Apolipoprotein E abundance is elevated in the brains of individuals with Down syndrome–Alzheimer’s disease

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

DSAD is in part a result of triplication of the APP gene on Hsa21, which results in increased production of amyloid-β peptide and other APP gene products.

“and is in part a result of triplication of the amyloid precursor protein gene (APP) on Hsa21, which results in the increased production of the amyloid-β peptide and other APP gene products [12, 54].”

• cites [12] Doran E, Keator D, Head E, Phelan MJ, Kim R, Totoiu M et al (2017) Down syndrome, partial trisomy 21, and absence of Alzheimer’s disease: the role of APP. J Alzheimers Dis 56:459–470. https://doi.org/10.3233/JAD-160836 sourcePartly supported

  The Introduction (page unavailable) states that APP triplication in Down syndrome increases brain Aβ levels, and the Discussion links increased APP copy number to Alzheimer’s disease in Down syndrome. Our copy does not state that triplication increases production of other APP gene products. (LLM, conf=0.83)

  Experimental — accuracy not yet measured
• cites [54] Prasher VP, Farrer MJ, Kessling AM, Fisher EMC, West RJ, Barber PC et al (1998) Molecular mapping of alzheimer-type dementia in Down’s syndrome. Ann Neurol 43:380–383. https://doi.org/10.1002/ana.410430316 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

In DSAD, tau pathology develops faster in relation to amyloid-β than in AD in the general population.

“These include a faster development of tau pathology in relation to amyloid-β [72]”

• cites [72] Zammit MD, Betthauser TJ, McVea AK, Laymon CM, Tudorascu DL, Johnson SC et al (2024) Characterizing the emergence of amyloid and tau burden in Down syndrome. Alzheimers Dement 20:388–398. https://doi.org/10.1002/alz.13444 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

Evidence in preclinical models demonstrates that genes other than APP being in three copies modify aspects of DSAD, such as cognition and amyloid-β load.

“Evidence in preclinical models demonstrates that genes other than APP being in three copies modify aspects of DSAD, such as cognition and amyloid-β load [1, 50, 70]”

• cites [1] Alić I, Goh PA, Murray A, Portelius E, Gkanatsiou E, Gough G et al (2021) Patient-specific Alzheimer-like pathology in trisomy 21 cerebral organoids reveals BACE2 as a gene dose-sensitive AD suppressor in human brain. Mol Psychiatry 26:5766–5788. https://doi.org/10.1038/s41380-020-0806-5 sourcePartly supported

  The Results section (‘Trisomy of BACE2 skews non-amyloidogenic Aβ peptide ratios and suppresses AD-like pathology in organoids’; page unavailable) reports that removing the third BACE2 copy led to amyloid deposits in trisomy 21 cerebral organoids. This supports the claim about a gene other than APP modifying amyloid pathology in a preclinical model, but the paper does not demonstrate an effect on cognition. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [50] Mumford P, Tosh J, Anderle S, Wikberg EG, Lau G, Noy S et al (2022) Genetic mapping of APP and amyloid-β biology modulation by trisomy 21. J Neurosci 42:6453–6468. https://doi.org/10.1523/JNEUROSCI.0521-22.2022 sourcePartly supported

  The Conclusion reports that extra copies of chromosome 21 genes reduced brain amyloid-β accumulation in mouse models, supporting the amyloid-β part of the claim. The paper does not report that its models demonstrate a change in cognition; its discussion of cognitive deficits appears in references to other work. No page numbers are available in our copy. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [70] Wiseman FK, Pulford LJ, Barkus C, Liao F, Portelius E, Webb R et al (2018) Trisomy of human chromosome 21 enhances amyloid-β deposition independently of an extra copy of APP. Brain 141:2457–2474. https://doi.org/10.1093/brain/awy159 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

DSAD is the most commonly occurring single genetic cause of AD.

“Down syndrome–Alzheimer’s disease (DSAD) is the most commonly occurring single genetic cause of AD”

• cites [12] Doran E, Keator D, Head E, Phelan MJ, Kim R, Totoiu M et al (2017) Down syndrome, partial trisomy 21, and absence of Alzheimer’s disease: the role of APP. J Alzheimers Dis 56:459–470. https://doi.org/10.3233/JAD-160836 sourcePartly supported

  The Introduction links trisomy 21 and increased APP dosage in Down syndrome to Alzheimer’s disease, and the Discussion describes APP copy number as central to Alzheimer’s disease in Down syndrome. Neither section compares Down syndrome with other genetic causes or establishes that it is the most common single genetic cause. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [54] Prasher VP, Farrer MJ, Kessling AM, Fisher EMC, West RJ, Barber PC et al (1998) Molecular mapping of alzheimer-type dementia in Down’s syndrome. Ann Neurol 43:380–383. https://doi.org/10.1002/ana.410430316 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

By age 40 years, most individuals with DS will have developed Alzheimer's disease pathology, characterised by amyloid-β plaques and neurofibrillary tau tangles within the brain.

“By age 40 years, most individuals with DS will have developed Alzheimer’s disease (AD) pathology, characterised by the accumulation of amyloid-β plaques and neurofibrillary tau tangles (NFT) within the brain [17, 69].”

• cites [17] Fortea J, Zaman SH, Hartley S, Rafii MS, Head E, Carmona-Iragui M (2021) Alzheimer’s disease associated with Down syndrome: a genetic form of dementia. Lancet Neurol 20:930–942. https://doi.org/10.1016/S1474-4422(21)00245-3 sourceSupported
• cites [69] Wiseman FK, Al-Janabi T, Hardy J, Karmiloff-Smith A, Nizetic D, Tybulewicz VLJ et al (2015) A genetic cause of Alzheimer disease: mechanistic insights from Down syndrome. Nat Rev Neurosci 16:564–574. https://doi.org/10.1038/nrn3983 sourceSupported

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

By age 55 years, more than half of people with DS will have developed clinical dementia caused by AD, and by age 70 years, virtually all individuals with DS will have AD-dementia.

“By the age of 55 years, more than half of people with DS will have developed clinical dementia, caused by AD, and by age 70 years, virtually all individuals with DS will have AD-dementia [28, 33, 41, 47].”

• cites [28] Hithersay R, Startin CM, Hamburg S, Mok KY, Hardy J, Fisher EMC et al (2019) Association of dementia with mortality among adults with down syndrome older than 35 years. JAMA Neurol 76:152–160. https://doi.org/10.1001/jamaneurol.2018.3616 sourcePartly supported

  The Introduction reports a mean age of dementia diagnosis of 55 years and estimates that as many as 88% of people with Down syndrome develop dementia by 65. It does not establish that more than half have clinical dementia by 55 or that virtually all do by 70; its reference to near-universal Alzheimer disease neuropathology is not the same as clinical dementia. The Results also describe a participant who died at 73 without a dementia diagnosis. Page numbers are unavailable in our copy. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [33] Iulita MF, Garzón Chavez D, Klitgaard Christensen M, Valle Tamayo N, Plana-Ripoll O, Rasmussen SA et al (2022) Association of Alzheimer disease with life expectancy in people with Down syndrome. JAMA Netw Open 5:e2212910. https://doi.org/10.1001/jamanetworkopen.2022.12910 sourcePartly supported

  The Results (Systematic Review and Meta-analysis; page unavailable) give a pooled mean age of 53.8 years for onset of Alzheimer dementia in people with Down syndrome, but do not establish that more than half have developed it by age 55. The Introduction reports an Alzheimer disease risk above 90% by the seventh decade, and the Discussion suggests near-full penetrance; neither establishes that virtually all have clinical AD dementia by age 70. (LLM, conf=0.83)

  Experimental — accuracy not yet measured
• cites [41] Margallo-Lana ML, Moore PB, Kay DWK, Perry RH, Reid BE, Berney TP et al (2007) Fifteen-year follow-up of 92 hospitalized adults with Down’s syndrome: incidence of cognitive decline, its relationship to age and neuropathology. J Intellect Disabil Res 51:463–477. https://doi.org/10.1111/j.1365-2788.2006.00902.x sourceNot checked — no full text of the source
• cites [47] McCarron M, McCallion P, Reilly E, Dunne P, Carroll R, Mulryan N (2017) A prospective 20-year longitudinal follow-up of dementia in persons with Down syndrome. J Intellect Disabil Res 61:843–852. https://doi.org/10.1111/jir.12390 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

DSAD has an increased incidence of seizures compared with AD in the general population.

