Multifaceted roles of APOE in Alzheimer disease

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APOE R136S is a very rare mutation (0.0004% allele frequency in the European population) that was originally described in APOEε2 alleles of people with type III hyperlipoproteinaemia, but is much more common in APOEε3 homozygotes than in any other genotype and has also been associated with increased plasma apolipoprotein B levels.

“APOE R136S is a very rare mutation (0.0004% allele frequency in the European population37) that was originally described in APOEε2 alleles of people with type III hyperlipoproteinaemia38,39, but is much more common in APOEε3 homozygotes than in any other genotype and has also been associated with increased plasma apolipoprotein B (APOB) levels37.”

• cites [37] He, K. Y. et al. Characterization of APOE Christchurch carriers in 455,306 UK Biobank participants. Mol. Neurodegener. 18, 92 (2023). sourceDisputed

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• cites [38] Wardell, M. R., Brennan, S. O., Janus, E. D., Fraser, R. & Carrell, R. W. Apolipoprotein E2-Christchurch (136 Arg–Ser). New variant of human apolipoprotein E in a patient with type III hyperlipoproteinemia. J. Clin. Invest. 80, 483–490 (1987). sourceSupported
• cites [39] Pocovi, M. et al. Incomplete dominance of type III hyperlipoproteinemia is associated with the rare apolipoprotein E2 (Arg136→Ser) variant in multigenerational pedigree studies. Atherosclerosis 122, 33–46 (1996). sourcePartly supported

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Relative to the APOEε3 homozygote reference group, carrying one or two APOEε4 alleles is independently associated with a higher Aβ plaque burden and more severe cerebral amyloid angiopathy, whereas APOEε2/ε2 and ε2/ε3 individuals have fewer Aβ plaques but are more likely to have cerebral amyloid angiopathy.

“Relative to the APOEε3 homozygote reference group, carrying one or two APOEε4 alleles is independently associated with a higher Aβ plaque burden and more severe cerebral amyloid angiopathy (CAA), whereas APOEε2/ε2 and ε2/ε3 individuals have fewer Aβ plaques46–50 but are more likely to have CAA51.”

• cites [46] Bennett, D. A. et al. Amyloid mediates the association of apolipoprotein E e4 allele to cognitive function in older people. J. Neurol. Neurosurg. Psychiatry 76, 1194–1199 (2005). sourcePartly supported

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• cites [47] Mungas, D., Tractenberg, R., Schneider, J. A., Crane, P. K. & Bennett, D. A. A 2-process model for neuropathology of Alzheimer’s disease. Neurobiol. Aging 35, 301–308 (2014). sourcePartly supported

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• cites [48] Serrano-Pozo, A., Qian, J., Monsell, S. E., Betensky, R. A. & Hyman, B. T. APOEε2 is associated with milder clinical and pathological Alzheimer disease. Ann. Neurol. 77, 917–929 (2015). sourceDisputed

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APOEε4 carriage has been independently associated with increased odds and severity of Lewy body pathology and TDP-43 pathology and with the presence of TDP-43-related hippocampal sclerosis in the scenario of a primary neuropathological diagnosis of Alzheimer disease.

“Specifically, APOEε4 carriage has been independently associated with increased odds and severity of Lewy body pathology49,62 and TDP-43 pathology59,63,64 and with the presence of TDP-43-related hippocampal sclerosis63 in the scenario of a primary neuropathological diagnosis of AD.”

• cites [49] Goldberg, T. E., Huey, E. D. & Devanand, D. P. Association of APOE ε2 genotype with Alzheimer’s and non-Alzheimer’s neurodegenerative pathologies. Nat. Commun. 11, 4727 (2020). sourcePartly supported

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• cites [62] Dickson, D. W. et al. APOE ε4 is associated with severity of Lewy body pathology independent of Alzheimer pathology. Neurology 91, e1182–e1195 (2018). sourcePartly supported

  The Results report increased odds of diffuse Lewy body disease and greater Lewy body counts among APOE ε4 carriers, including associations independent of Alzheimer pathology. But the study examines Lewy body disease cases stratified by Alzheimer pathology; it does not establish this finding specifically among cases with a primary neuropathological diagnosis of Alzheimer disease. The TDP-43 claims are attached to other citations in the citing sentence and are not assessed here. (LLM, conf=0.86)

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• cites [59] Robinson, J. L. et al. The development and convergence of co-pathologies in Alzheimer’s disease. Brain 144, 953–962 (2021). sourceDisputed

  The ‘Co-pathology prevalence varies by age, APOE allele and dementia status’ section states that APOE ε4 was associated with cerebral amyloid angiopathy but not with any other co-pathology. Table 4 likewise shows no significant APOE ε4 association with LATE-NC (TDP-43 pathology) or Lewy body stage, contrary to the claimed increased odds and severity. The cited passages do not establish the separate hippocampal-sclerosis association. (LLM, conf=0.89)

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APOEε4 has been associated with the burden of α-synuclein inclusions in Lewy body disease with minimal Alzheimer disease co-pathology, although other studies have only found an association between APOEε4 and Lewy body disease in the presence of Alzheimer disease neuropathology, but not in pure Lewy body disease.

“APOEε4 has also been associated with the burden of α-synuclein inclusions in LBD with minimal AD co-pathology62,71, although other studies have only found an association between APOEε4 and LBD in the presence of AD neuropathology, but not in pure LBD72,73.”

• cites [62] Dickson, D. W. et al. APOE ε4 is associated with severity of Lewy body pathology independent of Alzheimer pathology. Neurology 91, e1182–e1195 (2018). sourceDisputed

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• cites [71] Zhao, N. et al. APOE4 exacerbates α-synuclein pathology and related toxicity independent of amyloid. Sci. Transl. Med. 12, eaay1809 (2020). sourceDisputed

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• cites [72] Kaivola, K., Shah, Z. & Chia, R., International LBD Genomics Consortium & Scholz, S. W. Genetic evaluation of dementia with Lewy bodies implicates distinct disease subgroups. Brain 145, 1757–1762 (2022). sourceDisputed

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APOE3 from both astrocytes and neurons can protect against neuronal hyperexcitability, whereas neuron-derived (but not astrocyte-derived) APOE4 is detrimental.

“Mouse models expressing APOE3 or APOE4 exclusively in either astrocytes or neurons (Box 3) show that APOE3 from both cell types can protect against neuronal hyperexcitability, whereas neuron-derived (but not astrocyte-derived) APOE4 is detrimental159,160.”

• cites [159] Buttini, M. et al. Cellular source of apolipoprotein E4 determines neuronal susceptibility to excitotoxic injury in transgenic mice. Am. J. Pathol. 177, 563–569 (2010). sourcePartly supported

  The Discussion and Figure 3 (p. 569) support the cell-source distinction for excitotoxic injury: apoE3 from either cell type was protective, while neuron-derived apoE4 increased vulnerability and astrocyte-derived apoE4 was protective. They do not establish protection against neuronal hyperexcitability itself. The Kainic Acid Treatment and Tissue Preparation section says seizure onset, intensity, and duration were comparable across genotypes. (LLM, conf=0.88)

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• cites [160] Konings, S. C., Torres-Garcia, L., Martinsson, I. & Gouras, G. K. Astrocytic and neuronal apolipoprotein E isoforms differentially affect neuronal excitability. Front. Neurosci. 15, 734001 (2021). sourceDisputed

  The Discussion supports a potential protective effect of astrocytic ApoE3, but reports enhanced neuronal activity with astrocytic ApoE4—contrary to the claim that astrocyte-derived ApoE4 is not detrimental. The Results section ‘ApoE3 Neurons Show Increased Neuronal Activity Compared to ApoE4 Neurons’ also reports greater activity in ApoE3 neurons, while the Discussion says hyperexcitability was not seen in its ApoE4-expressing neuronal cultures. Page numbers are unavailable in our copy. (LLM, conf=0.88)

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Starting antisense oligonucleotide treatment before Aβ plaque deposition prevented Aβ plaque development, whereas animals treated after the onset of plaque deposition actually showed an increase in Aβ plaque size and plaque-associated dystrophic neurites.

“starting before Aβ plaque deposition prevented Aβ plaque development, whereas animals treated after the onset of plaque deposition actually showed an increase in Aβ plaque size and plaque-associated dystrophic neurites.”

• cites [124] Huynh, T.-P. V. et al. Age-dependent effects of apoE reduction using antisense oligonucleotides in a model of β-amyloidosis. Neuron 96, 1013–1023.e4 (2017). sourceDisputed

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APOEε4 increases the risk of developing Alzheimer disease, and APOEε2 is protective against developing Alzheimer disease in a dose-dependent fashion, so that APOEε4 homozygotes have the highest risk and rare APOEε2 homozygotes have the lowest.

“APOEε4 increases the risk of developing AD, and APOEε2 is protective against developing AD in a dose-dependent fashion, so that APOEε4 homozygotes have the highest risk and the rare APOEε2 homozygotes have the lowest5,7,8.”

• cites [5] Corder, E. H. et al. Gene dose of apolipoprotein E type 4 allele and the risk of Alzheimer’s disease in late onset families. Science 261, 921–923 (1993). sourceNot checked — no full text of the source
• cites [7] Corder, E. H. et al. Protective effect of apolipoprotein E type 2 allele for late onset Alzheimer disease. Nat. Genet. 7, 180–184 (1994). sourceNot checked — no full text of the source
• cites [8] Reiman, E. M. et al. Exceptionally low likelihood of Alzheimer’s dementia in APOE2 homozygotes from a 5,000-person neuropathological study. Nat. Commun. 11, 667 (2020). sourceSupported

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The risk associated with the APOEε3/ε4 genotype is highest in women of ages 60-70 years (or 70-80 years according to ref. 6) but decreases in older women and equalizes to that of non-Hispanic White, Black and Hispanic men of the same age.

“Rather, age and sex moderate the effects of the APOE genotype on AD risk so that the risk associated with the APOEε3/ε4 genotype is highest in women of ages 60–70 years (or 70–80 years according to ref. 6) but decreases in older women and equalizes to that of non-Hispanic White, Black and Hispanic men of the same age10.”

• cites [10] Belloy, M. E. et al. APOE genotype and Alzheimer disease risk across age, sex, and population ancestry. JAMA Neurol. 80, 1284–1294 (2023). sourcePartly supported

  The Results (Race and Ethnicity Analyses; page unavailable) find greater APOE ε3/ε4-associated AD risk in women than men at ages 60–70, including a replicated association in Black and Hispanic individuals. The Discussion likewise identifies this age-specific finding, but our copy does not establish that risk decreases in older women or equalizes with that of men of the same age across all three groups. (LLM, conf=0.84)

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• cites [6] Farrer, L. A. et al. Effects of age, sex, and ethnicity on the association between apolipoprotein E genotype and Alzheimer disease. A meta-analysis. APOE and Alzheimer Disease Meta Analysis Consortium. JAMA 278, 1349–1356 (1997). sourceNot checked — no full text of the source

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The protective effect of APOEε2 is attenuated in Black versus white people, whereas in Hispanic and East Asian individuals, the APOEε2 allele confers essentially no protection against Alzheimer disease relative to APOEε3 homozygosis, and only in the presence of APOEε4 does APOEε2 confer protection in Hispanic people.

