Is ApoE epsilon4 associated with cognitive functioning in African Americans diagnosed with Alzheimer Disease? An exploratory study.

OBJECTIVE: The effect of the apolipoprotein epsilon4 allele (ApoE epsilon4) on cognitive performance in patients with probable Alzheimer disease (AD) has been studied in primarily Caucasian samples. The aim of this exploratory study was to examine whether the presence of ApoE epsilon4 is associated with cognitive performance in African American AD patients.
METHODS: A cross-sectional, retrospective design was used to address the study objective. Data were extracted from the records of 65 African American patients who participated in the National Institutes of Health-National Institute on Aging (NIH-NIA) Emory University Alzheimer Disease Center Registry. Inclusion criteria were a clinical diagnosis of probable AD, cognitive testing using the Mattis Dementia Rating Scale and the Consortium to Establish a Registry for Alzheimer Disease (CERAD) neuropsychological battery, and ApoE genotyping.
RESULTS: Seventy percent of the patients were ApoE epsilon4 positive. Multiple regression analyses indicated that ApoE epsilon4 was significantly associated with poorer design copying (CERAD Constructional Praxis subtest), but other significant relationships were not observed between positive epsilon4 status and cognitive performance.
CONCLUSIONS: These preliminary findings suggest that the ApoE epsilon4 allele is not strongly associated with a particular pattern of cognitive functioning in African Americans once they are diagnosed with AD. However, these findings require replication in a large prospectively recruited and population-based sample of African American AD patients before firm conclusions can be reached.