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    16,361Registered studies name a cognitive test in an outcome measure11,688 name a test you can run hereExplore the studies
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  1. Home
  2. /Data
  3. /Clinical trials
  4. /Conditions
  5. /Stroke
  6. /Symbol Coding

Clinical trials data

Symbol Coding in stroke trials: 61 registered studies

Every registered stroke study on ClinicalTrials.gov that names Symbol Coding 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 stroke studies name it in an outcome measure
61
Name it in a primary outcome, 21%
13 of 61
Of the condition's 1,233 studies name it, against 9% of all registered studies
5%
Other conditions
Median participants per study
78
By phase
Try the Symbol Key GameTry Symbol Coding

Tests named in the same studies

The library tests that stroke studies naming Symbol Coding name most often beside it.
  1. 1

    Trail Making Test21 studies, 5 as a primary outcome

  2. 2

    Verbal Fluency18 studies, 6 as a primary outcome

  3. 3

    Digit Span Test16 studies, 4 as a primary outcome

  4. 4

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

  5. 5

    Verbal Learning11 studies, 5 as a primary outcome

  6. 6

    Category Fluency5 studies, 1 as a primary outcome

  7. 7

    Picture Naming Test5 studies, 1 as a primary outcome

  8. 8

    Complex Figure Copy and Recall4 studies, 1 as a primary outcome

  9. 9

    Tower Planning4 studies, 0 as a primary outcome

  10. 10

    Matrix Reasoning3 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: 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: 0 studies, 0 with a test as a primary outcome2012: 0 studies, 0 with a test as a primary outcome2013: 1 studies, 0 with a test as a primary outcome2014: 0 studies, 0 with a test as a primary outcome2015: 0 studies, 0 with a test as a primary outcome20152016: 1 studies, 1 with a test as a primary outcome2017: 7 studies, 0 with a test as a primary outcome2018: 7 studies, 2 with a test as a primary outcome2019: 4 studies, 1 with a test as a primary outcome2020: 5 studies, 0 with a test as a primary outcome20202021: 3 studies, 0 with a test as a primary outcome2022: 6 studies, 2 with a test as a primary outcome2023: 10 studies, 2 with a test as a primary outcome2024: 5 studies, 2 with a test as a primary outcome2025: 10 studies, 3 with a test as a primary outcome20252026: 2 studies, 0 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
201100
201200
201310
201400
201500
201611
201770
201872
201941
202050
202130
202262
2023102
202452
2025103
202620

Phases and study sizes

By phase

  • Phase 211 studies, 3 as a primary outcome
  • Phase 32 studies, 0 as a primary outcome
  • Phase 41 studies, 1 as a primary outcome
  • Not applicable41 studies, 7 as a primary outcome
  • Observational6 studies, 2 as a primary outcome

Participants per study

102050100
  • Phase 270 median, 34 to 100
  • Not applicable76 median, 41 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 stroke study that names Symbol Coding, by phase
PhaseStudies with a sizeMedianMiddle half
Phase 2117034 to 100
Not applicable417641 to 104

When stroke trials measure it

Half of the primary outcomes that name Symbol Coding are measured within 15 weeks of the start, and the middle half from 6 weeks to 6 months. 12 primary outcomes give a duration.

Latest time point of each outcome

  • Within a day10 outcomes, 1 as a primary outcome
  • Up to 4 weeks8 outcomes, 1 as a primary outcome
  • 1 to 3 months22 outcomes, 4 as a primary outcome
  • 3 to 6 months11 outcomes, 4 as a primary outcome
  • 6 to 12 months8 outcomes, 2 as a primary outcome
  • Over 2 years1 outcomes, 0 as a primary outcome
  • No duration given1 outcomes, 1 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

60 of the 61 outcome measures give a duration. A single visit counts as within a day.

Status, results, interventions and countries

Status

  • Recruiting16 studies, 4 as a primary outcome
  • Not yet recruiting4 studies, 0 as a primary outcome
  • Active, not recruiting6 studies, 1 as a primary outcome
  • Completed18 studies, 4 as a primary outcome
  • Stopped early3 studies, 0 as a primary outcome
  • Status unknown14 studies, 4 as a primary outcome

