Clinical trials data
Cognitive tests in substance use and addiction trials: 895 registered studies
Every registered substance use and addiction study on ClinicalTrials.gov that names a cognitive test in an outcome measure: the tests used most, how often as a primary outcome, which tests go together, how large the studies are and when they measure the outcome.
- Registered substance use and addiction studies name a cognitive test in an outcome
- 895
- Led by industry
- 31
The tests substance use and addiction trials use most
The Cue Reactivity Task leads: 158 of the 895 studies name it, 18%. Next comes Delay Discounting (104). As a primary outcome, the Cue Reactivity Task leads with 89 studies.
- 1
Cue Reactivity Task158 studies, 89 as a primary outcome
- 2
Delay Discounting104 studies, 34 as a primary outcome
- 3
Stop-Signal Task92 studies, 42 as a primary outcome
- 4
Go/No-Go Task80 studies, 31 as a primary outcome
- 5
Purchase Task78 studies, 30 as a primary outcome
- 6
Verbal Learning77 studies, 33 as a primary outcome
- 7
Stroop Color-Word Test75 studies, 26 as a primary outcome
- 8
N-Back Task68 studies, 37 as a primary outcome
- 9
Symbol Coding60 studies, 17 as a primary outcome
- 10
Continuous Performance Test53 studies, 17 as a primary outcome
- 11
Trail Making Test52 studies, 15 as a primary outcome
- 12
Digit Span Test48 studies, 20 as a primary outcome
- 13
Balloon Risk34 studies, 10 as a primary outcome
- 14
Dot-Probe Task30 studies, 17 as a primary outcome
- 15
Paced Visual Serial Addition Test30 studies, 13 as a primary outcome
- 16
Iowa Gambling Lite30 studies, 10 as a primary outcome
- 17
Verbal Fluency29 studies, 9 as a primary outcome
- 18
Card Sorting Test (Berg)27 studies, 13 as a primary outcome
- 19
Monetary Incentive Delay26 studies, 19 as a primary outcome
- 20
AX Continuous Performance Test24 studies, 1 as a primary outcome
- 21
Psychomotor Vigilance Task20 studies, 6 as a primary outcome
- 22
Eriksen Flanker Task15 studies, 6 as a primary outcome
- 23
Letter-Number Sequencing Task15 studies, 6 as a primary outcome
- 24
Paired Associate Learning15 studies, 5 as a primary outcome
- 25
Approach-Avoidance Task14 studies, 6 as a primary outcome
A test as a primary outcomeOnly in secondary or other outcomes
6% of substance use and addiction studies name only instruments outside the library, such as clinician-administered screening scales. They count in every figure on this page and are not listed. The explorer below holds all 129 tests.
Tests used together
- AX Continuous Performance Test and Continuous Performance Test23 studies name both
- Continuous Performance Test and Verbal Learning16 studies name both
- Cue Reactivity Task and Stop-Signal Task16 studies name both
- Paced Visual Serial Addition Test and Symbol Coding16 studies name both
- Stroop Color-Word Test and Trail Making Test15 studies name both
- Trail Making Test and Verbal Learning15 studies name both
- Delay Discounting and Purchase Task14 studies name both
- Digit Span Test and Verbal Learning14 studies name both
- N-Back Task and Stop-Signal Task12 studies name both
- Balloon Risk and Stop-Signal Task11 studies name both
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 | 1 | 0 |
| 2002 | 2 | 0 |
| 2003 | 6 | 2 |
| 2004 | 3 | 1 |
| 2005 | 3 | 1 |
| 2006 | 7 | 3 |
| 2007 | 11 | 8 |
| 2008 | 10 | 4 |
| 2009 | 13 | 8 |
| 2010 | 17 | 8 |
| 2011 | 22 | 10 |
| 2012 | 18 | 5 |
| 2013 | 22 | 15 |
| 2014 | 26 | 7 |
| 2015 | 31 | 14 |
| 2016 | 42 | 22 |
| 2017 | 45 | 18 |
| 2018 | 62 | 22 |
| 2019 | 68 | 36 |
| 2020 | 50 | 31 |
| 2021 | 72 | 31 |
| 2022 | 65 | 21 |
| 2023 | 69 | 32 |
| 2024 | 78 | 42 |
| 2025 | 63 | 27 |
| 2026 | 76 | 37 |
Phases and sponsors
By phase
- Early phase 143 studies, 26 as a primary outcome
- Phase 176 studies, 38 as a primary outcome
- Phase 1/226 studies, 8 as a primary outcome
- Phase 2145 studies, 62 as a primary outcome
- Phase 2/39 studies, 3 as a primary outcome
- Phase 318 studies, 5 as a primary outcome
- Phase 434 studies, 14 as a primary outcome
- Not applicable474 studies, 212 as a primary outcome
- Observational70 studies, 43 as a primary outcome
Sponsors and study types
Lead sponsor: industry 31, NIH 12, universities, hospitals and others 852. Interventional 825, observational 70.
