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  1. Home
  2. /Data
  3. /Clinical trials
  4. /Conditions
  5. /Anxiety, PTSD and OCD
  6. /Digit Span Test

Clinical trials data

Digit Span Test in anxiety, PTSD and OCD trials: 72 registered studies

Every registered anxiety, PTSD and OCD 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 anxiety, PTSD and OCD studies name it in an outcome measure
72
Name it in a primary outcome, 38%
27 of 72
Of the condition's 692 studies name it, against 10% of all registered studies
10%
Other conditions
Median participants per study
76
By phase
Try the Digit Span Test

Tests named in the same studies

The library tests that anxiety, PTSD and OCD studies naming the Digit Span Test name most often beside it.
  1. 1

    Trail Making Test30 studies, 13 as a primary outcome

  2. 2

    Verbal Fluency25 studies, 10 as a primary outcome

  3. 3

    Verbal Learning23 studies, 8 as a primary outcome

  4. 4

    Stroop Color-Word Test13 studies, 5 as a primary outcome

  5. 5

    Symbol Coding11 studies, 4 as a primary outcome

  6. 6

    Continuous Performance Test9 studies, 4 as a primary outcome

  7. 7

    Go/No-Go Task9 studies, 4 as a primary outcome

  8. 8

    Letter-Number Sequencing Task8 studies, 1 as a primary outcome

  9. 9

    Paced Visual Serial Addition Test6 studies, 4 as a primary outcome

  10. 10

    N-Back Task6 studies, 3 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: 0 studies, 0 with a test as a primary outcome2004: 0 studies, 0 with a test as a primary outcome2005: 0 studies, 0 with a test as a primary outcome20052006: 0 studies, 0 with a test as a primary outcome2007: 0 studies, 0 with a test as a primary outcome2008: 0 studies, 0 with a test as a primary outcome2009: 1 studies, 0 with a test as a primary outcome2010: 0 studies, 0 with a test as a primary outcome20102011: 3 studies, 0 with a test as a primary outcome2012: 4 studies, 0 with a test as a primary outcome2013: 1 studies, 0 with a test as a primary outcome2014: 2 studies, 0 with a test as a primary outcome2015: 3 studies, 3 with a test as a primary outcome20152016: 4 studies, 2 with a test as a primary outcome2017: 2 studies, 1 with a test as a primary outcome2018: 3 studies, 2 with a test as a primary outcome2019: 9 studies, 3 with a test as a primary outcome2020: 2 studies, 1 with a test as a primary outcome20202021: 6 studies, 3 with a test as a primary outcome2022: 4 studies, 1 with a test as a primary outcome2023: 4 studies, 2 with a test as a primary outcome2024: 12 studies, 5 with a test as a primary outcome2025: 5 studies, 2 with a test as a primary outcome20252026: 6 studies, 2 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
200300
200400
200500
200600
200700
200800
200910
201000
201130
201240
201310
201420
201533
201642
201721
201832
201993
202021
202163
202241
202342
2024125
202552
202662

Phases and study sizes

By phase

  • Early phase 11 studies, 0 as a primary outcome
  • Phase 11 studies, 0 as a primary outcome
  • Phase 1/25 studies, 3 as a primary outcome
  • Phase 26 studies, 1 as a primary outcome
  • Phase 2/31 studies, 0 as a primary outcome
  • Phase 31 studies, 1 as a primary outcome
  • Phase 41 studies, 1 as a primary outcome
  • Not applicable50 studies, 18 as a primary outcome
  • Observational6 studies, 3 as a primary outcome

Participants per study

102050100
  • Not applicable77 median, 50 to 104
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 anxiety, PTSD and OCD study that names the Digit Span Test, by phase
PhaseStudies with a sizeMedianMiddle half
Not applicable487750 to 104

When anxiety, PTSD and OCD trials measure it

Half of the primary outcomes that name the Digit Span Test are measured within 6 weeks of the start, and the middle half from 1 week to 13 weeks. 25 primary outcomes give a duration.

Latest time point of each outcome

  • Within a day9 outcomes, 5 as a primary outcome
  • Up to 4 weeks14 outcomes, 5 as a primary outcome
  • 1 to 3 months21 outcomes, 9 as a primary outcome
  • 3 to 6 months22 outcomes, 5 as a primary outcome
  • 6 to 12 months1 outcomes, 0 as a primary outcome
  • 1 to 2 years3 outcomes, 1 as a primary outcome
  • No duration given2 outcomes, 2 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

70 of the 72 outcome measures give a duration. A single visit counts as within a day.