What they test

  • Behavioral11 studies, 3 as a primary outcome
  • Drug11 studies, 3 as a primary outcome
  • Device18 studies, 5 as a primary outcome
  • Dietary supplement1 studies, 0 as a primary outcome
  • Procedure4 studies, 0 as a primary outcome
  • Diagnostic test5 studies, 1 as a primary outcome
  • Biological1 studies, 0 as a primary outcome
  • Radiation1 studies, 0 as a primary outcome
  • Combination product1 studies, 0 as a primary outcome
  • Other19 studies, 3 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 States14 studies, 4 as a primary outcome
  • Italy11 studies, 4 as a primary outcome
  • Canada7 studies, 1 as a primary outcome
  • China6 studies, 1 as a primary outcome
  • Belgium5 studies, 0 as a primary outcome
  • Denmark5 studies, 0 as a primary outcome
  • Germany3 studies, 1 as a primary outcome
  • Netherlands3 studies, 0 as a primary outcome
  • Sweden3 studies, 0 as a primary outcome
  • Australia2 studies, 1 as a primary outcome
  • Brazil2 studies, 0 as a primary outcome
  • France2 studies, 0 as a primary outcome

34 countries in all. A study with sites in several counts in each; 4 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 stroke studies that name Symbol Coding: 8 of 18, 44%

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

Completed stroke studies that name Symbol Coding and every completed study, by how they reported results
ResultsCompleted stroke studies that name Symbol CodingEvery completed study
Results on ClinicalTrials.gov and a paper1, 6%776, 10%
Results on ClinicalTrials.gov only3, 17%1,139, 14%
A results paper only4, 22%1,711, 22%
Neither10, 56%4,327, 54%

The 61 studies

Filter by phase, sponsor, status, country, intervention, outcome list, size and start year. Each study links to its record on ClinicalTrials.gov.
ConditionStroke
TestSymbol Coding

61 studies match. 13 name Symbol Coding in a primary outcome. Median size 78 participants. Median time to the primary outcome: 15 weeks.

Loading 61 studies; the filters turn on when they arrive.

By start year
02.557.5102000: 0 studies, 0 naming Symbol Coding in a primary outcome20002001: 0 studies, 0 naming Symbol Coding in a primary outcome2002: 0 studies, 0 naming Symbol Coding in a primary outcome2003: 0 studies, 0 naming Symbol Coding in a primary outcome2004: 0 studies, 0 naming Symbol Coding in a primary outcome2005: 0 studies, 0 naming Symbol Coding in a primary outcome20052006: 0 studies, 0 naming Symbol Coding in a primary outcome2007: 0 studies, 0 naming Symbol Coding in a primary outcome2008: 0 studies, 0 naming Symbol Coding in a primary outcome2009: 0 studies, 0 naming Symbol Coding in a primary outcome2010: 0 studies, 0 naming Symbol Coding in a primary outcome20102011: 0 studies, 0 naming Symbol Coding in a primary outcome2012: 0 studies, 0 naming Symbol Coding in a primary outcome2013: 1 studies, 0 naming Symbol Coding in a primary outcome2014: 0 studies, 0 naming Symbol Coding in a primary outcome2015: 0 studies, 0 naming Symbol Coding in a primary outcome20152016: 1 studies, 1 naming Symbol Coding in a primary outcome2017: 7 studies, 0 naming Symbol Coding in a primary outcome2018: 7 studies, 2 naming Symbol Coding in a primary outcome2019: 4 studies, 1 naming Symbol Coding in a primary outcome2020: 5 studies, 0 naming Symbol Coding in a primary outcome20202021: 3 studies, 0 naming Symbol Coding in a primary outcome2022: 6 studies, 2 naming Symbol Coding in a primary outcome2023: 10 studies, 2 naming Symbol Coding in a primary outcome2024: 5 studies, 2 naming Symbol Coding in a primary outcome2025: 10 studies, 3 naming Symbol Coding in a primary outcome20252026: 2 studies, 0 naming Symbol Coding 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
200400
200500
200600
200700
200800
200900
201000
201100
201200
201310
201400
201500
201611
201770
201872
201941
202050
202130
202262
2023102
202452
2025103
202620

Library tests named most

  • Symbol Coding61 studies, 13 as a primary outcome
  • Trail Making Test21 studies, 5 as a primary outcome
  • Verbal Fluency18 studies, 6 as a primary outcome
  • Digit Span Test16 studies, 4 as a primary outcome
  • Stroop Color-Word Test13 studies, 4 as a primary outcome
  • Verbal Learning11 studies, 5 as a primary outcome
  • Category Fluency5 studies, 1 as a primary outcome
  • Picture Naming Test5 studies, 1 as a primary outcome
  • Complex Figure Copy and Recall4 studies, 1 as a primary outcome
  • Tower Planning4 studies, 0 as a primary outcome

Largest condition groups

  • Stroke61 studies, 13 as a primary outcome
  • Multiple sclerosis4 studies, 0 as a primary outcome
  • Cardiovascular disease4 studies, 0 as a primary outcome
  • Parkinson's disease3 studies, 0 as a primary outcome
  • Delirium, surgery and intensive care3 studies, 0 as a primary outcome
  • Pain and fatigue2 studies, 0 as a primary outcome
  • Dementia and Alzheimer's1 study, 0 as a primary outcome
  • Mild cognitive impairment1 study, 1 as a primary outcome
  • Brain injury and concussion1 study, 0 as a primary outcome
  • Depression and bipolar disorder1 study, 1 as a primary outcome
  • Cancer1 study, 0 as a primary outcome
  • Aging, frailty and exercise1 study, 0 as a primary outcome

Phases

Participants

Lead sponsor: industry 5, other 56. Interventional 55, observational 6.

