Clinical trials data
Cognitive tests in epilepsy trials: 138 registered studies
Every registered epilepsy 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 epilepsy studies name a cognitive test in an outcome
- 138
- Led by industry
- 17
The tests epilepsy trials use most
Verbal Learning leads: 25 of the 138 studies name it, 18%. Next comes Verbal Fluency (17). As a primary outcome, Verbal Learning leads with 9 studies.
- 1
Verbal Learning25 studies, 9 as a primary outcome
- 2
Verbal Fluency17 studies, 6 as a primary outcome
- 3
Digit Span Test15 studies, 4 as a primary outcome
- 4
Trail Making Test15 studies, 3 as a primary outcome
- 5
Stroop Color-Word Test12 studies, 8 as a primary outcome
- 6
Continuous Performance Test10 studies, 7 as a primary outcome
- 7
Complex Figure Copy and Recall10 studies, 3 as a primary outcome
- 8
Vocabulary Test9 studies, 2 as a primary outcome
- 9
Picture Order Memory Test9 studies, 1 as a primary outcome
- 10
Picture Naming Test8 studies, 3 as a primary outcome
- 11
Symbol Coding7 studies, 0 as a primary outcome
- 12
Choice Reaction Time6 studies, 2 as a primary outcome
- 13
Go/No-Go Task5 studies, 4 as a primary outcome
- 14
Psychomotor Vigilance Task5 studies, 2 as a primary outcome
- 15
Card Sorting Test (Berg)5 studies, 1 as a primary outcome
- 16
Dimensional Change Card Sort5 studies, 1 as a primary outcome
- 17
Pattern and Letter Comparison5 studies, 0 as a primary outcome
- 18
Size Order Memory Test5 studies, 0 as a primary outcome
- 19
Symbol Scan Task4 studies, 1 as a primary outcome
- 20
Matrix Reasoning4 studies, 0 as a primary outcome
- 21
Simple Reaction Time4 studies, 0 as a primary outcome
- 22
Category Fluency3 studies, 1 as a primary outcome
- 23
N-Back Task3 studies, 1 as a primary outcome
- 24
Short Story Recall3 studies, 0 as a primary outcome
- 25
Associative Recognition Test2 studies, 2 as a primary outcome
A test as a primary outcomeOnly in secondary or other outcomes
26% of epilepsy 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 54 tests.
Tests used together
- Trail Making Test and Verbal Learning8 studies name both
- Digit Span Test and Verbal Fluency7 studies name both
- Digit Span Test and Verbal Learning7 studies name both
- Verbal Fluency and Verbal Learning7 studies name both
- Picture Naming Test and Verbal Learning6 studies name both
- Trail Making Test and Verbal Fluency6 studies name both
- Complex Figure Copy and Recall and Verbal Learning5 studies name both
- Digit Span Test and Trail Making Test5 studies name both
- Dimensional Change Card Sort and Picture Order Memory Test5 studies name both
- Pattern and Letter Comparison and Size Order Memory Test5 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 | 0 | 0 |
| 2002 | 0 | 0 |
| 2003 | 0 | 0 |
| 2004 | 1 | 0 |
| 2005 | 1 | 0 |
| 2006 | 0 | 0 |
| 2007 | 1 | 0 |
| 2008 | 2 | 1 |
| 2009 | 1 | 1 |
| 2010 | 3 | 1 |
| 2011 | 5 | 1 |
| 2012 | 3 | 1 |
| 2013 | 3 | 2 |
| 2014 | 5 | 2 |
| 2015 | 5 | 1 |
| 2016 | 6 | 2 |
| 2017 | 1 | 1 |
| 2018 | 2 | 1 |
| 2019 | 10 | 8 |
| 2020 | 9 | 5 |
| 2021 | 17 | 7 |
| 2022 | 17 | 4 |
| 2023 | 12 | 6 |
| 2024 | 18 | 8 |
| 2025 | 9 | 3 |
| 2026 | 7 | 2 |
Phases and sponsors
By phase
- Early phase 13 studies, 2 as a primary outcome
- Phase 15 studies, 0 as a primary outcome
- Phase 1/21 studies, 0 as a primary outcome
- Phase 210 studies, 4 as a primary outcome
- Phase 2/31 studies, 0 as a primary outcome
- Phase 39 studies, 1 as a primary outcome
- Phase 48 studies, 6 as a primary outcome
- Not applicable72 studies, 26 as a primary outcome
- Observational29 studies, 18 as a primary outcome
Sponsors and study types
Lead sponsor: industry 17, NIH 4, universities, hospitals and others 117. Interventional 109, observational 29.