Status, results, interventions and countries

Status

  • Recruiting14 studies, 4 as a primary outcome
  • Not yet recruiting4 studies, 0 as a primary outcome
  • Active, not recruiting3 studies, 2 as a primary outcome
  • Completed36 studies, 16 as a primary outcome
  • Stopped early5 studies, 1 as a primary outcome
  • Status unknown10 studies, 4 as a primary outcome

What they test

  • Behavioral39 studies, 10 as a primary outcome
  • Drug11 studies, 5 as a primary outcome
  • Device10 studies, 4 as a primary outcome
  • Dietary supplement5 studies, 3 as a primary outcome
  • Procedure2 studies, 1 as a primary outcome
  • Diagnostic test3 studies, 2 as a primary outcome
  • Radiation2 studies, 1 as a primary outcome
  • Other11 studies, 5 as a primary outcome
  • None given2 studies, 1 as a primary outcome

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

Where their sites are

  • United States31 studies, 12 as a primary outcome
  • Canada6 studies, 0 as a primary outcome
  • Netherlands4 studies, 1 as a primary outcome
  • China3 studies, 2 as a primary outcome
  • Israel3 studies, 1 as a primary outcome
  • United Kingdom3 studies, 1 as a primary outcome
  • Argentina2 studies, 1 as a primary outcome
  • Denmark2 studies, 1 as a primary outcome
  • Hong Kong2 studies, 0 as a primary outcome
  • Spain2 studies, 1 as a primary outcome
  • Sweden2 studies, 0 as a primary outcome
  • Brazil1 studies, 1 as a primary outcome

22 countries in all. A study with sites in several counts in each; 3 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 anxiety, PTSD and OCD studies that name the Digit Span Test: 10 of 36, 28%

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

Completed anxiety, PTSD and OCD studies that name the Digit Span Test and every completed study, by how they reported results
ResultsCompleted anxiety, PTSD and OCD studies that name the Digit Span TestEvery completed study
Results on ClinicalTrials.gov and a paper1, 3%776, 10%
Results on ClinicalTrials.gov only6, 17%1,139, 14%
A results paper only3, 8%1,711, 22%
Neither26, 72%4,327, 54%

The 72 studies

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

72 studies match. 27 name the Digit Span Test in a primary outcome. Median size 76 participants. Median time to the primary outcome: 6 weeks.

Loading 72 studies; the filters turn on when they arrive.

By start year
0510152000: 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: 0 studies, 0 naming the Digit Span Test in a primary outcome2004: 0 studies, 0 naming the Digit Span Test in a primary outcome2005: 0 studies, 0 naming the Digit Span Test in a primary outcome20052006: 0 studies, 0 naming the Digit Span Test in a primary outcome2007: 0 studies, 0 naming the Digit Span Test in a primary outcome2008: 0 studies, 0 naming the Digit Span Test in a primary outcome2009: 1 studies, 0 naming the Digit Span Test in a primary outcome2010: 0 studies, 0 naming the Digit Span Test in a primary outcome20102011: 3 studies, 0 naming the Digit Span Test in a primary outcome2012: 4 studies, 0 naming the Digit Span Test in a primary outcome2013: 1 studies, 0 naming the Digit Span Test in a primary outcome2014: 2 studies, 0 naming the Digit Span Test in a primary outcome2015: 3 studies, 3 naming the Digit Span Test in a primary outcome20152016: 4 studies, 2 naming the Digit Span Test in a primary outcome2017: 2 studies, 1 naming the Digit Span Test in a primary outcome2018: 3 studies, 2 naming the Digit Span Test in a primary outcome2019: 9 studies, 3 naming the Digit Span Test in a primary outcome2020: 2 studies, 1 naming the Digit Span Test in a primary outcome20202021: 6 studies, 3 naming the Digit Span Test in a primary outcome2022: 4 studies, 1 naming the Digit Span Test in a primary outcome2023: 4 studies, 2 naming the Digit Span Test in a primary outcome2024: 12 studies, 5 naming the Digit Span Test in a primary outcome2025: 5 studies, 2 naming the Digit Span Test in a primary outcome20252026: 6 studies, 2 naming the Digit Span Test in a primary outcome

2026 is partly planned starts. Not shown: 1 planned to start after 2026.

