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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. /Multiple sclerosis
  6. /Symbol Coding

Clinical trials data

Symbol Coding in multiple sclerosis trials: 375 registered studies

Every registered multiple sclerosis 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 multiple sclerosis studies name it in an outcome measure
375
Name it in a primary outcome, 25%
93 of 375
Of the condition's 612 studies name it, against 9% of all registered studies
61%
Other conditions
Median participants per study
67
By phase
Try the Symbol Key GameTry Symbol Coding

Tests named in the same studies

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

    Verbal Learning107 studies, 26 as a primary outcome

  2. 2

    Paced Visual Serial Addition Test66 studies, 30 as a primary outcome

  3. 3

    Verbal Fluency39 studies, 10 as a primary outcome

  4. 4

    Stroop Color-Word Test38 studies, 11 as a primary outcome

  5. 5

    Trail Making Test30 studies, 5 as a primary outcome

  6. 6

    Selective Reminding Task20 studies, 8 as a primary outcome

  7. 7

    Digit Span Test14 studies, 3 as a primary outcome

  8. 8

    Category Fluency10 studies, 4 as a primary outcome

  9. 9

    Go/No-Go Task7 studies, 1 as a primary outcome

  10. 10

    Line Angle Matching6 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: 1 studies, 0 with a test as a primary outcome2003: 1 studies, 0 with a test as a primary outcome2004: 1 studies, 0 with a test as a primary outcome2005: 0 studies, 0 with a test as a primary outcome20052006: 2 studies, 2 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: 3 studies, 2 with a test as a primary outcome2010: 2 studies, 1 with a test as a primary outcome20102011: 8 studies, 3 with a test as a primary outcome2012: 4 studies, 2 with a test as a primary outcome2013: 10 studies, 4 with a test as a primary outcome2014: 18 studies, 3 with a test as a primary outcome2015: 8 studies, 3 with a test as a primary outcome20152016: 23 studies, 5 with a test as a primary outcome2017: 23 studies, 4 with a test as a primary outcome2018: 20 studies, 6 with a test as a primary outcome2019: 21 studies, 7 with a test as a primary outcome2020: 27 studies, 5 with a test as a primary outcome20202021: 31 studies, 7 with a test as a primary outcome2022: 29 studies, 6 with a test as a primary outcome2023: 38 studies, 8 with a test as a primary outcome2024: 31 studies, 8 with a test as a primary outcome2025: 34 studies, 10 with a test as a primary outcome20252026: 39 studies, 7 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
200210
200310
200410
200500
200622
200710
200800
200932
201021
201183
201242
2013104
2014183
201583
2016235
2017234
2018206
2019217
2020275
2021317
2022296
2023388
2024318
20253410
2026397

Phases and study sizes

By phase

  • Early phase 14 studies, 1 as a primary outcome
  • Phase 19 studies, 1 as a primary outcome
  • Phase 1/29 studies, 2 as a primary outcome
  • Phase 236 studies, 5 as a primary outcome
  • Phase 2/37 studies, 3 as a primary outcome
  • Phase 346 studies, 2 as a primary outcome
  • Phase 416 studies, 5 as a primary outcome
  • Not applicable172 studies, 55 as a primary outcome
  • Observational76 studies, 19 as a primary outcome

Participants per study

1020501002005001,000
  • Phase 254 median, 35 to 104
  • Phase 3894 median, 204 to 1,072
  • Phase 4224 median, 95 to 279
  • Not applicable50 median, 30 to 92
  • Observational100 median, 58 to 200
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 multiple sclerosis study that names Symbol Coding, by phase
PhaseStudies with a sizeMedianMiddle half
Phase 2355435 to 104
Phase 346894204 to 1,072
Phase 41522495 to 279
Not applicable1715030 to 92
Observational7610058 to 200

When multiple sclerosis trials measure it

Half of the primary outcomes that name Symbol Coding are measured within 6 months of the start, and the middle half from 8 weeks to 12 months. 87 primary outcomes give a duration.

Latest time point of each outcome

  • Within a day46 outcomes, 8 as a primary outcome
  • Up to 4 weeks27 outcomes, 10 as a primary outcome
  • 1 to 3 months77 outcomes, 21 as a primary outcome
  • 3 to 6 months45 outcomes, 14 as a primary outcome
  • 6 to 12 months46 outcomes, 13 as a primary outcome
  • 1 to 2 years58 outcomes, 10 as a primary outcome
  • Over 2 years55 outcomes, 11 as a primary outcome
  • No duration given21 outcomes, 6 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

354 of the 375 outcome measures give a duration. A single visit counts as within a day.

