Clinical trials data
Symbol Coding in substance use and addiction trials: 60 registered studies
Every registered substance use and addiction 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 substance use and addiction studies name it in an outcome measure
- 60
- Name it in a primary outcome, 28%
- 17 of 60
Tests named in the same studies
- 1
Paced Visual Serial Addition Test16 studies, 7 as a primary outcome
- 2
Verbal Learning11 studies, 4 as a primary outcome
- 3
Stroop Color-Word Test8 studies, 2 as a primary outcome
- 4
Trail Making Test6 studies, 2 as a primary outcome
- 5
Digit Span Test5 studies, 2 as a primary outcome
- 6
Go/No-Go Task5 studies, 2 as a primary outcome
- 7
Card Sorting Test (Berg)4 studies, 2 as a primary outcome
- 8
Pattern and Letter Comparison4 studies, 1 as a primary outcome
- 9
Rapid Visual Information Processing4 studies, 1 as a primary outcome
- 10
Continuous Performance Test3 studies, 1 as a primary outcome
A test as a primary outcomeOnly in secondary or other outcomes
Studies by start year
A test as a primary outcomeOnly in secondary or other outcomes
Show as a table
| Start year | Studies | A test as a primary outcome |
|---|---|---|
| 2000 | 0 | 0 |
| 2001 | 0 | 0 |
| 2002 | 0 | 0 |
| 2003 | 1 | 0 |
| 2004 | 0 | 0 |
| 2005 | 0 | 0 |
| 2006 | 2 | 1 |
| 2007 | 1 | 1 |
| 2008 | 0 | 0 |
| 2009 | 2 | 0 |
| 2010 | 1 | 0 |
| 2011 | 0 | 0 |
| 2012 | 1 | 0 |
| 2013 | 0 | 0 |
| 2014 | 3 | 1 |
| 2015 | 3 | 0 |
| 2016 | 6 | 1 |
| 2017 | 1 | 1 |
| 2018 | 5 | 1 |
| 2019 | 4 | 2 |
| 2020 | 3 | 0 |
| 2021 | 1 | 0 |
| 2022 | 3 | 1 |
| 2023 | 2 | 1 |
| 2024 | 4 | 3 |
| 2025 | 5 | 0 |
| 2026 | 9 | 2 |
Phases and study sizes
By phase
- Early phase 15 studies, 0 as a primary outcome
- Phase 115 studies, 5 as a primary outcome
- Phase 1/22 studies, 2 as a primary outcome
- Phase 217 studies, 6 as a primary outcome
- Phase 46 studies, 1 as a primary outcome
- Not applicable13 studies, 2 as a primary outcome
- Observational2 studies, 1 as a primary outcome
Participants per study
- Phase 132 median, 24 to 67
- Phase 229 median, 18 to 62
- Not applicable48 median, 27 to 104
Show as a table
| Phase | Studies with a size | Median | Middle half |
|---|---|---|---|
| Phase 1 | 15 | 32 | 24 to 67 |
| Phase 2 | 15 | 29 | 18 to 62 |
| Not applicable | 13 | 48 | 27 to 104 |
When substance use and addiction trials measure it
Latest time point of each outcome
- Within a day21 outcomes, 8 as a primary outcome
- Up to 4 weeks19 outcomes, 4 as a primary outcome
- 1 to 3 months9 outcomes, 3 as a primary outcome
- 3 to 6 months7 outcomes, 1 as a primary outcome
- No duration given4 outcomes, 1 as a primary outcome
A test as a primary outcomeOnly in secondary or other outcomes
56 of the 60 outcome measures give a duration. A single visit counts as within a day.
Status, results, interventions and countries
Status
- Recruiting13 studies, 6 as a primary outcome
- Not yet recruiting7 studies, 1 as a primary outcome
- Completed30 studies, 9 as a primary outcome
- Stopped early8 studies, 1 as a primary outcome
- Status unknown2 studies, 0 as a primary outcome
What they test
- Behavioral11 studies, 2 as a primary outcome
- Drug48 studies, 14 as a primary outcome
- Device3 studies, 0 as a primary outcome
- Procedure1 studies, 0 as a primary outcome
- Other8 studies, 5 as a primary outcome
- None given1 studies, 0 as a primary outcome
Intervention types as registered. A study can list several; observational studies often list none.
Where their sites are
- United States42 studies, 15 as a primary outcome
- Canada5 studies, 0 as a primary outcome
- Hong Kong2 studies, 0 as a primary outcome
- Chile1 studies, 0 as a primary outcome
- Denmark1 studies, 0 as a primary outcome
- Finland1 studies, 0 as a primary outcome
- Netherlands1 studies, 0 as a primary outcome
- United Kingdom1 studies, 0 as a primary outcome
8 countries in all. A study with sites in several counts in each; 6 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 substance use and addiction studies that name Symbol Coding: 22 of 30, 73%
Every completed study with a cognitive outcome: 3,626 of 7,953, 46%
| Results | Completed substance use and addiction studies that name Symbol Coding | Every completed study |
|---|---|---|
| Results on ClinicalTrials.gov and a paper | 3, 10% | 776, 10% |
| Results on ClinicalTrials.gov only | 12, 40% | 1,139, 14% |
| A results paper only | 7, 23% | 1,711, 22% |
| Neither | 8, 27% | 4,327, 54% |
The 60 studies
60 studies match. 17 name Symbol Coding in a primary outcome. Median size 40 participants. Median time to the primary outcome: 1 day.
Loading 60 studies; the filters turn on when they arrive.
2026 is partly planned starts. Not shown: 1 that started before 2000 and 2 planned to start after 2026.
