Cited by 195Alzheimer's disease research and treatmentsDementia and Cognitive Impairment ResearchNeuroinflammation and Neurodegeneration Mechanisms

The DOI matches its Crossref record; 279 of the 279 references it cites were found in a registry or an index; 227 of the 264 sources its claims cite were checked for support.

Multifaceted roles of APOE in Alzheimer disease

Open access
Jackson, Rosemary J., Hyman, Bradley T., Serrano-Pozo, Alberto·2024·Nature Reviews Neurology

Abstract

For the past three decades, apolipoprotein E (APOE) has been known as the single greatest genetic modulator of sporadic Alzheimer disease (AD) risk, influencing both the average age of onset and the lifetime risk of developing AD. The APOEε4 allele significantly increases AD risk, whereas the ε2 allele is protective relative to the most common ε3 allele. However, large differences in effect size exist across ethnoracial groups that are likely to depend on both global genetic ancestry and local genetic ancestry, as well as gene–environment interactions. Although early studies linked APOE to amyloid-β — one of the two culprit aggregation-prone proteins that define AD — in the past decade, mounting work has associated APOE with other neurodegenerative proteinopathies and broader ageing-related brain changes, such as neuroinflammation, energy metabolism failure, loss of myelin integrity and increased blood–brain barrier permeability, with potential implications for longevity and resilience to pathological protein aggregates. Novel mouse models and other technological advances have also enabled a number of therapeutic approaches aimed at either attenuating the APOEε4-linked increased AD risk or enhancing the APOEε2-linked AD protection. This Review summarizes this progress and highlights areas for future research towards the development of APOE-directed therapeutics. Apolipoprotein E (APOE) is the greatest genetic modulator of sporadic Alzheimer disease risk. This Review provides a comprehensive update on our current knowledge of the genetics of APOE and its role in Alzheimer and other neurodegenerative diseases, and summarizes emerging APOE-targeted therapies designed to prevent or slow down Alzheimer disease. The risk of Alzheimer disease associated with the APOE genotype is modulated by global and local genetic ancestries, other genetic risk loci and the lifetime exposome of an individual. APOE missense mutations are providing key insights into the pathophysiology of the classic three APOE isoforms. The APOE genotype might modulate the risk of other neurodegenerative diseases by influencing the pathobiology of their culprit aggregation-prone proteins. The APOE isoforms affect a wide range of molecular and cellular functions in multiple brain cell types via cell-autonomous and non-autonomous mechanisms. Several strategies to target APOE therapeutically have shown efficacy in preclinical studies and hold promise for translation into clinical trials. The risk of Alzheimer disease associated with the APOE genotype is modulated by global and local genetic ancestries, other genetic risk loci and the lifetime exposome of an individual. APOE missense mutations are providing key insights into the pathophysiology of the classic three APOE isoforms. The APOE genotype might modulate the risk of other neurodegenerative diseases by influencing the pathobiology of their culprit aggregation-prone proteins. The APOE isoforms affect a wide range of molecular and cellular functions in multiple brain cell types via cell-autonomous and non-autonomous mechanisms. Several strategies to target APOE therapeutically have shown efficacy in preclinical studies and hold promise for translation into clinical trials.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

This review synthesizes three decades of evidence on APOE in Alzheimer disease, covering genetics, neuropathology, biomarkers, pathophysiology and therapeutics. It argues that APOEε4 increases and APOEε2 decreases AD risk, but effect sizes vary by ancestry, age, sex, genetic and environmental modifiers, and APOE influences multiple cell types and proteinopathies beyond Aβ.

Key findings

  • APOEε3 represents ~80% of alleles; APOEε4 increases AD risk and APOEε2 is protective in a dose-dependent manner. Traditional estimates: APOEε3/ε4 and APOEε4 homozygotes have ~2–3 and ~9–12 times higher AD risk than APOEε3 homozygotes, while APOEε2/ε3 carriers have about half the risk. Lifetime risk up to age 80–85 for MCI or AD dementia was estimated as 30–55% for APOEε4 homozygotes, 20–25% for APOEε3/ε4 carriers and 10–15% for APOEε3 homozygotes.
  • APOE effect sizes differ by genetic ancestry and age/sex. APOEε4 carrier frequencies were 21.6% in East Asian, 40.6% in white, 41.6% in Black and 29.9% in Hispanic people; APOEε2 protection is attenuated in Black versus white people and confers essentially no protection in Hispanic and East Asian individuals relative to APOEε3 homozygosis, except in Hispanic people with APOEε4. APOEε3/ε4-linked risk is highest in women aged 60–70 years (or 70–80 years according to another reference) and decreases in older women.
  • APOEε4 is associated with higher Aβ plaque burden and more severe cerebral amyloid angiopathy, increased Lewy body and TDP-43 pathology, and greater tau-mediated neurodegeneration in models; APOEε2 is generally protective but is also associated with more severe CAA and, in some studies, increased primary tauopathy or TDP-43 dystrophic neurites. Rare variants include Christchurch R136S (0.0004% allele frequency in Europeans), R145C (~2–3-fold higher AD risk in African ancestry) and V236E (reduces AD risk to APOEε2 carrier levels or lower).
  • Therapeutic approaches reviewed include blocking APOE interactions, increasing APOE2 levels, decreasing APOE4 levels, increasing APOE lipidation and correcting APOE4 conformation. A first human AAV-APOE2 trial in APOEε4 homozygotes reported promising safety results despite small participant numbers; bexarotene increased CSF APOE by only 25% and failed to reduce PET Aβ burden or alter brain Aβ metabolism.

