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  1. Home
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  3. /Clinical trials
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  5. /Depression and bipolar disorder
  6. /Digit Span Test

Clinical trials data

Digit Span Test in depression and bipolar disorder trials: 143 registered studies

Every registered depression and bipolar disorder study on ClinicalTrials.gov that names the Digit Span Test in an outcome measure: how often it is a primary outcome, the tests named with it, how large the studies are and when they measure it.

Registered depression and bipolar disorder studies name it in an outcome measure
143
Name it in a primary outcome, 31%
44 of 143
Of the condition's 1,247 studies name it, against 10% of all registered studies
11%
Other conditions
Median participants per study
70
By phase
Try the Digit Span Test

Tests named in the same studies

The library tests that depression and bipolar disorder studies naming the Digit Span Test name most often beside it.
  1. 1

    Trail Making Test67 studies, 24 as a primary outcome

  2. 2

    Verbal Fluency56 studies, 16 as a primary outcome

  3. 3

    Verbal Learning48 studies, 17 as a primary outcome

  4. 4

    Symbol Coding39 studies, 14 as a primary outcome

  5. 5

    Stroop Color-Word Test32 studies, 13 as a primary outcome

  6. 6

    Continuous Performance Test20 studies, 5 as a primary outcome

  7. 7

    Card Sorting Test (Berg)15 studies, 3 as a primary outcome

  8. 8

    Short Story Recall13 studies, 5 as a primary outcome

  9. 9

    Category Fluency12 studies, 4 as a primary outcome

  10. 10

    N-Back Task11 studies, 4 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

Studies by start year

Each study counted once. 2026 is partly planned starts.
02000: 0 studies, 0 with a test as a primary outcome20002001: 0 studies, 0 with a test as a primary outcome2002: 0 studies, 0 with a test as a primary outcome2003: 2 studies, 2 with a test as a primary outcome2004: 0 studies, 0 with a test as a primary outcome2005: 3 studies, 1 with a test as a primary outcome20052006: 1 studies, 0 with a test as a primary outcome2007: 1 studies, 0 with a test as a primary outcome2008: 2 studies, 1 with a test as a primary outcome2009: 1 studies, 0 with a test as a primary outcome2010: 2 studies, 0 with a test as a primary outcome20102011: 2 studies, 0 with a test as a primary outcome2012: 2 studies, 1 with a test as a primary outcome2013: 4 studies, 0 with a test as a primary outcome2014: 5 studies, 2 with a test as a primary outcome2015: 6 studies, 3 with a test as a primary outcome20152016: 4 studies, 3 with a test as a primary outcome2017: 9 studies, 1 with a test as a primary outcome2018: 7 studies, 1 with a test as a primary outcome2019: 7 studies, 2 with a test as a primary outcome2020: 5 studies, 2 with a test as a primary outcome20202021: 8 studies, 3 with a test as a primary outcome2022: 6 studies, 0 with a test as a primary outcome2023: 22 studies, 6 with a test as a primary outcome2024: 17 studies, 7 with a test as a primary outcome2025: 16 studies, 6 with a test as a primary outcome20252026: 11 studies, 3 with a test as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

Show as a table
Registered studies by start year
Start yearStudiesA test as a primary outcome
200000
200100
200200
200322
200400
200531
200610
200710
200821
200910
201020
201120
201221
201340
201452
201563
201643
201791
201871
201972
202052
202183
202260
2023226
2024177
2025166
2026113

Phases and study sizes

By phase

  • Phase 1/27 studies, 2 as a primary outcome
  • Phase 214 studies, 4 as a primary outcome
  • Phase 2/31 studies, 0 as a primary outcome
  • Phase 33 studies, 1 as a primary outcome
  • Phase 44 studies, 1 as a primary outcome
  • Not applicable98 studies, 26 as a primary outcome
  • Observational16 studies, 10 as a primary outcome

Participants per study

102050100200500
  • Phase 249 median, 39 to 98
  • Not applicable67 median, 40 to 102
  • Observational100 median, 83 to 371
Participants per study. The bar spans the middle half of the studies in each phase, the mark is the median, and the axis is logarithmic. Phases with fewer than 10 studies that give a size are left out.
Show as a table
Participants per depression and bipolar disorder study that names the Digit Span Test, by phase
PhaseStudies with a sizeMedianMiddle half
Phase 2144939 to 98
Not applicable966740 to 102
Observational1610083 to 371

When depression and bipolar disorder trials measure it

Half of the primary outcomes that name the Digit Span Test are measured within 8 weeks of the start, and the middle half from 4 weeks to 13 weeks. 41 primary outcomes give a duration.