“and increased incidence of seizures [2]”

• cites [2] Altuna M, Giménez S, Fortea J (2021) Epilepsy in Down syndrome: a highly prevalent comorbidity. J Clin Med 10:2776. https://doi.org/10.3390/jcm10132776 sourceSupported

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

Recent transcriptomic studies have demonstrated changes in the inhibitory-to-excitatory neuronal ratio and microglial cell states in the brain of people with DS.

“Recent transcriptomic studies have begun to address this by systematically interrogating how the extra copy of Hsa21 alters transcript expression within the brain of people with DS, demonstrating changes in the inhibitory-to-excitatory neuronal ratio, and microglial cell states [49, 51].”

• cites [49] Miyoshi E, Morabito S, Henningfield CM, Das S, Rahimzadeh N, Shabestari SK et al (2024) Spatial and single-nucleus transcriptomic analysis of genetic and sporadic forms of Alzheimer’s disease. Nat Genet. https://doi.org/10.1038/s41588-024-01961-x sourcePartly supported

  The Results section (“ST and cellular transcriptomics of AD”; page not provided) reports shifts in cell-state composition, especially among microglia, in samples from people with Down syndrome and Alzheimer’s disease (DSAD). It identifies excitatory and inhibitory neurons but does not report a change in their ratio. The study also examined DSAD, not Down syndrome without Alzheimer’s disease. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [51] Palmer CR, Liu CS, Romanow WJ, Lee M-H, Chun J (2021) Altered cell and RNA isoform diversity in aging Down syndrome brains. Proc Natl Acad Sci 118:e2114326118. https://doi.org/10.1073/pnas.2114326118 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

These data are consistent with a previous report comparing bulk proteomics and bulk RNAseq in brain samples from young individuals with DS compared with euploid-matched controls, which also reported a discordance between transcript and protein levels.

“These data are consistent with a previous report comparing bulk proteomics and bulk RNAseq in brain samples from young individuals with DS compared with euploid-matched controls, which also reported a discordance between transcript and protein levels [56].”

• cites [56] Rastogi M, Bartolucci M, Nanni M, Aloisio M, Vozzi D, Petretto A et al (2024) Integrative multi-omic analysis reveals conserved cell-projection deficits in human Down syndrome brains. Neuron 112:2503-2523.e10. https://doi.org/10.1016/j.neuron.2024.05.002 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

Classified as probably not a substantial claim. May combine two claims.

Transcript expression data were normalised to adjust for differences in sequencing depth between cells and scaled to correct for cell-to-cell variation in total UMI count, and also normalised to remove confounding sources of variation such as mitochondrial mapping percentage, post-mortem delay, age of death, and batch number.

“Using SCTransform, transcript expression data were normalised to adjust for differences in sequencing depth between cells and scaled to correct for cell-to-cell variation in total UMI count [22]. Data were also normalised to remove confounding sources of variation such as mitochondrial mapping percentage, post-mortem delay, age of death, and batch number.”

• cites [22] Hafemeister C, Satija R (2019) Normalization and variance stabilization of single-cell RNA-seq data using regularized negative binomial regression. Genome Biol 20:296. https://doi.org/10.1186/s13059-019-1874-1 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

The isoform variation of APOE is associated with an increased risk of developing AD in the general population.

“The isoform variation of the protein is associated with an increased risk of developing AD in the general population [11, 16, 44].”

• cites [11] Deb S, Braganza J, Norton N, Williams H, Kehoe PG, Williams J et al (2000) APOE epsilon 4 influences the manifestation of Alzheimer’s disease in adults with Down’s syndrome. Br J Psychiatry J Ment Sci 176:468–472. https://doi.org/10.1192/bjp.176.5.468 sourcePartly supported

  The Abstract reports that APOE ε4 is associated with Alzheimer’s disease in adults with Down’s syndrome, and the Age of onset section calls it a risk factor in that group. The paper mentions possible effects of APOE status in the general population, but the passages do not establish the claimed increased risk of developing Alzheimer’s disease in that population. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [16] Fortea J, Pegueroles J, Alcolea D, Belbin O, Dols-Icardo O, Vaqué-Alcázar L et al (2024) APOE4 homozygosity represents a distinct genetic form of Alzheimer’s disease. Nat Med 30:1284–1291. https://doi.org/10.1038/s41591-024-02931-w sourceSupported
• cites [44] Martens YA, Zhao N, Liu C-C, Kanekiyo T, Yang AJ, Goate AM et al (2022) ApoE cascade hypothesis in the pathogenesis of Alzheimer’s disease and related dementias. Neuron 110:1304–1317. https://doi.org/10.1016/j.neuron.2022.03.004 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

APOE is a lipoprotein involved in the transport of cholesterol and phospholipids between cells.

“APOE is a lipoprotein involved in the transport of cholesterol and phospholipids between cells, and allelic variation in the APOE gene is a strong genetic risk factor for AD [16, 44].”

• cites [16] Fortea J, Pegueroles J, Alcolea D, Belbin O, Dols-Icardo O, Vaqué-Alcázar L et al (2024) APOE4 homozygosity represents a distinct genetic form of Alzheimer’s disease. Nat Med 30:1284–1291. https://doi.org/10.1038/s41591-024-02931-w sourceCould not verify

  The cited paper’s Results discuss APOE genotype and Alzheimer’s disease neuropathology, but the passages do not describe APOE as a lipoprotein or say that it transports cholesterol and phospholipids between cells. Searches for those terms and for apolipoprotein E’s role in lipid transport found no passage addressing the quoted claim. (LLM, conf=0.74)

  Experimental — accuracy not yet measured
• cites [44] Martens YA, Zhao N, Liu C-C, Kanekiyo T, Yang AJ, Goate AM et al (2022) ApoE cascade hypothesis in the pathogenesis of Alzheimer’s disease and related dementias. Neuron 110:1304–1317. https://doi.org/10.1016/j.neuron.2022.03.004 sourceSupported

May combine two claims.

APOE staining resembles the pattern of amyloid-β plaque pathology in DSAD and EOAD cases, with minimal staining in HA cases.

“As previously reported [39], APOE staining resembles the pattern of amyloid-β plaque pathology in DSAD and EOAD cases, with minimal staining in HA cases (Supplementary Fig. 9).”