Status, results, interventions and countries

Status

  • Recruiting76 studies, 21 as a primary outcome
  • Not yet recruiting22 studies, 6 as a primary outcome
  • Active, not recruiting33 studies, 4 as a primary outcome
  • Completed173 studies, 47 as a primary outcome
  • Stopped early24 studies, 4 as a primary outcome
  • Status unknown47 studies, 11 as a primary outcome

What they test

  • Behavioral84 studies, 24 as a primary outcome
  • Drug115 studies, 18 as a primary outcome
  • Device49 studies, 18 as a primary outcome
  • Dietary supplement10 studies, 4 as a primary outcome
  • Procedure6 studies, 2 as a primary outcome
  • Diagnostic test10 studies, 3 as a primary outcome
  • Biological24 studies, 1 as a primary outcome
  • Combination product1 studies, 0 as a primary outcome
  • Other84 studies, 22 as a primary outcome
  • None given29 studies, 9 as a primary outcome

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

Where their sites are

  • United States138 studies, 36 as a primary outcome
  • Italy58 studies, 10 as a primary outcome
  • Spain54 studies, 7 as a primary outcome
  • France51 studies, 5 as a primary outcome
  • Germany50 studies, 5 as a primary outcome
  • Canada47 studies, 8 as a primary outcome
  • Türkiye47 studies, 11 as a primary outcome
  • Belgium46 studies, 4 as a primary outcome
  • United Kingdom44 studies, 1 as a primary outcome
  • Czechia38 studies, 4 as a primary outcome
  • Poland35 studies, 2 as a primary outcome
  • Netherlands33 studies, 5 as a primary outcome

76 countries in all. A study with sites in several counts in each; 16 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 multiple sclerosis studies that name Symbol Coding: 75 of 173, 43%

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

Completed multiple sclerosis studies that name Symbol Coding and every completed study, by how they reported results
ResultsCompleted multiple sclerosis studies that name Symbol CodingEvery completed study
Results on ClinicalTrials.gov and a paper25, 14%776, 10%
Results on ClinicalTrials.gov only21, 12%1,139, 14%
A results paper only29, 17%1,711, 22%
Neither98, 57%4,327, 54%

The 375 studies

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

375 studies match. 93 name Symbol Coding in a primary outcome. Median size 67 participants. Median time to the primary outcome: 6 months.

Loading 375 studies; the filters turn on when they arrive.

By start year
0102030402000: 0 studies, 0 naming Symbol Coding in a primary outcome20002001: 0 studies, 0 naming Symbol Coding in a primary outcome2002: 1 studies, 0 naming Symbol Coding in a primary outcome2003: 1 studies, 0 naming Symbol Coding in a primary outcome2004: 1 studies, 0 naming Symbol Coding in a primary outcome2005: 0 studies, 0 naming Symbol Coding in a primary outcome20052006: 2 studies, 2 naming Symbol Coding in a primary outcome2007: 1 studies, 0 naming Symbol Coding in a primary outcome2008: 0 studies, 0 naming Symbol Coding in a primary outcome2009: 3 studies, 2 naming Symbol Coding in a primary outcome2010: 2 studies, 1 naming Symbol Coding in a primary outcome20102011: 8 studies, 3 naming Symbol Coding in a primary outcome2012: 4 studies, 2 naming Symbol Coding in a primary outcome2013: 10 studies, 4 naming Symbol Coding in a primary outcome2014: 18 studies, 3 naming Symbol Coding in a primary outcome2015: 8 studies, 3 naming Symbol Coding in a primary outcome20152016: 23 studies, 5 naming Symbol Coding in a primary outcome2017: 23 studies, 4 naming Symbol Coding in a primary outcome2018: 20 studies, 6 naming Symbol Coding in a primary outcome2019: 21 studies, 7 naming Symbol Coding in a primary outcome2020: 27 studies, 5 naming Symbol Coding in a primary outcome20202021: 31 studies, 7 naming Symbol Coding in a primary outcome2022: 29 studies, 6 naming Symbol Coding in a primary outcome2023: 38 studies, 8 naming Symbol Coding in a primary outcome2024: 31 studies, 8 naming Symbol Coding in a primary outcome2025: 34 studies, 10 naming Symbol Coding in a primary outcome20252026: 39 studies, 7 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
200210
200310
200410
200500
200622
200710
200800
200932
201021
201183
201242
2013104
2014183
201583
2016235
2017234
2018206
2019217
2020275
2021317
2022296
2023388
2024318
20253410
2026397

