ApoE genotype and abnormal auditory cortical potentials in healthy older females

Apolipoprotein E (ApoE) status and gender are risk factors for the development of Alzheimer's disease. Alzheimer's disease is more prevalent in female relative to male carriers of the ApoE ɛ4 gene. We examined cortical sensory (P50, N100) and cognitive (P300) potentials in an auditory target detection task in females as a function of ApoE genotype (ApoE ɛ4 carriers, ApoE ɛ4 non-carriers) to define the incidence of abnormalities prior to the clinical expression of cognitive impairments. Both neuropsychological test scores and sensory cortical potentials did not differ between the two ApoE groups. In contrast, cognitive P300 potentials were significantly decreased in amplitude and delayed in latency for ApoE ɛ4 carriers compared to non-carriers. Four out of the 10 ApoE ɛ4 carriers had abnormally (>2S.D.) delayed P300 latency compared to one out of 20 non-carriers. Abnormal cognitive processes reflected by P300 latency delays are expressed at significantly higher incidence in normal older females who are carriers of the ɛ4 allele than in non-carriers of this allele.