• cites [39] Lemere CA, Blusztajn JK, Yamaguchi H, Wisniewski T, Saido TC, Selkoe DJ (1996) Sequence of deposition of heterogeneous amyloid β-peptides and APO E in Down syndrome: implications for initial events in amyloid plaque formation. Neurobiol Dis 3:16–32. https://doi.org/10.1006/nbdi.1996.0003 sourcePartly supported

  The ‘Temporal Sequence of Apo E Immunoreactivity’ section (page not specified) reports that Apo E plaque staining closely paralleled amyloid-β staining in Down syndrome cases. The Discussion (page not specified) also notes prior observations of Apo E in plaques in AD, but this paper does not establish the stated staining pattern specifically for EOAD or minimal staining in HA cases. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

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

APOE has a known key role in AD-related processes including amyloid-β clearance and aggregation, the immune response to pathology, tau pathology development, and the maintenance of cerebrovascular homeostasis.

“APOE has a known key role in AD-related processes including amyloid-β clearance and aggregation, the immune response to pathology, tau pathology development, and the maintenance of cerebrovascular homeostasis [44].”

• cites [44] Martens YA, Zhao N, Liu C-C, Kanekiyo T, Yang AJ, Goate AM et al (2022) ApoE cascade hypothesis in the pathogenesis of Alzheimer’s disease and related dementias. Neuron 110:1304–1317. https://doi.org/10.1016/j.neuron.2022.03.004 sourcePartly supported

  The Phenotypic phase section says apoE promotes Aβ aggregation and fibrillization, affects tau pathology and AD-related immune responses, and is associated with cerebrovascular dysfunction (page not available in our copy). These passages support most of the sentence, but the paper’s discussion does not establish the specifically attributed role in Aβ clearance; clearance appears in a reference title, not as a finding stated in the text. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

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

Previous reports have shown increased abundance of APP, S100B, and SYNJ1 in the frontal cortex and CSTB in the temporal cortex of people with DSAD.

“These findings were consistent with previous reports of increased abundance of APP (amyloid precursor protein), S100B (S100 calcium-binding protein B), and SYNJ1 (synaptojanin-1) in the frontal cortex and CSTB (cystatin-B) in the temporal cortex of people with DSAD [45, 58, 71].”

• cites [45] Martin SB, Dowling ALS, Lianekhammy J, Lott IT, Doran E, Murphy MP et al (2014) Synaptophysin and synaptojanin-1 in down syndrome are differentially affected by Alzheimer’s disease. J Alzheimers Dis 42:767–775. https://doi.org/10.3233/JAD-140795 sourcePartly supported

  The Introduction says the study measured SYNJ1 in frontal-cortex samples, and the Discussion reports higher SYNJ1 levels in DSAD than in DS alone. The sentence does not assign its three citations to individual proteins; judged as a whole, this paper does not establish increased frontal-cortex APP or S100B, or increased temporal-cortex CSTB, in DSAD. No page numbers are available in our copy. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [58] Sawa M, Overk C, Becker A, Derse D, Albay R, Weldy K et al (2022) Impact of increased APP gene dose in Down syndrome and the Dp16 mouse model. Alzheimers Dement 18:1203–1234. https://doi.org/10.1002/alz.12463 sourcePartly supported

  The Preliminary Findings (page unavailable) report increased full-length APP in frozen frontal-cortex samples from people with AD-DS compared with non-demented controls. The cited paper does not report the claimed increases in S100B or SYNJ1 in frontal cortex or CSTB in temporal cortex. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [71] Wu Y, Mumford P, Noy S, Cleverley K, Mrzyglod A, Luo D et al (2023) Cathepsin B abundance, activity and microglial localisation in Alzheimer’s disease-Down syndrome and early onset Alzheimer’s disease; the role of elevated cystatin B. Acta Neuropathol Commun 11:132. https://doi.org/10.1186/s40478-023-01632-8 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

A recent report in trisomy 21 iPSC-derived astrocytes showed upregulation of APP.

“consistent with a recent report in trisomy 21 iPSC-derived astrocytes that showed upregulation of APP [64].”

• cites [64] Thirumalai S, Livesey FJ, Patani R, Hung C (2025) APP antisense oligonucleotides are effective in rescuing mitochondrial phenotypes in human iPSC-derived trisomy 21 astrocytes. Alzheimers Dement 21:e14560. https://doi.org/10.1002/alz.14560 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

Allelic variation in the APOE gene is a strong genetic risk factor for AD.

“APOE is a lipoprotein involved in the transport of cholesterol and phospholipids between cells, and allelic variation in the APOE gene is a strong genetic risk factor for AD [16, 44].”

• cites [16] Fortea J, Pegueroles J, Alcolea D, Belbin O, Dols-Icardo O, Vaqué-Alcázar L et al (2024) APOE4 homozygosity represents a distinct genetic form of Alzheimer’s disease. Nat Med 30:1284–1291. https://doi.org/10.1038/s41591-024-02931-w sourceSupported
• cites [44] Martens YA, Zhao N, Liu C-C, Kanekiyo T, Yang AJ, Goate AM et al (2022) ApoE cascade hypothesis in the pathogenesis of Alzheimer’s disease and related dementias. Neuron 110:1304–1317. https://doi.org/10.1016/j.neuron.2022.03.004 sourceSupported

Classified as probably not a substantial claim.

Homeostatic processes can regulate the abundance of proteins, such that a raised level of a transcript does not always increase the abundance of the corresponding protein.

“Homeostatic processes can regulate the abundance of proteins, such that the raised level of a transcript does not always increase the abundance of the corresponding protein [8, 56, 59].”

• cites [8] Carlyle BC, Kitchen RR, Kanyo JE, Voss EZ, Pletikos M, Sousa AMM et al (2017) A multiregional proteomic survey of the postnatal human brain. Nat Neurosci 20:1787–1795. https://doi.org/10.1038/s41593-017-0011-2 sourcePartly supported

  The Results section on mRNA and protein abundance reports genes with regional RNA differences but no corresponding protein difference, supporting the claim that more transcript does not always mean more protein. The Discussion also says mRNA expression is an incomplete measure of protein abundance. Neither passage attributes this mismatch specifically to homeostatic processes; the paper discusses protein stability and localization instead. Page numbers were not supplied in our copy. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [56] Rastogi M, Bartolucci M, Nanni M, Aloisio M, Vozzi D, Petretto A et al (2024) Integrative multi-omic analysis reveals conserved cell-projection deficits in human Down syndrome brains. Neuron 112:2503-2523.e10. https://doi.org/10.1016/j.neuron.2024.05.002 sourcePartly supported

  The Results (page unavailable) show that mRNA and corresponding protein changes often differ in direction, supporting the point that a raised transcript level need not mean more protein. The Discussion (page unavailable) suggests posttranscriptional or posttranslational regulation, but does not establish that the processes responsible are homeostatic. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [59] Schwanhäusser B, Busse D, Li N, Dittmar G, Schuchhardt J, Wolf J et al (2011) Global quantification of mammalian gene expression control. Nature 473:337–342. https://doi.org/10.1038/nature10098 sourcePartly supported

  The Discussion (p. 15) reports that mRNA levels explain only about 40% of variation in protein levels and identifies translational control as important. The homeostasis discussion (p. 14) suggests that some homeostasis genes may be translationally regulated, but the paper does not show that an increase in a transcript is buffered so that its corresponding protein fails to increase; it says changes in translation rates under different conditions remain unclear. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

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

Quality control was performed to remove low-quality cells based on the number of detected genes and unique molecular identifiers, and cells with an unusually high number of UMIs, suggesting potential doublet events, were excluded using scDblFinder.