“Even more puzzling than these differences in APOEε4-linked AD risk are those associated with the APOEε2 allele; this study found that the protective effect of APOEε2 is attenuated in Black versus white people, whereas in Hispanic and East Asian individuals, the APOEε2 allele confers essentially no protection against AD relative to APOEε3 homozygosis, and only in the presence of APOEε4 does APOEε2”

• cites [10] Belloy, M. E. et al. APOE genotype and Alzheimer disease risk across age, sex, and population ancestry. JAMA Neurol. 80, 1284–1294 (2023). sourcePartly supported

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The age × sex interaction with the APOEε3/ε4 genotype was seen in non-Hispanic White people and replicated in Black and Hispanic individuals via meta-analysis, suggesting that the interaction is independent of race and ethnicity.

“Notably, this age × sex interaction with the APOEε3/ε4 genotype was not only seen in non-Hispanic White people but also replicated in Black and Hispanic individuals via meta-analysis of both groups, suggesting that the interaction is independent of race and ethnicity10.”

• cites [10] Belloy, M. E. et al. APOE genotype and Alzheimer disease risk across age, sex, and population ancestry. JAMA Neurol. 80, 1284–1294 (2023). sourceSupported

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The lifetime risk up to age 80-85 years for mild cognitive impairment or dementia owing to Alzheimer disease has been estimated as 30-55% for APOEε4 homozygotes, 20-25% for APOEε3/ε4 carriers and 10-15% for APOEε3 homozygotes according to population-based studies with a majority of individuals of European ancestry.

“the lifetime risk up to age 80–85 years for mild cognitive impairment or dementia owing to AD has been estimated as 30–55% for APOEε4 homozygotes, 20–25% for APOEε3/ε4 carriers and 10–15% for APOEε3 homozygotes according to population-based studies with a majority of individuals of European ancestry17,18.”

• cites [17] Qian, J. et al. APOE-related risk of mild cognitive impairment and dementia for prevention trials: an analysis of four cohorts. PLoS Med. 14, e1002254 (2017). sourcePartly supported

  The Results (Stratified cumulative incidence estimates; page unavailable) report lifetime MCI-or-dementia incidence to age 80–85 in the population-based Rotterdam and Framingham cohorts, rising from 11.94%–15.57% with no APOE-ε4 copies to 37.47%–46.66% for ε4/ε4 homozygotes. But the cited passage groups people by ε4 dose rather than the specific ε3/ε3 and ε3/ε4 genotypes, does not give the quoted 20%–25% range, and does not restrict the outcome to impairment owing to Alzheimer disease. It also does not establish a 55% upper estimate for ε4/ε4 homozygotes. (LLM, conf=0.88)

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• cites [18] Stites, S. D. et al. Patients asking about APOE gene test results? Here’s what to tell them. J. Fam. Pract. 71, E1–E7 (2022). sourcePartly supported

  Table 1 gives all three stated lifetime-risk ranges for MCI or dementia due to Alzheimer disease. Vignette 1 says the estimates are averaged across large population cohorts, and the discussion of sample diversity says most underlying data come from largely White samples. Our copy does not specify that these ranges measure risk up to age 80–85, so that age limit is unsupported. (LLM, conf=0.84)

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APOE allele frequencies for East Asian, white, Black and Hispanic people are: APOEε2 carriers 5.6%, 11.1%, 19.7% and 10.6%; APOEε3 homozygotes 72.8%, 50.6%, 43.3% and 61.3%; and APOEε4 carriers 21.6%, 40.6%, 41.6% and 29.9%, respectively.

“In the analysis, APOE allele frequencies for East Asian, white, Black and Hispanic people were as follows: APOEε2 carriers 5.6%, 11.1%, 19.7% and 10.6%; APOEε3 homozygotes 72.8%, 50.6%, 43.3% and 61.3% and APOEε4 carriers 21.6%, 40.6%, 41.6% and 29.9%, respectively10.”

• cites [10] Belloy, M. E. et al. APOE genotype and Alzheimer disease risk across age, sex, and population ancestry. JAMA Neurol. 80, 1284–1294 (2023). sourcePartly supported

  The Results table (Race and Ethnicity Analyses; page unavailable) gives carrier counts and sample sizes that yield the quoted percentages for White, Black, and Hispanic participants after rounding. Our copy does not give the three quoted East Asian percentages; it says East Asian genotype assessment was limited to results from prior studies. The figures are proportions of people in genotype or carrier categories, not allele frequencies. (LLM, conf=0.88)

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The protective effect of the APOE R136S mutation seems to require homozygosis, given that four individuals with PSEN1-E280A and heterozygous for APOEε3R136S developed mild cognitive impairment at the expected age of 45 years and some APOEε3R136S heterozygous individuals with autopsy-proven Alzheimer disease had early onset of symptoms.

“The protective effect of the APOE R136S mutation seems to require homozygosis, given that four individuals with PSEN1-E280A and heterozygous for APOEε3R136S developed mild cognitive impairment at the expected age of 45 years36 and some APOEε3R136S heterozygous individuals with autopsy-proven AD had early onset of symptoms40.”

• cites [36] Arboleda-Velasquez, J. F. et al. Resistance to autosomal dominant Alzheimer’s disease in an APOE3 Christchurch homozygote: a case report. Nat. Med. 25, 1680–1683 (2019). sourceSupported
• cites [40] Hernandez, I. et al. Heterozygous APOE Christchurch in familial Alzheimer’s disease without mutations in other Mendelian genes. Neuropathol. Appl. Neurobiol. 47, 579–582 (2021). sourceNot checked — no full text of the source

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KLOTHO-VS heterozygosity has been reported to decrease Aβ plaque deposition, tau accumulation and tau-mediated cognitive impairment.

“Of particular interest is the longevity-increasing KLOTHO-VS heterozygosity, which has been reported to operate by decreasing Aβ plaque deposition, tau accumulation and tau-mediated cognitive impairment23–26.”

• cites [23] Erickson, C. M. et al. KLOTHO heterozygosity attenuates APOE4-related amyloid burden in preclinical AD. Neurology 92, e1878–e1889 (2019). sourcePartly supported

  The Discussion reports that KL-VS heterozygosity attenuated APOE4-related Aβ burden in cognitively normal, late-middle-aged adults at risk for Alzheimer’s disease. The paper does not establish that heterozygosity decreases Aβ deposition generally or that it operates by this mechanism; its participants were cognitively normal, and the passages do not report reduced tau accumulation or tau-mediated cognitive impairment. (LLM, conf=0.90)

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• cites [24] Belloy, M. E. et al. Association of klotho vs heterozygosity with risk of Alzheimer disease in individuals who carry APOE4. JAMA Neurol. 77, 849–862 (2020). sourcePartly supported

  The Results in the Abstract (page unavailable) associate KL-VS heterozygosity with lower brain Aβ on PET scans in cognitively normal APOE4 carriers aged 60–80, supporting the reduced-plaque-burden part of the claim. The paper does not establish that the variant operates by reducing Aβ, and the passages searched for tau accumulation and tau-mediated cognitive impairment do not support those parts. (LLM, conf=0.88)

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• cites [25] Neitzel, J. et al. KL-VS heterozygosity is associated with lower amyloid-dependent tau accumulation and memory impairment in Alzheimer’s disease. Nat. Commun. 12, 3825 (2021). sourcePartly supported

  The Results report lower amyloid-related tau accumulation in KL-VS heterozygotes, and the Abstract reports better memory in amyloid-positive carriers mediated by lower tau-PET. But the Abstract says amyloid-PET levels did not differ between carriers and non-carriers; the Results find lower amyloid-PET only in a restricted subgroup of a larger sample. The paper reports associations, not an established mechanism by which heterozygosity decreases all three outcomes. (LLM, conf=0.88)

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The R145C mutation has been reported only in the APOEε3 allele in individuals with African ancestry and has been associated with both a ~2-3-fold higher risk of Alzheimer disease and an earlier age of symptom onset in those with the APOEε3R145C/ε4 genotype.

“The R145C mutation has been reported only in the APOEε3 allele in individuals with African ancestry and has been associated with both a ~2–3-fold higher risk of AD and an earlier age of symptom onset in those with the APOEε3R145C/ε4 genotype41.”

• cites [41] Le Guen, Y. et al. Association of African ancestry-specific APOE missense variant r145c with risk of Alzheimer disease. JAMA 329, 551–560 (2023). sourceSupported

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The V236E (Jacksonville) mutation has been described only in the APOEε3 allele and reduces the risk of Alzheimer disease down to that of APOEε2 carriers or even further.

“The V236E (Jacksonville) mutation has been described only in the APOEε3 allele and reduces the risk of AD down to that of APOEε2 carriers or even further42,43.”

• cites [42] Medway, C. W. et al. ApoE variant p.V236E is associated with markedly reduced risk of Alzheimer’s disease. Mol. Neurodegener. 9, 11 (2014). sourceSupported
• cites [43] Le Guen, Y. et al. Association of rare APOE missense variants V236E and R251G with risk of Alzheimer disease. JAMA Neurol. 79, 652–663 (2022). sourceSupported

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Relative to APOEε3 homozygotes, APOEε2/ε4 carriers have greater Aβ plaque burden, increased cerebral amyloid angiopathy severity and increased odds of macroinfarcts, whereas differences in tangle burden are conflicting.

“However, relative to APOEε3 homozygotes, APOEε2/ε4 carriers have greater Aβ plaque burden54, increased CAA severity50 and increased odds of macroinfarcts55, whereas differences in tangle burden are conflicting49,54.”

• cites [54] Oveisgharan, S. et al. APOE ε2ε4 genotype, incident AD and MCI, cognitive decline, and AD pathology in older adults. Neurology 90, e2127–e2134 (2018). sourceSupported
• cites [50] Goldberg, T. E., Huey, E. D. & Devanand, D. P. Associations of APOE ε2 genotype with cerebrovascular pathology: a postmortem study of 1275 brains. J. Neurol. Neurosurg. Psychiatry https://doi.org/10.1136/jnnp-2020-323746 (2020). sourcePartly supported

  The Results (CAA section; page unavailable) report that APOE ε2/ε4 carriers had CAA more often than ε3 homozygotes (76% versus 49%). They do not report a severity comparison for those two genotypes, so the cited finding supports increased CAA frequency, not the claimed increased severity. (LLM, conf=0.83)

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• cites [55] Lamar, M. et al. APOE genotypes as a risk factor for age-dependent accumulation of cerebrovascular disease in older adults. Alzheimers Dement. 15, 258–266 (2019). sourceSupported

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Carriers of the APOEε4 allele have increased odds of a multi-proteinopathy, whereas carrying the APOEε2 allele reduces these odds, relative to APOEε3 homozygosis.

