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  1. Home
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  5. /Substance use and addiction
  6. /N-Back Task

Clinical trials data

N-Back Task in substance use and addiction trials: 68 registered studies

Every registered substance use and addiction study on ClinicalTrials.gov that names the N-Back Task 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
68
Name it in a primary outcome, 54%
37 of 68
Of the condition's 895 studies name it, against 5% of all registered studies
8%
Other conditions
Median participants per study
50
By phase
Try the 1-Back TaskTry the 2-Back Task

Tests named in the same studies

The library tests that substance use and addiction studies naming the N-Back Task name most often beside it.
  1. 1

    Stop-Signal Task12 studies, 7 as a primary outcome

  2. 2

    Continuous Performance Test9 studies, 4 as a primary outcome

  3. 3

    Go/No-Go Task7 studies, 4 as a primary outcome

  4. 4

    Verbal Learning6 studies, 4 as a primary outcome

  5. 5

    Delay Discounting6 studies, 2 as a primary outcome

  6. 6

    Digit Span Test5 studies, 4 as a primary outcome

  7. 7

    Eriksen Flanker Task5 studies, 4 as a primary outcome

  8. 8

    AX Continuous Performance Test5 studies, 1 as a primary outcome

  9. 9

    Balloon Risk4 studies, 2 as a primary outcome

  10. 10

    Cue Reactivity Task4 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: 3 studies, 2 with a test as a primary outcome2008: 2 studies, 0 with a test as a primary outcome2009: 0 studies, 0 with a test as a primary outcome2010: 3 studies, 2 with a test as a primary outcome20102011: 4 studies, 1 with a test as a primary outcome2012: 3 studies, 0 with a test as a primary outcome2013: 3 studies, 3 with a test as a primary outcome2014: 2 studies, 2 with a test as a primary outcome2015: 1 studies, 1 with a test as a primary outcome20152016: 6 studies, 4 with a test as a primary outcome2017: 6 studies, 4 with a test as a primary outcome2018: 8 studies, 5 with a test as a primary outcome2019: 4 studies, 2 with a test as a primary outcome2020: 2 studies, 1 with a test as a primary outcome20202021: 3 studies, 2 with a test as a primary outcome2022: 3 studies, 2 with a test as a primary outcome2023: 4 studies, 2 with a test as a primary outcome2024: 4 studies, 2 with a test as a primary outcome2025: 4 studies, 0 with a test as a primary outcome20252026: 3 studies, 2 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
200732
200820
200900
201032
201141
201230
201333
201422
201511
201664
201764
201885
201942
202021
202132
202232
202342
202442
202540
202632

Phases and study sizes

By phase

  • Early phase 14 studies, 3 as a primary outcome
  • Phase 18 studies, 4 as a primary outcome
  • Phase 1/22 studies, 0 as a primary outcome
  • Phase 215 studies, 7 as a primary outcome
  • Phase 31 studies, 1 as a primary outcome
  • Phase 41 studies, 0 as a primary outcome
  • Not applicable31 studies, 17 as a primary outcome
  • Observational6 studies, 5 as a primary outcome

Participants per study

102050100
  • Phase 233 median, 19 to 80
  • Not applicable64 median, 38 to 121
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 substance use and addiction study that names the N-Back Task, by phase
PhaseStudies with a sizeMedianMiddle half
Phase 2133319 to 80
Not applicable306438 to 121

When substance use and addiction trials measure it

Half of the primary outcomes that name the N-Back Task are measured within 2 weeks of the start, and the middle half from the first day to 5 weeks. 36 primary outcomes give a duration.

Latest time point of each outcome

  • Within a day20 outcomes, 14 as a primary outcome
  • Up to 4 weeks20 outcomes, 11 as a primary outcome
  • 1 to 3 months16 outcomes, 6 as a primary outcome
  • 3 to 6 months2 outcomes, 1 as a primary outcome
  • 6 to 12 months3 outcomes, 1 as a primary outcome
  • 1 to 2 years2 outcomes, 1 as a primary outcome
  • Over 2 years2 outcomes, 2 as a primary outcome
  • No duration given2 outcomes, 1 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

65 of the 67 outcome measures give a duration. A single visit counts as within a day.