Latest time point of each outcome

  • Within a day10 outcomes, 4 as a primary outcome
  • Up to 4 weeks40 outcomes, 9 as a primary outcome
  • 1 to 3 months54 outcomes, 18 as a primary outcome
  • 3 to 6 months18 outcomes, 5 as a primary outcome
  • 6 to 12 months7 outcomes, 2 as a primary outcome
  • 1 to 2 years5 outcomes, 2 as a primary outcome
  • Over 2 years2 outcomes, 1 as a primary outcome
  • No duration given7 outcomes, 3 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

136 of the 143 outcome measures give a duration. A single visit counts as within a day.

Status, results, interventions and countries

Status

  • Recruiting32 studies, 12 as a primary outcome
  • Not yet recruiting6 studies, 1 as a primary outcome
  • Active, not recruiting5 studies, 2 as a primary outcome
  • Completed62 studies, 23 as a primary outcome
  • Stopped early11 studies, 2 as a primary outcome
  • Status unknown27 studies, 4 as a primary outcome

What they test

  • Behavioral49 studies, 10 as a primary outcome
  • Drug24 studies, 8 as a primary outcome
  • Device49 studies, 13 as a primary outcome
  • Dietary supplement10 studies, 5 as a primary outcome
  • Procedure3 studies, 1 as a primary outcome
  • Diagnostic test3 studies, 2 as a primary outcome
  • Radiation2 studies, 1 as a primary outcome
  • Other20 studies, 8 as a primary outcome
  • None given9 studies, 5 as a primary outcome

Intervention types as registered. A study can list several; observational studies often list none.

Where their sites are

  • United States33 studies, 13 as a primary outcome
  • China16 studies, 2 as a primary outcome
  • Denmark11 studies, 2 as a primary outcome
  • Canada10 studies, 2 as a primary outcome
  • Brazil9 studies, 5 as a primary outcome
  • Netherlands8 studies, 1 as a primary outcome
  • United Kingdom7 studies, 2 as a primary outcome
  • Taiwan6 studies, 2 as a primary outcome
  • Germany4 studies, 1 as a primary outcome
  • Italy4 studies, 2 as a primary outcome
  • Argentina3 studies, 2 as a primary outcome
  • Australia3 studies, 0 as a primary outcome

32 countries in all. A study with sites in several counts in each; 5 list no site.

Reported results

Completed studies with results posted on ClinicalTrials.gov, a results paper the registry links to the study, or both.

Completed depression and bipolar disorder studies that name the Digit Span Test: 28 of 62, 45%

Every completed study with a cognitive outcome: 3,626 of 7,953, 46%

Completed depression and bipolar disorder studies that name the Digit Span Test and every completed study, by how they reported results
ResultsCompleted depression and bipolar disorder studies that name the Digit Span TestEvery completed study
Results on ClinicalTrials.gov and a paper8, 13%776, 10%
Results on ClinicalTrials.gov only4, 6%1,139, 14%
A results paper only16, 26%1,711, 22%
Neither34, 55%4,327, 54%

The 143 studies

Filter by phase, sponsor, status, country, intervention, outcome list, size and start year. Each study links to its record on ClinicalTrials.gov.
ConditionDepression and bipolar disorder
TestThe Digit Span Test

143 studies match. 44 name the Digit Span Test in a primary outcome. Median size 70 participants. Median time to the primary outcome: 8 weeks.

Loading 143 studies; the filters turn on when they arrive.

