How can I identify whether each subject is cognitively normal or at risk of Alzheimer's disease? Is this information available through a command-line script, or in a separate file?

Hi,

the cognitive/diagnostic status isn't produced by a command-line script — it lives in the clinical data tables you download from the OASIS-3 data browser as spreadsheets (CSV). The download scripts only fetch the imaging/FreeSurfer/PUP files; they don't generate labels.

There are two places to look, both in the ADRC Clinical Data table:

1. CDR (Clinical Dementia Rating) global score — the quickest "normal vs. impaired" flag:
   
   
   
   • CDR = 0 → cognitively normal
   
   
   • CDR = 0.5 → very mild impairment (commonly treated as MCI / at-risk)
   
   
   • CDR ≥ 1 → dementia (1 mild, 2 moderate, 3 severe)
   
   
   
   
   
2. dx1–dx5 (coded clinician diagnosis) — more specific than CDR because it gives the etiology. dx1 is the primary diagnosis, with values like "Cognitively normal", "AD dementia", "vascular dementia", plus contributing factors (mood disorder, vitamin deficiency, etc.). So "at risk of AD" specifically means a CDR > 0 with dx1 pointing toward AD dementia / uncertain dementia, rather than just any impairment.
   

How to get it:

1. Open the OASIS-3 project in the data browser (central.xnat.org).
   
2. Load the Subjects and ADRC Clinical Data tables.
   
3. Export as a Spreadsheet (CSV). You'll get columns like cdr, dx1–dx5, mmse, ageAtEntry, plus a session label.
   

One important detail: OASIS-3 is longitudinal, so each clinical row is tagged with the subject ID + "days from entry" (the dXXXX suffix), and a subject's status can change over time. To label a given scan, match by subject ID and pick the clinical assessment closest in days-from-entry to that MR/PET session.

All of this is documented in the OASIS-3 Imaging Data Dictionary (the "ADRC Clinical Data / dx1–dx5" and CDR sections) on oasis-brains.org.

Hope this helps.

I will download the ADRC Clinical Data spreadsheet and use the subject ID together with the days-from-entry information to match the clinical assessments to the corresponding MRI/PET sessions. Since OASIS-3 is longitudinal, I will select the clinical assessment closest to each imaging session when assigning labels.

Thank you also for pointing me to the Imaging Data Dictionary and the ADRC Clinical Data documentation. This information is very useful for my study.

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