“Carriers of the APOEε4 allele have increased odds of a multi-proteinopathy, whereas carrying the APOEε2 allele reduces these odds, relative to APOEε3 homozygosis60,61.”

• cites [60] Karanth, S. et al. Prevalence and clinical phenotype of quadruple misfolded proteins in older adults. JAMA Neurol. 77, 1299–1307 (2020). sourcePartly supported

  The Results report higher odds of quadruple misfolded proteins among APOE ε4 carriers (adjusted OR 2.55). However, the Covariates section models ε4 carriage rather than ε2 carriage, and the Statistical Analysis section uses a tau-and-Aβ proteinopathy group—not APOE ε3 homozygotes—as the outcome reference. The paper therefore does not support the claimed reduction for ε2 or the stated genotype comparison. (LLM, conf=0.88)

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• cites [61] Walker, J. M. & Richardson, T. E. Cognitive resistance to and resilience against multiple comorbid neurodegenerative pathologies and the impact of APOE status. J. Neuropathol. Exp. Neurol. 82, 110–119 (2023). sourceNot checked — no full text of the source

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Neither APOEε4 nor APOEε2 is associated with atherosclerosis in the circle of Willis or microinfarcts.

“Neither allele is associated with atherosclerosis in the circle of Willis or microinfarcts55.”

• cites [55] Lamar, M. et al. APOE genotypes as a risk factor for age-dependent accumulation of cerebrovascular disease in older adults. Alzheimers Dement. 15, 258–266 (2019). sourceSupported

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APOEε2/ε4 individuals have a particularly high risk of intracerebral lobar haemorrhage in the presence of cerebral amyloid angiopathy, possibly because the APOEε2 allele has been associated with fibrinoid necrosis of the vessel wall.

“Of note, APOEε2/ε4 individuals have a particularly high risk of intracerebral lobar haemorrhage in the presence of CAA50, possibly because the APOEε2 allele has been associated with fibrinoid necrosis of the vessel wall56,57.”

• cites [50] Goldberg, T. E., Huey, E. D. & Devanand, D. P. Associations of APOE ε2 genotype with cerebrovascular pathology: a postmortem study of 1275 brains. J. Neurol. Neurosurg. Psychiatry https://doi.org/10.1136/jnnp-2020-323746 (2020). sourcePartly supported

  The Results (Gross hemorrhages; page unavailable) associate APOE ε2 with increased acute gross haemorrhage when CAA is present. But the Methods (Statistical Approach; page unavailable) explicitly exclude ε2/ε4 individuals from those analyses, so the finding does not establish particularly high risk for that genotype. The paper also says its gross-haemorrhage measure does not specifically identify lobar intracerebral haemorrhage. The vessel-wall explanation is attached to other citations in the citing sentence. (LLM, conf=0.90)

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• cites [56] Greenberg, S. M. et al. Association of apolipoprotein E ε2 and vasculopathy in cerebral amyloid angiopathy. Neurology 50, 961–965 (1998). sourceNot checked — no full text of the source
• cites [57] McCarron, M. O. et al. The apolipoprotein E ε2 allele and the pathological features in cerebral amyloid angiopathy-related hemorrhage. J. Neuropathol. Exp. Neurol. 58, 711–718 (1999). sourceNot checked — no full text of the source

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After controlling for the presence and severity of Alzheimer disease neuropathology and comorbid pathologies, carrying the APOEε4 allele might still accelerate the rate of cognitive decline in the normal ageing-sporadic Alzheimer disease continuum, whereas carrying the APOEε2 allele might slow down cognitive decline.

“However, after controlling for the presence and severity of AD neuropathology and comorbid pathologies, carrying the APOEε4 allele might still accelerate the rate of cognitive decline in the normal ageing-sporadic AD continuum, whereas carrying the APOEε2 allele might slow down cognitive decline47,77,80,81.”

• cites [47] Mungas, D., Tractenberg, R., Schneider, J. A., Crane, P. K. & Bennett, D. A. A 2-process model for neuropathology of Alzheimer’s disease. Neurobiol. Aging 35, 301–308 (2014). sourceCould not verify

  The Results (Structural Model) examine APOE’s relationship with plaques and tangles, not its effect on the rate of cognitive decline after controlling for pathology. The Discussion says comorbid pathologies were not incorporated and calls for future analyses of their relationship with APOE and cognitive decline. Searches for APOE ε2 and cognitive decline yielded no passage establishing either allele-specific claim. (LLM, conf=0.76)

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• cites [77] Shinohara, M. et al. APOE2 eases cognitive decline during aging: clinical and preclinical evaluations. Ann. Neurol. 79, 758–774 (2016). sourcePartly supported

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• cites [80] Qian, J., Betensky, R. A., Hyman, B. T. & Serrano-Pozo, A. Association of APOE genotype with heterogeneity of cognitive decline rate in Alzheimer disease. Neurology 96, e2414–e2428 (2021). sourcePartly supported

  The Results section reports that, after adjustment for Alzheimer disease neuropathology and comorbid pathologies, APOE ε4 carriers declined faster and APOE ε2 carriers generally declined more slowly. But the Methods and Discussion describe a sample with substantial Alzheimer neuropathology and say it was not suited to assess the earliest clinical stages or cognitively intact individuals. The finding therefore does not establish the claim across the full normal-ageing–sporadic-Alzheimer-disease continuum. Page numbers are unavailable in our copy. (LLM, conf=0.88)

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APOEε4 can accelerate age-related cognitive decline even in genetically determined Alzheimer disease, such as familial autosomal dominant Alzheimer disease and Down syndrome, whereas APOEε2 can delay age of onset even in familial autosomal dominant Alzheimer disease.

“Remarkably, APOEε4 can accelerate age-related cognitive decline even in genetically determined AD, such as familial autosomal dominant AD31 and Down syndrome82, whereas APOEε2 can delay age of onset even in familial autosomal dominant AD83.”

• cites [31] Langella, S. et al. Effect of apolipoprotein genotype and educational attainment on cognitive function in autosomal dominant Alzheimer’s disease. Nat. Commun. 14, 5120 (2023). sourceSupported
• cites [82] Bejanin, A. et al. Association of apolipoprotein E ɛ4 allele with clinical and multimodal biomarker changes of Alzheimer disease in adults with down syndrome. JAMA Neurol. 78, 937–947 (2021). sourceSupported
• cites [83] Vélez, J. I. et al. APOE*E2 allele delays age of onset in PSEN1 E280A Alzheimer’s disease. Mol. Psychiatry 21, 916–924 (2016). sourceSupported

May combine two claims.

In large health registries such as the UK BioBank, the APOEε4 allele has been associated with higher LDL cholesterol and triglycerides levels, lower HDL cholesterol levels and an increased risk of coronary artery disease.

“In large health registries such as the UK BioBank, the APOEε4 allele has been associated with higher LDL cholesterol and triglycerides levels, lower HDL cholesterol levels and an increased risk of coronary artery disease.”

• cites [87] Kuo, C.-L., Pilling, L. C., Atkins, J. L., Kuchel, G. A. & Melzer, D. ApoE ε2 and aging-related outcomes in 379,000 UK Biobank participants. Aging 12, 12222–12233 (2020). sourcePartly supported

  The Abstract in our copy states that APOE ε4 is associated with increased coronary artery disease, and the Methods identify UK Biobank as the study cohort. However, the Results > Biomarkers section reports lipid associations for ε2 genotypes, not ε4; it does not establish the claimed higher LDL and triglycerides or lower HDL for ε4. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [88] Lumsden, A. L., Mulugeta, A., Zhou, A. & Hyppönen, E. Apolipoprotein E (APOE) genotype-associated disease risks: a phenome-wide, registry-based, case–control study utilising the UK Biobank. eBioMedicine 59, 102954 (2020). sourceSupported

May combine two claims.

APOE3 has a higher affinity for HDL, whereas APOE4 is more likely to bind LDL and VLDL.

“APOE3 has a higher affinity for HDL, whereas APOE4 is more likely to bind LDL and VLDL102.”

• cites [102] Nguyen, D. et al. Molecular basis for the differences in lipid and lipoprotein binding properties of human apolipoproteins E3 and E4. Biochemistry 49, 10881–10889 (2010). sourcePartly supported

  The Discussion (Lipoprotein Interactions of ApoE3 and ApoE4; page unavailable) says apoE3 binds better than apoE4 to HDL3, while apoE4 binds better than apoE3 to VLDL. The study compares HDL3 and VLDL, but the passages do not establish a preference for LDL; the LDL part of the claim is unsupported. (LLM, conf=0.89)

  Experimental — accuracy not yet measured

May combine two claims.

Several studies of large populations of individuals from European ancestry have raised the possibility that APOE is a longevity gene, with the APOEε2 variant associated with longer survival and the APOEε4 with shorter survival in a dose-dependent manner.

“Several studies of large populations of individuals from European ancestry have raised the possibility that APOE is a longevity gene, with the APOEε2 variant associated with longer survival and the APOEε4 with shorter survival in a dose-dependent manner90–94.”

• cites [90] Joshi, P. K. et al. Genome-wide meta-analysis associates HLA-DQA1/DRB1 and LPA and lifestyle factors with human longevity. Nat. Commun. 8, 910 (2017). sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured
• cites [91] Pilling, L. C. et al. Human longevity: 25 genetic loci associated in 389,166 UK biobank participants. Aging 9, 2504–2520 (2017). sourcePartly supported

  Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured
• cites [92] Deelen, J. et al. A meta-analysis of genome-wide association studies identifies multiple longevity genes. Nat. Commun. 10, 3669 (2019). sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

May combine two claims.

The associations between APOE and survival seem to be independent of baseline serum LDL cholesterol, cardiovascular risk and even Alzheimer disease diagnosis or the burden of Alzheimer disease neuropathology.

“Of note, contrary to expectation, these associations seem to be independent of baseline serum LDL cholesterol93, cardiovascular risk93,94 and even AD diagnosis or the burden of AD neuropathology94.”

• cites [93] Wolters, F. J. et al. The impact of APOE genotype on survival: results of 38,537 participants from six population-based cohorts (E2-CHARGE). PLoS ONE 14, e0219668 (2019). sourceSupported
• cites [94] Shinohara, M. et al. APOE2 is associated with longevity independent of Alzheimer’s disease. eLife 9, e62199 (2020). sourceSupported

May combine two claims.

In the same registries, APOEε2 has been associated with lower LDL cholesterol levels, increased triglyceride levels and increased risk of peripheral vascular disease.