“Quality control was performed to remove low-quality cells based on the number of detected genes and unique molecular identifiers (UMIs). Cells with an unusually high number of UMIs, suggesting potential doublet events, were also excluded using scDblFinder [18].”

• cites [18] Germain P-L, Lun A, Garcia Meixide C, Macnair W, Robinson MD (2022) Doublet identification in single-cell sequencing data using scDblFinder. F1000Research. 10:979. https://doi.org/10.12688/f1000research.73600.2 sourcePartly supported

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

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

Raised abundance of CBR1 and PFKL in the brain of individuals with DSAD has recently been reported.

“Raised abundance of CBR1 (carbonyl reductase 1) and PFKL (6-phosphofructokinase) in the brain of individuals with DSAD has recently been reported [43].”

• cites [43] Martá-Ariza M, Leitner DF, Kanshin E, Suazo J, Giusti Pedrosa A, Thierry M et al (2025) Comparison of the amyloid plaque proteome in Down syndrome, early onset Alzheimer’s disease, and late-onset Alzheimer’s disease. Acta Neuropathol (Berl) 149:9. https://doi.org/10.1007/s00401-025-02844-z sourcePartly supported

  The Results section, under “Protein-coding genes present in Hsa21,” reports significant enrichment of CBR1 in Down syndrome non-plaque brain tissue. Our copy does not report raised PFKL abundance; searches for PFKL and 6-phosphofructokinase found no supporting passage. No page number is available in the indexed copy. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

Blood-brain barrier breakdown has been demonstrated to occur in AD in the general population.

“Blood–brain barrier breakdown has been demonstrated to occur in AD in the general population [63], but whether the blood–brain barrier is disrupted in DS or DSAD is currently unknown.”

• cites [63] Sweeney MD, Sagare AP, Zlokovic BV (2018) Blood–brain barrier breakdown in Alzheimer disease and other neurodegenerative disorders. Nat Rev Neurol 14:133–150. https://doi.org/10.1038/nrneurol.2017.188 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

In the context of AD, APOE has been shown to be upregulated in response to pathology in microglia undergoing a damage-associated immune response.

“In the context of AD, APOE has been shown to be upregulated in response to pathology in microglia undergoing a damage-associated immune response [38].”

• cites [38] Keren-Shaul H, Spinrad A, Weiner A, Matcovitch-Natan O, Dvir-Szternfeld R, Ulland TK et al (2017) A unique microglia type associated with restricting development of Alzheimer’s disease. Cell 169:1276-1290.e17. https://doi.org/10.1016/j.cell.2017.05.018 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

Recent PET imaging studies found no evidence that APOEε4 influences amyloid-β load in individuals with DSAD.

“However, recent PET imaging studies found no evidence that APOEε4 influences amyloid-β load in individuals with DSAD [6].”

• cites [6] Boerwinkle AH, Gordon BA, Wisch J, Flores S, Henson RL, Butt OH et al (2023) Comparison of amyloid burden in individuals with Down syndrome versus autosomal dominant Alzheimer’s disease: a cross-sectional study. Lancet Neurol 22:55–65. https://doi.org/10.1016/S1474-4422(22)00408-2 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

A previous report found no significant difference in the abundance of APOE in amyloid-β plaques in the hippocampus and surrounding entorhinal/temporal cortex, from cases of DSAD and EOAD.

“However, a previous report found no significant difference in the abundance of APOE in amyloid-β plaques in the hippocampus and surrounding entorhinal/temporal cortex, from cases of DSAD and EOAD [13].”

• cites [13] Drummond E, Kavanagh T, Pires G, Marta-Ariza M, Kanshin E, Nayak S et al (2022) The amyloid plaque proteome in early onset Alzheimer’s disease and Down syndrome. Acta Neuropathol Commun 10:53. https://doi.org/10.1186/s40478-022-01356-1 sourcePartly supported

  The Results section, “Proteins enriched in plaques in both EOAD and DS” (page unavailable), identifies APOE as one of the most abundant plaque proteins in both groups. The Methods section, “Laser capture microdissection for localized proteomics” (page unavailable), says plaques were sampled from hippocampal sections that included entorhinal and temporal cortex. Our copy does not report an APOE-specific test showing no significant difference in abundance between DS and EOAD plaques; the reported correlation across plaque proteins does not establish that result. (LLM, conf=0.82)

  Experimental — accuracy not yet measured

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

Recent natural history studies have highlighted evidence of accelerated AD progression in people who have DSAD, including a more rapid development of tau spread as measured by positron emission tomography and plasma phospho-tau217, and enhanced rates of cortical thinning, after normalising for amyloid-β accumulation.

“Recent natural history studies comparing the development of AD in the general population and DSAD have highlighted evidence of accelerated AD progression in people who have DSAD. This includes a more rapid development of tau spread as measured by positron emission tomography and plasma phospho-tau217 [60, 68, 72], and enhanced rates of cortical thinning [37], after normalising for amyloid-β accum”

• cites [60] Schworer EK, Zammit MD, Wang J, Handen BL, Betthauser T, Laymon CM et al (2024) Timeline to symptomatic Alzheimer’s disease in people with Down syndrome as assessed by amyloid-PET and tau-PET: a longitudinal cohort study. Lancet Neurol 23:1214–1224. https://doi.org/10.1016/S1474-4422(24)00426-5 sourcePartly supported

  The Results report tau-PET increases at successive neurofibrillary-tangle stages after amyloid-β positivity in adults with Down syndrome. The paper does not establish that tau spreads faster than in the general population at comparable amyloid accumulation, and it does not report plasma phospho-tau217. Cortical thinning is cited separately in the citing sentence, so it is not attributed to this source. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [68] Wisch JK, McKay NS, Boerwinkle AH, Kennedy J, Flores S, Handen BL et al (2024) Comparison of tau spread in people with Down syndrome versus autosomal-dominant Alzheimer’s disease: a cross-sectional study. Lancet Neurol 23:500–510. https://doi.org/10.1016/S1474-4422(24)00084-X 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 [72] Zammit MD, Betthauser TJ, McVea AK, Laymon CM, Tudorascu DL, Johnson SC et al (2024) Characterizing the emergence of amyloid and tau burden in Down syndrome. Alzheimers Dement 20:388–398. https://doi.org/10.1002/alz.13444 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 [37] Kennedy JT, Wisch JK, Dincer A, Roman J, Gordon BA, Handen B et al (2025) Decoding brain structure to stage Alzheimer’s disease pathology in Down syndrome. Alzheimers Dement. https://doi.org/10.1002/alz.14519 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

Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing).

Raised APOE leads to an increase in APP transcript expression in preclinical models via an effect on the transcription factor AP1.

“A previous report has indicated that raised APOE leads to an increase in APP transcript expression in preclinical models via an effect on the transcription factor AP1 [29].”

• cites [29] Huang Y-WA, Zhou B, Wernig M, Südhof TC (2017) ApoE2, ApoE3, and ApoE4 differentially stimulate APP transcription and Aβ secretion. Cell 168:427-441.e21. https://doi.org/10.1016/j.cell.2016.12.044 sourceSupported

May combine two claims.

In a recent proteomic report comparing the plaque and non-plaque-associated proteome of DSAD, EOAD, and LOAD cases, an 8-fold enrichment of APOE was observed in DSAD, and a 5.9-fold enrichment of APOE in EOAD was observed.