Methods

  • Narrative Review in *Nature Reviews Neurology*; synthesizes genetic, neuropathological, biomarker, pathophysiological and therapeutic literature on APOE in AD and related conditions. No primary data are reported.
  • The text describes evidence from human genetic epidemiology, post-mortem neuropathology, biofluid and imaging biomarkers, hiPSC and mouse models, and clinical trials, but does not report a systematic search strategy, inclusion criteria or meta-analysis.
  • Main analysis is thematic synthesis and interpretation of published findings, including proposed future research directions.

Limitations

  • The paper states that most neuropathological studies addressing APOE correlates have been conducted in samples with a majority of non-Hispanic white participants, limiting generalizability to other ethnoracial groups.
  • The paper states that more epidemiological research is needed to confirm APOE gene × environment interactions and more preclinical studies to dissect mechanisms; the direct versus indirect effects of APOE on tau and non-AD proteinopathies remain controversial, and the biological basis of the APOE × sex and age interaction remains poorly understood.
  • Evident from the text: as a narrative review, it does not systematically appraise or quantify the included evidence, and no formal risk-of-bias assessment or meta-analysis is reported.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1038/s41582-024-00988-2

Cites

279 of 279 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

76 Partly supported · 52 Supported · 11 No full text of the sources · 8 Own interpretation · 7 Supported so far · 5 Mixed support · 2 Not supported · accuracy not yet measured

Show all 76 claims

  • It may state two separate claims as one. 82
  • Probably not a substantial claim. 5
85 of 85
  • The paper relies on this without support.

    Findings from APOE-targeted replacement mouse models and other animal models translate to human Alzheimer disease pathophysiology and therapeutic response.

    “These preclinical data, together with a case study of an APOE null individual with hyperlipoproteinaemia type III but normal cognition and AD biomarkers123, indicate that lowering APOE expression levels is a valid therapeutic strategy.”
  • The paper relies on this without support.

    The associations between APOE genotype and Alzheimer disease risk observed in the cited studies are causal rather than solely correlative.

    “The link between APOE4 and Aβ has been studied extensively for the past three decades, and the interaction between the two proteins has now been established as one of the mechanisms by which the APOEε4 allele increases AD risk109.”
  • The paper relies on this without support.

    The ethnoracial differences in APOE effect size are not solely due to ascertainment, diagnostic or other methodological biases.

    “Deciphering the substrate (substrates) of ethnicity and race-based differences in the odds of developing AD associated with the APOE genotype could provide new molecular targets for prevention and therapeutic development.”
  • The paper relies on this without support.

    Astrocytes are the primary producers of APOE in the brain.

    “Given that astrocytes are the primary producers of APOE in the brain”
4 of 4

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

1 of 1

Citations

Cites

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Metadata

Authors
Jackson, R. J., Hyman, B. T., & Serrano-Pozo, A.
Affiliations
Harvard University (US)
Corresponding author
Hyman, Bradley T.
Venue
Nature Reviews Neurology
Published
2024-06-21
Volume
20
Issue
8
Pages
457-474
ISSN
  • 1759-4758 (ISSN-L)
  • 1759-4766
OpenAlex
W4399893048
Cited by
193
References
279
Citations by year
2026: 86 · 2025: 95 · 2024: 12
FWCI
11.01
Type
journal article
Language
en
Open access
Locations
  • Nature Reviews Neurology (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
  • Discovery Research Portal (University of Dundee) (submittedVersion)
Funders
  • JPB Foundation
  • Karen Toffler Charitable Trust
  • National Institutes of Health
  • National Institute on Aging (RF1AG073236, R56AG080525, R01AG047644, K08AG064039, RF1AG047644, R01AG073236, P30AG062421)
  • National Institute of Neurological Disorders and Stroke (U01NS111671)
Topics
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Alzheimer's disease research and treatments
  • Health Sciences › Medicine › Psychiatry and Mental health › Dementia and Cognitive Impairment Research
  • Life Sciences › Neuroscience › Neurology › Neuroinflammation and Neurodegeneration Mechanisms
Keywords
apolipoprotein E, APOE ε4, APOE ε2, sporadic Alzheimer's disease, genetic risk, amyloid-beta, neurodegenerative proteinopathies, neuroinflammation, energy metabolism, myelin integrity, blood-brain barrier permeability, aging, gene-environment interaction, genetic ancestry, mouse model
MeSH terms
Alzheimer Disease, Animals, Apolipoproteins E, Brain, Humans

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