“By contrast, in the same registries, APOEε2 has been associated with lower LDL cholesterol levels, increased triglyceride levels and increased risk of peripheral vascular disease87,88.”

• cites [87] Kuo, C.-L., Pilling, L. C., Atkins, J. L., Kuchel, G. A. & Melzer, D. ApoE ε2 and aging-related outcomes in 379,000 UK Biobank participants. Aging 12, 12222–12233 (2020). sourcePartly supported

  The Results (Biomarkers; page unavailable) report lower LDL cholesterol and higher triglycerides for both APOE e2e2 and e2e3 compared with e3e3. The Disease outcomes section does not report an increased risk of peripheral vascular disease, so that part of the claim is unsupported by our copy. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [88] Lumsden, A. L., Mulugeta, A., Zhou, A. & Hyppönen, E. Apolipoprotein E (APOE) genotype-associated disease risks: a phenome-wide, registry-based, case–control study utilising the UK Biobank. eBioMedicine 59, 102954 (2020). sourcePartly supported

  The Results (Sensitivity analyses of disease biomarkers) report low LDL and very high triglycerides for ε2ε2 compared with ε3ε3; the Results (Genotype PheWAS analyses) also report elevated odds of peripheral vascular disease for ε2ε2. The claim omits the important homozygosity qualifier: the paper does not establish that increased triglycerides and peripheral vascular disease apply to APOE ε2 carriers generally. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

In the central nervous system, APOE is produced predominantly by astrocytes, although it can also be produced by reactive microglia and, to a lesser extent, stressed neurons and other glial cells.

“In the CNS, APOE is produced predominantly by astrocytes, although it can also be produced by reactive microglia and, to a lesser extent, stressed neurons and other glial cells96,97.”

• cites [96] Xu, Q. et al. Profile and regulation of apolipoprotein E (ApoE) expression in the CNS in mice with targeting of green fluorescent protein gene to the ApoE locus. J. Neurosci. 26, 4985–4994 (2006). sourceNot checked — no full text of the source
• cites [97] Mathys, H. et al. Single-cell transcriptomic analysis of Alzheimer’s disease. Nature 570, 332–337 (2019). sourcePartly supported

  In “Systematic differential expression analysis” (page unavailable), the paper reports APOE expression in both astrocytes and microglia, with APOE upregulated in microglia but downregulated in astrocytes in AD pathology. “Identification of AD-associated cellular subpopulations” also identifies APOE as a marker of an AD-associated microglial subpopulation. Neither passage establishes that astrocytes are the predominant CNS source or that stressed neurons and other glial cells produce smaller amounts. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

APOE4 is associated with increased Aβ deposition, and the mechanism behind this is multifaceted.

“APOE4 is associated with increased Aβ deposition, and the mechanism behind this is multifaceted.”

• cites [109] Tzioras, M., Davies, C., Newman, A., Jackson, R. & Spires-Jones, T. Invited review: APOE at the interface of inflammation, neurodegeneration and pathological protein spread in Alzheimer’s disease. Neuropathol. Appl. Neurobiol. 45, 327–346 (2019). sourceSupported

May combine two claims.

APOE is a protein canonically secreted to the extracellular space where it functions as a lipid transporter.

“APOE is a protein canonically secreted to the extracellular space where it functions as a lipid transporter95.”

• cites [95] Yang, L. G., March, Z. M., Stephenson, R. A. & Narayan, P. S. Apolipoprotein E in lipid metabolism and neurodegenerative disease. Trends Endocrinol. Metab. 34, 430–445 (2023). sourceSupported

May combine two claims.

APOE isoforms can differentially influence the transcription of Aβ precursor protein and the generation of Aβ; these factors are most increased by APOE4, followed by APOE3, then APOE2.

“Besides promoting Aβ aggregation and impairing its clearance, APOE isoforms can also differentially influence the transcription of Aβ precursor protein and the generation of Aβ; these factors are most increased by APOE4, followed by APOE3, then APOE2 (ref. 121).”

• cites [121] Huang, Y.-W. A., Zhou, B., Wernig, M. & Südhof, T. C. ApoE2, ApoE3, and ApoE4 differentially stimulate APP transcription and Aβ secretion. Cell 168, 427–441.e21 (2017). sourceSupported

May combine two claims.

A study using adeno-associated viral vectors to overexpress TDP-43 in the brains of APOE-TR mice of all three isoforms and in Apoe knockout mice revealed that APOE2-targeted replacement TDP43-overexpressing mice have greater reactive gliosis, neurodegeneration and motor impairments compared with APOE3-TR, APOE4-TR and Apoe knockout mice, which had very mild or no phenotypic alterations.

“A study using adeno-associated viral (AAV) vectors to overexpress TDP-43 in the brains of APOE-TR mice of all three isoforms and in Apoe knockout mice revealed that, surprisingly, APOE2-targeted replacement TDP43-overexpressing mice have greater reactive gliosis, neurodegeneration and motor impairments75, compared with APOE3-TR, APOE4-TR and Apoe knockout mice, which had very mild or no phenotypic”

• cites [75] Meneses, A. D. et al. APOE2 exacerbates TDP-43 related toxicity in the absence of Alzheimer pathology. Ann. Neurol. 93, 830–843 (2023). sourceSupported

May combine two claims.

The effect of APOE4 in Alzheimer disease is due not only to the increased propensity of proteins to aggregate in the presence of APOE4, but also to the way APOE4 modulates the brain response to those aggregates once formed.

“These results bear a striking resemblance to those from the Aβ plaque-depositing mice120,128 and indicate that the effect of APOE4 in AD is due not only to the increased propensity of proteins to aggregate in the presence of APOE4, but also to the way APOE4 modulates the brain response to those aggregates once formed.”

• cites [120] Youmans, K. L. et al. APOE4-specific changes in Aβ accumulation in a new transgenic mouse model of Alzheimer disease. J. Biol. Chem. 287, 41774–41786 (2012). sourcePartly supported

  The Discussion reports that prior work found greater oligomeric Aβ-induced deficits in synaptic plasticity and neuronal viability with APOE4, which supports the idea of an altered response to aggregates. This paper’s own EFAD-mouse findings, however, concern Aβ accumulation and plaque morphology; it does not directly establish how the brain responds to formed aggregates, or extend that finding to proteins generally. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [128] Hudry, E. et al. Gene transfer of human Apoe isoforms results in differential modulation of amyloid deposition and neurotoxicity in mouse brain. Sci. Transl. Med. 5, 212ra161 (2013). sourceSupported

May combine two claims.

Apoe knockout plaque-depositing mice still exhibit deposition of Aβ plaques, but the plaques are less compact and do not cause the synaptic and cognitive deficits typical of plaque-depositing mice with Apoe intact.

“Apoe knockout plaque-depositing mice highlight the complexity of the APOE–Aβ interaction, as these mice still exhibit deposition of Aβ plaques, but the plaques are less compact and do not cause the synaptic and cognitive deficits typical of plaque-depositing mice with Apoe intact117,119,122.”

• cites [117] Fagan, A. M. et al. Human and murine ApoE markedly alters A beta metabolism before and after plaque formation in a mouse model of Alzheimer’s disease. Neurobiol. Dis. 9, 305–318 (2002). sourceNot checked — no full text of the source
• cites [119] Irizarry, M. C. et al. Apolipoprotein E affects the amount, form, and anatomical distribution of amyloid beta-peptide deposition in homozygous APP(V717F) transgenic mice. Acta Neuropathol. 100, 451–458 (2000). sourceNot checked — no full text of the source
• cites [122] Hudry, E. et al. Opposing roles of apolipoprotein E in aging and neurodegeneration. Life Sci. Alliance 2, e201900325 (2019). sourcePartly supported

  The Results sections on amyloid burden and synaptic integrity report that APP/PSEN1/APOEnull mice retain Aβ deposits, have fewer dense-core plaques, and lack the plaque-adjacent synaptic loss seen in APP/PSEN1 mice. The paper reports improved neuronal responses in adult mice, but it does not establish that these plaque-depositing knockout mice lack cognitive deficits; the Discussion notes age-dependent neuronal dysfunction despite the earlier improvement. No page numbers were available in our copy. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

Studies using APOE-targeted replacement mice crossed with mutant α-synuclein mice have reported that APOE4 mice have increased aggregation of α-synuclein, whereas APOE2 mice have very limited α-synuclein aggregates.

“Studies using APOE-targeted replacement (APOE-TR) mice crossed with mutant α-synuclein (αSyn) mice have reported that APOE4 mice have increased aggregation of αSyn, whereas APOE2 mice have very limited αSyn aggregates.”

• cites [69] Davis, A. A. et al. APOE genotype regulates pathology and disease progression in synucleinopathy. Sci. Transl. Med. 12, eaay3069 (2020). sourceSupported

May combine two claims.

Preclinical data, together with a case study of an APOE null individual with hyperlipoproteinaemia type III but normal cognition and Alzheimer disease biomarkers, indicate that lowering APOE expression levels is a valid therapeutic strategy.

“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.”

• cites [123] Mak, A. C. Y. et al. Effects of the absence of apolipoprotein E on lipoproteins, neurocognitive function, and retinal function. JAMA Neurol. 71, 1228 (2014). sourceSupported

• AssumptionRests on an assumption: Findings from APOE-targeted replacement mouse models and other animal models translate to human Alzheimer disease pathophysiology and therapeutic response.

May combine two claims.

The APOE2 mice have improved motor function and prolonged survival compared with APOE3-expressing mice, suggesting that the effect of APOE on α-synucleinopathies is independent of its effect on Aβ.

“Furthermore, the APOE2 mice have improved motor function and prolonged survival compared with APOE3-expressing mice, suggesting that the effect of APOE on α-synucleinopathies is independent of its effect on Aβ69.”

• cites [69] Davis, A. A. et al. APOE genotype regulates pathology and disease progression in synucleinopathy. Sci. Transl. Med. 12, eaay3069 (2020). sourceSupported

May combine two claims.

APOE4 astrocytes have an increased number of lipid droplets and impaired glucose utilization and mitochondrial function.

“APOE4 astrocytes have an increased number of lipid droplets and impaired glucose utilization and mitochondrial function, lending further support to this hypothesis143,146,147 (Fig. 2b).”