Show as a table
| Start year | Studies | As a primary outcome |
|---|---|---|
| 2000 | 0 | 0 |
| 2001 | 0 | 0 |
| 2002 | 0 | 0 |
| 2003 | 1 | 0 |
| 2004 | 0 | 0 |
| 2005 | 0 | 0 |
| 2006 | 2 | 1 |
| 2007 | 1 | 1 |
| 2008 | 0 | 0 |
| 2009 | 2 | 0 |
| 2010 | 1 | 0 |
| 2011 | 0 | 0 |
| 2012 | 1 | 0 |
| 2013 | 0 | 0 |
| 2014 | 3 | 1 |
| 2015 | 3 | 0 |
| 2016 | 6 | 1 |
| 2017 | 1 | 1 |
| 2018 | 5 | 1 |
| 2019 | 4 | 2 |
| 2020 | 3 | 0 |
| 2021 | 1 | 0 |
| 2022 | 3 | 1 |
| 2023 | 2 | 1 |
| 2024 | 4 | 3 |
| 2025 | 5 | 0 |
| 2026 | 9 | 2 |
Library tests named most
Conditions
Phases
Participants
Lead sponsor: industry 6, other 54. Interventional 58, observational 2.
As a primary outcomeSecondary or other outcomeSymbol Coding
The studies, newest registration first
Each number opens the study's record on ClinicalTrials.gov.
| Study | Start | Phase | Conditions | Participants | Lead sponsor | Status | Library tests named, with the latest time point |
|---|---|---|---|---|---|---|---|
| NCT07870187 | Start2027 | PhasePhase 1 | ConditionsSubstance use and addiction | Participants70 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07736742 | Start2026 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants40 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07633392 | Start2026 | PhaseNot applicable | ConditionsAging, frailty and exercise, Substance use and addiction, Sleep and sleep disorders, Cardiovascular disease | Participants240 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07471347 | Start2026 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants10 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07417059 | Start2025 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants21 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07218471 | Start2026 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants176 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07216690 | Start2026 | PhasePhase 2 | ConditionsSubstance use and addiction | Participants20 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07214155 | Start2026 | PhasePhase 1 | ConditionsSubstance use and addiction | Participants70 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07105449 | Start2025 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants48 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07091292 | Start2025 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants60 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT06899594 | Start2025 | PhaseEarly phase 1 | ConditionsSubstance use and addiction | Participants20 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT06334016 | Start2026 | PhaseEarly phase 1 | ConditionsSubstance use and addiction | Participants60 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT06293040 | Start2024 | PhasePhase 1 | ConditionsSubstance use and addiction | Participants90 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT06055231 | Start2026 | PhasePhase 1 | ConditionsCancer, Substance use and addiction | Participants40 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT05974293 | Start2026 | PhasePhase 2 | ConditionsSubstance use and addiction | ParticipantsNot given | Lead sponsorOther | StatusStopped early | Library tests named
|
| NCT05908552 | Start2023 | PhaseObservational | ConditionsSubstance use and addiction, Pain and fatigue | Participants77 | Lead sponsorOther | StatusStatus unknown | Library tests named
|
| NCT05822362 | Start2024 | PhasePhase 2 | ConditionsDementia and Alzheimer's, Mild cognitive impairment, Substance use and addiction | Participants236 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT05602649 | Start2024 | PhasePhase 1 | ConditionsSubstance use and addiction | Participants80 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT05432284 | Start2027 | PhasePhase 1 | ConditionsSubstance use and addiction | Participants32 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT05324982 | Start2022 | PhasePhase 1 | ConditionsSubstance use and addiction | Participants12 | Lead sponsorOther | StatusCompleted | Library tests named
|
| NCT05287256 | Start2022 | PhasePhase 1 | ConditionsSubstance use and addiction | Participants28 | Lead sponsorOther | StatusCompleted | Library tests named
|
| NCT05160688 | Start2023 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants146 | Lead sponsorOther | StatusCompleted | Library tests named
|
| NCT05049733 | Start2022 | PhasePhase 1 | ConditionsSubstance use and addiction | Participants21 | Lead sponsorOther | StatusCompleted | Library tests named
|
| NCT05006079 | Start2024 | PhasePhase 2 | ConditionsSubstance use and addiction | Participants24 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT04855526 | Start2025 | PhaseEarly phase 1 | ConditionsSubstance use and addiction | Participants9 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
Questions, answered from the data
How many substance use and addiction trials use Symbol Coding?
60 registered substance use and addiction studies on ClinicalTrials.gov name it in an outcome measure, 17 of them in a primary outcome: 7% of the condition's 895 studies with a cognitive outcome, against 9% of all of them. It is the 9th most named test in substance use and addiction trials.
Which tests do substance use and addiction trials use with Symbol Coding?
The Paced Visual Serial Addition Test (16 studies), Verbal Learning (11 studies) and the Stroop Color-Word Test (8 studies).
How many participants do phase 2 substance use and addiction trials that use Symbol Coding enroll?
Half of the phase 2 studies that name it enroll 29 participants or fewer, and the middle half enroll 18 to 62. 15 of them give a size.
When do substance use and addiction trials measure Symbol Coding?
Half of the primary outcomes that name Symbol Coding are measured within 1 day of the start, and the middle half from the first day to 5 weeks. 16 primary outcomes give a duration.
How many completed substance use and addiction trials that use Symbol Coding have reported results?
22 of the 30 completed studies that name it, 73%, have reported results: 15 posted them on ClinicalTrials.gov, 10 have a results paper linked to the registry record, and 3 did both. The other 8 show neither. Of all completed studies with a cognitive outcome, 46% have reported results.
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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