Hippocampal Volume Differences Between Healthy Young Apolipoprotein E ε2 and ε4 Carriers

The apolipoprotein E (APOE) epsilon 4 allele is the major genetic risk factor for the development of late-onset Alzheimer's disease (AD), whereas the presence of the APOE epsilon 2 allele seems to confer protection. Here, we report that healthy young APOE epsilon 4 carriers have statistically significantly smaller hippocampal volumes than APOE epsilon 2 carriers, while no differences were detected between the two groups in memory performance. The difference in hippocampal morphology is cognitively/clinically silent in young adulthood, but could render APOE epsilon 4 carriers more prone to the later development of AD possibly due to lower reserve cognitive capacity.