For the roughly 7% of the population carrying at least one APOE ε2 allele, this report offers a striking window into what extreme aging can look like when the genome is working in your favor. While most Alzheimer's research has obsessed over the ε4 risk allele, the protective counterpart—ε2—has received far less translational attention, and this case series begins to address that gap with rare, high-resolution human data.
Five Colombian siblings sharing the APOE ε2/ε3 genotype, ranging in age from 94 to 105, underwent comprehensive clinical evaluation, standardized cognitive testing, structural MRI, and FDG-PET neuroimaging. Cognition across the group spanned from entirely normal to mild dementia—a range itself notable given their extreme age. Structurally, brain atrophy was measurably less severe than age-matched norms would predict, while FDG-PET data indicated preservation of cerebral glucose metabolism in regions typically ravaged by Alzheimer's pathology. The coherence across both imaging modalities strengthens the biological credibility of these findings.
Placing this in broader context: APOE ε2's protective mechanism is still incompletely understood, with proposed pathways including reduced amyloid aggregation, enhanced synaptic repair, and differential microglial activation. This family's Colombian origin is also relevant—prior landmark research in that population identified the Paisa APOE ε3 Christchurch variant conferring extraordinary resilience, suggesting certain genetic backgrounds may create compounding protective effects. The current report is not a clinical trial and involves only five individuals, which limits statistical inference and generalizability. Nonetheless, case series of superagers with documented neuroimaging provide irreplaceable phenotypic anchors for mechanistic studies. The finding that ε2 can underpin functional cognition and metabolic brain preservation past age 100 is incremental but meaningful—it reinforces ε2 as a legitimate translational target for resilience-focused therapies and biomarker development in late-life cognitive research.
