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Diagnostic Performance of the α-Synuclein Seed Amplification Assay for Dementia With Lewy Bodies: A Comparison Across 4 Laboratories
Kumar R, Gravett S, Jelic V, Lange J, Oftedal L, Ciullini A, Bacınoğlu MB, De Luca CMG, Hamied L, Birck C, et al.. Neurology, 2026-01-28
Topic: Amyloid, tau and blood-test diagnosis
Background and objectives The α-synuclein (α-syn) seed amplification assay (SAA) has shown promising results for diagnosing dementia with Lewy bodies (DLB) using CSF samples. CSF samples were provided by a fifth independent laboratory, which also performed statistical and result analyses. Results We included 20 patients with DLB (mean age 67 ± 6 years, 60% male) and 10 controls (mean age 67 ± 2 years, 70% male). On average, the 4 laboratories achieved 78.8% sensitivity (minimum 55%, maximum 100%), 77.5% specificity (minimum 60%, maximum 100%), and 78.5% accuracy (minimum 57%, maximum 100%) for discriminating DLB from controls, but our findings show that diagnostic performance of SAA varied across laboratories: Lab A achieved 100% sensitivity (CI 84%-100%) and 100% specificity (CI 72%-100%); Lab B achieved 85% sensitivity (CI 64%-95%) and 90% specificity (CI 59%-99%); Lab C achieved 55% sensitivity (CI 34%-74%) and 60% specificity (CI 31%-83%); and Lab D achieved 75% sensitivity (CI 53%-89%) and 60% specificity (CI 31%-83%). In general, SAA results showed numerically lower sensitivity in β-amyloid (Aβ)-positive patients with DLB (70%) compared with Aβ-negative patients with DLB (87.5%) (nonstatistically significant). A fair agreement of SAA results was obtained across the 4 laboratories (average κ = 0.246). Discussion This study highlights challenges for the reproducibility of α-syn SAA results across different protocols applied by different laboratories.
Key findings
- Background and objectives The α-synuclein (α-syn) seed amplification assay (SAA) has shown promising results for diagnosing dementia with Lewy bodies (DLB) using CSF samples.
- CSF samples were provided by a fifth independent laboratory, which also performed statistical and result analyses.
- Results We included 20 patients with DLB (mean age 67 ± 6 years, 60% male) and 10 controls (mean age 67 ± 2 years, 70% male).
- On average, the 4 laboratories achieved 78.8% sensitivity (minimum 55%, maximum 100%), 77.5% specificity (minimum 60%, maximum 100%), and 78.5% accuracy (minimum 57%, maximum 100%) for discriminating DLB from controls, but our findings show that diagnostic performance of SAA varied across laboratories: Lab A achieved 100% sensitivity (CI 84%-100%) and 100% specificity (CI 72%-100%); Lab B achieved 85% sensitivity (CI 64%-95%) and 90% specificity (CI 59%-99%); Lab C achieved 55% sensitivity (CI 34%-74%) and 60% specificity (CI 31%-83%); and Lab D achieved 75% sensitivity (CI 53%-89%) and 60% specificity (CI 31%-83%).
- In general, SAA results showed numerically lower sensitivity in β-amyloid (Aβ)-positive patients with DLB (70%) compared with Aβ-negative patients with DLB (87.5%) (nonstatistically significant).
Why it matters
This study tested the α-synuclein seed amplification assay for diagnosing dementia with Lewy bodies across four laboratories using CSF samples from 20 patients and 10 controls. Diagnostic performance varied widely across laboratories, with sensitivity ranging from 55% to 100% and specificity from 60% to 100%, highlighting challenges for reproducibility.
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Study details
- Study designcross-sectional
- Participants30
- Effect sizeSensitivity 55-100% and specificity 60-100% across 4 laboratories; average kappa 0.246
- Evidence strengthEarly
Limitations
Only 30 samples; neuropathological confirmation in just 2 patients; Class III evidence; laboratories used deliberately different protocols.
How this study scored 63/100
Published in a leading specialty journal, and it is a snapshot of people at one point in time. Scored zero for randomised / blinded because the record does not state it. We have no data on senior author's track record and free to read, so those were left out: it earned 59 of the 94 points we could judge it on, which is 63 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (Neurology) |
| Journal's citation record | 4 / 4 | Neurology: journal h-index 525 (OpenAlex, 2026-10-29) |
| Study design | 4 / 12 | A snapshot of people at one point in time |
| Strength of evidence | 2 / 5 | Rated “early” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 5 / 5 | 2026 — within 1 year(s) of the newest study here |
| Sample size | 1 / 4 | 30 participants |
| Effect reported | 2 / 3 | Effect reported as a number, without an interval or test |
| Studied in people | 3 / 3 | Studied in people (participant count stated) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 2 / 7 | Cited 9 times (OpenAlex, 2026-10-10) |
| Citations per year | 2 / 5 | 4.5 citations a year over 2 year(s) since 2026 |
| Impact for its field and year | 5 / 6 | Cited 39.0× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 1 / 6 | Cited by 1 other studies in this library |
| Still being cited | 1 / 4 | Cited 9 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | — / 4 | OpenAlex's profile for last-listed author Daniel Ferreira holds only 1 work(s), too few to judge a track record — left out of this score |
| Institution's track record | 3 / 3 | Centre National de la Recherche Scientifique: institution h-index 2,511 (OpenAlex) |
| Multi-centre collaboration | 3 / 3 | OpenAlex lists 19 institution(s) in 7 countries |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 41604609) |
| Free to read | — / 2 | Access not recorded — left out of this score |
| Points | 59 / 94 | Scored on 18 of 20 parts. We have no data for the rest, so they are left out: 59 of the 94 points we could judge it on is 63 out of 100. |
| Total | 63 / 100 | — |
What each of these 20 components measures, and what this score is not →
Read the original
- DOI: 10.1212/WNL.0000000000214614
- PubMed: 41604609
- Original source →
- Free full text: PubMed Central →
Full text: free to read — PubMed Central lists this copy as free to read: the link above (checked 10 Oct 2026).
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. The record's author list ends in “et al.”, so not every author is named. Check the citation against the original before you use it.
APA 7th
Kumar, R., Gravett, S., Jelic, V., Lange, J., Oftedal, L., Ciullini, A., et al. (2026). Diagnostic Performance of the α-Synuclein Seed Amplification Assay for Dementia With Lewy Bodies: A Comparison Across 4 Laboratories. Neurology. https://doi.org/10.1212/WNL.0000000000214614
Vancouver
Kumar R, Gravett S, Jelic V, Lange J, Oftedal L, Ciullini A, et al. Diagnostic Performance of the α-Synuclein Seed Amplification Assay for Dementia With Lewy Bodies: A Comparison Across 4 Laboratories. Neurology. 2026. doi:10.1212/WNL.0000000000214614. PMID: 41604609.
BibTeX
@article{kumar2026-41604609,
author = {Kumar, R. and Gravett, S. and Jelic, V. and Lange, J. and Oftedal, L. and Ciullini, A. and Bacınoğlu, M. B. and De Luca, C. M. G. and Hamied, L. and Birck, C. and others},
title = {{Diagnostic Performance of the α-Synuclein Seed Amplification Assay for Dementia With Lewy Bodies: A Comparison Across 4 Laboratories}},
journal = {Neurology},
year = {2026},
doi = {10.1212/WNL.0000000000214614},
pmid = {41604609},
url = {https://doi.org/10.1212/WNL.0000000000214614}
}
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