Status, results, interventions and countries
Status
- Recruiting164 studies, 80 as a primary outcome
- Not yet recruiting49 studies, 21 as a primary outcome
- Active, not recruiting31 studies, 12 as a primary outcome
- Completed499 studies, 233 as a primary outcome
- Stopped early77 studies, 35 as a primary outcome
- Status unknown75 studies, 30 as a primary outcome
What they test
- Behavioral284 studies, 133 as a primary outcome
- Drug387 studies, 178 as a primary outcome
- Device142 studies, 63 as a primary outcome
- Dietary supplement16 studies, 5 as a primary outcome
- Procedure20 studies, 8 as a primary outcome
- Diagnostic test10 studies, 8 as a primary outcome
- Biological3 studies, 2 as a primary outcome
- Radiation2 studies, 2 as a primary outcome
- Combination product3 studies, 0 as a primary outcome
- Genetic1 studies, 0 as a primary outcome
- Other167 studies, 78 as a primary outcome
- None given30 studies, 17 as a primary outcome
Intervention types as registered. A study can list several; observational studies often list none.
Where their sites are
- United States551 studies, 289 as a primary outcome
- China41 studies, 17 as a primary outcome
- Canada37 studies, 8 as a primary outcome
- France35 studies, 8 as a primary outcome
- Germany29 studies, 19 as a primary outcome
- Spain20 studies, 6 as a primary outcome
- United Kingdom18 studies, 7 as a primary outcome
- Switzerland15 studies, 5 as a primary outcome
- Netherlands11 studies, 1 as a primary outcome
- Australia10 studies, 0 as a primary outcome
- Israel9 studies, 2 as a primary outcome
- Denmark8 studies, 0 as a primary outcome
42 countries in all. A study with sites in several counts in each; 43 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: 283 of 499, 57%
Every completed study with a cognitive outcome: 3,626 of 7,953, 46%
| Results | Completed substance use and addiction studies | Every completed study |
|---|---|---|
| Results on ClinicalTrials.gov and a paper | 68, 14% | 776, 10% |
| Results on ClinicalTrials.gov only | 126, 25% | 1,139, 14% |
| A results paper only | 89, 18% | 1,711, 22% |
| Neither | 216, 43% | 4,327, 54% |
How many participants they enroll
- Early phase 138 median, 19 to 69
- Phase 131 median, 17 to 65
- Phase 1/228 median, 20 to 41
- Phase 250 median, 24 to 85
- Phase 381 median, 46 to 174
- Phase 444 median, 18 to 78
- Not applicable70 median, 38 to 128
- Observational93 median, 59 to 203
Show as a table
| Phase | Studies with a size | Median | Middle half |
|---|---|---|---|
| Early phase 1 | 43 | 38 | 19 to 69 |
| Phase 1 | 74 | 31 | 17 to 65 |
| Phase 1/2 | 25 | 28 | 20 to 41 |
| Phase 2 | 139 | 50 | 24 to 85 |
| Phase 3 | 16 | 81 | 46 to 174 |
| Phase 4 | 32 | 44 | 18 to 78 |
| Not applicable | 463 | 70 | 38 to 128 |
| Observational | 69 | 93 | 59 to 203 |
When the cognitive outcome is measured
Latest time point of each outcome
- Within a day345 outcomes, 179 as a primary outcome
- Up to 4 weeks498 outcomes, 231 as a primary outcome
- 1 to 3 months328 outcomes, 114 as a primary outcome
- 3 to 6 months133 outcomes, 41 as a primary outcome
- 6 to 12 months62 outcomes, 7 as a primary outcome
- 1 to 2 years21 outcomes, 8 as a primary outcome
- Over 2 years26 outcomes, 16 as a primary outcome
- No duration given141 outcomes, 68 as a primary outcome
A test as a primary outcomeOnly in secondary or other outcomes
1,413 of the 1,554 outcome measures give a duration. A single visit counts as within a day.
Median time to the primary outcome, by test
| Test | Primary outcomes | Median |
|---|---|---|
| Cue Reactivity Task | 73 | 2 weeks |
| N-Back Task | 36 | 2 weeks |
| Stop-Signal Task | 36 | 4 weeks |
| Delay Discounting | 30 | 4 weeks |
| Verbal Learning | 30 | 4 weeks |
| Purchase Task | 28 | 1 week |
| Go/No-Go Task | 27 | 1 week |
| Stroop Color-Word Test | 23 | 3 weeks |
| Digit Span Test | 20 | 4 weeks |
| Monetary Incentive Delay | 18 | 2 weeks |
Explore the substance use and addiction studies
841 studies match. 393 name a library test in a primary outcome. Median size 60 participants. Median time to the primary outcome: 3 weeks.
Loading 841 studies; the filters turn on when they arrive.
2026 is partly planned starts. Not shown: 2 that started before 2000 and 11 planned to start after 2026.