Show as a table
Matching studies by start year
Start yearStudiesAs a primary outcome
200000
200100
200200
200300
200400
200500
200600
200700
200800
200910
201000
201130
201240
201310
201420
201533
201642
201721
201832
201993
202021
202163
202241
202342
2024125
202552
202662

Library tests named most

  • Digit Span Test72 studies, 27 as a primary outcome
  • Trail Making Test30 studies, 13 as a primary outcome
  • Verbal Fluency25 studies, 10 as a primary outcome
  • Verbal Learning23 studies, 8 as a primary outcome
  • Stroop Color-Word Test13 studies, 5 as a primary outcome
  • Symbol Coding11 studies, 4 as a primary outcome
  • Continuous Performance Test9 studies, 4 as a primary outcome
  • Go/No-Go Task9 studies, 4 as a primary outcome
  • Letter-Number Sequencing Task8 studies, 1 as a primary outcome
  • Paced Visual Serial Addition Test6 studies, 4 as a primary outcome

Largest condition groups

  • Anxiety, PTSD and OCD72 studies, 27 as a primary outcome
  • Depression and bipolar disorder33 studies, 12 as a primary outcome
  • Brain injury and concussion11 studies, 5 as a primary outcome
  • Pain and fatigue11 studies, 6 as a primary outcome
  • Sleep and sleep disorders8 studies, 4 as a primary outcome
  • Cancer4 studies, 2 as a primary outcome
  • Substance use and addiction4 studies, 1 as a primary outcome
  • Mild cognitive impairment3 studies, 3 as a primary outcome
  • Healthy volunteers3 studies, 1 as a primary outcome
  • Obesity and diabetes2 studies, 1 as a primary outcome
  • COVID-19 and long COVID2 studies, 2 as a primary outcome
  • Delirium, surgery and intensive care2 studies, 1 as a primary outcome

Phases

Participants

Lead sponsor: industry 5, other 67. Interventional 66, observational 6.

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
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
NCT07693686Start2027PhaseNot applicableConditionsAnxiety, PTSD and OCDParticipants176Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Verbal LearningOther outcome10 weeks
  • Verbal FluencyOther outcome10 weeks
  • Digit Span TestOther outcome10 weeks
  • Continuous Performance TestOther outcome10 weeks
  • Choice Reaction TimeOther outcome10 weeks
  • AX Continuous Performance TestOther outcome10 weeks
  • Letter-Number Sequencing TaskOther outcome10 weeks
NCT07659171Start2019PhaseNot applicableConditionsDepression and bipolar disorder, Sleep and sleep disorders, Anxiety, PTSD and OCDParticipants39Lead sponsorOtherStatusCompletedLibrary tests named
  • Digit Span TestSecondary3 weeks
  • Operation SpanSecondary3 weeks
NCT07393672Start2026PhasePhase 2ConditionsAnxiety, PTSD and OCD, Pain and fatigueParticipants104Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary13 weeks
  • Stroop Color-Word TestSecondary13 weeks
  • Verbal LearningSecondary13 weeks
  • Verbal FluencySecondary13 weeks
  • Digit Span TestSecondary13 weeks
  • Symbol CodingSecondary
  • N-Back TaskSecondary13 weeks
  • Go/No-Go TaskSecondary13 weeks
  • Simple Reaction TimeSecondary13 weeks
  • Corsi Block-Tapping TestSecondary13 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
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
NCT07055633Start2026PhaseNot applicableConditionsBrain injury and concussion, Anxiety, PTSD and OCDParticipants144Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal LearningPrimary10 weeks
  • Digit Span TestPrimary10 weeks
NCT06885996Start2026PhasePhase 2ConditionsAnxiety, PTSD and OCDParticipants76Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestSecondary6 months
  • Digit Span TestSecondary6 months
  • Card Sorting Test (Berg)Secondary6 months
  • Choice Reaction TimeSecondary6 months
NCT06831916Start2025PhasePhase 2ConditionsAnxiety, PTSD and OCD, Pain and fatigueParticipants104Lead sponsorOtherStatusCompletedLibrary tests named
  • Trail Making TestSecondary13 weeks
  • Stroop Color-Word TestSecondary13 weeks
  • Verbal LearningSecondary13 weeks
  • Verbal FluencySecondary13 weeks
  • Digit Span TestSecondary13 weeks
  • Symbol CodingSecondary
  • N-Back TaskSecondary13 weeks
  • Go/No-Go TaskSecondary13 weeks
  • Simple Reaction TimeSecondary13 weeks
  • Corsi Block-Tapping TestSecondary13 weeks
  • DRM False Memory TaskSecondary13 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
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
NCT06809218Start2022PhasePhase 3ConditionsAnxiety, PTSD and OCD, Delirium, surgery and intensive careParticipants312Lead sponsorIndustryStatusActive, not recruitingLibrary tests named
  • Verbal FluencyPrimary13 weeks
  • Digit Span TestPrimary13 weeks
  • Sentence Completion Inhibition TestPrimary13 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
NCT06638996Start2024PhaseNot applicableConditionsAnxiety, PTSD and OCD, Pain and fatigueParticipants100Lead sponsorOtherStatusCompletedLibrary tests named
  • Verbal LearningPrimary1 week
  • Digit Span TestPrimary1 week
  • DRM False Memory TaskPrimary1 week
NCT06569849Start2024PhaseNot applicableConditionsAnxiety, PTSD and OCD, Pain and fatigueParticipants60Lead sponsorIndustryStatusStatus unknownLibrary tests named
  • Trail Making TestPrimary9 weeks
  • Digit Span TestPrimary9 weeks
  • Complex Figure Copy and RecallPrimary9 weeks
NCT06542419Start2024PhaseNot applicableConditionsDepression and bipolar disorder, Anxiety, PTSD and OCDParticipants24Lead sponsorOtherStatusCompletedLibrary tests named
  • Trail Making TestPrimary1 week
  • Digit Span TestPrimary1 week
  • Symbol CodingPrimary1 week
NCT06429956Start2024PhaseNot applicableConditionsDepression and bipolar disorder, Anxiety, PTSD and OCDParticipants93Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestOther outcomesame day
  • Stroop Color-Word TestOther outcomesame day
  • Verbal FluencyOther outcomesame day
  • Digit Span TestOther outcomesame day
NCT06354361Start2024PhaseNot applicableConditionsAnxiety, PTSD and OCDParticipants33Lead sponsorOtherStatusCompletedLibrary tests named
  • Verbal LearningSecondary13 weeks
  • Digit Span TestSecondary13 weeks
  • Go/No-Go TaskPrimary13 weeks
NCT06273527Start2024PhasePhase 2/3ConditionsDepression and bipolar disorder, Anxiety, PTSD and OCDParticipants128Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary16 weeks
  • Digit Span TestSecondary16 weeks
  • Matrix ReasoningSecondary16 weeks
  • Dimensional Change Card SortSecondary16 weeks
  • Vocabulary TestSecondary16 weeks
  • Size Order Memory TestSecondary16 weeks
  • Pattern and Letter ComparisonSecondary16 weeks
  • Picture Order Memory TestSecondary16 weeks
  • Reading Span TaskSecondary4 weeks
NCT06236919Start2024PhaseNot applicableConditionsDepression and bipolar disorder, Anxiety, PTSD and OCDParticipants160Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary5 weeks
  • Stroop Color-Word TestSecondary5 weeks
  • Digit Span TestSecondary5 weeks
  • Card Sorting Test (Berg)Secondary5 weeks
NCT06063265Start2023PhaseNot applicableConditionsAnxiety, PTSD and OCDParticipants120Lead sponsorOtherStatusCompletedLibrary tests named
  • Trail Making TestPrimary6 months
  • Verbal FluencyPrimary6 months
  • Digit Span TestPrimary6 months
  • Category FluencyPrimary6 months
NCT06054243Start2023PhaseNot applicableConditionsSleep and sleep disorders, Anxiety, PTSD and OCDParticipants137Lead sponsorOtherStatusCompletedLibrary tests named
  • Digit Span TestSecondary6 months
  • N-Back TaskSecondary6 months
  • Go/No-Go TaskSecondary6 months
  • Balloon RiskSecondary6 months

