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Alpha-synuclein seed amplification assay longitudinal outcomes in Lewy body disease spectrum

Mastrangelo, Andrea ; Mammana, Angela ; Hall, Sara LU ; Stomrud, Erik LU orcid ; Zenesini, Corrado ; Rossi, Marcello ; Janelidze, Shorena LU ; Ticca, Alice ; Palmqvist, Sebastian LU orcid and Magliocchetti, Franco , et al. (2025) In Brain 148(6). p.2038-2048
Abstract

Evidence from neuropathological cohorts indicates that a CSF α-synuclein (α-syn) seed amplification assay (SAA) might provide quantitative kinetic parameters correlating with α-syn pathology burden in patients with Lewy body disease (LBD). Studies are needed to assess their longitudinal trend during the presymptomatic and clinical disease phases and their correlation with measures of disease progression. We aimed to assess the baseline α-syn CSF SAA kinetic parameters, their longitudinal variations and associations with clinical outcomes in a longitudinal cohort of repeatedly sampled LBD patients, including clinically unimpaired (asymptomatic LBD) and neurologically impaired individuals. Participants from the prospective BioFINDER-1... (More)

Evidence from neuropathological cohorts indicates that a CSF α-synuclein (α-syn) seed amplification assay (SAA) might provide quantitative kinetic parameters correlating with α-syn pathology burden in patients with Lewy body disease (LBD). Studies are needed to assess their longitudinal trend during the presymptomatic and clinical disease phases and their correlation with measures of disease progression. We aimed to assess the baseline α-syn CSF SAA kinetic parameters, their longitudinal variations and associations with clinical outcomes in a longitudinal cohort of repeatedly sampled LBD patients, including clinically unimpaired (asymptomatic LBD) and neurologically impaired individuals. Participants from the prospective BioFINDER-1 study with longitudinal CSF collections (n = 718) were screened by α-syn SAA. CSF samples were tested in four replicates blinded to clinical diagnoses. The number of positive replicates (Nrep), the time needed by the fluorescence signal to reach the threshold (Lag) and the highest intensity of the fluorescent signal were analysed at baseline (time of first positive SAA) in all participants and longitudinally in those with at least two α-syn-positive CSF samples available. One hundred and ninety-six individuals (whole cohort) showing α-syn seeding activity were included. Of those, 170 participants tested positive by SAA in all available samples, while 26 converted from a negative to a positive test result during follow-up (LBD-converters), suggesting an early LBD stage. At baseline, LBD-converters showed lower Nrep (P = 0.001) and a longer Lag (P = 0.001) than subjects displaying α-syn seeding activity from the first available sample. The Nrep increased longitudinally in the whole cohort [β = 0.09, 95% confidence interval (95% CI) 0.06-0.12, P < 0.001], in asymptomatic LBD (β = 0.15, 95% CI 0.09-0.21, P < 0.001) and in Parkinson's disease individuals without dementia (β = 0.07, 95% CI 0.02-0.12, P = 0.01). The Lag decreased longitudinally in asymptomatic LBD (β = -0.24, 95% CI -0.42 to -0.06, P = 0.008). Baseline Nrep predicted the subsequent appearance of dementia in the whole cohort [hazard ratio (HR) 1.57, 95% CI 1.19-2.07, P = 0.001] and the Parkinson's disease subgroup (HR 1.83, 95% CI 1.17-2.85, P = 0.008). The difference between the Lag at each sampling and that at baseline was negatively associated with the appearance of dementia in the whole cohort (HR 0.76, 95% CI 0.59-0.99, P = 0.04) and in the Parkinson's disease subgroup (HR 0.69, 95% CI 0.50-0.95, P = 0.02). The α-syn SAA parameters Nrep and Lag showed associations with the LBD stage and the development of dementia. Furthermore, their longitudinal variation is coherent with progression of pathology over time. These data support the use of SAA kinetic parameters to monitor disease progression and therapeutic response.