Status, results, interventions and countries

Status

  • Recruiting11 studies, 5 as a primary outcome
  • Not yet recruiting1 studies, 0 as a primary outcome
  • Active, not recruiting2 studies, 2 as a primary outcome
  • Completed41 studies, 23 as a primary outcome
  • Stopped early8 studies, 4 as a primary outcome
  • Status unknown5 studies, 3 as a primary outcome

What they test

  • Behavioral15 studies, 9 as a primary outcome
  • Drug37 studies, 20 as a primary outcome
  • Device15 studies, 7 as a primary outcome
  • Dietary supplement2 studies, 0 as a primary outcome
  • Procedure1 studies, 0 as a primary outcome
  • Other10 studies, 7 as a primary outcome
  • None given1 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 States44 studies, 28 as a primary outcome
  • Canada6 studies, 2 as a primary outcome
  • Germany4 studies, 4 as a primary outcome
  • China3 studies, 2 as a primary outcome
  • Brazil2 studies, 0 as a primary outcome
  • Switzerland2 studies, 1 as a primary outcome
  • United Kingdom2 studies, 0 as a primary outcome
  • Australia1 studies, 0 as a primary outcome
  • Spain1 studies, 0 as a primary outcome
  • Taiwan1 studies, 0 as a primary outcome

10 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 substance use and addiction studies that name the N-Back Task: 27 of 41, 66%

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

Completed substance use and addiction studies that name the N-Back Task and every completed study, by how they reported results
ResultsCompleted substance use and addiction studies that name the N-Back TaskEvery completed study
Results on ClinicalTrials.gov and a paper5, 12%776, 10%
Results on ClinicalTrials.gov only15, 37%1,139, 14%
A results paper only7, 17%1,711, 22%
Neither14, 34%4,327, 54%

The 68 studies

Filter by phase, sponsor, status, country, intervention, outcome list, size and start year. Each study links to its record on ClinicalTrials.gov.
ConditionSubstance use and addiction
TestThe N-Back Task

68 studies match. 37 name the N-Back Task in a primary outcome. Median size 50 participants. Median time to the primary outcome: 2 weeks.

Loading 68 studies; the filters turn on when they arrive.

By start year
024682000: 0 studies, 0 naming the N-Back Task in a primary outcome20002001: 0 studies, 0 naming the N-Back Task in a primary outcome2002: 0 studies, 0 naming the N-Back Task in a primary outcome2003: 0 studies, 0 naming the N-Back Task in a primary outcome2004: 0 studies, 0 naming the N-Back Task in a primary outcome2005: 0 studies, 0 naming the N-Back Task in a primary outcome20052006: 0 studies, 0 naming the N-Back Task in a primary outcome2007: 3 studies, 2 naming the N-Back Task in a primary outcome2008: 2 studies, 0 naming the N-Back Task in a primary outcome2009: 0 studies, 0 naming the N-Back Task in a primary outcome2010: 3 studies, 2 naming the N-Back Task in a primary outcome20102011: 4 studies, 1 naming the N-Back Task in a primary outcome2012: 3 studies, 0 naming the N-Back Task in a primary outcome2013: 3 studies, 3 naming the N-Back Task in a primary outcome2014: 2 studies, 2 naming the N-Back Task in a primary outcome2015: 1 studies, 1 naming the N-Back Task in a primary outcome20152016: 6 studies, 4 naming the N-Back Task in a primary outcome2017: 6 studies, 4 naming the N-Back Task in a primary outcome2018: 8 studies, 5 naming the N-Back Task in a primary outcome2019: 4 studies, 2 naming the N-Back Task in a primary outcome2020: 2 studies, 1 naming the N-Back Task in a primary outcome20202021: 3 studies, 2 naming the N-Back Task in a primary outcome2022: 3 studies, 2 naming the N-Back Task in a primary outcome2023: 4 studies, 2 naming the N-Back Task in a primary outcome2024: 4 studies, 2 naming the N-Back Task in a primary outcome2025: 4 studies, 0 naming the N-Back Task in a primary outcome20252026: 3 studies, 2 naming the N-Back Task 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
200732
200820
200900
201032
201141
201230
201333
201422
201511
201664
201764
201885
201942
202021
202132
202232
202342
202442
202540
202632