• cites [143] Lin, Y.-T. et al. APOE4 causes widespread molecular and cellular alterations associated with Alzheimer’s disease phenotypes in human iPSC-derived brain cell types. Neuron 98, 1141–1154.e7 (2018). sourcePartly supported

  The Results section (‘APOE4 astrocytes exhibit compromised Aβ uptake’; page unavailable) reports increased cholesterol in APOE4 astrocytes, supporting altered lipid accumulation. It does not establish an increased number of lipid droplets or impaired glucose utilization or mitochondrial function in astrocytes. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [146] Farmer, B. C., Kluemper, J. & Johnson, L. A. Apolipoprotein E4 alters astrocyte fatty acid metabolism and lipid droplet formation. Cells 8, 182 (2019). sourcePartly supported

  The Conclusions report more lipid droplets in E4 than E3 astrocytes and altered fatty-acid oxidation. Results §3.3 reports lower oxygen consumption in E4 astrocytes, but only suggests that reduced glucose oxidation is the likely cause; it does not establish impaired glucose utilization or mitochondrial function generally. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [147] Schmukler, E. et al. Altered mitochondrial dynamics and function in APOE4-expressing astrocytes. Cell Death Dis. 11, 578 (2020). sourcePartly supported

  The Results section, “APOE4 astrocytes exhibit impaired mitochondrial function” (page unavailable), reports reduced mitochondrial metabolism and ATP levels, supporting the mitochondrial-function part of the claim. Our copy does not report an increased number of lipid droplets or impaired glucose utilization; it describes lower medium pH as suggestive of increased compensatory glycolysis. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

The APOE-TREM2 axis has been found in transcriptomic post-mortem analyses of human brains, with APOEε4 carriers exhibiting a more prominent pro-inflammatory and phagocytic microglial transcriptomic signature.

“this APOE–TREM2 axis has also been found in transcriptomic post-mortem analyses of human brains, with APOEε4 carriers exhibiting a more prominent pro-inflammatory and phagocytic microglial transcriptomic signature152,153.”

• cites [152] Serrano-Pozo, A. et al. Effect of APOE alleles on the glial transcriptome in normal aging and Alzheimer’s disease. Nat. Aging 1, 919–931 (2021). sourceSupported
• cites [153] Das, S. et al. Distinct transcriptomic responses to Aβ plaques, neurofibrillary tangles, and APOE in Alzheimer’s disease. Alzheimers Dement. 20, 74–90 (2023). sourceSupported

May combine two claims.

Astrocytes provide the vast majority of the cholesterol required by mature neurons, and the APOE they produce is crucial for efficient cholesterol transport.

“Astrocytes provide the vast majority of the cholesterol required by mature neurons, and the APOE they produce is crucial for efficient cholesterol transport142.”

• cites [142] Suidan, G. L. & Ramaswamy, G. Targeting apolipoprotein E for Alzheimer’s disease: an industry perspective. Int. J. Mol. Sci. 20, 2161 (2019). sourcePartly supported

  The Abstract says astrocytes play a critical role in cholesterol synthesis and delivery, and the Introduction says they are the predominant producers of apoE, which transports lipids to neurons. Section 3.5 adds that apoE is important for delivering cholesterol to neurons. The paper does not establish that astrocytes provide the vast majority of the cholesterol required specifically by mature neurons. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

May combine two claims.

Astrocytes derived from APOE4 human-inducible pluripotent stem cells are less efficient at secreting lipidated APOE particles and exhibit impaired cholesterol metabolism relative to APOE3 hiPSC-derived astrocytes.

“Astrocytes derived from APOE4 human-inducible pluripotent stem cells (hiPSCs) are less efficient at secreting lipidated APOE particles and exhibit impaired cholesterol metabolism relative to APOE3 hiPSC-derived astrocytes143,144.”

• cites [143] Lin, Y.-T. et al. APOE4 causes widespread molecular and cellular alterations associated with Alzheimer’s disease phenotypes in human iPSC-derived brain cell types. Neuron 98, 1141–1154.e7 (2018). sourcePartly supported

  The Results section ('APOE4 astrocytes exhibit compromised Aβ uptake'; page unavailable) reports less secreted APOE and altered cholesterol metabolism in APOE4 than APOE3 iPSC-derived astrocytes. It does not establish that the secreted APOE particles were lipidated or measure an efficiency of secreting such particles; it also reports increased, not decreased, cholesterol in APOE4 culture media. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [144] Tcw, J. et al. Cholesterol and matrisome pathways dysregulated in astrocytes and microglia. Cell 185, 2213–2233.e25 (2022). sourcePartly supported

  The Results section, “Impaired cholesterol trafficking in APOE4 astrocytes and microglia” (page unavailable), reports 63% less secreted APOE in APOE4 than APOE3 astrocytes, along with increased cellular cholesterol and reduced cholesterol efflux. The study used hiPSC-derived astrocytes, but the cited passages do not establish that the secreted APOE was lipidated or measure secretion of lipidated APOE particles specifically. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

The protective APOE Jacksonville mutation reduces APOE oligomerization and Aβ deposition, which could point to APOE oligomerization being biologically detrimental and adds weight to the hypothesis that APOE oligomerization might facilitate Aβ oligomerization.

“Intriguingly, the protective APOE Jacksonville mutation (Fig. 1) has been found to reduce APOE oligomerization and Aβ deposition, which could point to APOE oligomerization being biologically detrimental and adds weight to the hypothesis that APOE oligomerization might facilitate Aβ oligomerization44.”

• cites [44] Liu, C.-C. et al. APOE3-Jacksonville (V236E) variant reduces self-aggregation and risk of dementia. Sci. Transl. Med. 13, eabc9375 (2021). sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

May combine two claims.

APOE4 microglia-like hiPSCs show decreased phagocytosis and increased inflammatory genes relative to APOE3 microglia.

“APOE4 microglia-like hiPSCs show decreased phagocytosis and increased inflammatory genes relative to APOE3 microglia143.”

• cites [143] Lin, Y.-T. et al. APOE4 causes widespread molecular and cellular alterations associated with Alzheimer’s disease phenotypes in human iPSC-derived brain cell types. Neuron 98, 1141–1154.e7 (2018). sourceSupported

May combine two claims.

Removal of astrocytic APOE reduced microglial reaction to Aβ plaques and neurofibrillary tangles, but astrocyte response to plaques and tangles was largely unchanged.

“removal of astrocytic APOE reduced microglial reaction to Aβ plaques and neurofibrillary tangles, but that astrocyte response to plaques and tangles was largely unchanged148,149”

• cites [148] Mahan, T. E. et al. Selective reduction of astrocyte apoE3 and apoE4 strongly reduces Aβ accumulation and plaque-related pathology in a mouse model of amyloidosis. Mol. Neurodegener. 17, 13 (2022). sourcePartly supported

  The Discussion reports lower microglial activation around Aβ plaques after astrocytic apoE reduction, and the Results (Astrocyte activation after the loss of astrocytic apoE) report unchanged GFAP staining around plaques. The paper’s findings concern Aβ plaques, not neurofibrillary tangles; it does not support either claimed response to tangles. Page numbers were not supplied in our copy. (LLM, conf=0.91)

  Experimental — accuracy not yet measured
• cites [149] Wang, C. et al. Selective removal of astrocytic APOE4 strongly protects against tau-mediated neurodegeneration and decreases synaptic phagocytosis by microglia. Neuron https://doi.org/10.1016/j.neuron.2021.03.024 (2021). sourcePartly supported

  In the Results section on microglial genes (page unavailable), astrocytic APOE4 removal reduced markers of microglial activation in mice with tau pathology. But the Results section on astrocytes reports fewer activated astrocytes and significantly lower activated-astrocyte gene expression, rather than a largely unchanged response. This paper does not report the claimed effects on responses to Aβ plaques. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

• AssumptionRests on an assumption: Astrocytes are the primary producers of APOE in the brain.

May combine two claims.

Cholesterol transport is impaired both within oligodendrocytes and from astrocytes to oligodendrocytes.

“These studies indicate that cholesterol transport is impaired both within oligodendrocytes163 and from astrocytes to oligodendrocytes164.”

• cites [163] Blanchard, J. W. et al. APOE4 impairs myelination via cholesterol dysregulation in oligodendrocytes. Nature 611, 769–779 (2022). sourceSupported
• cites [164] Mok, K. K.-S. et al. Apolipoprotein E ε4 disrupts oligodendrocyte differentiation by interfering with astrocyte-derived lipid transport. J. Neurochem. 165, 55–75 (2023). sourceSupported

May combine two claims.

Reactive microglia migrate towards Aβ plaques, surround them and upregulate APOE, which binds to TREM2 and promotes plaque compaction.

“Reactive microglia migrate towards Aβ plaques, surround them and upregulate APOE, which binds to TREM2 and promotes plaque compaction154.”

• cites [154] Stephen, T. L. et al. APOE genotype and sex affect microglial interactions with plaques in Alzheimer’s disease mice. Acta Neuropathol. Commun. 7, 82 (2019). sourcePartly supported

  The Introduction says activated microglia associate with Aβ plaques, apoE is a TREM2 ligand, and TREM2-dependent microglial barriers help compact plaques. The Discussion links APOE loss with reduced microglial clustering and plaque compaction, but says the mechanism of APOE’s effect on plaque coverage is unclear. The paper does not establish that plaque-associated microglia upregulate APOE or that APOE binding to TREM2 directly promotes compaction; it also does not document migration toward plaques. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

May combine two claims.

APOEε4 is linked to altered expression of proteins involved in mitochondrial fission and fusion in both a mouse model and human postmortem brains, suggesting that an alteration in mitochondrial dynamics might lead to or arise from impaired mitochondrial function.

“in both a mouse model and human postmortem brains, APOEε4 is linked to altered expression of proteins involved in mitochondrial fission and fusion, suggesting that an alteration in mitochondrial dynamics might lead to or arise from impaired mitochondrial function147,170.”

• cites [147] Schmukler, E. et al. Altered mitochondrial dynamics and function in APOE4-expressing astrocytes. Cell Death Dis. 11, 578 (2020). sourcePartly supported

  Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured
• cites [170] Yin, J. et al. Effect of ApoE isoforms on mitochondria in Alzheimer disease. Neurology 94, e2404–e2411 (2020). sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

May combine two claims.

APOE4-TR mice exhibit multiple alterations of energy metabolism compared with APOE3-TR mice, including impaired mitochondrial respiration in the cortex and hippocampus, upregulation of oxidative phosphorylation genes in the entorhinal cortex and differential levels of fatty acids and other metabolites.

“APOE4-TR mice exhibit multiple alterations of energy metabolism compared with APOE3-TR mice, including impaired mitochondrial respiration in the cortex and hippocampus, upregulation of oxidative phosphorylation genes in the entorhinal cortex and differential levels of fatty acids and other metabolites174.”

• cites [174] Area-Gomez, E. et al. APOE4 is associated with differential regional vulnerability to bioenergetic deficits in aged APOE mice. Sci. Rep. 10, 4277 (2020). sourceSupported

May combine two claims.

Glial cells store excess free fatty acids as triglycerides and cholesterol esters in intracellular lipid droplets, which are catabolized in mitochondria via β-oxidation, and this process is compromised in the presence of APOE4.

