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  1. Home
  2. /Data
  3. /Clinical trials
  4. /Conditions
  5. /Pain and fatigue
  6. /Verbal Fluency

Clinical trials data

Verbal Fluency in pain and fatigue trials: 53 registered studies

Every registered pain and fatigue study on ClinicalTrials.gov that names Verbal Fluency 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 pain and fatigue studies name it in an outcome measure
53
Name it in a primary outcome, 32%
17 of 53
Of the condition's 681 studies name it, against 11% of all registered studies
8%
Other conditions
Median participants per study
80
By phase
Try Verbal Fluency

Tests named in the same studies

The library tests that pain and fatigue studies naming Verbal Fluency name most often beside it.
  1. 1

    Digit Span Test19 studies, 11 as a primary outcome

  2. 2

    Trail Making Test18 studies, 7 as a primary outcome

  3. 3

    Verbal Learning16 studies, 5 as a primary outcome

  4. 4

    Stroop Color-Word Test13 studies, 4 as a primary outcome

  5. 5

    Category Fluency11 studies, 4 as a primary outcome

  6. 6

    Symbol Coding10 studies, 3 as a primary outcome

  7. 7

    Paced Visual Serial Addition Test7 studies, 3 as a primary outcome

  8. 8

    Tower Planning4 studies, 3 as a primary outcome

  9. 9

    Matrix Reasoning4 studies, 2 as a primary outcome

  10. 10

    Psychomotor Vigilance Task3 studies, 2 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: 3 studies, 1 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: 1 studies, 0 with a test as a primary outcome2008: 0 studies, 0 with a test as a primary outcome2009: 0 studies, 0 with a test as a primary outcome2010: 0 studies, 0 with a test as a primary outcome20102011: 2 studies, 1 with a test as a primary outcome2012: 2 studies, 1 with a test as a primary outcome2013: 1 studies, 0 with a test as a primary outcome2014: 1 studies, 1 with a test as a primary outcome2015: 3 studies, 2 with a test as a primary outcome20152016: 3 studies, 1 with a test as a primary outcome2017: 3 studies, 1 with a test as a primary outcome2018: 0 studies, 0 with a test as a primary outcome2019: 3 studies, 1 with a test as a primary outcome2020: 4 studies, 3 with a test as a primary outcome20202021: 3 studies, 0 with a test as a primary outcome2022: 1 studies, 0 with a test as a primary outcome2023: 8 studies, 2 with a test as a primary outcome2024: 4 studies, 0 with a test as a primary outcome2025: 6 studies, 2 with a test as a primary outcome20252026: 5 studies, 1 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
200431
200500
200600
200710
200800
200900
201000
201121
201221
201310
201411
201532
201631
201731
201800
201931
202043
202130
202210
202382
202440
202562
202651

Phases and study sizes

By phase

  • Phase 1/21 studies, 0 as a primary outcome
  • Phase 29 studies, 3 as a primary outcome
  • Phase 2/31 studies, 0 as a primary outcome
  • Phase 34 studies, 2 as a primary outcome
  • Phase 41 studies, 1 as a primary outcome
  • Not applicable29 studies, 7 as a primary outcome
  • Observational8 studies, 4 as a primary outcome

Participants per study

102050100200
  • Not applicable70 median, 39 to 151
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 pain and fatigue study that names Verbal Fluency, by phase
PhaseStudies with a sizeMedianMiddle half
Not applicable287039 to 151

When pain and fatigue trials measure it

Half of the primary outcomes that name Verbal Fluency are measured within 10 weeks of the start, and the middle half from 6 weeks to 7 months. 16 primary outcomes give a duration.