Library tests named most

  • N-Back Task68 studies, 37 as a primary outcome
  • Stop-Signal Task12 studies, 7 as a primary outcome
  • Continuous Performance Test9 studies, 4 as a primary outcome
  • Go/No-Go Task7 studies, 4 as a primary outcome
  • Verbal Learning6 studies, 4 as a primary outcome
  • Delay Discounting6 studies, 2 as a primary outcome
  • Digit Span Test5 studies, 4 as a primary outcome
  • Eriksen Flanker Task5 studies, 4 as a primary outcome
  • AX Continuous Performance Test5 studies, 1 as a primary outcome
  • Balloon Risk4 studies, 2 as a primary outcome

Conditions

  • Substance use and addiction68 studies, 37 as a primary outcome
  • Schizophrenia and psychosis5 studies, 3 as a primary outcome
  • ADHD4 studies, 3 as a primary outcome
  • Depression and bipolar disorder3 studies, 3 as a primary outcome
  • Sleep and sleep disorders3 studies, 0 as a primary outcome
  • Anxiety, PTSD and OCD2 studies, 2 as a primary outcome
  • Cardiovascular disease2 studies, 1 as a primary outcome
  • Brain injury and concussion1 study, 1 as a primary outcome
  • Obesity and diabetes1 study, 1 as a primary outcome

Phases

Participants

Lead sponsor: industry 1, NIH 1, other 66. Interventional 62, observational 6.

As a primary outcomeSecondary or other outcomeThe N-Back Task

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
NCT07802990Start2026PhasePhase 1/2ConditionsSubstance use and addictionParticipants28Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • N-Back TaskSecondary3 weeks
  • Tower PlanningSecondary3 weeks
NCT07734623Start2025PhaseNot applicableConditionsSubstance use and addictionParticipants60Lead sponsorOtherStatusRecruitingLibrary tests named
  • N-Back TaskSecondary2 years
  • Betting Choice TaskSecondary2 years
NCT07532460Start2026PhaseNot applicableConditionsSubstance use and addictionParticipants40Lead sponsorOtherStatusRecruitingLibrary tests named
  • N-Back TaskPrimary
  • Paired Associate LearningPrimary
  • Letter-Number Sequencing TaskPrimary
NCT07510113Start2025PhaseNot applicableConditionsSubstance use and addictionParticipants38Lead sponsorOtherStatusCompletedLibrary tests named
  • N-Back TaskSecondary4 weeks
  • Go/No-Go TaskSecondary4 weeks
  • Visual Search TestSecondary4 weeks
NCT07296874Start2026PhasePhase 1ConditionsSubstance use and addictionParticipants92Lead sponsorOtherStatusRecruitingLibrary tests named
  • Stroop Color-Word TestPrimarysame day
  • Verbal FluencyPrimarysame day
  • Digit Span TestPrimarysame day
  • N-Back TaskPrimarysame day
  • Go/No-Go TaskPrimarysame day
  • Category FluencyOther outcomesame day
  • Probabilistic Reversal LearningPrimarysame day
  • Intra/Extra Dimensional Set ShiftPrimarysame day
  • Prospective Memory TaskPrimarysame day
NCT07001930Start2025PhasePhase 1ConditionsSubstance use and addictionParticipants90Lead sponsorOtherStatusRecruitingLibrary tests named
  • N-Back TaskSecondarysame day
  • Purchase TaskSecondarysame day
  • Sustained Attention to ResponseSecondarysame day
NCT06977178Start2024PhaseNot applicableConditionsSubstance use and addiction, Anxiety, PTSD and OCDParticipants180Lead sponsorOtherStatusRecruitingLibrary tests named
  • N-Back TaskPrimary2 years
  • Stop-Signal TaskPrimary2 years
  • Perceptual Load TaskPrimary2 years
NCT06837649Start2023PhaseNot applicableConditionsSubstance use and addictionParticipants66Lead sponsorOtherStatusCompletedLibrary tests named
  • N-Back TaskPrimary8 weeks
  • Eriksen Flanker TaskPrimary8 weeks
NCT06798324Start2025PhasePhase 4ConditionsSubstance use and addictionParticipants160Lead sponsorOtherStatusRecruitingLibrary tests named
  • N-Back TaskSecondary12 months
  • Stop-Signal TaskSecondary12 months
  • Sustained Attention to ResponseSecondary12 months
NCT06346353Start2024PhaseObservationalConditionsDepression and bipolar disorder, Substance use and addiction, Anxiety, PTSD and OCDParticipants756Lead sponsorOtherStatusCompletedLibrary tests named
  • N-Back TaskPrimarysame day
  • Stop-Signal TaskPrimarysame day
NCT06326684Start2024PhaseEarly phase 1ConditionsSubstance use and addictionParticipants30Lead sponsorOtherStatusRecruitingLibrary tests named
  • N-Back TaskSecondary3 weeks
  • Stop-Signal TaskSecondary3 weeks
  • Delay DiscountingSecondary3 weeks
NCT06299787Start2022PhaseNot applicableConditionsDepression and bipolar disorder, Substance use and addictionParticipants40Lead sponsorOtherStatusStatus unknownLibrary tests named
  • N-Back TaskPrimary4 weeks
  • Eriksen Flanker TaskPrimary4 weeks
NCT06286774Start2024PhaseNot applicableConditionsSubstance use and addiction, Sleep and sleep disordersParticipants256Lead sponsorOtherStatusRecruitingLibrary tests named
  • Stroop Color-Word TestSecondary13 weeks
  • N-Back TaskSecondary13 weeks
  • Delay DiscountingSecondary6 months
NCT05976672Start2023PhaseNot applicableConditionsSubstance use and addictionParticipants500Lead sponsorOtherStatusActive, not recruitingLibrary tests named
  • N-Back TaskPrimary5 years
  • Eriksen Flanker TaskPrimary5 years
  • Balloon RiskPrimary5 years
NCT05903495Start2023PhaseNot applicableConditionsSubstance use and addictionParticipants1Lead sponsorOtherStatusCompleted