“Glial cells then store excess free fatty acids in the form of triglycerides and cholesterol esters in intracellular lipid droplets, which serve as an energy storage until they are catabolized in mitochondria via β-oxidation, and this process is compromised in the presence of APOE4 (refs. 146,177)”

• cites [146] Farmer, B. C., Kluemper, J. & Johnson, L. A. Apolipoprotein E4 alters astrocyte fatty acid metabolism and lipid droplet formation. Cells 8, 182 (2019). sourcePartly supported

  The Introduction describes lipid droplets as containing triacylglycerols and cholesterol esters, and the Discussion says astrocyte lipid droplets sequester fatty acids and provide an energy reservoir. Results §3.3 shows that APOE4 alters fatty-acid oxidation in astrocytes, but not as a uniform reduction in catabolism of stored lipids: E4 astrocytes had higher oxygen consumption attributed to endogenous fatty-acid oxidation and no difference in CO2 production from intracellular fatty acids. The claim's broad description of this process as ‘compromised’ therefore misses the distinction between stored and externally supplied fatty acids. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [177] Qi, G. et al. ApoE4 impairs neuron–astrocyte coupling of fatty acid metabolism. Cell Rep. 34, 108572 (2021). sourceSupported

May combine two claims.

Impaired calcium flux has been observed in vitro in an APOE4-expressing neuronal cell line compared with an APOE3-expressing line and could be partially responsible for the hyperexcitability seen in APOE4 neurons in culture.

“Impaired calcium flux has been observed in vitro in an APOE4-expressing neuronal cell line compared with an APOE3-expressing line and could be partially responsible for the hyperexcitability seen in APOE4 neurons in culture173.”

• cites [173] Orr, A. L. et al. Neuronal apolipoprotein E4 expression results in proteome-wide alterations and compromises bioenergetic capacity by disrupting mitochondrial function. J. Alzheimers Dis. 68, 991–1011 (2019). sourcePartly supported

  The Results section (page unavailable) reports altered calcium flux in cultured N2a-apoE4 cells compared with N2a-apoE3 cells, including faster mitochondrial calcium uptake. The cited paper does not establish or propose that this alteration contributes to hyperexcitability in APOE4 neurons; its Discussion instead links mitochondrial calcium overload to mitochondrial impairment and neurodegeneration. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

Neurons shuttle fatty acids to glial cells via APOE, with APOE4 being less efficient than APOE3 at this transport.

“Neurons shuttle fatty acids to glial cells via APOE, with APOE4 being less efficient than APOE3 at this transport177.”

• cites [177] Qi, G. et al. ApoE4 impairs neuron–astrocyte coupling of fatty acid metabolism. Cell Rep. 34, 108572 (2021). sourceSupported

May combine two claims.

APOE4 has a negative impact on cerebral blood flow and neurovascular coupling; APOE4 mice show reduced cerebral blood flow both at baseline and in stimulus-evoked paradigms, relative to APOE3 mice.

“APOE4 has a negative impact on cerebral blood flow and neurovascular coupling; APOE4 mice show reduced cerebral blood flow both at baseline and in stimulus-evoked paradigms, relative to APOE3 mice187–189.”

• cites [187] Bonnar, O. et al. APOE4 expression confers a mild, persistent reduction in neurovascular function in the visual cortex and hippocampus of awake mice. J. Cereb. Blood Flow Metab. 43, 1826–1841 (2023). sourcePartly supported

  The Results sections (page unavailable) support mildly impaired neurovascular coupling: some APOE4 vessels responded less reliably to neuronal activity. But they report no genotype difference in baseline blood-flow measures or in overall cerebral blood-flow responses to visual stimulation in awake mice. The Introduction describes reduced baseline and stimulus-induced flow in earlier studies of anaesthetised mice, not as this study’s finding. (LLM, conf=0.90)

  Experimental — accuracy not yet measured
• cites [188] Koizumi, K. et al. Apoε4 disrupts neurovascular regulation and undermines white matter integrity and cognitive function. Nat. Commun. 9, 3816 (2018). sourceSupported
• cites [189] Wiesmann, M. et al. A dietary treatment improves cerebral blood flow and brain connectivity in aging apoE4 mice. Neural Plast. 2016, 6846721 (2016). sourcePartly supported

  The Results (§3.2.1) report lower resting cerebral blood flow in the cortex and thalamus of 18-month-old apoE4 mice. But the controls were wild-type mice, not apoE3 mice; the Methods (§2.3) describe resting-condition measurements, not stimulus-evoked blood flow or neurovascular coupling. The Discussion (§4.1) also says cerebral blood flow was unaffected at 10–12 months. (LLM, conf=0.90)

  Experimental — accuracy not yet measured

May combine two claims.

APOE circulating in the blood is predominantly produced by the liver; however, the BBB keeps this pool of peripheral APOE separated from that produced in the CNS.

“APOE circulating in the blood is predominantly produced by the liver; however, the BBB keeps this pool of peripheral APOE separated from that produced in the CNS181,182.”

• cites [181] Huynh, T.-P. V. et al. Lack of hepatic apoE does not influence early Aβ deposition: observations from a new APOE knock-in model. Mol. Neurodegener. 14, 37 (2019). sourceSupported
• cites [182] Linton, M. F. et al. Phenotypes of apolipoprotein B and apolipoprotein E after liver transplantation. J. Clin. Invest. 88, 270–281 (1991). sourcePartly supported

  The Results report that at least 90% of serum apoE is synthesized by the liver. They also report that CSF apoE retained the recipient’s phenotype after liver transplantation, implying that most CSF apoE is produced locally. The paper does not establish that the blood–brain barrier keeps the two pools wholly separate; it considers entry from plasma as a possible source of CSF apoE. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

FDA-approved anti-Aβ monoclonal antibodies are very effective at removing Aβ from the brain parenchyma, but a substantial proportion of treated individuals, especially APOEε4 carriers, exhibit amyloid-related imaging abnormalities (ARIA) consisting of oedema (ARIA-E) and haemosiderin deposits (ARIA-H).

“although the FDA-approved anti-Aβ monoclonal antibodies are very effective at removing Aβ from the brain parenchyma, a substantial proportion of treated individuals, especially APOEε4 carriers, exhibit amyloid-related imaging abnormalities (ARIA) consisting of oedema (ARIA-E) and haemosiderin deposits (ARIA-H)2.”

• cites [2] van Dyck, C. H. et al. Lecanemab in early Alzheimer’s disease. N. Engl. J. Med. 388, 9–21 (2023). sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

May combine two claims.

APOE4 reduces the density of blood vessels in these mice, thereby potentially impairing oxygen availability to neurons.

“APOE4 also reduces the density of blood vessels in these mice, thereby potentially impairing oxygen availability to neurons188.”

• cites [188] Koizumi, K. et al. Apoε4 disrupts neurovascular regulation and undermines white matter integrity and cognitive function. Nat. Commun. 9, 3816 (2018). sourceSupported

May combine two claims.

A leaky BBB increases plasma proteins in the brain parenchyma, leading to oxidative stress and neuroinflammation, and is another mechanism by which APOE could prime the brain for neurodegeneration.

“A leaky BBB increases plasma proteins in the brain parenchyma, thereby leading to oxidative stress and neuroinflammation, and is yet another mechanism by which APOE could prime the brain for neurodegeneration145.”

• cites [145] Steele, O. G. et al. A multi‐hit hypothesis for an APOE4‐dependent pathophysiological state. Eur. J. Neurosci. 56, 5476–5515 (2022). sourcePartly supported

  In ‘HIT 2: Neurovascular Dysfunction’ (page unavailable), Figure 2 says that APOE4-related BBB leakage increases blood-borne proteins in the CSF, increasing neuroinflammation and oxidative stress. The discussion links this inflammatory state to degenerative risk. The cited passage specifies CSF, however, not the brain parenchyma named in the claim. (LLM, conf=0.83)

  Experimental — accuracy not yet measured

May combine two claims.

Compared with wild-type mice, both Apoe knockout mice and mice expressing APOE4 have a leaky BBB, a phenomenon also reported in cognitively unimpaired and mildly impaired individuals who carry an APOEε4 allele.

“When compared with wild-type mice, both Apoe knockout mice and mice expressing APOE4 have a leaky BBB, a phenomenon also reported in cognitively unimpaired and mildly impaired individuals who carry an APOEε4 allele183–185.”

• cites [183] Bell, R. D. et al. Apolipoprotein E controls cerebrovascular integrity via cyclophilin A. Nature 485, 512–516 (2012). sourcePartly supported

  The paper reports a leaky BBB in APOE4-expressing and Apoe knockout mice, compared with mice expressing APOE2 or APOE3 (Abstract; no page given). It also mentions neurovascular dysfunction in normal human APOE4 carriers, but does not establish BBB leakage in cognitively unimpaired or mildly impaired carriers. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [184] Jackson, R. J. et al. APOE4 derived from astrocytes leads to blood–brain barrier impairment. Brain 145, 3582–3593 (2022). sourcePartly supported

  The Results (page not available in our copy) report a leaky BBB in Apoe knockout and APOE4 mice, but compare the APOE4 mice with APOE2 and APOE3 mice rather than explicitly with wild-type mice. The Introduction mentions BBB leakage in aged humans with APOE4, but does not specify cognitively unimpaired or mildly impaired individuals. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [185] Montagne, A. et al. APOE4 leads to blood–brain barrier dysfunction predicting cognitive decline. Nature 581, 71–76 (2020). sourcePartly supported

  The Introductory Paragraph reports BBB breakdown in cognitively normal APOE4 carriers, with greater breakdown in carriers with mild cognitive impairment. It mentions APOE knock-in mice and mouse pericytes in connection with a molecular pathway, but does not report the claimed BBB-leak comparison between wild-type, Apoe knockout, and APOE4-expressing mice. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

APOE affects mitochondrial structure and function, and mitochondrial dysfunction impacts APOE gene and protein expression and secretion.

“not only has APOE been shown to affect mitochondrial structure and function, but also mitochondrial dysfunction has been shown to impact APOE gene and protein expression and secretion180.”

• cites [180] Wynne, M. E. et al. APOE expression and secretion are modulated by mitochondrial dysfunction. eLife 12, e85779 (2023). sourcePartly supported

  The Results report that mitochondrial perturbations increased APOE mRNA, cellular protein, and secreted protein; the Discussion likewise concludes that mitochondria regulate APOE expression and secretion. The Introduction says APOE4 is thought to cause mitochondrial dysfunction, but the passages do not establish the broader claim that APOE affects mitochondrial structure. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

Classified as probably not a substantial claim.

In 2024, a consensus panel concluded that lowering APOE4 levels is a reasonable approach to prevent or slow down AD progression.

“in 2024 a consensus panel191 concluded that lowering APOE4 levels is a reasonable approach to prevent or slow down AD progression.”

• cites [191] Vance, J. M. et al. Report of the APOE4 National Institute on Aging/Alzheimer Disease Sequencing Project Consortium Working Group: reducing APOE4 in carriers is a therapeutic goal for Alzheimer’s disease. Ann. Neurol. 95, 625–634 (2024). sourceSupported

May combine two claims.

