Indianapolis Ibadan Epidemiological Study of Dementia

The Indianapolis-Ibadan Dementia Project, established in 1991, is a longitudinal, prospective population-based comparative epidemiological study of the prevalence and incidence rates and risk factors for Alzheimer's disease and other age associated dementias. The project compares samples of community-dwelling elderly (age > 70 years) African Americans living in Indianapolis to Yoruba living in Ibadan, Nigeria, employing the same research design, methods, and investigators. It initially reported significantly lower prevalence rates of disorders in the Yoruba compared to the African Americans. In subsequent waves of the study (1994-1995, 1997-1998,) incidence rates, rates of newly diagnosed cases, were also found to be significantly lower in the Yoruba. In genetic studies, the frequency of the APOE ε4 allele was about the same in the two groups. APOE ε4 was a significant risk factor for Alzheimer's disease and dementia in the African Americans while no association was found for the Yoruba.

Vascular risk, including a history of hypertension, diabetes, obesity, and high lipid levels, has been implicated in risk for dementia and Alzheimer's disease, and these factors are much less common in the Yoruba than in the African Americans. Study participants continue to be followed with the most recent assessment in 2010. Currently genome wide association study analyses for African Americans are being conducted in collaboration with Dr. Denis Evans of Rush University in Chicago and Dr. Phillip De Jager at the Broad Institute in Cambridge. In April 2011 the project was approved for a genome wide association analysis for the Yoruba to be carried out by the Center for Inherited Diseases Research at Johns Hopkins. The project has collaborative relationships with several external investigators.

This work is funded through a grant from the National Institute on Aging R01AG009956-19.