Status, results, interventions and countries
Status
- Recruiting37 studies, 15 as a primary outcome
- Not yet recruiting8 studies, 2 as a primary outcome
- Active, not recruiting9 studies, 4 as a primary outcome
- Completed44 studies, 21 as a primary outcome
- Stopped early20 studies, 7 as a primary outcome
- Status unknown20 studies, 8 as a primary outcome
What they test
- Behavioral20 studies, 11 as a primary outcome
- Drug39 studies, 17 as a primary outcome
- Device41 studies, 10 as a primary outcome
- Dietary supplement1 studies, 0 as a primary outcome
- Procedure3 studies, 2 as a primary outcome
- Diagnostic test10 studies, 5 as a primary outcome
- Radiation2 studies, 1 as a primary outcome
- Other32 studies, 17 as a primary outcome
- None given8 studies, 5 as a primary outcome
Intervention types as registered. A study can list several; observational studies often list none.
Where their sites are
- United States64 studies, 30 as a primary outcome
- China19 studies, 3 as a primary outcome
- France13 studies, 4 as a primary outcome
- Italy8 studies, 5 as a primary outcome
- Poland6 studies, 2 as a primary outcome
- Türkiye6 studies, 3 as a primary outcome
- United Kingdom6 studies, 3 as a primary outcome
- Belgium5 studies, 0 as a primary outcome
- Spain5 studies, 1 as a primary outcome
- Hungary4 studies, 1 as a primary outcome
- Netherlands4 studies, 2 as a primary outcome
- Czechia3 studies, 0 as a primary outcome
44 countries in all. A study with sites in several counts in each; 9 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 epilepsy studies: 22 of 44, 50%
Every completed study with a cognitive outcome: 3,626 of 7,953, 46%
| Results | Completed epilepsy studies | Every completed study |
|---|---|---|
| Results on ClinicalTrials.gov and a paper | 10, 23% | 776, 10% |
| Results on ClinicalTrials.gov only | 5, 11% | 1,139, 14% |
| A results paper only | 7, 16% | 1,711, 22% |
| Neither | 22, 50% | 4,327, 54% |
How many participants they enroll
- Phase 232 median, 14 to 79
- Not applicable46 median, 19 to 99
- Observational120 median, 33 to 354
Show as a table
| Phase | Studies with a size | Median | Middle half |
|---|---|---|---|
| Phase 2 | 10 | 32 | 14 to 79 |
| Not applicable | 70 | 46 | 19 to 99 |
| Observational | 27 | 120 | 33 to 354 |
When the cognitive outcome is measured
Latest time point of each outcome
- Within a day35 outcomes, 16 as a primary outcome
- Up to 4 weeks25 outcomes, 15 as a primary outcome
- 1 to 3 months61 outcomes, 19 as a primary outcome
- 3 to 6 months40 outcomes, 7 as a primary outcome
- 6 to 12 months25 outcomes, 5 as a primary outcome
- 1 to 2 years20 outcomes, 7 as a primary outcome
- Over 2 years14 outcomes, 2 as a primary outcome
- No duration given11 outcomes, 6 as a primary outcome
A test as a primary outcomeOnly in secondary or other outcomes
220 of the 231 outcome measures give a duration. A single visit counts as within a day.
Explore the epilepsy studies
102 studies match. 49 name a library test in a primary outcome. Median size 50 participants. Median time to the primary outcome: 10 weeks.
Loading 102 studies; the filters turn on when they arrive.
2026 is partly planned starts.
Show as a table
| Start year | Studies | As a primary outcome |
|---|---|---|
| 2000 | 0 | 0 |
| 2001 | 0 | 0 |
| 2002 | 0 | 0 |
| 2003 | 0 | 0 |
| 2004 | 1 | 0 |
| 2005 | 1 | 0 |
| 2006 | 0 | 0 |
| 2007 | 1 | 0 |
| 2008 | 2 | 1 |
| 2009 | 1 | 1 |
| 2010 | 2 | 1 |
| 2011 | 5 | 1 |
| 2012 | 3 | 1 |
| 2013 | 3 | 2 |
| 2014 | 1 | 1 |
| 2015 | 4 | 1 |
| 2016 | 6 | 2 |
| 2017 | 1 | 1 |
| 2018 | 2 | 1 |
| 2019 | 8 | 7 |
| 2020 | 7 | 5 |
| 2021 | 13 | 6 |
| 2022 | 11 | 2 |
| 2023 | 10 | 5 |
| 2024 | 10 | 7 |
| 2025 | 5 | 2 |
| 2026 | 5 | 2 |
Library tests named most
Largest condition groups
Phases
Participants
Lead sponsor: industry 17, NIH 3, other 82. Interventional 83, observational 19.