This prediction was confirmed in vivo in 2023 by two studies that used mouse models expressing human APOE3 or APOE4 with the Christchurch mutation, which showed amelioration of AD phenotypes when compared with APOE3 or APOE4 mice, particularly those related to tau accumulation and microglial response.

“This prediction was confirmed in vivo in 2023 by two studies that used mouse models expressing human APOE3 or APOE4 with the Christchurch mutation, which showed amelioration of AD phenotypes when compared with APOE3 or APOE4 mice, particularly those related to tau accumulation and microglial response197,198.”

• cites [197] Nelson, M. R. et al. The APOE-R136S mutation protects against APOE4-driven Tau pathology, neurodegeneration and neuroinflammation. Nat. Neurosci. 26, 2104–2121 (2023). sourceSupported
• cites [198] Chen, Y. et al. APOE3ch alters microglial response and suppresses Aβ-induced tau seeding and spread. Cell 187, 428–445.e20 (2023). sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The risk of developing these potentially serious adverse effects is higher in APOEε4 carriers, particularly homozygotes, and current recommendations are that patients are genotyped for APOE before starting these therapies.

“The risk of developing these potentially serious adverse effects is higher in APOEε4 carriers, particularly homozygotes, and current recommendations are that patients are genotyped for APOE before starting these therapies to offer a balanced benefit–risk discussion190.”

• cites [190] Cummings, J. et al. Lecanemab: appropriate use recommendations. J. Prev. Alzheimers Dis. 10, 362–377 (2023). sourcePartly supported

  The section on APOE genotyping says APOE4 carriers, especially homozygotes, have increased risk of ARIA and recommends genotyping all candidates before starting lecanemab to inform risk discussions. The source makes these recommendations for lecanemab; it does not establish them for the broader group of therapies implied by “these therapies.” (LLM, conf=0.85)

  Experimental — accuracy not yet measured

May combine two claims.

The APOE Christchurch protective mutation weakens the interaction between APOE and heparan sulfate proteoglycans, and blocking APOE-heparan sulfate proteoglycan binding might have therapeutic value.

“Initial in vitro functional experiments with the APOE Christchurch protective mutation (see the section ‘R136C (Christchurch)’) suggest that this mutation weakens the interaction between APOE and heparan sulfate proteoglycans — located on the surface of neurons and implicated in tau uptake — and, therefore, that blocking APOE–heparan sulfate proteoglycan binding might have therapeutic value36”

• cites [36] Arboleda-Velasquez, J. F. et al. Resistance to autosomal dominant Alzheimer’s disease in an APOE3 Christchurch homozygote: a case report. Nat. Med. 25, 1680–1683 (2019). sourceSupported

May combine two claims.

A small molecule mimetic homologous to the domain of Aβ that interacts with APOE but modified to be more protease-resistant can reduce the oligomerization of Aβ in vitro and ameliorate Aβ and tau pathology in a triple transgenic mouse model of AD.

“this has been achieved using a small molecule mimetic homologous to the domain of Aβ that interacts with APOE but is modified to be more protease-resistant. This small peptide can reduce the oligomerization of Aβ in vitro and ameliorate Aβ and tau pathology in a triple transgenic mouse model of AD193,194”

• cites [193] Kuszczyk, M. A. et al. Blocking the interaction between apolipoprotein E and Aβ reduces intraneuronal accumulation of Aβ and inhibits synaptic degeneration. Am. J. Pathol. 182, 1750–1768 (2013). sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured
• cites [194] Liu, S. et al. Blocking the apolipoprotein E/amyloid β interaction in triple transgenic mice ameliorates Alzheimer’s disease related amyloid β and tau pathology. J. Neurochem. 128, 577–591 (2014). sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

May combine two claims.

An antibody that preferentially binds to non-lipidated APOE4 has shown promise in reducing Aβ plaques and CAA in a mouse model of β-amyloidosis, as well as decreasing Aβ-driven tau seeding in mice.

“An antibody that preferentially binds to non-lipidated APOE4 has shown promise in reducing Aβ plaques and CAA in a mouse model of β-amyloidosis, as well as decreasing Aβ-driven tau seeding in mice137–139.”

• cites [137] Xiong, M. et al. APOE immunotherapy reduces cerebral amyloid angiopathy and amyloid plaques while improving cerebrovascular function. Sci. Transl. Med. 13, eabd7522 (2021). sourcePartly supported

  The Introduction identifies HAE-4 as an antibody that recognizes poorly lipidated human APOE, and the Results report reduced parenchymal Aβ plaques and CAA in APOE4-expressing mice. The Discussion states that these mice do not develop intracellular tau accumulation and that HAE-4’s effect on tau spreading remains unknown; this paper therefore does not support the tau-seeding part of the sentence. (LLM, conf=0.91)

  Experimental — accuracy not yet measured
• cites [138] Gratuze, M. et al. APOE antibody inhibits Aβ‐associated tau seeding and spreading in a mouse model. Ann. Neurol. 91, 847–852 (2022). sourceSupported
• cites [139] Liao, F. et al. Targeting of nonlipidated, aggregated apoE with antibodies inhibits amyloid accumulation. J. Clin. Invest. 128, 2144–2155 (2018). sourcePartly supported

  The Discussion (p. 7) reports that HAE-4 preferentially binds nonlipidated apoE and reduces Aβ plaque load in APP transgenic mice expressing human apoE4. It does not support the CAA or Aβ-driven tau-seeding parts of the sentence: the Discussion (p. 8) says this mouse model had very little amyloid angiopathy, and our copy reports no tau-seeding result. (LLM, conf=0.90)

  Experimental — accuracy not yet measured

May combine two claims.

Antisense oligonucleotides against APOE4 have been effective in mouse models of both Aβ plaque deposition and tauopathy, although the timing of administration seems to be crucial for success.

“Another mechanism of decreasing APOE4 expression is using antisense oligonucleotides against APOE4 (Fig. 3d). This method has been effective in mouse models of both Aβ plaque deposition and tauopathy, although the timing of administration seems to be crucial for success124,206.”

• cites [124] Huynh, T.-P. V. et al. Age-dependent effects of apoE reduction using antisense oligonucleotides in a model of β-amyloidosis. Neuron 96, 1013–1023.e4 (2017). sourcePartly supported

  The Results and Discussion report that apoE-lowering antisense treatment reduced Aβ plaque pathology in mice when begun before deposition, while treatment begun at the onset of aggregation did not substantially reduce plaque burden. This supports the timing qualification. The paper does not report an antisense-treatment result in a tauopathy mouse model, so it does not support that part of the sentence. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [206] Litvinchuk, A. et al. Apolipoprotein E4 reduction with antisense oligonucleotides decreases neurodegeneration in a tauopathy model. Ann. Neurol. 89, 952–966 (2021). sourceSupported

Probably not a substantial claim: may not pass S2 (checkable).

These results indicate that clinical trials with antisense oligonucleotide therapeutics should be carefully designed.

“These results indicate that clinical trials with these therapeutics should be carefully designed124.”

• cites [124] Huynh, T.-P. V. et al. Age-dependent effects of apoE reduction using antisense oligonucleotides in a model of β-amyloidosis. Neuron 96, 1013–1023.e4 (2017). sourceSupported

May combine two claims.

Targeting the non-lipidated version of APOE4 is predicted to be more successful than targeting the lipidated version, as non-lipidated APOE is more likely to co-deposit with Aβ plaques and also to self-associate.

“Targeting of the non-lipidated version of APOE4 is predicted to be more successful than targeting the lipidated version, as non-lipidated APOE is more likely to co-deposit with Aβ plaques and also to self-associate139”

• cites [139] Liao, F. et al. Targeting of nonlipidated, aggregated apoE with antibodies inhibits amyloid accumulation. J. Clin. Invest. 128, 2144–2155 (2018). sourcePartly supported

  The Discussion (pp. 7–8) reports that HAE-4 preferentially binds nonlipidated, aggregated apoE in plaques and reduces Aβ accumulation in mice expressing human apoE4. It also proposes that poorly lipidated apoE may be more prone to aggregation. The paper does not establish that nonlipidated apoE is more likely than lipidated apoE to co-deposit with plaques or self-associate, or directly show that targeting it is more successful than targeting lipidated apoE. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

May combine two claims.

The introduction of human APOE2 into plaque-depositing mice expressing endogenous mouse Apoe via AAV-mediated delivery was shown to prevent and even reverse the deposition of Aβ into plaques, whereas delivery of APOE4 had the opposite effect.

“The introduction of human APOE2 into plaque-depositing mice expressing endogenous mouse Apoe via AAV-mediated delivery was shown to prevent and even reverse the deposition of Aβ into plaques, whereas delivery of APOE4 had the opposite effect128”

• cites [128] Hudry, E. et al. Gene transfer of human Apoe isoforms results in differential modulation of amyloid deposition and neurotoxicity in mouse brain. Sci. Transl. Med. 5, 212ra161 (2013). sourceSupported

May combine two claims.

Bexarotene is an FDA-approved liver X receptor/retinoid X receptor agonist for use in refractory cutaneous T cell lymphoma and has been shown to enhance Aβ clearance and improve cognitive performance in plaque-depositing mouse models.

“Bexarotene is an FDA-approved liver X receptor/retinoid X receptor agonist for use in refractory cutaneous T cell lymphoma and has been shown to enhance Aβ clearance and improve cognitive performance in plaque-depositing mouse models209.”

• cites [209] Cramer, P. E. et al. ApoE-directed therapeutics rapidly clear β-amyloid and reverse deficits in AD mouse models. Science 335, 1503–1506 (2012). sourcePartly supported

  The paper’s text indexed under Abstract (page not specified) identifies bexarotene as an FDA-approved RXR agonist and reports enhanced Aβ clearance and improved cognition in plaque-depositing mouse models. It describes activation of LXR:RXR but does not call bexarotene an LXR agonist or specify FDA approval for refractory cutaneous T-cell lymphoma. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

In phase Ib and II trials, bexarotene increased cerebrospinal fluid APOE by only 25% and failed to reduce PET Aβ burden or alter brain Aβ metabolism, probably owing to poor BBB penetration, although it caused hyperlipidaemia in most participants.

“in phase Ib and II trials, bexarotene increased cerebrospinal fluid APOE by only 25% and failed to reduce PET Aβ burden or alter brain Aβ metabolism, probably owing to poor BBB penetration, although it caused hyperlipidaemia in most participants210,211.”

• cites [210] Ghosal, K. et al. A randomized controlled study to evaluate the effect of bexarotene on amyloid-β and apolipoprotein E metabolism in healthy subjects. Alzheimers Dement. (N. Y.) 2, 110–120 (2016). sourcePartly supported

  Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured
• cites [211] Cummings, J. L. et al. Double-blind, placebo-controlled, proof-of-concept trial of bexarotene Xin moderate Alzheimer’s disease. Alzheimers Res. Ther. 8, 4 (2016). sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

May combine two claims.

