosis were available.

METHOD: Data were obtained from 36 members of COSMIC, representing 28 countries across 6 continents (HICs: Australia, Canada, Faroe Islands, France, Germany, Greece, Italy, Japan, Netherlands, South Korea, Spain, Sweden, & USA; LMICs: Brazil, China, Cuba, Dominican Republic, Ecuador, Indonesia, Malaysia, Mexico, Nigeria, Peru, Philippines, Republic of Congo, & Tanzania). For each member study, we calculated incidence rates for all-cause dementia. Findings from 14 studies, with a consensus diagnosis are presented in the results. Using an Item Response Theory approach, we are currently calculating a comparable incidence rate for those studies without a consensus diagnosis.

RESULT: Consistent with previous trends, incidence rates (per 100 person-years) increased with age, from 65-70 years-old to 85-90 years-old, for both males (i.e., Republic of Congo, 4.41 to 19.57; France, 0.46 to 3.89; USA, 0.17 to 3.22; Spain, 0.31 to 4.22; 65-70 & 85-90 cohorts respectively) and females (i.e., Republic of Congo, 3.57 to 15.31; France, 0.45 to 3.72; USA, 0.22 to 4.25; Spain, 0.36 to 4.96; 65-70 & 85-90 cohorts respectively). There were no sex differences in incidence rates in younger age groups (60-65). Among older age groups, however, women tended to have higher incidence rates than men, in some countries (Faroe Islands, Germany, Sweden, and USA).

CONCLUSION: Geographical differences in dementia incidence rates likely represent inherent variation among countries, beyond methodological considerations. We are working to expand the range of studies and regions for which we calculate dementia incidence rates. This involves the development of approaches to classify and harmonise incident dementia in studies lacking consensus diagnoses. Doing so will bolster LMIC representation.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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