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A head-to-head comparison of multiple amyloid PET radiotracers for Down syndrome clinical trials
Zammit MD, Price JC, Christian BT, Rafii MS, Alzheimer’s Biomarker Consortium – Down Syndrome.. medRxiv, 2025-03-19
Topic: Brain proteins, microglia and lab models
Plain-language summary
Adults with Down syndrome carry high risk of developing Alzheimer’s disease and efforts to include this population in clinical trials remain limited. A barrier to recruitment for anti-amyloid trials includes the availability of the same amyloid PET radiotracer to multiple treatment centers. 237 adults with Down syndrome from the Trial-Ready Cohort – Down syndrome and Alzheimer Biomarker Consortium – Down syndrome studies were imaged using T1-w MRI and using PET images of PiB, Florbetapir (FBP), NAV4694 (NAV) or Flutemetamol (FMM) to screen for amyloid plaque (Aβ) burden. PiB displayed the largest effect size to measure amyloid change while FBP had a small effect size.
What this study adds
Evidence grade: Moderate
This is a follow-up (cohort) study of 237 participants. This head-to-head comparison of amyloid PET radiotracers in 237 adults with Down syndrome found that PiB had the largest effect size for measuring amyloid change while florbetapir had a small effect size. It is a methods comparison for trial screening and tests no treatment or prevention.
Taken from this record’s own fields, not from reading the paper. The grade is assigned from the abstract’s wording; what that means.
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
APA 7th
Zammit, M. D., Price, J. C., Christian, B. T., Rafii, M. S., & Alzheimer’s Biomarker Consortium – Down Syndrome. (2025). A head-to-head comparison of multiple amyloid PET radiotracers for Down syndrome clinical trials. medRxiv. https://doi.org/10.1101/2025.03.18.25324200
Vancouver
Zammit MD, Price JC, Christian BT, Rafii MS, Alzheimer’s Biomarker Consortium – Down Syndrome. A head-to-head comparison of multiple amyloid PET radiotracers for Down syndrome clinical trials. medRxiv. 2025. doi:10.1101/2025.03.18.25324200.
BibTeX
@article{zammit2025-8ec63439,
author = {Zammit, M. D. and Price, J. C. and Christian, B. T. and Rafii, M. S. and {Alzheimer’s Biomarker Consortium – Down Syndrome}},
title = {{A head-to-head comparison of multiple amyloid PET radiotracers for Down syndrome clinical trials}},
journal = {medRxiv},
year = {2025},
doi = {10.1101/2025.03.18.25324200},
url = {https://doi.org/10.1101/2025.03.18.25324200}
}
Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. Check the citation against the original before you use it.
Key findings
- A barrier to recruitment for anti-amyloid trials includes the availability of the same amyloid PET radiotracer to multiple treatment centers. 237 adults with Down syndrome from the Trial-Ready Cohort – Down syndrome and Alzheimer Biomarker Consortium – Down syndrome studies were imaged using T1-w MRI and using PET images of PiB, Florbetapir (FBP), NAV4694 (NAV) or Flutemetamol (FMM) to screen for amyloid plaque (Aβ) burden.
- PiB displayed the largest effect size to measure amyloid change while FBP had a small effect size.
- NAV and PiB, which are structurally similar compounds, displayed similar sensitivity to measure longitudinal amyloid increase.
- The estimated age at amyloid onset showed no significant difference between PiB, FBP, NAV or FMM.
Why it matters
This head-to-head comparison of amyloid PET radiotracers in 237 adults with Down syndrome found that PiB had the largest effect size for measuring amyloid change while florbetapir had a small effect size. It is a methods comparison for trial screening and tests no treatment or prevention.
Study details
- Study designlongitudinal study
- Participants237
- Evidence strengthModerate
How this study scored 16/100
Preprint — not yet peer-reviewed. It scored 37 on the same rubric, but non-peer-reviewed sources are capped at 16, so it shows as 16. Scored zero for effect reported and randomized / blinded because the record does not state it. We have no data on impact for its field and year, so that was left out: it earned 35 of the 94 points we could judge it on, which is 37 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 2 / 10 | Tier 4 — not a peer-reviewed journal (medRxiv) |
| Journal's citation record | 0 / 4 | Not a journal article, so the journal's record does not count |
| Study design | 7 / 12 | A longitudinal study following the same people over time |
| Strength of evidence | 3 / 5 | Rated “moderate” in our summary |
| Peer-review validation | 4 / 10 | Preprint — not yet peer-reviewed. Hosted on a preprint server. |
| How recent | 4 / 5 | 2025 — within 3 year(s) of the newest study here |
| Sample size | 2 / 4 | 237 participants |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 3 / 3 | Studied in people (participant count stated) |
| Randomized / blinded | 0 / 2 | No randomization or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 1 / 7 | Cited 1 times (OpenAlex, 2026-10-10) |
| Citations per year | 0 / 5 | 0.3 citations a year over 3 year(s) since 2025 |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | 0 / 6 | No other study in this library cites it |
| Still being cited | 0 / 4 | Cited 1 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 3 / 4 | Last-listed author Michael S. Rafii: h-index 50 (OpenAlex, whole career) |
| Institution's track record | 3 / 3 | Harvard University: institution h-index 3,235 (OpenAlex) |
| Multicenter collaboration | 2 / 3 | OpenAlex lists 4 institution(s) in 1 country |
| Indexed in PubMed | 1 / 2 | Not in PubMed, but has a DOI |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 35 / 94 | Scored on 19 of 20 parts. We have no data for the rest, so they are left out: 35 of the 94 points we could judge it on is 37 out of 100. |
| Total | 37 / 100 | Capped to 16 because this is not a peer-reviewed article. |
What each of these 20 components measures, and what this score is not →
Read the original
Full text: free to read — OpenAlex lists this copy as free to read: the link above (checked 6 Feb 1020).
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