Library tests named most

  • Symbol Coding375 studies, 93 as a primary outcome
  • Verbal Learning107 studies, 26 as a primary outcome
  • Paced Visual Serial Addition Test66 studies, 30 as a primary outcome
  • Verbal Fluency39 studies, 10 as a primary outcome
  • Stroop Color-Word Test38 studies, 11 as a primary outcome
  • Trail Making Test30 studies, 5 as a primary outcome
  • Selective Reminding Task20 studies, 8 as a primary outcome
  • Digit Span Test14 studies, 3 as a primary outcome
  • Category Fluency10 studies, 4 as a primary outcome
  • Go/No-Go Task7 studies, 1 as a primary outcome

Largest condition groups

  • Multiple sclerosis375 studies, 93 as a primary outcome
  • Pain and fatigue35 studies, 7 as a primary outcome
  • Aging, frailty and exercise11 studies, 2 as a primary outcome
  • Depression and bipolar disorder8 studies, 1 as a primary outcome
  • Cancer6 studies, 1 as a primary outcome
  • Sleep and sleep disorders6 studies, 3 as a primary outcome
  • Parkinson's disease5 studies, 0 as a primary outcome
  • Stroke4 studies, 0 as a primary outcome
  • Healthy volunteers4 studies, 0 as a primary outcome
  • Mild cognitive impairment3 studies, 0 as a primary outcome
  • COVID-19 and long COVID2 studies, 0 as a primary outcome
  • Dementia and Alzheimer's1 study, 0 as a primary outcome

Phases

Participants

Lead sponsor: industry 92, NIH 1, other 282. Interventional 299, observational 76.

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
NCT07898371Start2026PhaseObservationalConditionsMultiple sclerosisParticipants3,000Lead sponsorIndustryStatusRecruitingLibrary tests named
  • Symbol CodingSecondary3 years
NCT07893925Start2026PhaseNot applicableConditionsMultiple sclerosisParticipants38Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal LearningSecondary8 weeks
  • Symbol CodingSecondary8 weeks
NCT07889271Start2024PhaseObservationalConditionsMultiple sclerosisParticipants300Lead sponsorOtherStatusCompletedLibrary tests named
  • Symbol CodingPrimary
NCT07880418Start2026PhaseNot applicableConditionsMultiple sclerosisParticipants20Lead sponsorOtherStatusCompletedLibrary tests named
  • Verbal LearningSecondary5 weeks
  • Symbol CodingSecondary5 weeks
NCT07868887Start2026PhaseObservationalConditionsMultiple sclerosisParticipants200Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Symbol CodingOther outcome12 months
NCT07852156Start2026PhaseNot applicableConditionsMultiple sclerosis, Pain and fatigueParticipants42Lead sponsorOtherStatusRecruitingLibrary tests named
  • Symbol CodingSecondary2 weeks
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
NCT07827716Start2026PhasePhase 2ConditionsMultiple sclerosisParticipants100Lead sponsorOtherStatusRecruitingLibrary tests named
  • Symbol CodingSecondary12 months
  • Paced Visual Serial Addition TestSecondary12 months
NCT07805850Start2026PhaseNot applicableConditionsMultiple sclerosisParticipants60Lead sponsorOtherStatusRecruitingLibrary tests named
  • Symbol CodingPrimary3 weeks
NCT07804264Start2026PhaseNot applicableConditionsMultiple sclerosisParticipants40Lead sponsorOtherStatusCompletedLibrary tests named
  • Symbol CodingPrimary4 weeks
NCT07786987Start2026PhaseObservationalConditionsMultiple sclerosis, Pain and fatigueParticipants50Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Symbol CodingSecondarysame day
NCT07783074Start2026PhaseObservationalConditionsMultiple sclerosis, Healthy volunteers, COVID-19 and long COVID, Pain and fatigueParticipants122Lead sponsorOtherStatusRecruitingLibrary tests named
  • Symbol CodingSecondary9 weeks
  • Finger Tapping TaskPrimary9 weeks
NCT07766213Start2026PhaseObservationalConditionsMultiple sclerosis, Pain and fatigueParticipants60Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal LearningSecondarysame day
  • Symbol CodingSecondarysame day
NCT07759115Start2026PhaseNot applicableConditionsMultiple sclerosisParticipants64Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary4 weeks
  • Stroop Color-Word TestSecondary4 weeks
  • Symbol CodingSecondary4 weeks
NCT07753928Start2022PhaseObservationalConditionsMultiple sclerosisParticipants2,400Lead sponsorIndustryStatusRecruitingLibrary tests named
  • Symbol CodingOther outcome
NCT07738120Start2025PhaseNot applicableConditionsMultiple sclerosis, Aging, frailty and exerciseParticipants30Lead sponsorOtherStatusRecruitingLibrary tests named
  • Symbol CodingPrimarysame day
NCT07734675Start2026PhaseNot applicableConditionsMultiple sclerosisParticipants130Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Stroop Color-Word TestPrimary2 years
  • Verbal LearningPrimary2 years
  • Symbol CodingPrimary2 years
  • Picture Naming TestPrimary2 years
  • Paced Visual Serial Addition TestPrimary2 years
  • Cancellation TestPrimary2 years
  • Selective Reminding TaskPrimary2 years
NCT07680738Start2023PhaseNot applicableConditionsMultiple sclerosis, Pain and fatigueParticipants38Lead sponsorOtherStatusCompletedLibrary tests named
  • Verbal LearningSecondary4 weeks
  • Symbol CodingSecondary4 weeks
NCT07666958Start2026PhaseNot applicableConditionsMultiple sclerosis, Pain and fatigueParticipants45Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Symbol CodingSecondary9 weeks
NCT07631143Start2026PhasePhase 1/2ConditionsMultiple sclerosisParticipants9Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Symbol CodingSecondary5 weeks
NCT07595081Start2024PhaseNot applicableConditionsMultiple sclerosisParticipants22Lead sponsorOtherStatusCompletedLibrary tests named
  • Symbol CodingSecondary9 months
NCT07580820Start2025PhaseObservationalConditionsMultiple sclerosis, Healthy volunteersParticipants32Lead sponsorOtherStatusRecruitingLibrary tests named
  • Symbol CodingOther outcomesame day
NCT07578740Start2026PhaseNot applicableConditionsMultiple sclerosisParticipants40Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Verbal LearningSecondary8 weeks
  • Symbol CodingSecondary8 weeks
NCT07571304Start2026PhaseNot applicableConditionsMultiple sclerosisParticipants22Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal LearningPrimary8 weeks
  • Symbol CodingPrimary8 weeks
  • Paced Visual Serial Addition TestSecondary8 weeks
NCT07555379Start2026PhaseNot applicableConditionsMultiple sclerosis, Sleep and sleep disorders, Pain and fatigueParticipants40Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Symbol CodingSecondary4 weeks

