Abstract
Objective To determine changes in the incidence of dementia between 1988 and 2015.
Methods This analysis was performed in aggregated data from individuals >65 years of age in 7 population-based cohort studies in the United States and Europe from the Alzheimer Cohort Consortium. First, we calculated age- and sex-specific incidence rates for all-cause dementia, and then defined nonoverlapping 5-year epochs within each study to determine trends in incidence. Estimates of change per 10-year interval were pooled and results are presented combined and stratified by sex.
Results Of 49,202 individuals, 4,253 (8.6%) developed dementia. The incidence rate of dementia increased with age, similarly for women and men, ranging from about 4 per 1,000 person-years in individuals aged 65–69 years to 65 per 1,000 person-years for those aged 85–89 years. The incidence rate of dementia declined by 13% per calendar decade (95% confidence interval [CI], 7%–19%), consistently across studies, and somewhat more pronouncedly in men than in women (24% [95% CI 14%–32%] vs 8% [0%–15%]).
Conclusion The incidence rate of dementia in Europe and North America has declined by 13% per decade over the past 25 years, consistently across studies. Incidence is similar for men and women, although declines were somewhat more profound in men. These observations call for sustained efforts to finding the causes for this decline, as well as determining their validity in geographically and ethnically diverse populations.
Glossary
- 3C=
- Three-City Study;
- ACC=
- Alzheimer Cohorts Consortium;
- AD=
- Alzheimer disease;
- AGES–Reykjavik Study=
- Age, Gene/Environment Susceptibility–Reykjavik Study;
- ARIC=
- Atherosclerosis Risk in Communities;
- CFAS=
- Cognitive Function and Ageing Studies;
- CHS=
- Cardiovascular Health Study;
- CI=
- confidence interval;
- DSM-III-R=
- Diagnostic and Statistical Manual of Mental Disorders, 3rd edition, revised;
- DSM-IV=
- Diagnostic and Statistical Manual of Mental Disorders, 4th edition;
- FHS=
- Framingham Heart Study;
- HR=
- hazard ratio;
- IR=
- incidence rate;
- PAQUID=
- Personnes Agées QUID;
- RS=
- Rotterdam Study
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
↵The Article Processing Charge was funded by Association of Universities in the Netherlands (VSNU) Association of Universities in the Netherlands (VSNU).
* These authors contributed equally to this work.
- Received July 11, 2019.
- Accepted in final form January 31, 2020.
- Copyright © 2020 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.
This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND), which permits downloading and sharing the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.
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