“In a recent proteomic report comparing the plaque and non-plaque-associated proteome of DSAD, EOAD, and LOAD cases, an 8-fold enrichment of APOE was observed in DSAD, and a 5.9-fold enrichment of APOE in EOAD was observed [43].”

• cites [43] Martá-Ariza M, Leitner DF, Kanshin E, Suazo J, Giusti Pedrosa A, Thierry M et al (2025) Comparison of the amyloid plaque proteome in Down syndrome, early onset Alzheimer’s disease, and late-onset Alzheimer’s disease. Acta Neuropathol (Berl) 149:9. https://doi.org/10.1007/s00401-025-02844-z sourceSupported

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

In DSAD, the effect of APOEε4 genotype on the age of onset of clinical features of disease and AD biomarkers is significant, but relatively modest compared with the effect of the genotype in LOAD, and may be limited to females.

“Notably, recent work has indicated that in DSAD, the effect of APOEε4 genotype on the age of onset of clinical features of disease and AD biomarkers is significant, but relatively modest compared with the effect of the genotype in LOAD, and may be limited to females [5, 20, 32].”

• cites [5] Bejanin A, Iulita MF, Vilaplana E, Carmona-Iragui M, Benejam B, Videla L et al (2021) 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. https://doi.org/10.1001/jamaneurol.2021.1893 sourcePartly supported

  The Results (Clinical and Neuropsychological Findings; page not available) report that APOE ε4 carriers with Down syndrome received a symptomatic AD diagnosis about two years earlier than noncarriers; the Discussion also reports earlier biomarker changes. The paper does not establish that this effect is smaller than in late-onset AD or that it may be limited to females. It reports a similar association with AD processes in the general population, but does not compare effect sizes or show a female-specific clinical effect. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [20] Gorijala P, Aslam MM, Dang L-HT, Xicota L, Fernandez MV, Sung YJ et al (2024) Alzheimer’s polygenic risk scores are associated with cognitive phenotypes in Down syndrome. Alzheimers Dement J Alzheimers Assoc 20:1038–1049. https://doi.org/10.1002/alz.13506 sourcePartly supported

  The Results section (page not specified) reports significant associations of APOE ε4 carrier status with several CSF biomarkers in Down syndrome, and the Discussion links APOE ε4 to poorer memory scores. The cited paper does not establish an effect on the age of onset of clinical features or biomarkers, compare the magnitude of an onset effect with LOAD, or report that the effect may be limited to females. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [32] Iulita MF, Bejanin A, Vilaplana E, Carmona-Iragui M, Benejam B, Videla L et al (2023) Association of biological sex with clinical outcomes and biomarkers of Alzheimer’s disease in adults with Down syndrome. Brain Commun 5:fcad074. https://doi.org/10.1093/braincomms/fcad074 sourcePartly supported

  The Results section reports that female APOE ε4 carriers with Down syndrome were diagnosed about three years earlier than female non-carriers (P = 0.01), with no corresponding difference in males. It also reports exploratory biomarker differences, but does not establish a significant effect on the age of onset of biomarkers or compare the magnitude of the effect with LOAD. The biomarker results include trends in males, so they do not establish that the effect is limited to females. Page numbers were not provided in our copy. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

One study has highlighted that plasma GFAP (produced by astrocytes), raised in response to amyloid-β accumulation in the brain, may contribute to the more rapid development of tau pathology.

“One study has highlighted that plasma GFAP (produced by astrocytes), raised in response to amyloid-β accumulation in the brain, may contribute to the more rapid development of tau pathology [7].”

• cites [7] Boerwinkle AH, Wisch JK, Handen BL, Head E, Mapstone M, Rafii MS et al (2025) The mediating role of plasma glial fibrillary acidic protein in amyloid and tau pathology in Down’s syndrome. Alzheimers Dement 21:e14359. https://doi.org/10.1002/alz.14359 sourceSupported

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

People with DSAD have a significant burden of cerebral amyloid angiopathy (CAA), with more severe CAA found than in sporadic AD.

“People with DSAD have a significant burden of cerebral amyloid angiopathy (CAA), with more severe CAA found than in sporadic AD [25, 40].”

• cites [25] Head E, Phelan MJ, Doran E, Kim RC, Poon WW, Schmitt FA et al (2017) Cerebrovascular pathology in Down syndrome and Alzheimer disease. Acta Neuropathol Commun 5:93. https://doi.org/10.1186/s40478-017-0499-4 sourceSupported
• cites [40] Mann DMA, Davidson YS, Robinson AC, Allen N, Hashimoto T, Richardson A et al (2018) Patterns and severity of vascular amyloid in Alzheimer’s disease associated with duplications and missense mutations in APP gene, Down syndrome and sporadic Alzheimer’s disease. Acta Neuropathol (Berl) 136:569–587. https://doi.org/10.1007/s00401-018-1866-3 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

APOE is sequestered in amyloid-β plaques within the brain, including in individuals with DSAD.

“Previous studies have shown that APOE is sequestered in amyloid-β plaques within the brain, including in individuals with DSAD [3, 13], similar to what we have observed (Supplementary Fig. 9).”

• cites [3] Arai Y, Mizuguchi M, Ikeda K, Takashima S (1995) Developmental changes of apolipoprotein E immunoreactivity in Down syndrome brains. Dev Brain Res 87:228–232. https://doi.org/10.1016/0165-3806(95)00066-M sourceNot checked — no full text of the source
• cites [13] Drummond E, Kavanagh T, Pires G, Marta-Ariza M, Kanshin E, Nayak S et al (2022) The amyloid plaque proteome in early onset Alzheimer’s disease and Down syndrome. Acta Neuropathol Commun 10:53. https://doi.org/10.1186/s40478-022-01356-1 sourceSupported

May combine two claims.

Increased expression of Hsa21 genes that also had elevated protein levels, as well as other Hsa21 genes not identified by mass spectrometry, was found in DSAD cases compared with euploid controls.

“We found increased expression of the Hsa21 genes that also had elevated protein levels in our proteomic study, as well as other Hsa21 genes that we did not identify by mass spectrometry in our proteomic analysis, in DSAD cases compared with euploid controls (Fig. 2m, n).”

May combine two claims.

There was a significant effect of age at death, and a negative correlation between age at death and APOE abundance in posterior cingulate cortex samples.

“No significant difference in APOE abundance was identified between YC and DS cases using either antibody, but we find a significant effect of age at death, and a negative correlation between age at death and APOE abundance in these samples (Supplementary Fig. 7a–f).”

May combine two claims.

When the three technical outliers were removed, a significant effect of case type on APOE abundance (Calbiochem) remained, with DSAD significantly higher than EOAD.

“When removed from univariate ANOVA analysis, we continued to see a significant effect of case type on APOE abundance (Calbiochem) [Univariate ANOVA, F(2,40) = 5.005, p = 0.011)] with DSAD being significantly higher than EOAD (post hoc correction with Bonferroni, p = 0.010).”

• AssumptionRests on an assumption: The anti-APOE antibodies used in western blot specifically detect APOE.

May combine two claims.

64 unique peptides mapped to APOE, and 16 of these were significantly elevated in DSAD cases.

“We identified 64 unique peptides that mapped to APOE, and 16 of these were significantly elevated in DSAD cases”

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

RIN was variable but was not affected by age, sex or PMI.

“RIN was variable but was not affected by age, sex or PMI.”

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

After quality control preprocessing, 89,649 nuclei were recovered across all samples, and 38 molecularly unique clusters were identified.

