Age and Apolipoprotein E ε4 Effects on Neural Correlates of Odor Memory

Alzheimer's disease (AD) affects 5.4 million Americans. Evidence suggests that individuals who are positive for the apolipoprotein E (ApoE) epsilon 4 allele are at higher risk for developing the disease. Studies have also shown that the epsilon 4 allele is linked to olfactory decline. Olfactory functioning may be investigated using olfactory event-related potentials (OERPs). The high temporal resolution of OERPs enables an understanding of the neural correlates of olfactory processing and functioning. This study investigated the effects of age, ApoE epsilon 4 status, response type, and electrode site on OERP latency and amplitude during encoding and retrieval in an odor recognition memory task. The 60 participants were equally divided into 3 age groups matched on epsilon 4 status: younger, middle, and older. Odors were presented using a computer-controlled olfactometer. Participants were notified during encoding that this was a task of odor memory. Results indicated differences in OERP activity as a function of age, ApoE epsilon 4 status, response type, and electrode site. These findings highlight the potential of OERPs to distinguish epsilon 4- and epsilon 4+ individuals and to contribute to an earlier diagnosis of AD.