By start year
01020302000: 0 studies, 0 naming the Digit Span Test in a primary outcome20002001: 0 studies, 0 naming the Digit Span Test in a primary outcome2002: 0 studies, 0 naming the Digit Span Test in a primary outcome2003: 2 studies, 2 naming the Digit Span Test in a primary outcome2004: 0 studies, 0 naming the Digit Span Test in a primary outcome2005: 3 studies, 1 naming the Digit Span Test in a primary outcome20052006: 1 studies, 0 naming the Digit Span Test in a primary outcome2007: 1 studies, 0 naming the Digit Span Test in a primary outcome2008: 2 studies, 1 naming the Digit Span Test in a primary outcome2009: 1 studies, 0 naming the Digit Span Test in a primary outcome2010: 2 studies, 0 naming the Digit Span Test in a primary outcome20102011: 2 studies, 0 naming the Digit Span Test in a primary outcome2012: 2 studies, 1 naming the Digit Span Test in a primary outcome2013: 4 studies, 0 naming the Digit Span Test in a primary outcome2014: 5 studies, 2 naming the Digit Span Test in a primary outcome2015: 6 studies, 3 naming the Digit Span Test in a primary outcome20152016: 4 studies, 3 naming the Digit Span Test in a primary outcome2017: 9 studies, 1 naming the Digit Span Test in a primary outcome2018: 7 studies, 1 naming the Digit Span Test in a primary outcome2019: 7 studies, 2 naming the Digit Span Test in a primary outcome2020: 5 studies, 2 naming the Digit Span Test in a primary outcome20202021: 8 studies, 3 naming the Digit Span Test in a primary outcome2022: 6 studies, 0 naming the Digit Span Test in a primary outcome2023: 22 studies, 6 naming the Digit Span Test in a primary outcome2024: 17 studies, 7 naming the Digit Span Test in a primary outcome2025: 16 studies, 6 naming the Digit Span Test in a primary outcome20252026: 11 studies, 3 naming the Digit Span Test in a primary outcome

2026 is partly planned starts.

Show as a table
Matching studies by start year
Start yearStudiesAs a primary outcome
200000
200100
200200
200322
200400
200531
200610
200710
200821
200910
201020
201120
201221
201340
201452
201563
201643
201791
201871
201972
202052
202183
202260
2023226
2024177
2025166
2026113

Library tests named most

  • Digit Span Test143 studies, 44 as a primary outcome
  • Trail Making Test67 studies, 24 as a primary outcome
  • Verbal Fluency56 studies, 16 as a primary outcome
  • Verbal Learning48 studies, 17 as a primary outcome
  • Symbol Coding39 studies, 14 as a primary outcome
  • Stroop Color-Word Test32 studies, 13 as a primary outcome
  • Continuous Performance Test20 studies, 5 as a primary outcome
  • Card Sorting Test (Berg)15 studies, 3 as a primary outcome
  • Short Story Recall13 studies, 5 as a primary outcome
  • Category Fluency12 studies, 4 as a primary outcome

Largest condition groups

  • Depression and bipolar disorder143 studies, 44 as a primary outcome
  • Anxiety, PTSD and OCD33 studies, 12 as a primary outcome
  • Sleep and sleep disorders12 studies, 8 as a primary outcome
  • Pain and fatigue10 studies, 7 as a primary outcome
  • Cancer9 studies, 5 as a primary outcome
  • Dementia and Alzheimer's5 studies, 2 as a primary outcome
  • Mild cognitive impairment5 studies, 4 as a primary outcome
  • Parkinson's disease5 studies, 1 as a primary outcome
  • Schizophrenia and psychosis4 studies, 1 as a primary outcome
  • Stroke3 studies, 1 as a primary outcome
  • Aging, frailty and exercise3 studies, 2 as a primary outcome
  • Obesity and diabetes3 studies, 1 as a primary outcome

Phases

Participants

Lead sponsor: industry 6, other 137. Interventional 127, observational 16.

As a primary outcomeSecondary or other outcomeThe Digit Span Test

The studies, newest registration first

Each number opens the study's record on ClinicalTrials.gov.

