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  1. Home
  2. /Data
  3. /Clinical trials
  4. /Conditions
  5. /Cognitive impairment and decline
  6. /Verbal Fluency

Clinical trials data

Verbal Fluency in cognitive impairment and decline trials: 63 registered studies

Every registered cognitive impairment and decline 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 cognitive impairment and decline studies name it in an outcome measure
63
Name it in a primary outcome, 56%
35 of 63
Of the condition's 354 studies name it, against 11% of all registered studies
18%
Other conditions
Median participants per study
93
By phase
Try Verbal Fluency

Tests named in the same studies

The library tests that cognitive impairment and decline studies naming Verbal Fluency name most often beside it.
  1. 1

    Trail Making Test29 studies, 11 as a primary outcome

  2. 2

    Verbal Learning24 studies, 11 as a primary outcome

  3. 3

    Digit Span Test17 studies, 7 as a primary outcome

  4. 4

    Stroop Color-Word Test13 studies, 6 as a primary outcome

  5. 5

    Symbol Coding13 studies, 3 as a primary outcome

  6. 6

    Picture Naming Test11 studies, 9 as a primary outcome

  7. 7

    Category Fluency10 studies, 6 as a primary outcome

  8. 8

    Clock Drawing Task9 studies, 3 as a primary outcome

  9. 9

    Complex Figure Copy and Recall6 studies, 3 as a primary outcome

  10. 10

    Short Story Recall6 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: 0 studies, 0 with a test as a primary outcome2010: 0 studies, 0 with a test as a primary outcome20102011: 1 studies, 0 with a test as a primary outcome2012: 2 studies, 1 with a test as a primary outcome2013: 4 studies, 3 with a test as a primary outcome2014: 0 studies, 0 with a test as a primary outcome2015: 2 studies, 1 with a test as a primary outcome20152016: 4 studies, 1 with a test as a primary outcome2017: 4 studies, 3 with a test as a primary outcome2018: 8 studies, 4 with a test as a primary outcome2019: 6 studies, 3 with a test as a primary outcome2020: 5 studies, 2 with a test as a primary outcome20202021: 4 studies, 4 with a test as a primary outcome2022: 3 studies, 0 with a test as a primary outcome2023: 8 studies, 5 with a test as a primary outcome2024: 2 studies, 1 with a test as a primary outcome2025: 5 studies, 2 with a test as a primary outcome20252026: 4 studies, 4 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
200900
201000
201110
201221
201343
201400
201521
201641
201743
201884
201963
202052
202144
202230
202385
202421
202552
202644

Phases and study sizes

By phase

  • Phase 11 studies, 1 as a primary outcome
  • Phase 1/21 studies, 1 as a primary outcome
  • Phase 22 studies, 1 as a primary outcome
  • Phase 31 studies, 0 as a primary outcome
  • Phase 42 studies, 1 as a primary outcome
  • Not applicable42 studies, 25 as a primary outcome
  • Observational14 studies, 6 as a primary outcome

Participants per study

102050100200
  • Not applicable81 median, 44 to 163
  • Observational170 median, 103 to 288
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 cognitive impairment and decline study that names Verbal Fluency, by phase
PhaseStudies with a sizeMedianMiddle half
Not applicable428144 to 163
Observational14170103 to 288

When cognitive impairment and decline trials measure it

Half of the primary outcomes that name Verbal Fluency are measured within 13 weeks of the start, and the middle half from 8 weeks to 6 months. 34 primary outcomes give a duration.

Latest time point of each outcome

  • Within a day12 outcomes, 6 as a primary outcome
  • Up to 4 weeks3 outcomes, 2 as a primary outcome
  • 1 to 3 months12 outcomes, 10 as a primary outcome
  • 3 to 6 months14 outcomes, 8 as a primary outcome
  • 6 to 12 months9 outcomes, 4 as a primary outcome
  • 1 to 2 years5 outcomes, 4 as a primary outcome
  • Over 2 years4 outcomes, 0 as a primary outcome
  • No duration given4 outcomes, 1 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

59 of the 63 outcome measures give a duration. A single visit counts as within a day.

