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Open Imaging Index
MRI PET Brain

ABC-DS

Alzheimer Biomarker Consortium - Down Syndrome (ABC-DS)

Multi-site longitudinal study of Alzheimer's disease biomarkers in over 500 adults with Down syndrome and 59 sibling controls in the US and UK, with MRI (T1w, FLAIR, T2*, SWI, DTI, ASL, fMRI), amyloid, tau and FDG PET, fluid biomarkers, genetics and cognitive data.

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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%

Age

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

Contrast / sequence

subjects, values 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%

PET tracer

subjects

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

Condition

subjects, values can overlap

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

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
  • 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.

All numbers

Every number on this page, as stored in stats.csv, with its source.

MeasureBreakdownValueSource
Subjectstotal
sum of 503 adults with Down syndrome and 59 sibling controls, Freeze 4 (September 2023)
562handen2025
Table 3
Subjectscondition=down_syndrome 503handen2025
Table 3
Subjectscondition=healthy
sibling controls without Down syndrome; all cognitively stable
59handen2025
Table 3
Subjectscondition=mci
MCI-DS at the first consensus conference
59handen2025
Table 3; Results
Subjectscondition=dementia
dementia (diagnosed as AD) at the first consensus conference
54handen2025
Table 3; Results
Subjectscondition=alzheimers
diagnosed with AD at baseline
54handen2025
Results
Subjectssex=female
sum of 231 DS and 46 siblings
277handen2025
Table 3
Subjectssex=male
sum of 272 DS and 13 siblings
285handen2025
Table 3
Subjectsage=25-34
age at baseline; sum of 104 DS and 14 siblings
118handen2025
Table 3
Subjectsage=35-44
age at baseline; sum of 171 DS and 19 siblings
190handen2025
Table 3
Subjectsage=45-54
age at baseline; sum of 147 DS and 13 siblings
160handen2025
Table 3
Subjectsage=55-64
age at baseline; sum of 72 DS and 10 siblings
82handen2025
Table 3
Subjectsage=65+
age at baseline; sum of 9 DS and 3 siblings
12handen2025
Table 3
Subjectscontrast=T1w
with a T1w scan at the baseline visit; 426 DS and 59 siblings
485handen2025
Table 4
Subjectscontrast=FLAIR
with a FLAIR scan at the baseline visit; 412 DS and 57 siblings
469handen2025
Table 4
Subjectscontrast=T2starw
with a T2* scan at the baseline visit; 327 DS and 53 siblings
380handen2025
Table 4
Subjectscontrast=swi
with an SWI scan at the baseline visit; 165 DS and 15 siblings
180handen2025
Table 4
Subjectscontrast=T2w
with a T2 FSE scan at the baseline visit; 276 DS and 58 siblings
334handen2025
Table 4
Subjectscontrast=dwi
with a DTI scan at the baseline visit; 395 DS and 56 siblings
451handen2025
Table 4
Subjectscontrast=asl
with an ASL scan at the baseline visit; 277 DS and 55 siblings
332handen2025
Table 4
Scanscontrast=T1w
all visits through Freeze 4; 824 DS and 83 siblings
907handen2025
Table 4
Scanscontrast=FLAIR
all visits; 765 DS and 78 siblings
843handen2025
Table 4
Scanscontrast=T2starw
all visits; 506 DS and 71 siblings
577handen2025
Table 4
Scanscontrast=swi
all visits; 268 DS and 20 siblings
288handen2025
Table 4
Scanscontrast=T2w
T2 FSE, all visits; 406 DS and 76 siblings
482handen2025
Table 4
Scanscontrast=dwi
all visits; 717 DS and 77 siblings
794handen2025
Table 4
Scanscontrast=asl
all visits; 415 DS and 74 siblings
489handen2025
Table 4
Scanscontrast=bold
all visits; fMRI_1 (528 DS, 65 siblings) plus fMRI_2 (88 DS, 9 siblings)
690handen2025
Table 4
Subjectstracer=flortaucipir
baseline column of Table 4; 300 DS and 54 siblings
354handen2025
Table 4
Scanstracer=flortaucipir
all visits; 524 DS and 76 siblings
600handen2025
Table 4
Subjectstracer=fdg
97 DS and 25 siblings; FDG PET is done at one visit only
122handen2025
Table 4
Scanstracer=fdg
97 DS and 25 siblings
122handen2025
Table 4

Sources

The keys used in the table above.