Latest time point of each outcome

  • Within a day4 outcomes, 1 as a primary outcome
  • Up to 4 weeks9 outcomes, 3 as a primary outcome
  • 1 to 3 months18 outcomes, 6 as a primary outcome
  • 3 to 6 months8 outcomes, 2 as a primary outcome
  • 6 to 12 months4 outcomes, 2 as a primary outcome
  • 1 to 2 years4 outcomes, 2 as a primary outcome
  • No duration given6 outcomes, 1 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

47 of the 53 outcome measures give a duration. A single visit counts as within a day.

Status, results, interventions and countries

Status

  • Recruiting8 studies, 2 as a primary outcome
  • Not yet recruiting3 studies, 1 as a primary outcome
  • Active, not recruiting2 studies, 1 as a primary outcome
  • Completed28 studies, 7 as a primary outcome
  • Stopped early3 studies, 3 as a primary outcome
  • Status unknown9 studies, 3 as a primary outcome

What they test

  • Behavioral8 studies, 4 as a primary outcome
  • Drug15 studies, 6 as a primary outcome
  • Device12 studies, 5 as a primary outcome
  • Dietary supplement3 studies, 0 as a primary outcome
  • Procedure4 studies, 0 as a primary outcome
  • Diagnostic test1 studies, 1 as a primary outcome
  • Biological2 studies, 0 as a primary outcome
  • Radiation3 studies, 1 as a primary outcome
  • Other13 studies, 2 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 States24 studies, 8 as a primary outcome
  • Italy4 studies, 1 as a primary outcome
  • Türkiye4 studies, 1 as a primary outcome
  • Brazil3 studies, 1 as a primary outcome
  • France3 studies, 0 as a primary outcome
  • Germany3 studies, 0 as a primary outcome
  • Canada2 studies, 0 as a primary outcome
  • Denmark2 studies, 1 as a primary outcome
  • Greece2 studies, 0 as a primary outcome
  • Hungary2 studies, 0 as a primary outcome
  • Netherlands2 studies, 1 as a primary outcome
  • Spain2 studies, 1 as a primary outcome

27 countries in all. A study with sites in several counts in each; 2 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 pain and fatigue studies that name Verbal Fluency: 16 of 28, 57%

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

Completed pain and fatigue studies that name Verbal Fluency and every completed study, by how they reported results
ResultsCompleted pain and fatigue studies that name Verbal FluencyEvery completed study
Results on ClinicalTrials.gov and a paper6, 21%776, 10%
Results on ClinicalTrials.gov only3, 11%1,139, 14%
A results paper only7, 25%1,711, 22%
Neither12, 43%4,327, 54%

The 53 studies

Filter by phase, sponsor, status, country, intervention, outcome list, size and start year. Each study links to its record on ClinicalTrials.gov.
ConditionPain and fatigue
TestVerbal Fluency

53 studies match. 17 name Verbal Fluency in a primary outcome. Median size 80 participants. Median time to the primary outcome: 10 weeks.

Loading 53 studies; the filters turn on when they arrive.

By start year
024682000: 0 studies, 0 naming Verbal Fluency in a primary outcome20002001: 0 studies, 0 naming Verbal Fluency in a primary outcome2002: 0 studies, 0 naming Verbal Fluency in a primary outcome2003: 0 studies, 0 naming Verbal Fluency in a primary outcome2004: 3 studies, 1 naming Verbal Fluency in a primary outcome2005: 0 studies, 0 naming Verbal Fluency in a primary outcome20052006: 0 studies, 0 naming Verbal Fluency in a primary outcome2007: 1 studies, 0 naming Verbal Fluency in a primary outcome2008: 0 studies, 0 naming Verbal Fluency in a primary outcome2009: 0 studies, 0 naming Verbal Fluency in a primary outcome2010: 0 studies, 0 naming Verbal Fluency in a primary outcome20102011: 2 studies, 1 naming Verbal Fluency in a primary outcome2012: 2 studies, 1 naming Verbal Fluency in a primary outcome2013: 1 studies, 0 naming Verbal Fluency in a primary outcome2014: 1 studies, 1 naming Verbal Fluency in a primary outcome2015: 3 studies, 2 naming Verbal Fluency in a primary outcome20152016: 3 studies, 1 naming Verbal Fluency in a primary outcome2017: 3 studies, 1 naming Verbal Fluency in a primary outcome2018: 0 studies, 0 naming Verbal Fluency in a primary outcome2019: 3 studies, 1 naming Verbal Fluency in a primary outcome2020: 4 studies, 3 naming Verbal Fluency in a primary outcome20202021: 3 studies, 0 naming Verbal Fluency in a primary outcome2022: 1 studies, 0 naming Verbal Fluency in a primary outcome2023: 8 studies, 2 naming Verbal Fluency in a primary outcome2024: 4 studies, 0 naming Verbal Fluency in a primary outcome2025: 6 studies, 2 naming Verbal Fluency in a primary outcome20252026: 5 studies, 1 naming Verbal Fluency 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
200300
200431
200500
200600
200710
200800
200900
201000
201121
201221
201310
201411
201532
201631
201731
201800
201931
202043
202130
202210
202382
202440
202562
202651

