Abstract
Ageing has occurred in all regions of the world, with impact on neuropsychiatric disorders, particularly dementia. However, previous meta-analysis and reviews have shown high variability in world dementia prevalence rates. Objective: The aim of this study was to perform a wide-ranging review of the dementia prevalence studies published in recent years. Methods: The search was made on Medline, Lilacs and Embase databases for research conducted between 1994 and 2000. The main inclusion criteria were: use of standard diagnostic criteria and investigation of community samples. Results: The final selection included 42 papers, from all continents. The mean prevalence rate of dementia in subjects aged 65 years and older, for continents, ranged from 2.2% in Africa to 8.9% in Europe, and among countries, from 1.3% in India to 14.9% in Spain. However, there was a trend of clustering of the world prevalence rates with the majority of studies reporting rates between 4.2% and 7.2% (³65 years). Age directly influenced the rates, with a mean prevalence rate of 1.2% (95% CI: 0.8-1.5) for the 65-69 years group and 39.9% (95% CI: 34.4-45.3) for the 90-94 year group, but showing less pronounced influence in the very elderly age group. The urban samples had higher rates, where no significant gender difference was evidenced. Conclusion: The age influence over dementia rates apparently leveled off in the very elderly group while a trend toward similar dementia prevalence rates around the world was probably influenced by greater homogeneity in diagnostic criteria.
Key words:
epidemiology; prevalence; dementia; Alzheimer disease; review.