ANTICIPATING ALZHEIMER'S: THE RELATIONS OF APOE POLYMORPHISM AND BRAIN ATROPHY TO COGNITIVE PERFORMANCE IN URBAN DWELLING AFRICAN AMERICAN AND WHITE ADULTS

Abstract

Historically, APOE ?4 carrier status has been associated with increased risk forearly AlzheimerÕs Disease (AD)-related cognitive decline, but the full extent of the underlying mechanisms and how these differ by race in preclinical samples requires further investigation. This study investigated whether the association between APOE ?4 status and AD-associated cognitive outcomes Ð verbal memory and semantic fluency - are mediated by Spatial Pattern of Abnormality for Recognition of Early Alzheimer's disease (SPARE-AD) when moderated by race. The study was conducted on a sample of socioeconomically diverse urban-dwelling African American and White adults. The samples were based on 158 participants in the Semantic Fluency analysis (mean age = 53.4, 35.4% African American, 57% Female, 31% below poverty status) and 140 participants across the California Verbal Learning Test (CVLT: total recall, short and long delay free recall) analyses (mean age = 53, 37.9% African American, 55.7% Female, 34.3% below poverty status). Moderated mediation analyses were computed to test study hypotheses. Results indicated that race moderated the relation of APOE ?4 status to cognitive performance for two of the four outcome measures, although not in the direction that was expected. Specifically, race moderated the relation of APOE ?4 status to semantic fluency (B = -4.05, t(157) = -2.39, p < .05), but when the interaction was probed, the relation was only significant for Whites. Unexpectedly, White carriers of ?4 performed better than non-carriers. Conversely, race moderated the relation of APOE ?4 status to CVLT short free-recall (B = -2.46, t(157) = -2.18, p < .05); however, African- Americans ?4 carriers performed worse than African American non-carriers. All other model paths, including moderated mediation, were nonsignificant. In conclusion, the relationship between APOE ?4 carriership, race, and cognitive performance is complex and may vary depending on the specific cognitive measure. There is some evidence that ?4 carriership may be detrimental for the domain of memory in middle-aged African Americans. It is important to note that investigating the relations of ?4 to cognitive and neuroanatomical outcomes in relatively young preclinical samples may be difficult due to the less pronounced AD-pathophysiological effects which may be difficult to detect.