Results

Library tests named
  • N-Back TaskSecondary12 weeks
  • Psychomotor Vigilance TaskSecondary12 weeks
  • Cue Reactivity TaskSecondary12 weeks
NCT05387148Start2022PhasePhase 2ConditionsSubstance use and addictionParticipants20Lead sponsorOtherStatusStatus unknown

Paper

Library tests named
  • Trail Making TestSecondary6 weeks
  • Stroop Color-Word TestSecondary6 weeks
  • N-Back TaskSecondary6 weeks
  • Balloon RiskSecondary6 weeks
  • Approach-Avoidance TaskSecondary6 weeks
  • Columbia Card TaskSecondary6 weeks
NCT05170217Start2017PhaseNot applicableConditionsSubstance use and addictionParticipants46Lead sponsorOtherStatusCompleted

Paper 1Paper 2

Library tests named
  • Verbal LearningPrimarysame day
  • Digit Span TestSecondarysame day
  • N-Back TaskSecondarysame day
  • Spatial N-Back TaskSecondarysame day
NCT05062369Start2022PhaseNot applicableConditionsSubstance use and addictionParticipants100Lead sponsorOtherStatusRecruitingLibrary tests named
  • Digit Span TestPrimary4 months
  • N-Back TaskPrimary4 weeks
NCT05048758Start2021PhaseObservationalConditionsSubstance use and addictionParticipants43Lead sponsorOtherStatusCompletedLibrary tests named
  • N-Back TaskPrimarysame day
  • Go/No-Go TaskPrimarysame day
  • Stop-Signal TaskPrimarysame day
  • Cue Reactivity TaskPrimarysame day
NCT04964843Start2023PhasePhase 2ConditionsSubstance use and addictionParticipantsNot givenLead sponsorOtherStatusStopped earlyLibrary tests named
  • Trail Making TestOther outcome7 weeks
  • N-Back TaskOther outcome7 weeks
  • Stop-Signal TaskOther outcome7 weeks
  • Cue Reactivity TaskSecondary7 weeks
  • Purchase TaskSecondary7 weeks
NCT04856566Start2021PhaseEarly phase 1ConditionsSubstance use and addictionParticipants41Lead sponsorOtherStatusCompletedLibrary tests named
  • N-Back TaskPrimarysame day
  • Go/No-Go TaskPrimarysame day
  • Hidden Path LearningPrimarysame day
  • Time Estimation TaskPrimarysame day
  • Pursuit Tracking TestPrimarysame day
NCT04725617Start2021PhaseNot applicableConditionsSubstance use and addiction, Sleep and sleep disorders, Cardiovascular diseaseParticipants200Lead sponsorOtherStatusRecruitingLibrary tests named
  • N-Back TaskOther outcome6 months
  • Psychomotor Vigilance TaskOther outcome6 months
  • Balloon RiskOther outcome6 months
NCT04498988Start2014PhaseObservationalConditionsSubstance use and addictionParticipants338Lead sponsorOtherStatusCompleted

