Individuals at risk for Alzheimer's disease show differential patterns of ERP brain activation during odor identification

Abstract

Background: Studies suggest that older adults at risk of developing Alzheimer's disease may show olfactory processing deficits before other signs of dementia appear.Methods: We studied 60 healthy non-demented individuals, half of whom were positive for the genetic risk factor the Apolipoprotein E e{open}4 allele, in three different age groups. Event-related potentials to visual and olfactory identification tasks were recorded and analyzed for latency and amplitude differences, and plotted via topographical maps. Results: Varying patterns of brain activation were observed over the post-stimulus epoch for e{open}4- versus e{open}4+ individuals on topographical maps. Individuals with the e{open}4 allele demonstrated different ERP peak latencies during identification of olfactory but not visual stimuli. High correct ApoE classification rates were obtained utilizing the olfactory ERP. Conclusions: Olfactory ERPs demonstrate functional decline in individuals at risk for Alzheimer's disease at much earlier ages than previously observed, suggesting the potential for pre-clinical detection of AD at very early stages. © 2012 Morgan and Murphy; licensee BioMed Central Ltd.