Dementia Epidemiology: Prevalence and Incidence

Abstract

The prevalence and incidence of dementia rises steeply with age. Up to age 90, the rise is approximately exponential. After that age, there is differing opinion about the steepness of the rise because of the limited data available. Some authorities believe there is a levelling off of the rise in very old age. There is little sex difference in the age‐specific prevalence or incidence of dementia. However, women may be at greater risk of Alzheimer's disease and men of vascular dementia. There appears to be important regional differences in prevalence and incidence, although these are hard to quantify without using identical methodologies in the various sites and few studies have achieved this.