APOE and hippocampal atrophy: Uncertainty persists regarding the potential neuroprotective effects of APOE2 on brain aging, due largely to its low population prevalence of only 10%, making it understudied relative to APOE4. Although lower amyloid burden has been observed among APOE2 carriers, differences in tau or atrophy have been inconclusive [11, 12], with some reports of slower hippocampal atrophy among APOE2 carriers [13].