Status, results, interventions and countries

Status

  • Recruiting12 studies, 7 as a primary outcome
  • Not yet recruiting2 studies, 2 as a primary outcome
  • Active, not recruiting6 studies, 5 as a primary outcome
  • Completed25 studies, 14 as a primary outcome
  • Stopped early2 studies, 1 as a primary outcome
  • Status unknown16 studies, 6 as a primary outcome

What they test

  • Behavioral16 studies, 10 as a primary outcome
  • Drug6 studies, 5 as a primary outcome
  • Device8 studies, 6 as a primary outcome
  • Dietary supplement3 studies, 2 as a primary outcome
  • Procedure1 studies, 1 as a primary outcome
  • Diagnostic test3 studies, 1 as a primary outcome
  • Biological1 studies, 0 as a primary outcome
  • Combination product1 studies, 0 as a primary outcome
  • Other25 studies, 12 as a primary outcome
  • None given4 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 States11 studies, 7 as a primary outcome
  • China8 studies, 3 as a primary outcome
  • Spain8 studies, 6 as a primary outcome
  • Italy6 studies, 3 as a primary outcome
  • United Kingdom4 studies, 1 as a primary outcome
  • Canada3 studies, 1 as a primary outcome
  • France3 studies, 1 as a primary outcome
  • Mexico3 studies, 3 as a primary outcome
  • Netherlands2 studies, 2 as a primary outcome
  • Türkiye2 studies, 2 as a primary outcome
  • Argentina1 studies, 0 as a primary outcome
  • Australia1 studies, 1 as a primary outcome

24 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 cognitive impairment and decline studies that name Verbal Fluency: 11 of 25, 44%

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

Completed cognitive impairment and decline studies that name Verbal Fluency and every completed study, by how they reported results
ResultsCompleted cognitive impairment and decline studies that name Verbal FluencyEvery completed study
Results on ClinicalTrials.gov and a paper1, 4%776, 10%
Results on ClinicalTrials.gov only1, 4%1,139, 14%
A results paper only9, 36%1,711, 22%
Neither14, 56%4,327, 54%

The 63 studies

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

63 studies match. 35 name Verbal Fluency in a primary outcome. Median size 93 participants. Median time to the primary outcome: 13 weeks.

Loading 63 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: 0 studies, 0 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: 0 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: 1 studies, 0 naming Verbal Fluency in a primary outcome2012: 2 studies, 1 naming Verbal Fluency in a primary outcome2013: 4 studies, 3 naming Verbal Fluency in a primary outcome2014: 0 studies, 0 naming Verbal Fluency in a primary outcome2015: 2 studies, 1 naming Verbal Fluency in a primary outcome20152016: 4 studies, 1 naming Verbal Fluency in a primary outcome2017: 4 studies, 3 naming Verbal Fluency in a primary outcome2018: 8 studies, 4 naming Verbal Fluency in a primary outcome2019: 6 studies, 3 naming Verbal Fluency in a primary outcome2020: 5 studies, 2 naming Verbal Fluency in a primary outcome20202021: 4 studies, 4 naming Verbal Fluency in a primary outcome2022: 3 studies, 0 naming Verbal Fluency in a primary outcome2023: 8 studies, 5 naming Verbal Fluency in a primary outcome2024: 2 studies, 1 naming Verbal Fluency in a primary outcome2025: 5 studies, 2 naming Verbal Fluency in a primary outcome20252026: 4 studies, 4 naming Verbal Fluency 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
200900
201000
201110
201221
201343
201400
201521
201641
201743
201884
201963
202052
202144
202230
202385
202421
202552
202644

Library tests named most

  • Verbal Fluency63 studies, 35 as a primary outcome
  • Trail Making Test29 studies, 11 as a primary outcome
  • Verbal Learning24 studies, 11 as a primary outcome
  • Digit Span Test17 studies, 7 as a primary outcome
  • Stroop Color-Word Test13 studies, 6 as a primary outcome
  • Symbol Coding13 studies, 3 as a primary outcome
  • Picture Naming Test11 studies, 9 as a primary outcome
  • Category Fluency10 studies, 6 as a primary outcome
  • Clock Drawing Task9 studies, 3 as a primary outcome
  • Complex Figure Copy and Recall6 studies, 3 as a primary outcome

Conditions

  • Cognitive impairment and decline63 studies, 35 as a primary outcome

Phases

Participants

Lead sponsor: industry 3, other 60. Interventional 49, observational 14.