“After quality control preprocessing, we recovered a total of 89,649 nuclei across all samples of which we identified a total of 38 molecularly unique clusters (Fig. 2a).”

May combine two claims.

S100B had increased expression in astrocytes and OPCs, and PFKL in a subtype of astrocytes, OPCs, and excitatory neurons.

“S100B had increased expression in astrocytes and OPCs, and PFKL in a subtype of astrocytes, OPCs, and excitatory neurons (Fig. 2m, n).”

May combine two claims.

APOE abundance was higher in DS than in LOAD (Sigma antibody only), with values comparable to the DSAD group.

“However, we show that APOE abundance is higher in DS than in LOAD (Sigma antibody only), with values comparable to the DSAD group (Fig. 3h).”

• AssumptionRests on an assumption: The anti-APOE antibodies used in western blot specifically detect APOE.

May combine two claims.

APOE expression was upregulated in endothelial, pericytic, and astrocytic nuclei in DSAD compared to EOAD, and in a second subtype of astrocytes in DSAD compared to HA.

“This analysis identified that APOE expression was upregulated in endothelial (CD34 expressing, Fig. 2j), pericytic (PDGFRB expressing, Fig. 2f), and astrocytic (AQP4, ALDH1L or GFAP expressing, Fig. 2h) nuclei in DSAD compared to EOAD, and in a second subtype of astrocytes in DSAD compared to HA (Fig. 2n).”

May combine two claims.

Although CCT8 and USP16 were not observed to have changed abundance at the protein level, expressions of these Hsa21 genes were elevated in several cell types in DSAD cases.

“Although CCT8 and USP16 were not observed to have changed abundance at the protein level (Supplementary Information 1), expressions of these Hsa21 genes were elevated in several cell types in the cases of DSAD”

May combine two claims.

5 proteins were commonly upregulated, and 13 proteins were commonly downregulated, in DSAD compared with HA, and EOAD compared with HA.

“Our analysis found 5 proteins that were commonly upregulated, and 13 proteins that were commonly downregulated, in DSAD compared with HA, and EOAD compared with HA”

Probably not a substantial claim: may not pass S3 (load-bearing).

RIN was also affected by Braak and Braak NFT stage [univariate ANOVA, F(1,35) = 5.453, p = 0.025].

“RIN was also affected by Braak and Braak NFT stage [univariate ANOVA, F(1,35) = 5.453, p = 0.025].”

May combine two claims.

CSTB was found to have elevated expression in subtypes of astrocytes, and PDKX was raised in a broad range of cell types.

“Of the Hsa21 proteins we identified to have increased abundance in our proteomic study, CSTB was found to have elevated expression in subtypes of astrocytes, and PDKX was raised in a broad range of cell types (Fig. 2m, n).”

May combine two claims.

Three cases had significantly lower total protein abundance than other cases, resulting in three technical outliers (ROUT Q=1%), two in DSAD and one in HA, with higher abundances.

“For western blots carried out on the discovery and validation A cohorts of HA, DSAD, and EOAD samples, three cases had significantly lower total protein abundance than other cases. This resulted in three technical outliers (as measured by the ROUT method Q = 1%) for these western blots, two in the DSAD group, and one in the HA group, with higher abundances than other samples.”

May combine two claims.

Considerable overlap in altered pathways was observed between DSAD vs HA and EOAD vs HA, including upregulation of neutrophil degranulation and mitochondrial dysfunction, and downregulation of oxidative phosphorylation.

“Considerable overlap in the pathways altered was observed when comparing DSAD with HA, and EOAD with HA, including upregulation of both neutrophil degranulation and mitochondrial dysfunction, and a downregulation of oxidative phosphorylation (Supplementary Fig. 1).”

May combine two claims.

Differential transcript expression identified increased transcriptomic variability in astrocytic and excitatory neuron clusters of DSAD compared to EOAD and HA groups, with fewer but significant changes in microglia, isolated oligodendrocytes, and OPCs clusters.

“Differential transcript expression identified increased transcriptomic variability in the astrocytic and excitatory neuron clusters of DSAD when compared to EOAD and HA groups, with fewer but significant changes in transcript expression seen in microglia, isolated oligodendrocytes, and OPCs clusters (Fig. 2l).”

May combine two claims.

When outliers removed, a significant effect of case type on APOE abundance (Sigma) remained, with APOE higher in DSAD than EOAD, and lower in EOAD than HA.

“We also continue to see a significant effect of case type on APOE abundance (Sigma) [Univariate ANOVA, F(2, 43) = 15.386, p < 0.001] with APOE being significantly higher in DSAD than EOAD (post hoc correction with Bonferroni, p < 0.001), and APOE being significantly lower in EOAD than HA (post hoc correction with Bonferroni, p = 0.011).”

• AssumptionRests on an assumption: The anti-APOE antibodies used in western blot specifically detect APOE.

Probably not a substantial claim: may not pass S3 (load-bearing).

APOE abundance in the partial trisomy case without the APP gene region was comparable to DS and DSAD.

“As only one case of partial trisomy 21 was included, conclusions on APOE abundance in this individual cannot be made; however, APOE abundance in this sample was comparable to DS and DSAD (Supplementary Fig. 8).”

May combine two claims.

In the frontal cortex of DSAD and EOAD cases, the abundances of full-length APP, APP-CTF-α, and APP-CTF-β each positively correlated with APOE abundance.

“We found that the abundance of full-length APP, APP-CTF-α, and APP-CTF-β, positively correlated with the abundance of APOE in the frontal cortex in cases of DSAD and EOAD (Fig. 4h–j).”

• Also stated in: § APOE abundance correlates with the abundance of APP, APP-CTFs, and amyloid-β, in the frontal cortex of DSAD and EOAD cases · plain

  “We also found these positive correlations with APOE (Sigma) by western blot (Supplementary Table 4).”

• Also stated in: § Conclusion · plain

  “Moreover, we observe a correlation between APP gene products and APOE in DSAD and EOAD.”

• AssumptionRests on an assumption: Full-length APP is processed in the brain into APP-CTF-α, APP-CTF-β, amyloid-β40, and amyloid-β42, which accumulate in plaques in AD and DSAD.

May combine two claims.

The EOAD cases studied here have unchanged APP and amyloid-β40 abundance, but elevated amyloid-β42 abundance compared to HA controls.

“Whereas our data indicate that the EOAD cases studied here have unchanged APP and amyloid-β40 abundance, but elevated amyloid-β42 abundance compared to HA controls.”

May combine two claims.

In western blots on validation cohort B, the Calbiochem antibody showed no difference between DS and LOAD samples, but the Sigma antibody showed that DS cases have a significantly higher abundance of APOE than LOAD.

“In our western blots on validation cohort B, we see varying results between these antibodies, with the Calbiochem antibody showing no difference between DS and LOAD samples, but the Sigma antibody showing that DS cases have a significantly higher abundance of APOE than LOAD.”

May combine two claims.

Trisomy 21 alters both the transcriptome and proteome of people with DS in the context of AD.

“Overall, these data highlight that trisomy 21 alters both the transcriptome and proteome of people with DS in the context of AD”

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

DSAD shares many features of AD in the general population, but the additional copy of Hsa21 alters cellular and molecular processes, resulting in differences in some aspects of the disease.

“DSAD shares many features of AD in the general population, but the additional copy of Hsa21 alters cellular and molecular processes, resulting in differences in some aspects of the disease.”

