In a community-based study of Alzheimer's disease in African Americans age 65 and over, subjects were classified into three levels of performance based on their scores as measured by the Community Screening Instrument for Dementia (CSI"D"), consisting of cognitive and functioning components. In a subset of 268 subjects with apolipoprotein E (APOE) genotype data, we found that the epsilon 4 allele of APOE was associated with intermediate/poor performance (single copy epsilon 4 odds ratio 1.51, 95% CI 1.18 to 1.92; double copy epsilon 4 odds ratio 3.42, 95% CI 2.18 to 5.43). From these data, we believe it would be possible to conduct population screening for the effects of possession of the APOE-epsilon 4 allele using information derived from the CSI"D".