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Open Imaging Index
MRI PET Brain

ABC-DS

Alzheimer Biomarker Consortium - Down Syndrome (ABC-DS)

Brain MRI, amyloid, tau and FDG PET, fluid biomarkers, genetics and cognition from adults with Down syndrome, followed to study how Alzheimer's disease develops in this group, with sibling controls. Over 500 participants and 59 siblings at sites in the US and UK.

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Overview

The Alzheimer Biomarker Consortium - Down Syndrome (ABC-DS) is an NIA and NICHD funded longitudinal study of Alzheimer's disease in adults with Down syndrome, who almost all develop amyloid pathology by about age 40. It started in 2015 by joining two programs, NiAD and ADDS, and follows participants every 16 months with clinical, cognitive, imaging and fluid biomarker assessments. Data are shared with qualified researchers through LONI without embargo.

Composition

Through Freeze 4 (September 2023) the study enrolled 503 adults with Down syndrome aged 25 and older and 59 sibling controls without Down syndrome. At the first consensus conference, 369 participants with Down syndrome were cognitively stable, 59 had MCI-DS, 54 had dementia due to Alzheimer's disease and 21 could not be classified. About 350 had at least one follow-up visit. The release includes demographics, medical history, cognitive tests, caregiver questionnaires, APOE, karyotype, GWAS, proteomics, metabolomics and CSF results.

Acquisition

Sites are in Pittsburgh, New York, Boston, Irvine, Madison, St. Louis, Kentucky, Kansas, Puerto Rico and Cambridge (UK). MRI follows ADNI-style protocols with T1w MPRAGE, T2w FSE, FLAIR, T2* gradient echo, SWI, DTI, ASL and resting-state fMRI; the current protocol follows the ADNI4 sequences. Through Freeze 4 there were 288 SWI and 577 T2* scans. Amyloid PET uses PiB at some sites and florbetapir at others; all sites use flortaucipir for tau and some add FDG. Raw images that pass ADNI-style quality control are shared.

Annotations

No voxel-level labels are published. Derived outcomes shared on LONI include amyloid centiloids, tau SUVRs, cortical thickness and volumes, white matter hyperintensities and microbleeds.

Known limitations

  • About 91% of participants with Down syndrome are white, so minority groups are under-represented.
  • The study combines two programs with different age ranges, PET tracers and visit schedules.
  • Scanner models, field strengths and image formats are not stated in the cited papers.
  • Many participants cannot complete every sequence, so counts differ by sequence and visit.

Cohort

Aggregate numbers from the sources below. Bars are relative to the 562 subjects.

Sex

  • Female 277 49%
  • Male 285 51%

Table 3 in Handen et al. 2025, The ABC-DS 10-year report, Alzheimer's & Dementia (data through Freeze 4, September 2023)

Contrast / sequence

Groups can overlap

  • T1-weighted 485 86%
  • FLAIR 469 83%
  • Diffusion-weighted 451 80%
  • T2*-weighted 380 68%
  • T2-weighted 334 59%
  • Arterial spin labeling 332 59%
  • Susceptibility-weighted 180 32%

Table 4 in Handen et al. 2025, The ABC-DS 10-year report, Alzheimer's & Dementia (data through Freeze 4, September 2023)

Age

0
50
100
150
190
25-3435-4445-5455-6465+

Table 3 in Handen et al. 2025, The ABC-DS 10-year report, Alzheimer's & Dementia (data through Freeze 4, September 2023)

PET tracer

  • [18F]flortaucipir 354 63%
  • [18F]FDG 122 22%

Table 4 in Handen et al. 2025, The ABC-DS 10-year report, Alzheimer's & Dementia (data through Freeze 4, September 2023)

Condition

Groups can overlap

  • Down syndrome 503 90%
  • Healthy control 59 10%
  • Mild cognitive impairment 59 10%
  • Dementia 54 10%
  • Alzheimer's disease 54 10%

Table 3, Table 3; Results, Results in Handen et al. 2025, The ABC-DS 10-year report, Alzheimer's & Dementia (data through Freeze 4, September 2023)

License and access

Our reading of the license, not legal advice. Before you use the data, read the original license and confirm that your use is allowed. We take no responsibility for how you use a dataset. Full disclaimer

Access
Application

A research proposal is reviewed and approved

Access page

Alzheimer Biomarker Consortium - Down Syndrome (ABC-DS) Data Use Agreement

Agreement signed on LONI after a data request reviewed by the ABC-DS publication committee. Use is limited to scientific investigation, teaching or planning clinical research within the approved application. Redistribution is prohibited, manuscripts go to the ABC-DS Steering Committee before submission, and publications must carry the ABC-DS by-line, methods text and funding acknowledgement.

Original license text Version read: ABC-DS Data Use Agreement on LONI IDA, read 2026-10-08 Checked 2026-10-08

What you can do

  • Conditional
  • Not stated
  • Not stated
  • Not stated
  • Conditional

What you can share

  • No
  • Not stated
  • Share trained models Not stated

What you must do

  • Yes
  • Share alike No
  • Yes
  • Conditional
  • Yes
  • Release code No
  • Conditional
  • Delete after use No

Limits

  • Yes
  • No

Commercial license: Not stated

Citation

Handen BL, Lott IT, Christian BT, et al. The Alzheimer's Biomarker Consortium-Down Syndrome: Rationale and methodology. Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring 12(1):e12065 (2020). doi:10.1002/dad2.12065. The DUA also requires "for the Alzheimer's Biomarker Consortium on Down Syndrome study*" on the by-line and the ABC-DS funding acknowledgement.

Sources

Every number on this page comes from one of these documents. Each chart names the table or page it is taken from. The raw numbers are in stats.csv.