Rates of dementia in three ethnoracial groups.

Background: Rates of dementia may vary among ethnoracial groups. Any real and substantial such difference would merit serious attention by health planners, clinicians and those seeking to advance our understanding of the etiology of this group of disorders.

Methods: Randomly selected elderly persons from each of three ethnoracial groups (Latinos, African-Americans, non-Latino Whites) residing in a geographic area of northern Manhattan in New York City were screened for dementia and assessed with respect to functioning in daily tasks and other qualities of life. Systematic samples of each group were clinically evaluated for presence and subtype of dementia. Subjects were reassessed at an average of 18 months following the baseline interview.

Results: Age-specific prevalence of dementia was found to be higher in Latinos and African-Americans than in non-Latino Whites; incidence rates were consistent with this finding. Ethnoracial groups did not vary in the proportion of dementias diagnosed as Alzheimer's disease. Prevalence differences between ethnoracial groups remained consistent as diagnostic criteria were varied in breadth and when the possible mislabelling of depression was taken into account. However, level of education was strongly associated with rates of dementia and, when age and education were simultaneously controlled, the ethnoracial differences in rates were not consistently found.

Conclusions: Planning for the wide range of services necessary for care of those suffering from dementia should take into account ethnoracial differences in rates. The higher rates found in Latino and African-American groups, relative to non-Latino Whites, are associated with clear and substantial functional dependencies and hence have important implications for qualities of life and service needs.