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 |
|---|---|---|---|---|---|---|---|
| NCT07854093 | Start2026 | PhaseObservational | ConditionsEpilepsy | Participants40 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07680842 | Start2025 | PhaseNot applicable | ConditionsEpilepsy | Participants40 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07580183 | Start2024 | PhaseNot applicable | ConditionsDelirium, surgery and intensive care, Epilepsy | Participants620 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT07520955 | Start2026 | PhaseNot applicable | ConditionsEpilepsy | Participants24 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07373431 | Start2020 | PhaseNot applicable | ConditionsAutism, Epilepsy | Participants50 | Lead sponsorOther | StatusCompleted | Library tests named
|
| NCT07228338 | Start2026 | PhaseEarly phase 1 | ConditionsMild cognitive impairment, Epilepsy | Participants50 | Lead sponsorOther | StatusNot yet recruiting | Library tests named
|
| NCT07193277 | Start2025 | PhasePhase 4 | ConditionsEpilepsy | Participants220 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT06940089 | Start2025 | PhaseNot applicable | ConditionsADHD, Epilepsy | ParticipantsNot given | Lead sponsorOther | StatusStopped early | Library tests named
|
| NCT06769659 | Start2025 | PhasePhase 2 | ConditionsEpilepsy | Participants14 | Lead sponsorIndustry | StatusCompleted | Library tests named
|
| NCT06754124 | Start2024 | PhaseNot applicable | ConditionsDepression and bipolar disorder, Sleep and sleep disorders, Epilepsy | Participants30 | Lead sponsorOther | StatusCompleted | Library tests named
|
| NCT06681480 | Start2022 | PhaseNot applicable | ConditionsEpilepsy | Participants20 | Lead sponsorOther | StatusActive, not recruiting | Library tests named
|
| NCT06647056 | Start2024 | PhaseNot applicable | ConditionsEpilepsy | Participants4 | Lead sponsorOther | StatusCompleted | Library tests named
|
| NCT06608966 | Start2024 | PhaseNot applicable | ConditionsEpilepsy | Participants310 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT06600594 | Start2022 | PhaseNot applicable | ConditionsEpilepsy | Participants81 | Lead sponsorOther | StatusStatus unknown | Library tests named
|
| NCT06570954 | Start2025 | PhaseNot applicable | ConditionsEpilepsy | Participants50 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT06537986 | Start2022 | PhaseNot applicable | ConditionsEpilepsy | Participants60 | Lead sponsorOther | StatusStatus unknown | Library tests named
|
| NCT06500260 | Start2022 | PhaseObservational | ConditionsEpilepsy | Participants20 | Lead sponsorOther | StatusActive, not recruiting | Library tests named
|
| NCT06424977 | Start2026 | PhaseNot applicable | ConditionsEpilepsy | Participants40 | Lead sponsorIndustry | StatusNot yet recruiting | Library tests named
|
| NCT06376370 | Start2024 | PhaseNot applicable | ConditionsEpilepsy | Participants50 | Lead sponsorOther | StatusStatus unknown | Library tests named
|
| NCT06353620 | Start2024 | PhaseObservational | ConditionsEpilepsy | Participants120 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT06334029 | Start2023 | PhaseObservational | ConditionsEpilepsy | Participants150 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT06252532 | Start2024 | PhaseNot applicable | ConditionsEpilepsy | Participants50 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT06241963 | Start2024 | PhaseNot applicable | ConditionsEpilepsy | Participants90 | Lead sponsorOther | StatusStatus unknown | Library tests named
|
| NCT06210022 | Start2024 | PhaseObservational | ConditionsEpilepsy | Participants130 | Lead sponsorOther | StatusRecruiting | Library tests named
|
| NCT06052605 | Start2026 | PhaseNot applicable | ConditionsEpilepsy | Participants380 | Lead sponsorOther | StatusRecruiting | Library tests named
|
Questions, answered from the data
Which cognitive test do epilepsy trials use most?
Verbal Learning: 25 of the 138 registered studies name it in an outcome measure, 18%. Next come Verbal Fluency (17) and the Digit Span Test (15).
Which cognitive test do epilepsy trials use most as a primary outcome?
Verbal Learning, named in a primary outcome by 9 studies. 57 of the 138 studies, 41%, name a cognitive test in a primary outcome.
How many participants does a phase 2 epilepsy trial enroll?
Half of the phase 2 epilepsy studies enroll 32 participants or fewer, and the middle half enroll 14 to 79. 10 of them give a size.
How long after the start do epilepsy trials measure a cognitive outcome?
Half of the primary outcomes that name a library test are measured within 10 weeks of the start, and the middle half from 5 days to 6 months. 71 primary outcomes give a duration.
Which cognitive tests do epilepsy trials use together?
The Trail Making Test with Verbal Learning most often: 8 studies name both. Next, the Digit Span Test with Verbal Fluency (7).
How many completed epilepsy trials have reported results?
22 of the 44 completed epilepsy studies, 50%, have reported results: 15 posted them on ClinicalTrials.gov, 17 have a results paper linked to the registry record, and 10 did both. The other 22 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 epilepsy trial
Choose tests with a record in registered trials, and run them in a browser at every site, on the same version each visit.