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Open Imaging Index
MRI Brain

OASIS-1

OASIS-1: Cross-Sectional MRI Data in Young, Middle Aged, Nondemented and Demented Older Adults

Cross-sectional T1-weighted brain MRI of 416 right-handed adults aged 18 to 96, 100 of them with very mild to moderate Alzheimer's disease, with 3 or 4 repeated scans per session, averaged and atlas-registered images and tissue segmentations.

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Overview

OASIS-1 was the first release of the Open Access Series of Imaging Studies from Washington University in St. Louis, published in 2007. It provides structural brain MRI from one visit per person across the adult age range, covering young and middle-aged adults as well as older adults with and without Alzheimer's disease. It is commonly used to study brain volume changes with age and dementia and to develop and test segmentation and classification methods.

Composition

The set holds 416 right-handed subjects aged 18 to 96: 160 men and 256 women. 316 are nondemented and 100, all over 60, have a clinical diagnosis of probable Alzheimer's disease with a Clinical Dementia Rating of 0.5 (70 subjects), 1 (28) or 2 (2). A reliability subset of 20 nondemented subjects was scanned again within 90 days of the first session. The dataset page counts 434 MR sessions in total. A spreadsheet lists sex, handedness, age, education, socioeconomic status, MMSE, CDR and three derived anatomic measures: estimated total intracranial volume, atlas scaling factor and normalized whole-brain volume.

Acquisition

Each session contains 3 or 4 repeated T1-weighted acquisitions of the same structural protocol, stored sagittally at 1 x 1 x 1.25 mm. The repetitions were combined into a motion-corrected average, which was then gain-field corrected and registered to the Talairach and Tournoux atlas space at 1 mm isotropic resolution, with and without a brain mask. Faces were removed before release. All images are in Analyze 7.5 format, about 15.8 GB compressed. FreeSurfer outputs are offered as a separate download.

Annotations

There are no manual labels. Each session includes an automated grey matter, white matter and CSF segmentation of the masked atlas-registered image, and the clinical diagnosis and CDR serve as labels for classification.

Known limitations

  • Cross-sectional design: apart from the 20 reliability subjects, each person has a single session.
  • Dementia cases are limited to subjects over 60, and the under-60 range is dominated by people in their twenties (119 of 416).
  • Scanner model and field strength are not stated on the dataset page or in the fact sheet.
  • The OASIS team advises against pooling OASIS-1 with OASIS-2 or OASIS-3.

Cohort

Aggregate numbers from the sources below. Bars are relative to the 416 subjects.

Sex

  • Male 160 38%
  • Female 256 62%

Age

ยท range 18 to 96
0
50
100
119
0-1920-2930-3940-4950-5960-6970-7980-8990+

Contrast combinations

How many subjects have exactly each set of contrasts.

T1wSubjects with exactly this set
416

Contrast / sequence

subjects, values can overlap

  • T1-weighted 416 100%

Condition

subjects, values can overlap

  • Healthy control 316 76%
  • Alzheimer's disease 100 24%

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
Open download

Download without an account

Access page

OASIS Data Use Agreement

Non-commercial academic research only, after an application reviewed by OASIS staff. No sharing with anyone, collaborators included, without written permission; data must be destroyed or returned when the research ends. Publications must acknowledge OASIS, and work using AV45 or AV1451 PET must go to Avid Radiopharmaceuticals for review 30 days in advance.

The OASIS access page states that all OASIS data are distributed under these terms, but the OASIS-1 archives download directly from the dataset page without an access request.

Original license text Version read: OASIS Data Use Agreement Terms, July 2025 Checked 2026-10-07

What you can do

  • No
  • Not stated
  • Conditional
  • Conditional

What you can share

  • No
  • Not stated
  • Share trained models Not stated

What you must do

  • Yes
  • Share alike No
  • Yes
  • Ethics approval No
  • Conditional
  • Release code No
  • No
  • Yes

Limits

  • Yes
  • No

Commercial license: Conditional Commercial use needs explicit, prior written authorization from OASIS. No commercial license offer is published.