Library tests named most

  • Verbal Fluency53 studies, 17 as a primary outcome
  • Digit Span Test19 studies, 11 as a primary outcome
  • Trail Making Test18 studies, 7 as a primary outcome
  • Verbal Learning16 studies, 5 as a primary outcome
  • Stroop Color-Word Test13 studies, 4 as a primary outcome
  • Category Fluency11 studies, 4 as a primary outcome
  • Symbol Coding10 studies, 3 as a primary outcome
  • Paced Visual Serial Addition Test7 studies, 3 as a primary outcome
  • Tower Planning4 studies, 3 as a primary outcome
  • Matrix Reasoning4 studies, 2 as a primary outcome

Conditions

  • Pain and fatigue53 studies, 17 as a primary outcome
  • Depression and bipolar disorder13 studies, 6 as a primary outcome
  • Cancer13 studies, 4 as a primary outcome
  • Anxiety, PTSD and OCD10 studies, 3 as a primary outcome
  • Sleep and sleep disorders8 studies, 3 as a primary outcome
  • Multiple sclerosis5 studies, 2 as a primary outcome
  • COVID-19 and long COVID5 studies, 2 as a primary outcome
  • Aging, frailty and exercise3 studies, 1 as a primary outcome
  • Delirium, surgery and intensive care2 studies, 0 as a primary outcome
  • Stroke1 study, 0 as a primary outcome
  • Brain injury and concussion1 study, 0 as a primary outcome
  • Substance use and addiction1 study, 1 as a primary outcome

Phases

Participants

Lead sponsor: industry 2, other 51. Interventional 45, observational 8.

As a primary outcomeSecondary or other outcomeVerbal Fluency

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
NCT07842302Start2026PhaseNot applicableConditionsMultiple sclerosis, Pain and fatigueParticipants80Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestSecondary6 months
  • Stroop Color-Word TestSecondary6 months
  • Verbal FluencySecondary6 months
  • Symbol CodingPrimary6 months
  • Paced Visual Serial Addition TestSecondary6 months
  • Selective Reminding TaskSecondary6 months
NCT07766980Start2026PhasePhase 2ConditionsPain and fatigueParticipants20Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary10 weeks
  • Verbal FluencySecondary10 weeks
NCT07709234Start2026PhaseNot applicableConditionsCOVID-19 and long COVID, Pain and fatigueParticipants20Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Stroop Color-Word TestPrimary3 days
  • Verbal FluencyPrimary3 days
NCT07539116Start2024PhaseNot applicableConditionsPain and fatigueParticipants183Lead sponsorOtherStatusCompleted

