The changing prevalence and incidence of dementia over time — current evidence

Journal name:
Nature Reviews Neurology
Volume:
13,
Pages:
327–339
Year published:
DOI:
doi:10.1038/nrneurol.2017.63
Published online
Corrected online

Abstract

Dementia is an increasing focus for policymakers, civil organizations and multidisciplinary researchers. The most recent descriptive epidemiological research into dementia is enabling investigation into how the prevalence and incidence are changing over time. To establish clear trends, such comparisons need to be founded on population-based studies that use similar diagnostic and research methods consistently over time. This narrative Review synthesizes the findings from 14 studies that investigated trends in dementia prevalence (nine studies) and incidence (five studies) from Sweden, Spain, the UK, the Netherlands, France, the USA, Japan and Nigeria. Besides the Japanese study, these studies indicate stable or declining prevalence and incidence of dementia, and some provide evidence of sex-specific changes. No single risk or protective factor has been identified that fully explains the observed trends, but major societal changes and improvements in living conditions, education and healthcare might have favourably influenced physical, mental and cognitive health throughout an individual's life course, and could be responsible for a reduced risk of dementia in later life. Analytical epidemiological approaches combined with translational neuroscientific research could provide a unique opportunity to explore the neuropathology that underlies changing occurrence of dementia in the general population.

At a glance

Figures

  1. Odds ratios and prevalence ratios reported in nine studies of dementia prevalence.
    Figure 1: Odds ratios and prevalence ratios reported in nine studies of dementia prevalence.

    Reported figures are the ratios of the prevalence estimate for new cohorts to those for old cohorts. If prevalence estimates remain the same across two cohorts, the ratio is 1.0. If estimates are higher in the new cohort than the old cohort, the ratio is greater than 1.0. Estimates are adjusted as follows: Gothenburg study and HRS, unadjusted; IIDP, adjusted for age; Nordanstig, Zaragoza, Bordeaux and Hisayama studies, adjusted for age and sex; Stockholm study, adjusted for age, sex and education; CFAS, adjusted for age, sex, area and deprivation. In the Bordeaux study, clinical diagnosis was made by neuropsychologists using criteria in the Diagnostic and Statistical Manual III revised, and algorithmic diagnosis was based on cognitive and functional ability tests. CFAS, Cognitive Function and Ageing Study; HRS, Health and Retirement Study; IIDP, Indianapolis–Ibadan Dementia Project.

  2. Hazard ratio and incidence rate ratio from five studies of dementia incidence.
    Figure 2: Hazard ratio and incidence rate ratio from five studies of dementia incidence.

    Reported figures are the ratios of the incidence estimate in new cohorts to that in old cohorts. If incidence estimates remain the same across two cohorts, the ratio is 1.0. If estimates are higher in new cohorts than old cohorts, the ratio is greater than 1.0. Estimates are adjusted as follows: Rotterdam study, IIDP and Bordeaux study adjusted for age; Framingham Heart Study adjusted for age and sex; CFAS adjusted for age, sex, area and deprivation. In the Bordeaux study, clinical diagnosis was made by neuropsychologists and neurologists using criteria from the Diagnostic and Statistical Manual III revised and V, and algorithmic diagnosis was based on cognitive and functional ability tests. CFAS, Cognitive Function and Ageing Study; IIDP, Indianapolis–Ibadan Dementia Project.

  3. Life expectancy at birth in all countries included in population-based studies of dementia incidence and prevalence.
    Figure 3: Life expectancy at birth in all countries included in population-based studies of dementia incidence and prevalence.

    Data obtained from from Gapminder, the National Center for Health Statistics, USA84 and Wu, Y.-T. et al.5.

Change history

Corrected online 17 May 2017
In the version of this article initially published online, the affiliations for Karine Pérès, Chengxuan Qiu and Britt-Marie Sjölund were incorrect. These errors have been corrected in the print, HTML and PDF versions of the article.

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Author information

Affiliations

  1. REACH: The Centre for Research in Ageing and Cognitive Health, Department of Psychology, College of Life and Environmental Sciences, University of Exeter, Washington Singer Building, Perry Road, Exeter EX4 4QG, UK.

    • Yu-Tzu Wu
  2. Boston University School of Public Health, 72 East Concord St, B602 Boston, Massachusetts 02118, USA.