Citation

Marcus DS, Wang TH, Parker J, Csernansky JG, Morris JC, Buckner RL. Open Access Series of Imaging Studies (OASIS): Cross-Sectional MRI Data in Young, Middle Aged, Nondemented, and Demented Older Adults. Journal of Cognitive Neuroscience 19, 1498-1507 (2007). doi:10.1162/jocn.2007.19.9.1498

All numbers

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

MeasureBreakdownValueSource
Subjectstotal 416marcus2007
Abstract
Studiestotal
MR sessions
434oasis1-page
Subjectscondition=healthy
nondemented
316oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers
demented (CDR 0.5, 1 or 2); all diagnosed with probable AD
100oasis1-fact-sheet
Table 2
Subjectssex=male
sum of the disjoint nondemented (119) and demented (41) totals
160oasis1-fact-sheet
Table 2
Subjectssex=female
sum of the disjoint nondemented (197) and demented (59) totals
256oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=male 119oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=female 197oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;sex=male 41oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;sex=female 59oasis1-fact-sheet
Table 2
Subjectsage=0-19
table row <20; the youngest subject is 18
19oasis1-fact-sheet
Table 2
Subjectsage=20-29 119oasis1-fact-sheet
Table 2
Subjectsage=30-39 16oasis1-fact-sheet
Table 2
Subjectsage=40-49 31oasis1-fact-sheet
Table 2
Subjectsage=50-59 33oasis1-fact-sheet
Table 2
Subjectsage=60-69 40oasis1-fact-sheet
Table 2
Subjectsage=70-79
table row labelled 70
83oasis1-fact-sheet
Table 2
Subjectsage=80-89 62oasis1-fact-sheet
Table 2
Subjectsage=90+
table row >=90
13oasis1-fact-sheet
Table 2
Subjectscondition=healthy;age=0-19 19oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=male;age=0-19 10oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=female;age=0-19 9oasis1-fact-sheet
Table 2
Subjectscondition=healthy;age=20-29 119oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=male;age=20-29 51oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=female;age=20-29 68oasis1-fact-sheet
Table 2
Subjectscondition=healthy;age=30-39 16oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=male;age=30-39 11oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=female;age=30-39 5oasis1-fact-sheet
Table 2
Subjectscondition=healthy;age=40-49 31oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=male;age=40-49 10oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=female;age=40-49 21oasis1-fact-sheet
Table 2
Subjectscondition=healthy;age=50-59 33oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=male;age=50-59 11oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=female;age=50-59 22oasis1-fact-sheet
Table 2
Subjectscondition=healthy;age=60-69 25oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=male;age=60-69 7oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=female;age=60-69 18oasis1-fact-sheet
Table 2
Subjectscondition=healthy;age=70-79 35oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=male;age=70-79 10oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=female;age=70-79 25oasis1-fact-sheet
Table 2
Subjectscondition=healthy;age=80-89 30oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=male;age=80-89 8oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=female;age=80-89 22oasis1-fact-sheet
Table 2
Subjectscondition=healthy;age=90+ 8oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=male;age=90+ 1oasis1-fact-sheet
Table 2
Subjectscondition=healthy;sex=female;age=90+ 7oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;age=60-69 15oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;sex=male;age=60-69 6oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;sex=female;age=60-69 9oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;age=70-79 48oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;sex=male;age=70-79 20oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;sex=female;age=70-79 28oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;age=80-89 32oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;sex=male;age=80-89 13oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;sex=female;age=80-89 19oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;age=90+ 5oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;sex=male;age=90+ 2oasis1-fact-sheet
Table 2
Subjectscondition=alzheimers;sex=female;age=90+ 3oasis1-fact-sheet
Table 2
Subjectscontrast=T1w
3 or 4 T1-weighted scans per subject in one session
416marcus2007
Abstract
Subjectscontrast_set=T1w 416marcus2007
Abstract
Minimum agetotal 18marcus2007
Abstract
Maximum agetotal 96marcus2007
Abstract

Sources

The keys used in the table above.