A review of the epidemiological transition in dementia - cross-national comparisons of the indices related to Alzheimer's disease and vascular dementia

Objective: To examine temporal changes in the prevalence of dementia and associated factors. Method: All publications on the epidemiology of dementia were identified using a medline search for the years 1966-1999. Results: Alzheimer's disease (AD) has become nearly twice as prevalent as vascular dementia (VaD) in Korea, Japan, and China since transition in early 1990s. Prior to this, in the 1980s, VaD was more prevalent than AD in these countries. In Nigeria, the prevalence of dementia was low. Indian studies were contradictory, with both AD and VaD being more prevalent in different studies. American and European studies consistently reported AD to be more prevalent than VaD. Conclusion: A theoretical model of transition from low incidence-high mortality society to high incidence-high mortality society to low incidence-low mortality society may explain these findings. Rigorous testing in prospective, longitudinal and population-based cross-national studies using culture-fair diagnostic instruments is required.