Clinical trials data
Cognitive outcomes in clinical trials, 2026
The year's figures on cognitive tests in registered clinical trials, from every study on ClinicalTrials.gov that names a cognitive test in an outcome measure, read on 8 November 2026. Each finding links to the page with its chart and data.
- Registered studies name a cognitive test in an outcome measure
- 16,302
- Name one in a primary outcome
- 6,763
- Countries with a study site
- 131
Findings
- 1
The Trail Making Test is the cognitive test trials name most
2,293 of the 16,302 registered studies name it in an outcome measure, 14%. Next come the Stroop Color-Word Test (1,929) and Verbal Learning (1,832).
Trail Making Test in clinical trials - 2
The Stroop Color-Word Test leads as a primary outcome
785 studies name it in a primary outcome. Of all 16,302 studies, 6,763 (41%) name a cognitive test in a primary outcome.
Stroop Color-Word Test in clinical trials - 3
The Trail Making Test and Verbal Fluency go together most
728 studies name both. 3,496 of the 11,627 studies that name a library test name three or more: trials measure cognition with a set of tests.
Tests by condition - 4
The Attention Network Test is rising fastest
Its share of new studies is 50% larger for studies started in 2021 to 2025 than in 2016 to 2020. The Letter-Number Sequencing Task fell most, by 55%.
Rising and falling tests - 5
Phase 2 trials enroll a median of 60 participants
The middle half enroll 33 to 120. Phase 3 trials enroll a median of 246, the middle half 83 to 669.
Benchmark a trial design - 6
Half of primary cognitive outcomes are measured within 8 weeks
Half of the primary outcomes that name a library test are measured within 8 weeks of the start, and the middle half from 1 week to 6 months. 9,262 primary outcomes give a duration.
When trials measure the outcome - 7
55% of completed studies show no results
Of the 7,916 completed studies, 3,601 have reported results: 1,895 posted them on ClinicalTrials.gov and 2,477 have a results paper the registry links to. The other 4,315 show neither, though a paper that never gives the study's NCT number is missed. 3,010 studies are recruiting.
Reported results - 8
Trials with a cognitive outcome run in 131 countries
5,496 studies have sites in the United States, 1,347 in China and 1,058 in France.
Where the trials run - 9
Dementia and Alzheimer's has the most trials with a cognitive outcome
1,673 registered studies, then aging, frailty and exercise (1,397) and depression and bipolar disorder (1,247).
Every condition - 10
Industry leads 1,631 of the studies
In a primary outcome, industry-led studies name Symbol Coding most (60), then Verbal Learning (41) and Verbal Fluency (39).
What industry trials use
Cite this page
ConductCognition. Cognitive outcomes in clinical trials, 2026. Data release 2.0.0, ClinicalTrials.gov read 8 November 2026. https://conductcognition.com/data/clinical-trials/cognitive-outcomes-2026
The figures come from the same study lines as the rest of the clinical trials section, and every study line is in the data release.
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 8 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 a trial's cognitive outcomes
Choose tests with a record in registered trials, and run them in a browser at every site, on the same version each visit.