    • Alexa S. Beiser
  3. German Center for Neurodegenerative diseases (DZNE), Population Health Sciences, Sigmund-Freud-Straße 27, 53127 Bonn, Germany.

    • Monique M. B. Breteler
  4. Aging Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet-Stockholm University, Gävlegatan 16, S-113 30, Stockholm, Sweden.

    • Laura Fratiglioni,
    • Chengxuan Qiu &
    • Britt-Marie Sjölund
  5. INSERM, ISPED, Centre INSERM, U1219 - Bordeaux Population Health Research Center, Bordeaux, France.

    • Catherine Helmer &
    • Karine Pérès
  6. Department of Psychiatry, Indiana University School of Medicine, 410 West 10th Street, Indianapolis, Indiana 46202, USA.

    • Hugh C. Hendrie
  7. Department of Neuropathology, Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, 812–8582, Fukuoka, Japan.

    • Hiroyuki Honda
  8. Department of Epidemiology, Erasmus University Medical Center, Wytemaweg 80, 3015 CN Rotterdam, Netherlands.

    • M. Arfan Ikram
  9. Department of Internal Medicine, Veterans Affairs Center for Clinical Management Research, Institute for Social Research, and Institute for Healthcare Policy and Innovation, University of Michigan, 2800 Plymouth Road, Ann Arbor, Michigan 48109–2800, USA.

    • Kenneth M. Langa
  10. Department of Psychiatry, Universidad de Zaragoza and Instituto de Investigación Sanitaria Aragón, Zaragoza. CIBERSAM, Madrid, Spain.

    • Antonio Lobo
  11. Institute of Health and Society, Newcastle University, The Baddiley-Clark Building, Richardson Road, Newcastle Upon Tyne, NE4 5PL, UK.

    • Fiona E. Matthews
  12. Department of Epidemiology and Public Health, Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, 812–8582, Fukuoka, Japan.

    • Tomoyuki Ohara
  13. Boston University School of Medicine, The Framingham Study, 72 East Concord Street, B602 Boston, Massachusetts 02118, USA.

    • Sudha Seshadri
  14. Centre for Ageing and Health AgeCap, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Box 100, S-405 30, Gothenburg, Sweden.

    • Ingmar Skoog
  15. Department of Public Health and Primary Care, Cambridge Institute of Public Health, Forvie Site, University of Cambridge, School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge CB2 0SR, UK.

    • Carol Brayne

Contributions

All authors researched data for the article and reviewed and/or edited the manuscript before submission. Y.-T.W. and C.B. wrote the article and made substantial contributions to discussion of the content.

Competing interests statement

The authors declare no competing interests.

Corresponding author

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Author details

  • Yu-Tzu Wu

    Yu-Tzu Wu is a research fellow at the Centre for Research in Ageing and Cognitive Health, University of Exeter, UK. She has worked with longitudinal cohorts of ageing and dementia, including the Cognitive Function and Ageing Studies (CFAS), the European Prospective Investigation of Cancer – Norfolk study (EPIC–Norfolk) and the Improving the experience of Dementia and Enhancing Active Life (IDEAL) study. Her research interests include the epidemiology of dementia and contextual factors related to health in later life.

  • Alexa S. Beiser

    Alexa S. Beiser is Professor of Biostatistics and Neurology at the Boston University School of Public Health and the Boston University School of Medicine, MA, USA, and is the lead biostatistician for the Framingham Heart Study neurology group. She has been on the faculty at Boston University School of Public Health since 1985, engaged in teaching and collaborative public health research. She has examined temporal trends in prevalent and incident neurological diseases as well as risk factors for clinical and sub-clinical neurological outcomes including MRI measures of brain structure, cognitive performance, dementia, Alzheimer disease, stroke, Parkinson disease and seizures.

  • Monique M. B. Breteler

    Monique M. B. Breteler is Director of Population Health Sciences at the German Center for Neurodegenerative Diseases, Germany, Professor of Population Health Sciences at the University of Bonn, Germany, and Adjunct Professor of Epidemiology at the Harvard School of Public Health, Boston, MA, USA. She has a medical degree and received her PhD degree in epidemiology from the Erasmus University Rotterdam, Netherlands. Her research interest is in the aetiology and preclinical detection of age-related neurodegenerative disorders, including dementia. For more than 20 years, she has worked on the Rotterdam Study, a large prospective cohort study of older adults and developed the neurologic component in the study.