Paper

Library tests named
  • Trail Making TestPrimary12 weeks
  • Stroop Color-Word TestPrimary12 weeks
  • Verbal FluencyOther outcome12 weeks
  • Matrix ReasoningOther outcome12 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
NCT07357688Start2026PhaseNot applicableConditionsPain and fatigueParticipants99Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestSecondary8 weeks
  • Stroop Color-Word TestSecondary8 weeks
  • Verbal LearningSecondary8 weeks
  • Verbal FluencySecondary8 weeks
  • Digit Span TestSecondary8 weeks
  • Category FluencySecondary8 weeks
  • Picture Naming TestSecondary8 weeks
  • Complex Figure Copy and RecallSecondary8 weeks
NCT07304843Start2023PhasePhase 1/2ConditionsPain and fatigueParticipants207Lead sponsorIndustryStatusCompletedLibrary tests named
  • Verbal LearningSecondary4 weeks
  • Verbal FluencySecondary4 weeks
  • Symbol CodingSecondary4 weeks
  • Category FluencySecondary4 weeks
NCT07273604Start2015PhaseNot applicableConditionsMultiple sclerosis, Depression and bipolar disorder, Anxiety, PTSD and OCD, Pain and fatigueParticipants148Lead sponsorOtherStatusCompletedLibrary tests named
  • Verbal FluencyPrimary12 weeks
  • Symbol CodingPrimary12 weeks
  • Category FluencyPrimary12 weeks
  • Paced Visual Serial Addition TestPrimary12 weeks
  • Selective Reminding TaskPrimary12 weeks
NCT06922409Start2025PhaseNot applicableConditionsStroke, Depression and bipolar disorder, Sleep and sleep disorders, Pain and fatigueParticipants45Lead sponsorOtherStatusRecruitingLibrary tests named
  • Stroop Color-Word TestSecondary1 week
  • Verbal FluencySecondary1 week
  • Category FluencySecondary1 week
NCT06871852Start2025PhaseNot applicableConditionsAging, frailty and exercise, Pain and fatigueParticipants54Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencyPrimary13 weeks
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
NCT06808048Start2025PhaseNot applicableConditionsSubstance use and addiction, Pain and fatigueParticipants180Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal LearningPrimary4 months
  • Verbal FluencyPrimary4 months
  • Digit Span TestPrimary4 months
  • Go/No-Go TaskPrimary4 months
  • Tower PlanningPrimary4 months
  • Paired Associate LearningPrimary4 months
  • Iowa Gambling LitePrimary4 months
  • Word Pair LearningPrimary4 months
NCT06586398Start2025PhaseNot applicableConditionsCOVID-19 and long COVID, Pain and fatigueParticipants10Lead sponsorOtherStatusCompletedLibrary tests named
  • Verbal FluencySecondary12 weeks
  • Short Story RecallSecondary12 weeks
NCT06511674Start2024PhaseNot applicableConditionsCancer, Pain and fatigueParticipants625Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencySecondarysame day
NCT06476496Start2024PhaseNot applicableConditionsCOVID-19 and long COVID, Pain and fatigueParticipants93Lead sponsorOtherStatusCompleted

Results

Library tests named
  • Verbal FluencySecondary5 months
NCT06448923Start2025PhasePhase 2ConditionsPain and fatigueParticipants225Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal LearningSecondary13 weeks
  • Verbal FluencySecondary13 weeks
  • Digit Span TestSecondary13 weeks
  • Symbol Scan TaskSecondary13 weeks
NCT06352099Start2024PhaseNot applicableConditionsAging, frailty and exercise, Pain and fatigueParticipants36Lead sponsorOtherStatusCompleted

Paper

Library tests named
  • Verbal FluencySecondary16 weeks
  • Matrix ReasoningSecondary16 weeks
NCT06074848Start2023PhasePhase 2ConditionsDepression and bipolar disorder, COVID-19 and long COVID, Pain and fatigueParticipants48Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Trail Making TestPrimary2 weeks
  • Verbal FluencyPrimary2 weeks
  • Digit Span TestPrimary2 weeks
  • Arithmetic Fluency TaskPrimary2 weeks
NCT06032715Start2023PhaseNot applicableConditionsSleep and sleep disorders, Pain and fatigueParticipants120Lead sponsorOtherStatusRecruiting