May combine two claims.

In these groups, only one APOE ε2ε2, one ε2ε3, and two ε2ε4 cases were included, and the study was underpowered to assess the effects of these genotypes on APOE abundance.

“In these groups, only one APOE ε2ε2, one APOE ε2ε3, and two APOE ε2ε4 cases were included, and so, we were underpowered to assess the effects of these genotypes on APOE abundance (Fig. 3l, m).”

Probably not a substantial claim: may not pass S3 (load-bearing).

Age at death was significantly higher in HA cases compared to both DSAD and EOAD groups in validation cohort A.

“Age at death was significantly higher in HA cases compared to both DSAD and EOAD groups.”

Classified as probably not a substantial claim. May combine two claims.

When ANOVA was used for analysis, sex and case type (HA, EOAD, or DSAD) were used as variables, and age at death and post-mortem interval as covariates.

“When ANOVA was used for analysis, sex and case type (HA, EOAD, or DSAD) were used as variables, and age at death and post-mortem interval (PMI) as covariates.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Sample loading order was randomised for western blot.

“Sample loading order was randomised.”

Classified as probably not a substantial claim.

Individual post-mortem brain donor was used as the unit of replication.

“Individual post-mortem brain donor was used as the unit of replication.”

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

Post-mortem interval was significantly different in validation cohort B between DS cases compared to either DSAD or LOAD cases, and YC cases compared to either DSAD or LOAD.

“A significant difference in PMI [Univariate ANOVA, F(3,28) = 16.683, p < 0.001] was identified between DS cases compared to either DSAD or LOAD cases (Bonferroni correction p < 0.001), and YC cases compared to either DSAD or LOAD (Bonferroni corrections p = 0.003)”

Classified as probably not a substantial claim.

To control for multiple comparisons, post hoc pairwise comparisons with Bonferroni correction (for three comparisons) were made for all proteins with a main effect of case type.

“To control for multiple comparisons, post hoc pairwise comparisons with Bonferroni correction (for three comparisons) were made for all proteins with a main effect of case type.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The validation cohort A group size (ten cases per group) was determined by power calculation from experimentally observed effect size and standard deviation for raised APOE abundance observed by mass spectrometry in the discovery cohort (power 80%, α = 0.05).

“This group size was determined by power calculation from experimentally observed effect size and standard deviation for raised APOE abundance observed by mass spectrometry in the discovery cohort (power 80%, α = 0.05).”

Probably not a substantial claim: may not pass S3 (load-bearing).

No significant difference in post-mortem interval was found between case types in validation cohort A.

“No significant difference in PMI [Univariate ANOVA, F(2,27) = 0.008, p = 0.992] was found between case types”

Classified as probably not a substantial claim.

Samples were selected with advice from each brain bank on sample availability for matching age at death, sex, Braak and Braak stage, and APOE genotype across case types.

“Samples were selected with advice from each brain bank on sample availability for matching age at death, sex, Braak and Braak stage, and APOE genotype across case types.”

May combine two claims.

No significant difference in age at death or post-mortem interval was found between the three case types in the discovery cohort.

“No significant difference in age at death [Univariate ANOVA, F(2,13) = 2.640, p = 0.109] or PMI [Univariate ANOVA, F(2,13) = 0.698, p = 0.515] was found between case types”

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

Less than 5000 nuclei were obtained from four cases (two DSAD, two EOAD), but these cases were included to maintain a balanced sample size.

“Less than 5000 nuclei were obtained from four cases; two DSAD cases (DSAD6, DSAD8) and two EOAD cases (EOAD2, EOAD3), but we have included these cases in our analysis to maintain a balanced sample size (Fig. 2b, Supplementary Information 2).”

Classified as probably not a substantial claim.

All cases were matched as far as possible for age at death, sex, Braak and Braak stage, and APOE genotype.

“All cases were matched as far as possible for age at death, sex, Braak and Braak stage, and APOE genotype.”

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

Unique identification numbers were assigned to all samples to ensure the study remained blind and for technical randomisation during data acquisition and analysis.

“Unique identification numbers were assigned to all samples to ensure the study remained blind and for technical randomisation during data acquisition and analysis.”

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

Case EOAD4 was excluded from discovery analysis due to poor chromatographic separation of peptides; however, it was included in all subsequent studies.

“Case EOAD4 was excluded from discovery analysis due to poor chromatographic separation of peptides; however, it was included in all subsequent studies.”

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

For multiple cell types, less than 10 nuclei were recovered from some cases; thus, any identified differential expression should be treated as preliminary and requires independent validation.

“We noted that for multiple cell types, less than 10 nuclei were recovered from some cases; thus, any identified differential expression should be treated as preliminary and requires independent validation (Fig. 2a, b, Supplementary Information 2).”

Classified as probably not a substantial claim. May combine two claims.

All samples were normalised against the average HA or YC control value within a blot, and a minimum of two technical replicates per sample were averaged.

“All samples were normalised against the average HA or YC control value within a blot. A minimum of two technical replicates per sample were then averaged.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Linearity of signal was experimentally determined for western blot.

“Linearity of signal was experimentally determined.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Group sizes for the DSAD and LOAD groups in validation cohort B were determined by power calculation from experimentally observed effect size and standard deviation for raised APOE abundance by western blot in validation cohort A (power 80%, α = 0.05).

“Group sizes for the DSAD and LOAD groups were determined by power calculation from experimentally observed effect size and standard deviation for raised APOE abundance by western blot in validation cohort A (power 80%, α = 0.05).”

Probably not a substantial claim: may not pass S3 (load-bearing).

Analysis including APOE genotype as a variable for APOE abundance by western blot and mass spectrometry was exploratory because of a low number of cases, particularly of APOE ɛ2ɛ3 and ɛ2ɛ4 alleles.

“We also repeated our analysis including APOE genotype as a variable for the analysis of APOE abundance by western blot and mass spectrometry, but note that this is exploratory as we had a low number of cases, particularly of APOE ɛ2ɛ3 and ɛ2ɛ4 alleles, in this case series.”

May combine two claims.

Overall, trisomy of chromosome 21 may alter the biology of a subtype of astrocytes in the context of AD pathology, and both AD pathology and trisomy of chromosome 21 may affect the biology of endothelial cells.

“Overall, this analysis indicates that trisomy of chromosome 21 may alter the biology of a subtype of astrocytes in the context of AD pathology, and both AD pathology and trisomy of chromosome 21 may affect the biology of endothelial cells.”

May combine two claims.

Upregulation of LRP1, ATOX1, and EIF4E is likely driven by trisomy 21.

“indicating that their upregulation is likely to be driven by trisomy 21.”

Probably not a substantial claim: may not pass S3 (load-bearing).

RNA integrity was not found to correlate with the number of nuclei recovered (Pearson's R = 0.2255 p = 0.4382).

“RNA integrity was not found to correlate with the number of nuclei recovered (Pearson’s R = 0.2255 p = 0.4382) (Supplementary Table 2).”

May combine two claims.

Age at death was significantly different between the groups in validation cohort B, with YC and DS groups being significantly younger than both DSAD and LOAD groups, and DSAD also being significantly younger than LOAD.

“Age at death was significantly different between the groups, with YC and DS groups being significantly younger than both DSAD and LOAD groups, and DSAD also being significantly younger than LOAD (Table 3).”

May combine two claims.