Show as a table
| Start year | Studies | As a primary outcome |
|---|---|---|
| 2000 | 0 | 0 |
| 2001 | 1 | 0 |
| 2002 | 2 | 0 |
| 2003 | 6 | 2 |
| 2004 | 3 | 1 |
| 2005 | 3 | 1 |
| 2006 | 7 | 3 |
| 2007 | 11 | 8 |
| 2008 | 10 | 4 |
| 2009 | 13 | 8 |
| 2010 | 16 | 7 |
| 2011 | 22 | 10 |
| 2012 | 17 | 5 |
| 2013 | 21 | 15 |
| 2014 | 24 | 7 |
| 2015 | 28 | 14 |
| 2016 | 41 | 21 |
| 2017 | 42 | 17 |
| 2018 | 60 | 21 |
| 2019 | 62 | 34 |
| 2020 | 49 | 30 |
| 2021 | 67 | 29 |
| 2022 | 60 | 21 |
| 2023 | 65 | 29 |
| 2024 | 69 | 38 |
| 2025 | 61 | 26 |
| 2026 | 68 | 36 |
Library tests named most
Largest condition groups
Phases
Participants
Lead sponsor: industry 28, NIH 12, other 801. Interventional 780, observational 61.
As a primary outcomeSecondary or other outcome
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 |
|---|---|---|---|---|---|---|---|
| NCT07899827 | Start2027 | PhaseNot applicable | ConditionsCancer, Substance use and addiction | Participants50 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07886606 | Start2021 | PhaseEarly phase 1 | ConditionsSubstance use and addiction, Pain and fatigue | Participants34 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07885085 | Start2027 | PhaseObservational | ConditionsMild cognitive impairment, Substance use and addiction, Delirium, surgery and intensive care, Pain and fatigue | Participants552 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07879612 | Start2027 | PhasePhase 2 | ConditionsSubstance use and addiction | Participants40 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07878624 | Start2025 | PhaseObservational | ConditionsSubstance use and addiction | Participants120 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07878130 | Start2026 | PhasePhase 2 | ConditionsSubstance use and addiction | Participants100 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07870187 | Start2027 | PhasePhase 1 | ConditionsSubstance use and addiction | Participants70 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07852052 | Start2026 | PhaseObservational | ConditionsSubstance use and addiction, Sleep and sleep disorders | Participants34 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07843615 | Start2026 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants120 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07829510 | Start2026 | PhaseNot applicable | ConditionsDepression and bipolar disorder, Substance use and addiction, Anxiety, PTSD and OCD | Participants300 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07814755 | Start2026 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants50 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07802990 | Start2026 | PhasePhase 1/2 | ConditionsSubstance use and addiction | Participants28 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07802223 | Start2026 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants50 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07778511 | Start2026 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants72 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07775807 | Start2026 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants5 | Lead sponsorOther | StatusActive, not recruiting | Library tests named
|
| NCT07770555 | Start2027 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants12 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07748078 | Start2026 | PhaseNot applicable | ConditionsSchizophrenia and psychosis, Substance use and addiction | Participants140 | 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
|
| NCT07735923 | Start2026 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants104 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07734623 | Start2025 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants60 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07732426 | Start2026 | PhaseNot applicable | ConditionsObesity and diabetes, Substance use and addiction | Participants30 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07698470 | Start2026 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants45 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07689981 | Start2026 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants30 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07688304 | Start2026 | PhaseNot applicable | ConditionsSubstance use and addiction | Participants30 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07679581 | Start2025 | PhaseObservational | ConditionsSubstance use and addiction | Participants64 | Lead sponsorOther | StatusRecruiting | Library tests named
|
Questions, answered from the data
Which cognitive test do substance use and addiction trials use most?
The Cue Reactivity Task: 158 of the 895 registered studies name it in an outcome measure, 18%. Next come Delay Discounting (104) and the Stop-Signal Task (92).
Which cognitive test do substance use and addiction trials use most as a primary outcome?
The Cue Reactivity Task, named in a primary outcome by 89 studies. 411 of the 895 studies, 46%, name a cognitive test in a primary outcome.
How many participants does a phase 2 substance use and addiction trial enroll?
Half of the phase 2 substance use and addiction studies enroll 50 participants or fewer, and the middle half enroll 24 to 85. 139 of them give a size.
How long after the start do substance use and addiction trials measure a cognitive outcome?
Half of the primary outcomes that name a library test are measured within 3 weeks of the start, and the middle half from the first day to 6 weeks. 596 primary outcomes give a duration.
Which cognitive tests do substance use and addiction trials use together?
The AX Continuous Performance Test with the Continuous Performance Test most often: 23 studies name both. Next, the Continuous Performance Test with Verbal Learning (16).
How many completed substance use and addiction trials have reported results?
283 of the 499 completed substance use and addiction studies, 57%, have reported results: 194 posted them on ClinicalTrials.gov, 157 have a results paper linked to the registry record, and 68 did both. The other 216 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.
Plan the cognitive outcomes of a substance use and addiction trial
Choose tests with a record in registered trials, and run them in a browser at every site, on the same version each visit.