Paper 1Paper 2

Library tests named
  • Verbal FluencyOther outcome6 weeks
NCT05926986Start2023PhaseNot applicableConditionsPain and fatigueParticipants30Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Stroop Color-Word TestPrimarysame day
  • Verbal FluencySecondarysame day
  • Category FluencySecondarysame day
NCT05748483Start2023PhasePhase 3ConditionsPain and fatigueParticipants545Lead sponsorIndustryStatusCompleted

ResultsPaper

Library tests named
  • Verbal FluencySecondary6 weeks
NCT05625776Start2023PhaseNot applicableConditionsPain and fatigueParticipants23Lead sponsorOtherStatusCompletedLibrary tests named
  • Trail Making TestPrimary
  • Stroop Color-Word TestSecondary
  • Verbal LearningSecondary
  • Verbal FluencySecondary
  • Digit Span TestPrimary
  • Continuous Performance TestSecondary
  • Card Sorting Test (Berg)Secondary
NCT05624814Start2023PhaseObservationalConditionsPain and fatigueParticipants60Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Verbal FluencyPrimary
  • Clock Drawing TaskPrimary
  • Matrix ReasoningPrimary
  • Arithmetic Fluency TaskPrimary
NCT05356988Start2022PhaseNot applicableConditionsDepression and bipolar disorder, Cancer, Aging, frailty and exercise, Sleep and sleep disorders, Anxiety, PTSD and OCD, Pain and fatigueParticipants415Lead sponsorOtherStatusCompleted

Paper 1Paper 2

Library tests named
  • Verbal FluencySecondary12 months
NCT05321693Start2021PhasePhase 2ConditionsPain and fatigueParticipants70Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Verbal FluencySecondary5 days

Page 1 of 3

Questions, answered from the data

How many pain and fatigue trials use Verbal Fluency?

53 registered pain and fatigue studies on ClinicalTrials.gov name it in an outcome measure, 17 of them in a primary outcome: 8% of the condition's 681 studies with a cognitive outcome, against 11% of all of them. It is the 6th most named test in pain and fatigue trials.

Which tests do pain and fatigue trials use with Verbal Fluency?

The Digit Span Test (19 studies), the Trail Making Test (18 studies) and Verbal Learning (16 studies).

When do pain and fatigue trials measure Verbal Fluency?

Half of the primary outcomes that name Verbal Fluency are measured within 10 weeks of the start, and the middle half from 6 weeks to 7 months. 16 primary outcomes give a duration.

How many completed pain and fatigue trials that use Verbal Fluency have reported results?

16 of the 28 completed studies that name it, 57%, have reported results: 9 posted them on ClinicalTrials.gov, 13 have a results paper linked to the registry record, and 6 did both. The other 12 show neither. Of all completed studies with a cognitive outcome, 46% have reported results.

More on Verbal Fluency and pain and fatigue

  • Every cognitive test in pain and fatigue trials: 681 studies
  • Verbal Fluency in all clinical trials: 1,745 studies

Verbal Fluency in other conditions

  • Dementia and Alzheimer's248
  • Cancer200
  • Mild cognitive impairment177
  • Depression and bipolar disorder154
  • Parkinson's disease140
  • Aging, frailty and exercise136
  • Stroke110
  • Schizophrenia and psychosis107
  • Brain injury and concussion86
  • Cognitive impairment and decline63
  • Obesity and diabetes63
  • Anxiety, PTSD and OCD61
  • Cardiovascular disease61
  • Multiple sclerosis58
  • Sleep and sleep disorders58

Other tests in pain and fatigue trials

  • Stroop Color-Word Test114
  • Trail Making Test94
  • Symbol Coding82
  • Verbal Learning72
  • Digit Span Test61

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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