The first human trial using AAV to express APOE2 in APOEε4 homozygotes has been initiated, and the reported safety results from this phase I trial are promising despite the small number of participants.

“the first human trial using AAV to express APOE2 in APOEε4 homozygotes has been initiated, and the reported safety results from this phase I trial are promising despite the small number of participants204”

• cites [204] Rosenberg, J. B. et al. AAVrh.10-mediated APOE2 central nervous system gene therapy for APOE4-associated Alzheimer’s disease. Hum. Gene Ther. Clin. Dev. 29, 24–47 (2018). sourcePartly supported

  The Discussion and Results (pages unavailable) describe AAV-mediated APOE2 delivery and safety testing in nonhuman primates as a step toward clinical use. They do not report that a human phase I trial was initiated or provide safety results from human participants; the promising safety findings are from animals. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

In mice, administration of APOE2 was found to be beneficial at reducing plaque deposition even in the presence of APOE4, indicating that APOE2 can reduce some of the negative effects of APOE4.

“in mice, administration of APOE2 was found to be beneficial at reducing plaque deposition even in the presence of APOE4, indicating that APOE2 can reduce some of the negative effects of APOE4 (refs. 202,203).”

• cites [202] Zhao, L. et al. Intracerebral adeno-associated virus gene delivery of apolipoprotein E2 markedly reduces brain amyloid pathology in Alzheimer’s disease mouse models. Neurobiol. Aging 44, 159–172 (2016). sourceNot checked — no full text of the source
• cites [203] Jackson, R. J. et al. APOE2 gene therapy reduces amyloid deposition and improves markers of neuroinflammation and neurodegeneration in a mouse model of Alzheimer disease. Mol. Ther. 32, 1373–1386 (2024). sourceSupported

May combine two claims.

Some of these molecules have been shown to be effective in cell models, whereas others are in even earlier stages of development.

“Some of these molecules have been shown to be effective in cell models, whereas others are in even earlier stages of development216,217.”

• cites [216] Petros, A. M. et al. Fragment-based discovery of an apolipoprotein E4 (apoE4) stabilizer. J. Med. Chem. 62, 4120–4130 (2019). sourceNot checked — no full text of the source
• cites [217] Wang, C. et al. Gain of toxic apolipoprotein E4 effects in human iPSC-derived neurons is ameliorated by a small-molecule structure corrector. Nat. Med. 24, 647–657 (2018). sourcePartly supported

  The Results section (page unavailable) reports that the small-molecule structure corrector PH002 ameliorated several pathological effects in human iPSC-derived neurons, supporting effectiveness in a cell model. The paper does not establish that other molecules are at earlier stages of development. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Traditionally, APOEε3/ε4 individuals and APOEε4 homozygotes were asserted to have about 2-3 and 9-12 times higher risk of Alzheimer disease than APOEε3 homozygotes, respectively, and APOEε2/ε3 carriers were believed to have about half the risk of APOEε3 homozygotes.

“Traditionally, APOEε3/ε4 individuals and APOEε4 homozygotes were asserted to have ~2–3 and ~9–12 times higher risk of AD than APOEε3 homozygotes (reference group), respectively, and APOEε2/ε3 carriers were believed to have about half the risk of APOEε3 homozygotes5,7.”

• cites [5] Corder, E. H. et al. Gene dose of apolipoprotein E type 4 allele and the risk of Alzheimer’s disease in late onset families. Science 261, 921–923 (1993). sourceNot checked — no full text of the source
• cites [7] Corder, E. H. et al. Protective effect of apolipoprotein E type 2 allele for late onset Alzheimer disease. Nat. Genet. 7, 180–184 (1994). sourceNot checked — no full text of the source

May combine two claims.

The APOEε4 allele increases Alzheimer disease risk differentially across races and ethnicities, with the greatest increase in risk seen in East Asian people, followed by white, then Black, then Hispanic people.

“The initial intriguing observation that the APOEε4 allele increases AD risk differentially across races and ethnicities, with the greatest increase in risk seen in East Asian people, followed by white, then Black, then Hispanic people6, has now been confirmed by a larger meta-analysis using not only self-reported race and ethnicity but also global genetic ancestry to ascertain the biological basis”

• cites [6] Farrer, L. A. et al. Effects of age, sex, and ethnicity on the association between apolipoprotein E genotype and Alzheimer disease. A meta-analysis. APOE and Alzheimer Disease Meta Analysis Consortium. JAMA 278, 1349–1356 (1997). sourceNot checked — no full text of the source

May combine two claims.

Individuals with subjective cognitive decline and APOEε4 carriers were more likely to advance to Alzheimer disease dementia if they had a high polygenic risk score (calculated without APOE), whereas a low polygenic risk score attenuated the APOEε4 effect size.

“Similarly, individuals with subjective cognitive decline and APOEε4 carriers were more likely to advance to AD dementia if they had a high PRS (calculated without APOE), whereas a low PRS attenuated the APOEε4 effect size22.”

• cites [22] Ebenau, J. L. et al. Risk of dementia in APOE ε4 carriers is mitigated by a polygenic risk score. Alzheimers Dement. 13, e12229 (2021). sourceNot checked yet

  Checked before — its earlier verdict is held back until a new check runs.

May combine two claims.

The observations on APOE and survival argue against underlying competing risks and suggest that as-yet-unknown mechanisms mediate the impact of APOE on survival.

“Together, these observations argue against underlying competing risks and suggest that as-yet-unknown mechanisms mediate the impact of APOE on survival.”

May combine two claims.

In several different Aβ plaque-depositing mice that are genetically engineered to express the human APOE isoforms instead of mouse APOE, APOE4 induces greater Aβ fibrillization and deposition in compact plaques relative to APOE3, whereas APOE2 markedly delays the onset and decreases the extent of Aβ plaque deposition.

“In several different Aβ plaque-depositing mice that are genetically engineered to express the human APOE isoforms instead of mouse APOE (Box 3), APOE4 induces greater Aβ fibrillization and deposition in compact plaques relative to APOE3, whereas APOE2 markedly delays the onset and decreases the extent of Aβ plaque deposition117–120.”

• cites [117] Fagan, A. M. et al. Human and murine ApoE markedly alters A beta metabolism before and after plaque formation in a mouse model of Alzheimer’s disease. Neurobiol. Dis. 9, 305–318 (2002). sourceNot checked — no full text of the source
• cites [118] Bales, K. R. et al. Apolipoprotein E is essential for amyloid deposition in the APP(V717F) transgenic mouse model of Alzheimer’s disease. Proc. Natl Acad. Sci. USA 96, 15233–15238 (1999). sourceNot checked — no full text of the source
• cites [119] Irizarry, M. C. et al. Apolipoprotein E affects the amount, form, and anatomical distribution of amyloid beta-peptide deposition in homozygous APP(V717F) transgenic mice. Acta Neuropathol. 100, 451–458 (2000). sourceNot checked — no full text of the source

May combine two claims.

Animal and cell models of tauopathies have revealed that APOE4 is associated with a greater burden of misfolded and hyperphosphorylated tau and more severe tau-induced neurodegeneration, both in the presence and in the absence of Aβ.

“Although for many years the effects of APOE on tau were assumed to be mediated through Aβ, animal and cell models of tauopathies have revealed that APOE4 is associated with a greater burden of misfolded and hyperphosphorylated tau and more severe tau-induced neurodegeneration, both in the presence and in the absence of Aβ125,126.”

• cites [125] Hou, T. et al. Apolipoprotein E facilitates amyloid-β oligomer-induced tau phosphorylation. J. Alzheimers Dis. 74, 521–534 (2020). sourceNot checked — no full text of the source
• cites [126] Harris, F. M., Brecht, W. J., Xu, Q., Mahley, R. W. & Huang, Y. Increased tau phosphorylation in apolipoprotein E4 transgenic mice is associated with activation of extracellular signal-regulated kinase: modulation by zinc. J. Biol. Chem. 279, 44795–44801 (2004). sourceNot checked — no full text of the source

May combine two claims.

Neuron-derived APOE has an important role, and a deeper understanding of how APOE differs by source cell type is needed.

“This work highlights the important role of neuron-derived APOE and underscores the need for a deeper understanding of the ways in which APOE differs on the basis of the source cell type.”

May combine two claims.

Astrocytic APOE has paracrine effects on microglia, and APOE is essential in astrocyte-microglia crosstalk.

“suggesting ‘paracrine’ effects of astrocytic APOE on microglia and supporting the idea that APOE is essential in astrocyte–microglia crosstalk.”

• AssumptionRests on an assumption: Astrocytes are the primary producers of APOE in the brain.

May combine two claims.

Data from the past 5 years on novel mouse models support a complex interplay among microglia, astrocytes and AD neuropathology, but more research is needed to fully understand this complexity.

“data from the past 5 years on novel mouse models support a complex interplay among microglia, astrocytes and AD neuropathology, but more research is needed to fully understand this complexity.”

Classified as probably not a substantial claim.

APOE4 constitutes a loss-of-function APOE variant with respect to BBB maintenance.

“These observations have led to the hypothesis that APOE4 constitutes a loss-of-function APOE variant with respect to BBB maintenance.”

May combine two claims.

APOE mimetics (small peptides homologous to the receptor-binding region of APOE) have been shown to prevent microglial reaction in vitro, as well as Aβ deposition and associated memory deficits in APOE4 plaque-depositing mice.

“Such APOE mimetics have been shown to prevent microglial reaction in vitro, as well as Aβ deposition and associated memory deficits in APOE4 plaque-depositing mice195,196.”

• cites [195] Christensen, D. J. et al. Apolipoprotein E and peptide mimetics modulate inflammation by binding the SET protein and activating protein phosphatase 2A. J. Immunol. 186, 2535–2542 (2011). sourceNot checked — no full text of the source
• cites [196] Krishnamurthy, K. et al. ApoE mimetic improves pathology and memory in a model of Alzheimer’s disease. Brain Res. 1733, 146685 (2020). sourceNot checked — no full text of the source

May combine two claims.

Peptide mimetics used to upregulate ABCA1 were shown to increase APOE4 lipidation and reduce Aβ deposition and cognitive deficits in APOE4 knock-in (but not APOE3 knock-in) plaque-depositing mice.

“peptide mimetics used to upregulate ABCA1 were shown to increase APOE4 lipidation and reduce Aβ deposition and cognitive deficits in APOE4 knock-in (but not APOE3 knock-in) plaque-depositing mice, indicating that directly targeting APOE lipidation is an effective therapeutic approach212”

• cites [212] Boehm-Cagan, A. et al. ABCA1 agonist reverses the ApoE4-driven cognitive and brain pathologies. J. Alzheimers Dis. 54, 1219–1233 (2016). sourceNot checked — no full text of the source