Alzheimer disease in the US population: prevalence estimates using the 2000 census.

CONTEXT: Current and future estimates of Alzheimer disease (AD) are essential for public health planning.

OBJECTIVE: To provide prevalence estimates of AD for the US population from 2000 through 2050.

DESIGN: Alzheimer disease incidence estimates from a population-based, biracial, urban study, using a stratified random sampling design, were converted to prevalence estimates and applied to US Census Bureau estimates of US population growth.

SETTING: A geographically defined community of 3 adjacent neighborhoods in Chicago, Ill, applied to the US population.

PARTICIPANTS: Alzheimer disease incidence was measured in 3838 persons free of AD at baseline; 835 persons were evaluated for disease incidence. Main Outcome Measure Current and future estimates of prevalence of clinically diagnosed AD in the US population.

RESULTS: In 2000, there were 4.5 million persons with AD in the US population. By 2050, this number will increase by almost 3-fold, to 13.2 million. Owing to the rapid growth of the oldest age groups of the US population, the number who are 85 years and older will more than quadruple to 8.0 million. The number who are 75 to 84 years old will double to 4.8 million, while the number who are 65 to 74 years old will remain fairly constant at 0.3 to 0.5 million.

CONCLUSION: The number of persons with AD in the US population will continue to increase unless new discoveries facilitate prevention of the disease.