A few Hsa21 genes have significantly altered expression between EOAD and HA in both the proteomic and transcriptomic datasets, showing the specific effect of three copies of Hsa21 on the expression of genes on this chromosome.

“A few Hsa21 genes have significantly altered expression between EOAD and HA in both the proteomic and transcriptomic datasets, showing the specific effect of three copies of Hsa21 on the expression of genes on this chromosome (Supplementary Fig. 3, Table 4).”

Classified as probably not a substantial claim.

EOAD cases of unknown genetic cause were chosen to match age at death of individuals with DSAD, to remove age discrepancy as a confounding factor when comparing the AD-associated proteome or transcriptome.

“EOAD cases of unknown genetic cause were chosen to match age at death of individuals with DSAD, to remove age discrepancy as a confounding factor when comparing the AD-associated proteome or transcriptome.”

Probably not a substantial claim: may not pass S3 (load-bearing).

In western blot validation cohort B, only DSAD and LOAD cases were included in APOE genotype analysis because APOE genotype data were not available for YC or DS cases.

“In our western blot study of validation cohort B, we did not have APOE genotype data on YC or DS cases, and so, only DSAD and LOAD cases were included in the analysis.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Other genes on Hsa21 may also contribute to altered APOE abundance in addition to the correlative relationship between APP and APOE.

“Thus, in addition to the correlative relationship between APP and APOE we observe in our dataset, other genes on Hsa21 may also contribute to altered APOE abundance.”

May combine two claims.

The study design allowed identification of unique trisomy 21-driven changes, including the upregulation of APOE in the brains of people with DSAD compared with euploid individuals with EOAD or LOAD.

“Our study design allowed us to identify unique trisomy 21-driven changes, including the upregulation of APOE in the brains of people with DSAD compared with euploid individuals with EOAD or LOAD.”

May combine two claims.

Differences in the abundance of a subset of proteins occur in DSAD compared with EOAD in the general population, but common pathways are disrupted in both forms of disease.

“Together, our data indicate that differences in the abundance of a subset of proteins occur in DSAD compared with EOAD in the general population, but that common pathways are disrupted in both forms of disease.”

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

In the tissues studied, substantial changes will have occurred, including changes to the abundance of cell types particularly as a result of neuronal loss, which may confound the bulk analysis of protein abundance.

“In these tissues, substantial changes will have occurred, including changes to the abundance of cell types particularly as a result of neuronal loss. This may confound the bulk analysis of protein abundance presented here.”

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

All cases were end-stage AD, so a possible role of elevated APOE earlier in AD development cannot be ruled out.

“but note that all our cases were end-stage AD, so a possible role of elevated APOE earlier in the AD development cannot be ruled out.”

May combine two claims.

LOAD cases were not included in the omics experiments or initial validation studies, so comparisons between EOAD and LOAD were not possible.

“However, as LOAD cases were not included in our omics experiments or our initial validation studies, we were not able to make comparisons between EOAD and LOAD.”

Probably not a substantial claim: may not pass S2 (checkable). May combine two claims.

The data provide new insight into DSAD biology and expose some differences from AD in the general population.

“Our data provide new insight into DSAD biology and expose some differences from AD in the general population.”

Probably not a substantial claim: may not pass S3 (load-bearing).

High numbers of nuclei were not recovered for all cell types for all cases, which may bias the observed differentially expressed genes.

“In addition, we did not recover high numbers of nuclei for all cell types for all cases, which may bias the observed differentially expressed genes.”

May combine two claims.

In the proteomic dataset, Bonferroni corrected pairwise comparisons were used for proteins with a main effect of case type in ANOVA, rather than FDR q value, which elevates the risk of type I error compared with a more conservative FDR analytical approach.

“In our proteomic dataset, to minimise our risk of type II error, we use Bonferroni corrected pairwise comparisons for proteins observed to have a main effect of case type in our ANOVA, rather than the False Discovery Rate (FDR) q value. This approach elevates the risk of type I error in our proteomic study compared with a more conservative FDR analytical approach.”

May combine two claims.

The proteomic method identified 2855 proteins, including 23 encoded by Hsa21, representing only around 10-15% of the human proteome, and thus many differences in protein abundance are likely not observed within this dataset.

“The proteomic method used here identified 2855 proteins, including 23 encoded by Hsa21, representing only around 10–15% of the human proteome, and thus, because of this technical limitation, many differences in protein abundance are likely to not be observed within this dataset.”

May combine two claims.

The changes in DSAD include not only upregulation of transcripts and proteins encoded on Hsa21, such as APP/APP, but also wider dysregulation of the transcriptome and proteome beyond Hsa21, as exemplified by increased APOE/APOE abundance.

“These changes include not only the upregulation of transcripts and proteins encoded on Hsa21, such as APP/APP, but a wider dysregulation of the transcriptome and proteome beyond Hsa21, as exemplified by the increase in APOE/APOE abundance in DSAD.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Neuropathological evidence indicates that APOEε4 results in higher amyloid-β deposition in people with DSAD.

“Neuropathological evidence indicates that APOEε4 results in higher amyloid-β deposition in people with DSAD [31].”

• cites [31] Hyman BT, West HL, Rebeck GW, Buldyrev SV, Mantegna RN, Ukleja M et al (1995) Quantitative analysis of senile plaques in Alzheimer disease: observation of log-normal size distribution and molecular epidemiology of differences associated with apolipoprotein E genotype and trisomy 21 (Down syndrome). Proc Natl Acad Sci U S A 92:3586–3590. https://doi.org/10.1073/pnas.92.8.3586 sourceNot checked — no full text of the source

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

The snRNAseq transcriptomic study analysed the transcriptome of 89,649 nuclei from 16 cases, but nuclei recovery was less than 5000 for two of the four cases of EOAD, and two of the eight cases of DSAD.

“Our snRNAseq transcriptomic study analysed the transcriptome of 89,649 nuclei from 16 cases, but nuclei recovery was less than 5000 for two of the four cases of EOAD, and two of the eight cases of DSAD in our dataset.”

Classified as probably not a substantial claim. May combine two claims.

The study size is small, and a larger study of further cases with greater representation of ε2 and ε4 APOE alleles is required to verify the finding of no relationship between APOE genotype and APOE abundance.

“However, our study size is small and a larger study of further cases with greater representation of ε2 and ε4 APOE alleles is required to verify this finding.”

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

Validation cohort B has a relatively small sample size in the YC and DS groups, which may contribute to the difference between antibodies.

“Validation cohort B has a relatively small sample size in the YC and DS groups, which may contribute to this difference and further data are required to determine if APOE abundance differs between case types.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

The increased amyloid-β40 in DSAD is likely caused by increased production of this fragment due to trisomy 21.

“likely caused by the increased production of this fragment due to trisomy 21.”

• AssumptionRests on an assumption: Full-length APP is processed in the brain into APP-CTF-α, APP-CTF-β, amyloid-β40, and amyloid-β42, which accumulate in plaques in AD and DSAD.

Classified as probably not a substantial claim.

Two independent APOE antibodies were used to validate the finding of increased APOE abundance in DSAD.

“In this study, we used two independent APOE antibodies to validate our finding of increased APOE abundance in DSAD.”

May combine two claims.

Changes that occur during the earliest phases of disease will not be observed in the study, and thus the correlative relationships observed may not reflect all mechanisms important to disease development.

“Moreover, changes that occur during the earliest phases of disease will not be observed in our study, and thus, the correlative relationships we observe here may not reflect all mechanisms important to disease development.”