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
NCT07872189Start2027PhaseNot applicableConditionsCognitive impairment and declineParticipants136Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Verbal FluencyPrimary6 months
NCT07802392Start2026PhaseNot applicableConditionsCognitive impairment and declineParticipants230Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencyPrimary1 week
  • Digit Span TestPrimary1 week
NCT07751510Start2026PhaseNot applicableConditionsCognitive impairment and declineParticipants75Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Stroop Color-Word TestSecondary13 weeks
  • Verbal LearningPrimary13 weeks
  • Verbal FluencyPrimary13 weeks
  • Digit Span TestSecondary13 weeks
  • Symbol CodingSecondary13 weeks
NCT07668440Start2026PhaseNot applicableConditionsCognitive impairment and declineParticipants71Lead sponsorOtherStatusActive, not recruitingLibrary tests named
  • Verbal FluencyPrimary13 weeks
  • Symbol CodingPrimary13 weeks
  • Category FluencyPrimary13 weeks
NCT07531888Start2026PhaseNot applicableConditionsCognitive impairment and declineParticipants20Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal LearningPrimary6 weeks
  • Verbal FluencyPrimary6 weeks
  • Digit Span TestPrimary6 weeks
  • Tower PlanningPrimary6 weeks
  • Corsi Block-Tapping TestPrimary6 weeks
NCT07402161Start2025PhaseObservationalConditionsCognitive impairment and declineParticipants250Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary2 years
  • Verbal LearningSecondary2 years
  • Verbal FluencySecondary2 years
  • Category FluencySecondary2 years
  • Short Story RecallSecondary2 years
  • Complex Figure Copy and RecallSecondary2 years
NCT06927492Start2025PhaseNot applicableConditionsCognitive impairment and declineParticipants50Lead sponsorOtherStatusCompletedLibrary tests named
  • Stroop Color-Word TestPrimary12 weeks
  • Verbal FluencyPrimary12 weeks
NCT06836440Start2025PhaseNot applicableConditionsCognitive impairment and declineParticipants964Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencySecondary3 years
NCT06832839Start2024PhaseObservationalConditionsCognitive impairment and declineParticipants360Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestPrimary6 months
  • Stroop Color-Word TestPrimary6 months
  • Verbal LearningPrimary6 months
  • Verbal FluencyPrimary6 months
  • Picture Naming TestPrimary6 months
  • Complex Figure Copy and RecallPrimary6 months
NCT06666088Start2025PhaseNot applicableConditionsCognitive impairment and declineParticipants81Lead sponsorOtherStatusCompletedLibrary tests named
  • Trail Making TestPrimary12 weeks
  • Verbal FluencyPrimary12 weeks
  • Symbol CodingPrimary12 weeks
NCT06579664Start2025PhaseNot applicableConditionsCognitive impairment and declineParticipants58Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary1 week
  • Stroop Color-Word TestSecondary1 week
  • Verbal FluencySecondary1 week
NCT06549517Start2023PhaseNot applicableConditionsCognitive impairment and declineParticipants75Lead sponsorOtherStatusCompleted

Paper

Library tests named
  • Verbal FluencySecondary
NCT06515106Start2023PhaseNot applicableConditionsCognitive impairment and declineParticipants20Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestPrimary12 months
  • Stroop Color-Word TestPrimary12 months
  • Verbal LearningPrimary12 months
  • Verbal FluencyPrimary12 months
  • Digit Span TestPrimary12 months
  • Category FluencyPrimary12 months
  • Picture Naming TestPrimary12 months
  • Symbol Scan TaskPrimary12 months
NCT06442943Start2024PhaseNot applicableConditionsCognitive impairment and declineParticipants128Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal LearningSecondary6 months
  • Verbal FluencySecondary6 months
  • Picture Naming TestSecondary6 months
  • Complex Figure Copy and RecallSecondary6 months
NCT06258382Start2023PhaseObservationalConditionsCognitive impairment and declineParticipants600Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Trail Making TestSecondarysame day
  • Verbal FluencySecondarysame day
  • Symbol CodingSecondarysame day
NCT06227962Start2023PhaseObservationalConditionsCognitive impairment and declineParticipants240Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestPrimary
  • Stroop Color-Word TestPrimary
  • Verbal LearningPrimary
  • Verbal FluencyPrimary
  • Digit Span TestPrimary
  • Matrix ReasoningPrimary
  • Symbol Scan TaskPrimary
NCT06183788Start2023PhaseNot applicableConditionsCognitive impairment and declineParticipants20Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Trail Making TestPrimary18 months
  • Stroop Color-Word TestPrimary18 months
  • Verbal LearningPrimary18 months
  • Verbal FluencyPrimary18 months
  • Digit Span TestPrimary18 months
  • Continuous Performance TestPrimary18 months
  • Category FluencyPrimary18 months
  • Picture Naming TestPrimary18 months
  • Complex Figure Copy and RecallSecondary18 months
  • Emoji Emotion RecognitionSecondary18 months
  • Spatial Working MemorySecondary18 months
  • Line Angle MatchingSecondary18 months
  • Intra/Extra Dimensional Set ShiftSecondary18 months
NCT06013579Start2023PhaseNot applicableConditionsCognitive impairment and declineParticipants110Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencyPrimarysame day
NCT05856604Start2018PhaseNot applicableConditionsCognitive impairment and declineParticipants42Lead sponsorOtherStatusCompleted