  • Laura Fratiglioni

    Laura Fratiglioni is the director of the Aging Research Center and the Distinguished Professor at Karolinska Institutet, Sweden. She is a medical doctor, specialised in both neurology and epidemiology. She is the principal investigator of the SNAC-Kungsholmen population study, and the scientific coordinator for the Kungsholmen Project on Aging and Dementia. Her research areas include risk and protective factors for Alzheimer disease and other dementias, the natural history of the dementias, the body-mind connection, and health status and health trends in older people.

  • Catherine Helmer

    Catherine Helmer is a public health physician, epidemiologist and researcher at the Bordeaux Population Health research center (INSERM U1219, France). She is in charge of the coordination of the Bordeaux-3C Study. Her research areas include risk and protective factors for Alzheimer disease and other dementias, the natural history of the dementias, the trends in dementias frequency and the care of patients with dementia.

  • Hugh C. Hendrie

    Hugh C. Hendrie is Professor of Psychiatry at Indiana University (IU) School of Medicine and Distinguished Scientist at the IU Center for Aging Research and Regenstrief Institute, Indiana, USA. He was the co-principal investigator of the Indianapolis–Ibadan Dementia Project (IIDP), a multi-disciplinary group of researchers conducting international comparative studies of dementia, Alzheimer disease and their risk factors in Nigeria and the USA. His research focuses primarily on epidemiological research on ageing-related disorder, including Alzheimer disease, the related dementias, cognitive decline, depression and other psychiatric disorders, with a special interest in diverse populations. He has also participated in intervention trials for Alzheimer disease and depression.

  • Hiroyuki Honda

    Hiroyuki Honda is research associate at the Department of Neuropathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. He is a medical doctor, specialized in both clinical neurology and neuropathology. His research focuses on investigating neuropathology of neurodegenerative disease, including Alzheimer disease, prion disease and amyotrophic lateral sclerosis. He has also been involved in autopsy and post-mortem neuropathological assessment in the Hisayama study.

  • M. Arfan Ikram

    M. Arfan Ikram is Professor and Head of neuro-epidemiologic research at the Department of Epidemiology, Erasmus MC Rotterdam, the Netherlands. He is principal investigator of neurological diseases in the Rotterdam Study. His research focuses on investigating the aetiology of neurological diseases in the elderly, with a particular focus on dementia, Alzheimer disease, stroke, and Parkinson disease. The main areas of research are to elucidate the earliest signs of brain diseases, before clinical symptoms are present, and to understand how these lead to clinical manifestation of disease using MRI, neuropsychological testing and genome-wide data.

  • Kenneth M. Langa

    Kenneth M. Langa is the Cyrus Sturgis Professor of Medicine in the Department of Internal Medicine, Institute for Social Research, and the Veterans Affairs Ann Arbor Healthcare System, all at the University of Michigan, Michigan, USA. He is Associate Director for the Health and Retirement Study (HRS), a longitudinal study of 20,000 adults in the USA, and was a lead investigator for the Aging, Demographics, and Memory Study (ADAMS), a supplemental study to the HRS regarding the risk factors, epidemiology, and outcomes of dementia. His research focuses on the epidemiology and costs of chronic disease in older adults, with an emphasis on Alzheimer disease and other dementias.

  • Antonio Lobo

    Antonio Lobo has been Professor and Chairman, Department of Psychiatry, University of Zaragoza and Psychiatrist-in-Chief, University Hospital, Zaragoza, Spain. He is now Emeritus Professor and Neuroscience Program chairman, Institute of Biomedical Research Aragon (IIS Aragon), Zaragoza, Spain. He graduated in medicine and completed his doctoral thesis at Zaragoza University, Spain, and moved on to training in psychiatry at the New York Hospital–Cornell Medical Center, New York, USA. He was then appointed Instructor in Psychiatry, Johns Hopkins Hospital and Medical School, Maryland, USA, before he returned to Zaragoza University. His main research in this area has focused on cognition, dementia, depression and medical comorbidity in the elderly population. He is principal investigator in the ZARADEMP Project, a population-based, five-wave longitudinal cohort of older people and associated studies in Zaragoza, Spain.