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publishing date
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Contribution to journal
publication status
published
subject
keywords
disease progression, kinetic parameters, Lewy body disease, longitudinal study, prion, seed amplification assay
in
Brain
volume
148
issue
6
pages
11 pages
publisher
Oxford University Press
external identifiers
  • pmid:39689039
  • scopus:105008355353
ISSN
0006-8950
DOI
10.1093/brain/awae405
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2024 The Author(s).
id
cfb83a03-2bef-48c0-88cf-7e8f214fd77a
date added to LUP
2025-12-16 10:53:50
date last changed
2025-12-17 03:18:23
@article{cfb83a03-2bef-48c0-88cf-7e8f214fd77a,
  abstract     = {{<p>Evidence from neuropathological cohorts indicates that a CSF α-synuclein (α-syn) seed amplification assay (SAA) might provide quantitative kinetic parameters correlating with α-syn pathology burden in patients with Lewy body disease (LBD). Studies are needed to assess their longitudinal trend during the presymptomatic and clinical disease phases and their correlation with measures of disease progression. We aimed to assess the baseline α-syn CSF SAA kinetic parameters, their longitudinal variations and associations with clinical outcomes in a longitudinal cohort of repeatedly sampled LBD patients, including clinically unimpaired (asymptomatic LBD) and neurologically impaired individuals. Participants from the prospective BioFINDER-1 study with longitudinal CSF collections (n = 718) were screened by α-syn SAA. CSF samples were tested in four replicates blinded to clinical diagnoses. The number of positive replicates (Nrep), the time needed by the fluorescence signal to reach the threshold (Lag) and the highest intensity of the fluorescent signal were analysed at baseline (time of first positive SAA) in all participants and longitudinally in those with at least two α-syn-positive CSF samples available. One hundred and ninety-six individuals (whole cohort) showing α-syn seeding activity were included. Of those, 170 participants tested positive by SAA in all available samples, while 26 converted from a negative to a positive test result during follow-up (LBD-converters), suggesting an early LBD stage. At baseline, LBD-converters showed lower Nrep (P = 0.001) and a longer Lag (P = 0.001) than subjects displaying α-syn seeding activity from the first available sample. The Nrep increased longitudinally in the whole cohort [β = 0.09, 95% confidence interval (95% CI) 0.06-0.12, P &lt; 0.001], in asymptomatic LBD (β = 0.15, 95% CI 0.09-0.21, P &lt; 0.001) and in Parkinson's disease individuals without dementia (β = 0.07, 95% CI 0.02-0.12, P = 0.01). The Lag decreased longitudinally in asymptomatic LBD (β = -0.24, 95% CI -0.42 to -0.06, P = 0.008). Baseline Nrep predicted the subsequent appearance of dementia in the whole cohort [hazard ratio (HR) 1.57, 95% CI 1.19-2.07, P = 0.001] and the Parkinson's disease subgroup (HR 1.83, 95% CI 1.17-2.85, P = 0.008). The difference between the Lag at each sampling and that at baseline was negatively associated with the appearance of dementia in the whole cohort (HR 0.76, 95% CI 0.59-0.99, P = 0.04) and in the Parkinson's disease subgroup (HR 0.69, 95% CI 0.50-0.95, P = 0.02). The α-syn SAA parameters Nrep and Lag showed associations with the LBD stage and the development of dementia. Furthermore, their longitudinal variation is coherent with progression of pathology over time. These data support the use of SAA kinetic parameters to monitor disease progression and therapeutic response.</p>}},
  author       = {{Mastrangelo, Andrea and Mammana, Angela and Hall, Sara and Stomrud, Erik and Zenesini, Corrado and Rossi, Marcello and Janelidze, Shorena and Ticca, Alice and Palmqvist, Sebastian and Magliocchetti, Franco and Baiardi, Simone and Mattsson-Carlgren, Niklas and Hansson, Oskar and Parchi, Piero}},
  issn         = {{0006-8950}},
  keywords     = {{disease progression; kinetic parameters; Lewy body disease; longitudinal study; prion; seed amplification assay}},
  language     = {{eng}},
  month        = {{06}},
  number       = {{6}},
  pages        = {{2038--2048}},
  publisher    = {{Oxford University Press}},
  series       = {{Brain}},
  title        = {{Alpha-synuclein seed amplification assay longitudinal outcomes in Lewy body disease spectrum}},
  url          = {{http://dx.doi.org/10.1093/brain/awae405}},
  doi          = {{10.1093/brain/awae405}},
  volume       = {{148}},
  year         = {{2025}},
}