• Charlie D Morgan and Claire Murphy.
• Department of Psychology, San Diego State University, San Diego, CA 92120, USA.
• Behav Brain Funct. 2012 Jul 31; 8: 37.

BackgroundStudies suggest that older adults at risk of developing Alzheimer's disease may show olfactory processing deficits before other signs of dementia appear.MethodsWe studied 60 healthy non-demented individuals, half of whom were positive for the genetic risk factor the Apolipoprotein E ε4 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.ResultsVarying patterns of brain activation were observed over the post-stimulus epoch for ε4- versus ε4+ individuals on topographical maps. Individuals with the ε4 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.ConclusionsOlfactory 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.

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