Page 1 of 15

Questions, answered from the data

How many multiple sclerosis trials use Symbol Coding?

375 registered multiple sclerosis studies on ClinicalTrials.gov name it in an outcome measure, 93 of them in a primary outcome: 61% of the condition's 612 studies with a cognitive outcome, against 9% of all of them. It is the test multiple sclerosis trials name most.

Which tests do multiple sclerosis trials use with Symbol Coding?

Verbal Learning (107 studies), the Paced Visual Serial Addition Test (66 studies) and Verbal Fluency (39 studies).

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

Half of the phase 2 studies that name it enroll 54 participants or fewer, and the middle half enroll 35 to 104. 35 of them give a size.

When do multiple sclerosis trials measure Symbol Coding?

Half of the primary outcomes that name Symbol Coding are measured within 6 months of the start, and the middle half from 8 weeks to 12 months. 87 primary outcomes give a duration.

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

75 of the 173 completed studies that name it, 43%, have reported results: 46 posted them on ClinicalTrials.gov, 54 have a results paper linked to the registry record, and 25 did both. The other 98 show neither. Of all completed studies with a cognitive outcome, 46% have reported results.

More on Symbol Coding and multiple sclerosis

  • Every cognitive test in multiple sclerosis trials: 612 studies
  • Symbol Coding in all clinical trials: 1,457 studies

Symbol Coding in other conditions

  • Depression and bipolar disorder143
  • Dementia and Alzheimer's117
  • Aging, frailty and exercise116
  • Sleep and sleep disorders89
  • Mild cognitive impairment84
  • Pain and fatigue82
  • Stroke61
  • Substance use and addiction60
  • Obesity and diabetes59
  • Cancer58
  • Healthy volunteers56

Other tests in multiple sclerosis trials

  • Paced Visual Serial Addition Test169
  • Verbal Learning139
  • Verbal Fluency58
  • Stroop Color-Word Test56

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.

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