Risk of mortality for dementia in a developing country: the Yoruba in Nigeria

Background: Limited data exist on the impact of dementia in developing nations, including its association with mortality.

Objective: The purpose of this paper is to assess the relationship between dementia and five-year mortality on a community dwelling elderly Yoruba population in the developing country of Nigeria and to compare those results with those from an elderly African-American community in Indianapolis.

Methods: A two-phase design was used to ascertain dementia status in two sites. In the first phase, the Community Screening Instrument for Dementia (CSI-D) was administered. In the second phase, subjects were sampled for the clinical assessment according to their CSI-D performance category. Proportional hazards regression was used to assess the relationship between mortality and cognitive status at both sites after adjusting for demographics and chronic disease conditions.

Results: For the entire screened population, poor and intermediate performance on the CSI-D is associated with increased mortality at both sites; however the effect of CSI-D performance did not significantly differ between the two sites. For the clinically assessed sample, dementia was significantly associated with increased mortality at both sites (Ibadan RR = 2.83, Indianapolis RR = 2.05), but the effect was not significantly different across the two sites.

Conclusion: Dementia resulted in an increased risk of mortality for Yoruba of a magnitude similar to African-Americans suggesting that the impact of dementia on mortality risk may be similar for developing and developed countries.