Registered studies that match the filters, newest registration first, with the library tests each one names and the outcome list that names them.
StudyStartPhaseConditionsParticipantsLead sponsorStatusLibrary tests named, with the latest time point
NCT07848477Start2026PhaseNot applicableConditionsDepression and bipolar disorderParticipants60Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal LearningPrimary2 weeks
  • Digit Span TestSecondary2 weeks
  • Symbol CodingSecondary2 weeks
  • N-Back TaskSecondary2 weeks
  • Go/No-Go TaskSecondary2 weeks
  • Paired Associate LearningSecondary2 weeks
  • Probabilistic Reversal LearningSecondary2 weeks
  • Mnemonic Similarity TaskSecondary2 weeks
  • Affective Go/No-GoSecondary2 weeks
  • Grid Pattern Span TaskSecondary2 weeks
NCT07823218Start2026PhaseObservationalConditionsDepression and bipolar disorderParticipants100Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Digit Span TestSecondary8 weeks
  • Four-Armed BanditPrimary8 weeks
NCT07765355Start2025PhaseNot applicableConditionsDepression and bipolar disorder, Anxiety, PTSD and OCDParticipants60Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary4 weeks
  • Digit Span TestSecondary4 weeks
NCT07755839Start2026PhaseNot applicableConditionsDepression and bipolar disorder, Cancer, Anxiety, PTSD and OCDParticipants60Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestSecondary6 months
  • Stroop Color-Word TestSecondary6 months
  • Verbal FluencySecondary6 months
  • Digit Span TestSecondary6 months
  • Cancellation TestSecondary6 months
NCT07735910Start2026PhaseNot applicableConditionsMild cognitive impairment, Depression and bipolar disorder, Sleep and sleep disorders, Anxiety, PTSD and OCDParticipants60Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestPrimary2 weeks
  • Stroop Color-Word TestPrimary2 weeks
  • Digit Span TestPrimary2 weeks
NCT07710222Start2026PhaseNot applicableConditionsDepression and bipolar disorderParticipants60Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestSecondary13 weeks
  • Digit Span TestSecondary13 weeks
NCT07659171Start2019PhaseNot applicableConditionsDepression and bipolar disorder, Sleep and sleep disorders, Anxiety, PTSD and OCDParticipants39Lead sponsorOtherStatusCompletedLibrary tests named
  • Digit Span TestSecondary3 weeks
  • Operation SpanSecondary3 weeks
NCT07652775Start2026PhaseNot applicableConditionsMild cognitive impairment, Depression and bipolar disorderParticipants45Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary5 weeks
  • Stroop Color-Word TestSecondary5 weeks
  • Verbal LearningSecondary5 weeks
  • Digit Span TestSecondary5 weeks
NCT07633626Start2026PhaseObservationalConditionsDepression and bipolar disorder, CancerParticipants24Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestPrimary12 weeks
  • Verbal LearningPrimary12 weeks
  • Verbal FluencyPrimary12 weeks
  • Digit Span TestPrimary12 weeks
  • Symbol CodingPrimary12 weeks
  • Symbol Scan TaskPrimary12 weeks
NCT07610655Start2026PhaseNot applicableConditionsDepression and bipolar disorder, Delirium, surgery and intensive careParticipants40Lead sponsorOtherStatusRecruitingLibrary tests named
  • Digit Span TestSecondary2 days
NCT07610369Start2026PhasePhase 2ConditionsParkinson's disease, Depression and bipolar disorderParticipants40Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal LearningSecondary13 weeks
  • Digit Span TestSecondary13 weeks
  • Delay DiscountingSecondary13 weeks
  • Probabilistic Reversal LearningSecondary13 weeks
  • Simon TaskSecondary13 weeks
NCT07593807Start2025PhaseNot applicableConditionsMultiple sclerosis, Depression and bipolar disorderParticipants30Lead sponsorOtherStatusActive, not recruitingLibrary tests named
  • Verbal FluencySecondary4 weeks
  • Digit Span TestSecondary4 weeks
NCT07590999Start2025PhaseNot applicableConditionsDepression and bipolar disorderParticipants106Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal LearningSecondary9 weeks
  • Digit Span TestSecondary9 weeks
  • N-Back TaskSecondary9 weeks
  • Go/No-Go TaskSecondary9 weeks
  • Probabilistic Reversal LearningSecondary9 weeks
  • Affective Go/No-GoSecondary9 weeks
NCT07462013Start2025PhaseNot applicableConditionsDepression and bipolar disorderParticipants120Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestPrimary6 months
  • Digit Span TestPrimary6 months
  • Symbol CodingPrimary6 months
  • Card Sorting Test (Berg)Primary6 months
NCT07404085Start2025PhaseNot applicableConditionsSchizophrenia and psychosis, Depression and bipolar disorderParticipants160Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal LearningPrimary8 weeks
  • Verbal FluencyPrimary8 weeks
  • Digit Span TestPrimary8 weeks
  • Tower PlanningPrimary8 weeks
  • Rapid Visual Information ProcessingPrimary8 weeks
  • Emoji Emotion RecognitionPrimary8 weeks
  • Letter-Number Sequencing TaskPrimary8 weeks
  • Spatial Working MemoryPrimary8 weeks
  • One-Touch Tower PlanningPrimary8 weeks
NCT07350226Start2025PhaseNot applicableConditionsDepression and bipolar disorderParticipants86Lead sponsorOtherStatusActive, not recruitingLibrary tests named
  • Trail Making TestPrimary8 weeks
  • Stroop Color-Word TestPrimary8 weeks
  • Verbal LearningPrimary8 weeks
  • Verbal FluencySecondary8 weeks
  • Digit Span TestPrimary8 weeks
  • Symbol CodingPrimary8 weeks
  • Category FluencyPrimary8 weeks
  • Picture Naming TestPrimary8 weeks
  • Task Switching TestSecondary8 weeks
  • Clock Drawing TaskPrimary8 weeks
  • Complex Figure Copy and RecallSecondary8 weeks
NCT07319117Start2025PhaseNot applicableConditionsDepression and bipolar disorder, Sleep and sleep disorders, Anxiety, PTSD and OCD, Pain and fatigue, Cardiovascular diseaseParticipants40Lead sponsorOtherStatusRecruitingLibrary tests named
  • Digit Span TestPrimary
  • Stop-Signal TaskPrimary
  • Rapid Visual Information ProcessingPrimary
  • Intra/Extra Dimensional Set ShiftPrimary
NCT07300527Start2026PhaseNot applicableConditionsDepression and bipolar disorderParticipants80Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Digit Span TestPrimary5 weeks
NCT07186023Start2025PhaseNot applicableConditionsDepression and bipolar disorderParticipants124Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencySecondary4 weeks
  • Digit Span TestSecondary4 weeks
  • Symbol CodingSecondary4 weeks
NCT07168447Start2025PhaseObservationalConditionsDepression and bipolar disorder, Anxiety, PTSD and OCD, Pain and fatigueParticipants85Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Digit Span TestSecondary1 week
  • Symbol CodingSecondary1 week
NCT07135232Start2026PhaseNot applicableConditionsDepression and bipolar disorder, Anxiety, PTSD and OCDParticipants72Lead sponsorOtherStatusRecruitingLibrary tests named
  • Digit Span TestSecondary4 weeks
  • Tower PlanningSecondary4 weeks
  • Rapid Visual Information ProcessingPrimary1 week
  • One-Touch Tower PlanningSecondary4 weeks
  • Word Pair LearningSecondary4 weeks
NCT06816667Start2024PhasePhase 1/2ConditionsDepression and bipolar disorder, Healthy volunteers, Anxiety, PTSD and OCDParticipants40Lead sponsorIndustryStatusCompleted

