Recent global trends in the prevalence and incidence of dementia, and survival with dementia

Current projections of the scale of the coming dementia epidemic assume that the age- and sex-specific prevalence of dementia will not vary over time, and that population ageing alone (increasing the number of older people at risk) drives the projected increases. The basis for this assumption is doubtful, and secular trends (that is, gradual decreases or increases in prevalence over long-term periods) are perfectly plausible.

We carried out a systematic review of studies of trends in prevalence, incidence and mortality for people with dementia, conducted since 1980.