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@INPROCEEDINGS{RodrguezBaz:283150,
author = {Rodríguez-Baz, Íñigo and Bernhardt, Alexander M and
Aldecoa, Iban and Arranz, Javier and Arriola-Infante, José
Enrique and Maure-Blesa, Lucía and Carmona-Iragui, Maria
and Longen, Sebastian and Trossbach, Svenja Verena and
Giese, Armin and Matthias, Torsten and Benejam, Bessy and
Videla, Laura and Hoyo, Laura Del and Barroeta, Isabel and
Hernandez, Aida Sanjuan and Fernandez, Susana and
Vaqué-Alcázar, Lídia and Aranha, Mateus Rozalem and
Morcillo-Nieto, Alejandra O and Nübling, Georg and
Wagemann, Olivia and Stockbauer, Anna and Tondo, Mireia and
Bejanin, Alexandre and Lleó, Alberto and Alcolea, Daniel
and Molina, Laura and Fortea, Juan and Levin, Johannes},
title = {{A}lpha-{S}ynuclein {P}athology in {D}own
{S}yndrome-{A}ssociated {A}lzheimer's {D}isease: {I}nsights
from {S}eed {A}mplification {A}ssay and {N}europathology},
journal = {Alzheimer's and dementia},
volume = {21},
number = {S2},
issn = {1552-5260},
reportid = {DZNE-2026-00046},
pages = {e106390},
year = {2025},
abstract = {Down syndrome (DS) is a genetic cause of Alzheimer's
disease (AD), with virtually all individuals developing AD
pathology by their fourth decade due to Amyloid Precursor
Protein (APP) gene overexpression. In addition to amyloid
beta (Aβ) plaques and hyperphosphorylated tau (p-Tau)
aggregates, DS-associated AD (DSAD) often includes
α-synuclein (αSyn) aggregates, contributing to Lewy body
pathology (LBP). The αSyn Seed Amplification Assay (SAA) in
cerebrospinal fluid (CSF) enables the in vivo detection of
misfolded αSyn. While αSyn-SAA has revealed αSyn
pathology in autosomal dominant $(6\%-11\%)$ and sporadic
$(21\%-45\%)$ AD, its role in DSAD remains unexplored. This
study investigates αSyn-SAA positivity in DSAD, linking in
vivo findings to fluid biomarkers and neuropathology.We
analyzed CSF of 270 adults with DS from the DABNI and AD21
cohorts by αSyn-SAA, encompassing asymptomatic and
symptomatic AD stages (prodromal/dementia). Additional
biomarkers included CSF Aβ1-42/1-40, CSF and plasma
p-Tau181 and neurofilament light chain (NfL) levels.
Neuropathological evaluations in 19 brain donors, including
5 with antemortem CSF, assessed AD neuropathology and LBP.As
shown in Table 1, αSyn-SAA positivity was observed in
$9.2\%$ of participants, consistent across age groups
(Figure 1) and cognitive stages. Symptomatic
αSyn-SAA-positive individuals exhibited significantly
higher plasma NfL levels compared to αSyn-SAA-negative
individuals (31.0 vs. 21.1 pg/mL, p = 0.027).
Neuropathological analysis revealed LBP in $47\%$ of cases,
with the amygdala and olfactory bulb being the most
frequently affected regions (Table 2). Among the five donors
with antemortem CSF, the only αSyn-SAA-positive case
corresponded to an individual with severe neocortical
LBP.This study examines the relationship between LBP and
DSAD, identifying a prevalence of αSyn-SAA positivity
comparable to autosomal dominant AD but lower than sporadic
AD. A potential association was noted between severe
neocortical LBP and αSyn seeding activity, while age and
cognitive status did not significantly influence positivity
rates. Misfolded αSyn was detectable from early ages in
individuals with DS. Further research is required to
elucidate the mechanisms underlying LBP in DSAD, assess its
clinical impact on cognitive and motor symptoms, and explore
relationships with other biomarkers.},
month = {Jul},
date = {2025-07-27},
organization = {Alzheimer’s Association
International Conference, Toronto
(Canada), 27 Jul 2025 - 31 Jul 2025},
keywords = {Humans / Biomarkers: cerebrospinal fluid / Male / Female /
Alzheimer Disease: cerebrospinal fluid / Alzheimer Disease:
pathology / alpha-Synuclein: cerebrospinal fluid / Amyloid
beta-Peptides: cerebrospinal fluid / Down Syndrome:
cerebrospinal fluid / Down Syndrome: pathology / Middle Aged
/ tau Proteins: cerebrospinal fluid / Aged / Adult /
Neurofilament Proteins: cerebrospinal fluid / Cohort Studies
/ Peptide Fragments: cerebrospinal fluid / Biomarkers (NLM
Chemicals) / alpha-Synuclein (NLM Chemicals) / Amyloid
beta-Peptides (NLM Chemicals) / tau Proteins (NLM Chemicals)
/ Neurofilament Proteins (NLM Chemicals) / Peptide Fragments
(NLM Chemicals)},
cin = {Clinical Research (Munich) / AG Levin / AG Simons},
ddc = {610},
cid = {I:(DE-2719)1111015 / I:(DE-2719)1111016 /
I:(DE-2719)1110008},
pnm = {353 - Clinical and Health Care Research (POF4-353) / 351 -
Brain Function (POF4-351)},
pid = {G:(DE-HGF)POF4-353 / G:(DE-HGF)POF4-351},
typ = {PUB:(DE-HGF)1 / PUB:(DE-HGF)16},
pubmed = {pmid:41500202},
doi = {10.1002/alz70856_106390},
url = {https://pub.dzne.de/record/283150},
}