As a primary outcomeSecondary or other outcomeSymbol Coding

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
NCT07807176Start2026PhaseNot applicableConditionsStrokeParticipants150Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestPrimary13 weeks
  • Digit Span TestPrimary13 weeks
  • Symbol CodingSecondary13 weeks
  • Paired Associate LearningSecondary13 weeks
  • Rapid Visual Information ProcessingPrimary13 weeks
  • Intra/Extra Dimensional Set ShiftPrimary13 weeks
NCT07445841Start2026PhaseNot applicableConditionsStrokeParticipants120Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary12 months
  • Digit Span TestSecondary12 months
  • Symbol CodingSecondary12 months
  • Category FluencySecondary12 months
NCT07343895Start2025PhaseNot applicableConditionsStroke, Cardiovascular diseaseParticipants4,000Lead sponsorOtherStatusRecruitingLibrary tests named
  • Symbol CodingSecondary6 years
NCT07220538Start2025PhasePhase 4ConditionsStrokeParticipants400Lead sponsorIndustryStatusActive, not recruitingLibrary tests named
  • Trail Making TestPrimary12 months
  • Verbal FluencyPrimary12 months
  • Symbol CodingPrimary12 months
NCT07199322Start2025PhaseNot applicableConditionsStrokeParticipants100Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Symbol CodingSecondary1 week
NCT07159256Start2025PhaseObservationalConditionsStrokeParticipants100Lead sponsorOtherStatusRecruitingLibrary tests named
  • Symbol CodingPrimary
NCT07116187Start2025PhaseNot applicableConditionsStrokeParticipants100Lead sponsorOtherStatusRecruitingLibrary tests named
  • Stroop Color-Word TestPrimary6 months
  • Verbal FluencyPrimary6 months
  • Symbol CodingPrimary6 months
  • N-Back TaskPrimary6 months
NCT07030985Start2025PhaseNot applicableConditionsStrokeParticipants55Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Verbal LearningSecondary12 months
  • Verbal FluencySecondary12 months
  • Symbol CodingSecondary12 months
  • Picture Naming TestSecondary12 months
  • Card Sorting Test (Berg)Secondary12 months
NCT06978413Start2025PhaseNot applicableConditionsStrokeParticipants160Lead sponsorOtherStatusRecruitingLibrary tests named
  • Symbol CodingSecondary6 weeks
NCT06968923Start2018PhaseNot applicableConditionsStrokeParticipants90Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary6 months
  • Digit Span TestSecondary6 months
  • Symbol CodingSecondary6 months
NCT06956183Start2025PhaseNot applicableConditionsStroke, Pain and fatigueParticipants30Lead sponsorOtherStatusRecruitingLibrary tests named
  • Symbol CodingSecondary1 week
NCT06852209Start2025PhaseNot applicableConditionsStrokeParticipants20Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary6 weeks
  • Stroop Color-Word TestSecondary6 weeks
  • Verbal FluencySecondary6 weeks
  • Symbol CodingSecondary6 weeks
  • Cancellation TestSecondary6 weeks
NCT06834490Start2019PhasePhase 3ConditionsStrokeParticipants318Lead sponsorIndustryStatusCompleted