Paper

Library tests named
  • Verbal FluencySecondary5 weeks
  • Digit Span TestSecondary5 weeks
  • Paced Visual Serial Addition TestSecondary5 weeks
NCT06813313Start2025PhaseNot applicableConditionsDepression and bipolar disorderParticipants108Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestSecondary5 days
  • Stroop Color-Word TestSecondary5 days
  • Verbal FluencySecondary5 days
  • Digit Span TestSecondary5 days
  • N-Back TaskSecondary5 days
  • Go/No-Go TaskSecondary5 days
  • Card Sorting Test (Berg)Secondary5 days
NCT06812221Start2024PhasePhase 1/2ConditionsMild cognitive impairment, Depression and bipolar disorder, Anxiety, PTSD and OCDParticipants20Lead sponsorIndustryStatusCompletedLibrary tests named
  • Verbal FluencyPrimary5 weeks
  • Digit Span TestPrimary5 weeks
  • Paced Visual Serial Addition TestPrimary5 weeks
NCT06804304Start2025PhaseNot applicableConditionsStroke, Depression and bipolar disorder, Anxiety, PTSD and OCDParticipants100Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencyPrimary13 weeks
  • Digit Span TestPrimary13 weeks
  • Short Story RecallSecondary6 months
  • Cancellation TestSecondary6 months
  • Sustained Attention to ResponsePrimary13 weeks
  • Simon TaskPrimary13 weeks

Page 1 of 6

Questions, answered from the data

How many depression and bipolar disorder trials use the Digit Span Test?

