By Ana Espino | Published on August 20, 2025 | 2 min read
#APOE #Aging #GeneticFactor
Normal aging is accompanied by
progressive cognitive and biological changes, distinct from the alterations
observed in neurodegenerative diseases such as Alzheimer’s disease. However,
the molecular mechanisms governing this process remain incompletely understood.
Current approaches struggle to explain why some individuals preserve cognitive
functions, while others experience marked decline despite no diagnosed
pathology.
The major challenge is therefore to identify genetic factors that
influence the trajectory of brain aging independently of disease processes.
Among these, the APOE gene cluster—including the ε4 allele (already recognized as an Alzheimer’s
risk factor), but also neighboring genes—has drawn increasing attention. The
aim of this review is to analyze the role of APOE and its genomic cluster in
normal aging, highlighting their potential effects on cognition, lipid
metabolism, inflammation, and neuronal plasticity.
Aging with APOE: guardian angel or
achilles’ heel?
This review draws on genetic, transcriptomic, and clinical studies conducted in
elderly individuals without a dementia diagnosis. Genetic analyses evaluated
the impact of different APOE cluster alleles on the cognitive and biological
trajectory of aging. Transcriptomic approaches examined the expression of genes
linked to lipid metabolism and inflammation. Clinical cohorts, sometimes
combined with brain imaging data, made it possible to relate APOE status to
age-related cognitive and structural changes.
Findings show that the
APOE gene
significantly influences brain aging, with variable effects depending on
isoforms. The
ε4
allele, well known as a risk factor for Alzheimer’s, is associated with
increased age-related cognitive decline even in the absence of
neurodegenerative disease. Conversely, the
ε2 allele appears protective, slowing certain
aspects of cognitive decline. Analyses also indicate that the APOE cluster
modulates
brain lipid metabolism, inflammatory response, and
synaptic
function—all processes tied to neuronal resilience during aging. Brain imaging
studies confirm that ε4
carriers display
early structural and functional alterations, whereas ε2 carriers preserve better brain
integrity.
APOE: the key to a brain that stays
young?
Normal aging is a heterogeneous process, shaped by complex interactions among
environmental, biological, and genetic factors. The APOE cluster now emerges as
a strong candidate for explaining variability in individual cognitive
trajectories, beyond its well-established role in Alzheimer’s disease. The aim
of this review was to clarify its specific impact on normal brain aging.
Results show that APOE—particularly its ε2 and ε4 variants—acts as a key modulator of cognitive
and biological aging, steering trajectories toward either protection or
vulnerability.
Large-scale longitudinal studies,
combined with the development of
specific biomarkers and the exploration of
interactions with
environment and lifestyle, will be needed to confirm these
findings. Such advances could open the way toward
precision medicine in aging,
aimed at preserving cognitive health for longer.
Read next: Neurodegeneration: the shadow of a deficiency?
About the author – Ana EspinoPhD in Immunology, specialized in Virology