Page 1 of 3

Questions, answered from the data

How many anxiety, PTSD and OCD trials use the Digit Span Test?

72 registered anxiety, PTSD and OCD studies on ClinicalTrials.gov name it in an outcome measure, 27 of them in a primary outcome: 10% of the condition's 692 studies with a cognitive outcome, against 10% of all of them. It is the 2nd most named test in anxiety, PTSD and OCD trials.

Which tests do anxiety, PTSD and OCD trials use with the Digit Span Test?

The Trail Making Test (30 studies), Verbal Fluency (25 studies) and Verbal Learning (23 studies).

When do anxiety, PTSD and OCD trials measure the Digit Span Test?

Half of the primary outcomes that name the Digit Span Test are measured within 6 weeks of the start, and the middle half from 1 week to 13 weeks. 25 primary outcomes give a duration.

How many completed anxiety, PTSD and OCD trials that use the Digit Span Test have reported results?

10 of the 36 completed studies that name it, 28%, have reported results: 7 posted them on ClinicalTrials.gov, 4 have a results paper linked to the registry record, and 1 did both. The other 26 show neither. Of all completed studies with a cognitive outcome, 46% have reported results.

More on the Digit Span Test and anxiety, PTSD and OCD

  • Every cognitive test in anxiety, PTSD and OCD trials: 692 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
  • Depression and bipolar disorder143
  • Aging, frailty and exercise129
  • Cancer107
  • Stroke100
  • Brain injury and concussion98
  • Parkinson's disease86
  • 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 anxiety, PTSD and OCD trials

  • Stroop Color-Word Test79
  • Verbal Learning70
  • Trail Making Test69
  • Go/No-Go Task63
  • Verbal Fluency61

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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