143 registered depression and bipolar disorder studies on ClinicalTrials.gov name it in an outcome measure, 44 of them in a primary outcome: 11% of the condition's 1,247 studies with a cognitive outcome, against 10% of all of them. It is the 4th most named test in depression and bipolar disorder trials.

Which tests do depression and bipolar disorder trials use with the Digit Span Test?

The Trail Making Test (67 studies), Verbal Fluency (56 studies) and Verbal Learning (48 studies).

How many participants do phase 2 depression and bipolar disorder trials that use the Digit Span Test enroll?

Half of the phase 2 studies that name it enroll 49 participants or fewer, and the middle half enroll 39 to 98. 14 of them give a size.

When do depression and bipolar disorder trials measure the Digit Span Test?

Half of the primary outcomes that name the Digit Span Test are measured within 8 weeks of the start, and the middle half from 4 weeks to 13 weeks. 41 primary outcomes give a duration.

How many completed depression and bipolar disorder trials that use the Digit Span Test have reported results?

28 of the 62 completed studies that name it, 45%, have reported results: 12 posted them on ClinicalTrials.gov, 24 have a results paper linked to the registry record, and 8 did both. The other 34 show neither. Of all completed studies with a cognitive outcome, 46% have reported results.

More on the Digit Span Test and depression and bipolar disorder

  • Every cognitive test in depression and bipolar disorder trials: 1,247 studies
  • The Digit Span Test in all clinical trials: 1,629 studies

The Digit Span Test in other conditions

  • Dementia and Alzheimer's181
  • Mild cognitive impairment169
  • Aging, frailty and exercise129
  • Cancer107
  • Stroke100
  • Brain injury and concussion98
  • Parkinson's disease86
  • Anxiety, PTSD and OCD72
  • Schizophrenia and psychosis66
  • Healthy volunteers64
  • Obesity and diabetes64
  • Sleep and sleep disorders63
  • Pain and fatigue61
  • Cognitive impairment and decline60
  • Cardiovascular disease59
  • ADHD58

Other tests in depression and bipolar disorder trials

  • Trail Making Test204
  • Verbal Learning178
  • Verbal Fluency154
  • Symbol Coding143
  • Stroop Color-Word Test138
  • Go/No-Go Task79
  • N-Back Task79
  • Continuous Performance Test73
  • Card Sorting Test (Berg)65

How the studies are counted

For each test family, the census runs ClinicalTrials.gov's own outcome search for the family's names and reads every study first posted by the day the family was counted. These studies were read on 10 November 2026. A study counts once on a page, however many tests it names. Counts for a test cover every version of the task under any of its names, so a page can count studies that used a commercial version.

The census adds two things to each record and changes nothing in it: which outcome list names the test (primary, then secondary, then other), and the condition groups, matched on the study's condition names and MeSH terms. A study can fall in several groups; one whose only condition is cognitive impairment or decline falls in “Cognitive impairment and decline”. Studies that name only instruments outside the library count in every total and share but are not listed.

A second read on 10 November 2026 added each study's overall status, whether results are posted, its intervention types, the countries of its sites and the time frame of the outcome that names each test. A time frame counts by the latest time point it names: “Baseline, 12 and 24 weeks” is 24 weeks, a single visit is within a day, and one that names no duration, such as “end of treatment”, is left out of the timings.

A third read on 10 November 2026 added the papers the registry links to each study: those its sponsor lists as reporting results, and those PubMed links to it through the study's NCT number. A study has a results paper when one of them came out in or after the month of its primary completion and PubMed does not class it as a protocol, review or comment. A paper that never gives the NCT number is not linked, so some studies counted as reporting neither did publish.

Source: ClinicalTrials.gov, a database of the U.S. National Library of Medicine, which does not endorse these pages. Every study line is in the data release 2.1.0, and the explorer's own file is clinical-trials-studies.json.

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