Paper

Library tests named
  • Trail Making TestSecondary4 months
  • Verbal FluencySecondary4 months
  • Clock Drawing TaskSecondary4 months
NCT05854433Start2023PhaseObservationalConditionsCognitive impairment and declineParticipants100Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondarysame day
  • Verbal LearningSecondarysame day
  • Verbal FluencySecondarysame day
  • Digit Span TestSecondarysame day
  • Size Order Memory TestSecondarysame day
  • Pattern and Letter ComparisonSecondarysame day
  • Picture Order Memory TestSecondarysame day
NCT05504681Start2021PhaseObservationalConditionsCognitive impairment and declineParticipants200Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencyPrimary2 years
NCT05485025Start2022PhaseNot applicableConditionsCognitive impairment and declineParticipants134Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Stroop Color-Word TestSecondary3 years
  • Verbal LearningSecondary3 years
  • Verbal FluencySecondary3 years
  • Picture Naming TestSecondary3 years
  • Clock Drawing TaskSecondary3 years
NCT05232877Start2022PhaseNot applicableConditionsCognitive impairment and declineParticipants27Lead sponsorOtherStatusActive, not recruitingLibrary tests named
  • Trail Making TestSecondary4 months
  • Verbal FluencySecondary4 months
NCT05199142Start2021PhasePhase 1ConditionsCognitive impairment and declineParticipants5Lead sponsorIndustryStatusStopped earlyLibrary tests named
  • Verbal FluencyPrimary2 weeks
  • N-Back TaskSecondary2 weeks
  • Category FluencyPrimary2 weeks
NCT05166564Start2022PhaseNot applicableConditionsCognitive impairment and declineParticipants105Lead sponsorOtherStatusCompleted

Paper

Library tests named
  • Verbal FluencySecondary6 months
  • Category FluencySecondary6 months

Page 1 of 3

Questions, answered from the data

How many cognitive impairment and decline trials use Verbal Fluency?

63 registered cognitive impairment and decline studies on ClinicalTrials.gov name it in an outcome measure, 35 of them in a primary outcome: 18% of the condition's 354 studies with a cognitive outcome, against 11% of all of them. It is the 3rd most named test in cognitive impairment and decline trials.

Which tests do cognitive impairment and decline trials use with Verbal Fluency?

The Trail Making Test (29 studies), Verbal Learning (24 studies) and the Digit Span Test (17 studies).

When do cognitive impairment and decline trials measure Verbal Fluency?

Half of the primary outcomes that name Verbal Fluency are measured within 13 weeks of the start, and the middle half from 8 weeks to 6 months. 34 primary outcomes give a duration.

How many completed cognitive impairment and decline trials that use Verbal Fluency have reported results?

11 of the 25 completed studies that name it, 44%, have reported results: 2 posted them on ClinicalTrials.gov, 10 have a results paper linked to the registry record, and 1 did both. The other 14 show neither. Of all completed studies with a cognitive outcome, 46% have reported results.

More on Verbal Fluency and cognitive impairment and decline

  • Every cognitive test in cognitive impairment and decline trials: 354 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
  • Obesity and diabetes63
  • Anxiety, PTSD and OCD61
  • Cardiovascular disease61
  • Multiple sclerosis58
  • Sleep and sleep disorders58
  • Pain and fatigue53

Other tests in cognitive impairment and decline trials

  • Verbal Learning79
  • Trail Making Test77
  • Digit Span Test60

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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