Results

Library tests named
  • Symbol CodingSecondary11 weeks
NCT06822140Start2025PhaseNot applicableConditionsStrokeParticipants144Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Stroop Color-Word TestSecondary6 weeks
  • Verbal FluencySecondary6 weeks
  • Symbol CodingSecondary6 weeks
  • Go/No-Go TaskSecondary6 weeks
  • Category FluencySecondary6 weeks
  • Picture Naming TestSecondary6 weeks
NCT06547827Start2024PhaseNot applicableConditionsStrokeParticipants596Lead sponsorOtherStatusRecruitingLibrary tests named
  • Symbol CodingSecondarysame day
NCT06402123Start2024PhasePhase 2ConditionsStrokeParticipants43Lead sponsorIndustryStatusCompletedLibrary tests named
  • Symbol CodingPrimary12 weeks
  • Hidden Path LearningPrimary12 weeks
NCT06384495Start2024PhaseNot applicableConditionsStrokeParticipants3Lead sponsorOtherStatusStopped earlyLibrary tests named
  • Symbol CodingSecondarysame day
  • Choice Reaction TimeSecondarysame day
  • Lexical Decision TaskSecondarysame day
NCT06330298Start2021PhaseNot applicableConditionsStroke, Multiple sclerosis, CancerParticipants84Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Trail Making TestOther outcomesame day
  • Verbal LearningOther outcomesame day
  • Verbal FluencyOther outcomesame day
  • Digit Span TestOther outcomesame day
  • Symbol CodingOther outcomesame day
  • Category FluencyOther outcomesame day
  • Social Slips Stories TaskSecondary10 months
NCT06109324Start2023PhaseNot applicableConditionsStrokeParticipants126Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Symbol CodingSecondary6 months
  • Complex Figure Copy and RecallSecondary6 months
  • Tower PlanningSecondary6 months
NCT06096350Start2024PhaseObservationalConditionsStrokeParticipants55Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Symbol CodingPrimary6 weeks
NCT06027788Start2023PhaseNot applicableConditionsStroke, Delirium, surgery and intensive care, Cardiovascular diseaseParticipants842Lead sponsorOtherStatusActive, not recruitingLibrary tests named
  • Trail Making TestSecondarysame day
  • Verbal FluencySecondarysame day
  • Digit Span TestSecondarysame day
  • Symbol CodingSecondarysame day
  • Category FluencySecondarysame day
NCT06021470Start2023PhaseNot applicableConditionsStrokeParticipants64Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Verbal LearningPrimary4 months
  • Verbal FluencyPrimary4 months
  • Digit Span TestPrimary4 months
  • Symbol CodingPrimary4 months
  • Picture Naming TestPrimary4 months
  • Complex Figure Copy and RecallPrimary4 months
NCT06009770Start2023PhaseNot applicableConditionsStroke, Parkinson's disease, Multiple sclerosisParticipants90Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Trail Making TestSecondary9 weeks
  • Symbol CodingSecondary9 weeks
NCT05992571Start2023PhaseNot applicableConditionsStrokeParticipants30Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Stroop Color-Word TestSecondarysame day
  • Symbol CodingSecondarysame day
  • N-Back TaskSecondarysame day
NCT05976152Start2024PhasePhase 3ConditionsStrokeParticipants3,200Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary11 months
  • Symbol CodingSecondary11 months

Page 1 of 3

Questions, answered from the data

How many stroke trials use Symbol Coding?

61 registered stroke studies on ClinicalTrials.gov name it in an outcome measure, 13 of them in a primary outcome: 5% of the condition's 1,233 studies with a cognitive outcome, against 9% of all of them. It is the 8th most named test in stroke trials.

Which tests do stroke trials use with Symbol Coding?

The Trail Making Test (21 studies), Verbal Fluency (18 studies) and the Digit Span Test (16 studies).

How many participants do phase 2 stroke trials that use Symbol Coding enroll?

Half of the phase 2 studies that name it enroll 70 participants or fewer, and the middle half enroll 34 to 100. 11 of them give a size.

When do stroke trials measure Symbol Coding?

Half of the primary outcomes that name Symbol Coding are measured within 15 weeks of the start, and the middle half from 6 weeks to 6 months. 12 primary outcomes give a duration.

How many completed stroke trials that use Symbol Coding have reported results?

8 of the 18 completed studies that name it, 44%, have reported results: 4 posted them on ClinicalTrials.gov, 5 have a results paper linked to the registry record, and 1 did both. The other 10 show neither. Of all completed studies with a cognitive outcome, 46% have reported results.

More on Symbol Coding and stroke

  • Every cognitive test in stroke trials: 1,233 studies
  • Symbol Coding in all clinical trials: 1,457 studies

Symbol Coding in other conditions

  • Multiple sclerosis375
  • Depression and bipolar disorder143
  • Dementia and Alzheimer's117
  • Aging, frailty and exercise116
  • Sleep and sleep disorders89
  • Mild cognitive impairment84
  • Pain and fatigue82
  • Substance use and addiction60
  • Obesity and diabetes59
  • Cancer58
  • Healthy volunteers56

Other tests in stroke trials

  • Trail Making Test156
  • Verbal Fluency110
  • Stroop Color-Word Test105
  • Digit Span Test100
  • Picture Naming Test99
  • Cancellation Test75
  • Verbal Learning63

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.

The census counts Symbol Key Game and Symbol Coding as one test family, so this page counts their studies together.

Run Symbol Coding in your trial

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