  • Fiona E. Matthews

    Fiona E. Matthews is Professor of Epidemiology in Newcastle upon Tyne and a Programme Leader at the Medical Research Council Biostatistics Unit, University of Cambridge, both in the UK. She is a statistician by training and has been the Principal Statistician on the Cognitive Function and Ageing Studies (CFAS). She is particularly interested in using modern statistical methods to investigate ageing, healthy life expectancy and autism using population based epidemiological studies.

  • Tomoyuki Ohara

    Tomoyuki Ohara is an Assistant Professor at the Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Japan. He is a co-investigator of the Hisayama Study, a population-based prospective cohort study of cerebrocardiovascular diseases in the Japanese population. His research focuses on epidemiology of geriatric psychiatry, especially dementia. The main areas of his research are to elucidate the trend in prevalence, incidence, and survival rate of dementia and its risk or protective factors for the development of dementia.

  • Karine Pérès

    Karine Pérès is an epidemiologist and a researcher of the French Institute for Health and Medical Research (INSERM), in the Bordeaux Population Health Research Center, University of Bordeaux, France. She is a member of the Team Psycho-Epidemiology of Aging and Chronic Disease, where she coordinates the axis on a comprehensive approach of the changes in functional autonomy, cognitive, psychological and familial functioning associated with ageing and chronic diseases. She works on three population-based epidemiological studies: Paquid, Three City and Aging Multidisciplinary Investigation (the latter of which she is in charge of). She is particularly interested in disability free life expectancy, activity limitation in daily living and dementia.

  • Chengxuan Qiu

    Chengxuan Qiu is a senior lecture at Karolinska Institutet, Sweden. Since 1999 he has worked on longitudinal population-based studies of ageing and health including the Kungsholmen Project and Swedish National study on Aging and Care in Kungsholmen Project. His research focuses on health in ageing, especially on health trends, cardiovascular risk factors, and vascular mechanisms of brain ageing and dysfunction (for example, cognitive decline, dementia and functional dependence). He has collaborated with several groups within Sweden and across Europe, America, and Asia-Pacific regions.

  • Sudha Seshadri

    Sudha Seshadri is a medical doctor and Professor of Neurology at the Boston University School of Medicine, Massachusetts, USA. She completed a Fellowship in the Neurobiology of Aging and Alzheimer Disease at the University of Massachusetts Medical Center, Massachusetts, USA. She has been an investigator at the Framingham Heart Study since 1998, leading the clinical neurology and neurogenetics cores since 2005. Her research interests include the correlates of subclinical brain ageing (establishing norms for brain MRI and cognitive test performance); the epidemiology of stroke, vascular cognitive impairment, dementia, Alzheimer disease and their traditional and novel biomarkers, underlying genomic and epigenetic variation.

  • Britt-Marie Sjölund

    Britt-Marie Sjölund is a researcher at Aging Research Center, Karolinska Institutet, Sweden, and senior lecturer at the Department of Health and Caring Sciences, University of Gävle, Sweden. She has worked on longitudinal population-based studies including the Nordanstig project and Swedish National study on Aging and Care in Nordanstig since 1995. Her research focuses on physical functioning in old age, temporal trends and geographical variation in Sweden.

  • Ingmar Skoog

    Ingmar Skoog is professor in psychiatry and director and co-founder of the Centre for Health and Ageing, AGECAP, at the University of Gothenburg, Sweden. He has been involved in epidemiological research for more than three decades and is currently leading the H70-studies – population studies on ageing that have been ongoing since 1971. His work has focused on the relationship between cardiovascular disorders, in particular hypertension and Alzheimer disease and depression. Recent interests include how ageing has changed during the last four decades, and which factors enable people to keep their capability into very old age.

  • Carol Brayne

    Carol Brayne is Professor of Public Health Medicine and Director of the Cambridge Institute of Public Health at the University of Cambridge, UK. She graduated in medicine from the Royal Free Hospital School of Medicine, University of London, UK, and moved on to training in epidemiology with a Training Fellowship with the Medical Research Council. Her main research area has focused on cognition, dementia natural history and associated features in the general population. She is lead principal investigator in the Cognitive Function and Ageing Studies (CFAS), a network of population-based longitudinal cohorts of older people in the UK.

Supplementary information

Word documents

  1. Supplementary information S1 (table) (157 KB)

    Prevalence studies

  2. Supplementary information S2 (table) (54 KB)

    Incidence studies: estimates by 10-year age group

  3. Supplementary information S3 (table) (81 KB)

    Incidence studies: estimates by 5-year age group

Additional data