Paper

Library tests named
  • N-Back TaskPrimary6 years
  • Go/No-Go TaskPrimary6 years
  • Delay DiscountingPrimary6 years
  • AX Continuous Performance TestPrimary6 years
  • Probability Discounting TaskPrimary6 years
  • Loss Aversion TaskPrimary6 years
NCT04296604Start2014PhaseNot applicableConditionsBrain injury and concussion, Schizophrenia and psychosis, Depression and bipolar disorder, ADHD, Substance use and addictionParticipants600Lead sponsorOtherStatusRecruitingLibrary tests named
  • N-Back TaskPrimary1 week
  • Eriksen Flanker TaskSecondary1 week
  • Stop-Signal TaskSecondary1 week
  • Iowa Gambling LiteSecondary1 week
NCT04202926Start2019PhaseNot applicableConditionsSubstance use and addictionParticipants23Lead sponsorOtherStatusCompletedLibrary tests named
  • N-Back TaskSecondary13 weeks
  • Stop-Signal TaskSecondary13 weeks

Page 1 of 3

Questions, answered from the data

How many substance use and addiction trials use the N-Back Task?

68 registered substance use and addiction studies on ClinicalTrials.gov name it in an outcome measure, 37 of them in a primary outcome: 8% of the condition's 895 studies with a cognitive outcome, against 5% of all of them. It is the 8th most named test in substance use and addiction trials.

Which tests do substance use and addiction trials use with the N-Back Task?

The Stop-Signal Task (12 studies), the Continuous Performance Test (9 studies) and the Go/No-Go Task (7 studies).

How many participants do phase 2 substance use and addiction trials that use the N-Back Task enroll?

Half of the phase 2 studies that name it enroll 33 participants or fewer, and the middle half enroll 19 to 80. 13 of them give a size.

When do substance use and addiction trials measure the N-Back Task?

Half of the primary outcomes that name the N-Back Task are measured within 2 weeks of the start, and the middle half from the first day to 5 weeks. 36 primary outcomes give a duration.

How many completed substance use and addiction trials that use the N-Back Task have reported results?

27 of the 41 completed studies that name it, 66%, have reported results: 20 posted them on ClinicalTrials.gov, 12 have a results paper linked to the registry record, and 5 did both. The other 14 show neither. Of all completed studies with a cognitive outcome, 46% have reported results.

More on the N-Back Task and substance use and addiction

  • Every cognitive test in substance use and addiction trials: 895 studies
  • The N-Back Task in all clinical trials: 790 studies

The N-Back Task in other conditions

  • Depression and bipolar disorder79
  • Aging, frailty and exercise68
  • Schizophrenia and psychosis66
  • Healthy volunteers51
  • Sleep and sleep disorders51

Other tests in substance use and addiction trials

  • Cue Reactivity Task158
  • Delay Discounting104
  • Stop-Signal Task92
  • Go/No-Go Task80
  • Purchase Task78
  • Verbal Learning77
  • Stroop Color-Word Test75
  • Symbol Coding60
  • Continuous Performance Test53
  • Trail Making Test52

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 1-Back Task and 2-Back Task as one test family, so this page counts their studies together.

Run the N-Back Task in your trial

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