Phase IPhase 1NCT07818564
Pilot Study on the Effects of Psilocybin on Belief Updating and Insight Formation
A Phase 1 study testing Psilocybin (Usona Institute) in people with Phase I, run by Brown University at 1 site in United States.
Trial summary
The primary aim of this phase I mechanistic pilot study is to evaluate the effects of psilocybin on aspects of cognition in healthy adult volunteers. Up to 24 participants will receive a single dose of either psilocybin or inert placebo, and they will be asked to complete several computer-based behavioral tasks… Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Phase I
- What is being tested?
- Psilocybin (Usona Institute)
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 24 participants
- Where
- 1 siteUnited States
- Study dates
- Nov 2026to Nov 2027
- Phase
- Phase 1
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- be at least 18 years old at time of signing informed consent
- be fluent in speaking and reading English
- be able to swallow pills (capsules)
- agree to use highly effective birth control for at least one month prior to enrollment, and for the duration of study enrollment, whether male or female assigned at birth. Acceptable methods include: copper or hormonal coil intrauterine device (IUD), implanted or injected hormonal method, documented permanent sterilization, documented not able to become pregnant, or oral/intravaginal/transdermal hormones plus a barrier contraception. Two forms of contraception are required with any barrier method or with any oral, intravaginal, or transdermal hormonal method due to these methods not being considered highly effective alone. Abstinence alone is not an acceptable contraceptive method for this study.
- be healthy and psychologically stable as determined by screening for medical and psychiatric problems via a clinical interview, a medical questionnaire, a physical examination, an electrocardiogram (ECG), and routine laboratory tests
- agree to inform investigators within 48 hours of any new medical conditions, treatments, or procedures
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- agree to refrain from using any psychoactive or recreational drugs, including cannabis, for the duration of study enrollment (with the exception of limited alcohol, nicotine, and caffeine as below)
- agree to refrain from drinking alcohol within 24 hours of all experimental sessions
- agree to consume approximately the same amount of caffeine and nicotine as on a usual day before experimental sessions, but to not consume any nicotine or caffeine closer than 1 hour prior to the scheduled dosing time. If the participant does not routinely consume caffeine or nicotine, they must agree not to do so for the duration of the study.
- agree to refrain from taking any "as needed" or "over the counter" medications (e.g., medications for pain, insomnia, or allergies) within 24 hours of all experimental sessions, unless previously approved by a study physician
- agree to store their phone and car keys in a locked storage locker for the duration of the experimental dosing session, and agree to stay on site for at least 6 hours after drug administration and until a physician agrees they are safe to leave the premises
- be able to identify two trusted support people (e.g. friend or family member, at least age 18 years of age), who are willing and able to serve as an emergency contact, and to pick the participant up and transport them home after the dosing session. One of these will be designated the primary support person, and the second will be backup to pick the person up in the event that the primary becomes unavailable.
- agree to not drive a motor vehicle or heavy machinery for 24 hours after the dosing session
- have used a classical psychedelic (5-HT2A agonist, such as psilocybin, LSD, DMT, 5-MeO-DMT, ayahuasca, mescaline) at least once in lifetime without clinically significant adverse effects
Who cannot join
- have used any psychedelic, hallucinogen, or entactogen, including 3,4-methylenedioxymethamphetamine (MDMA) and ketamine/esketamine, but not including cannabis, within the past 3 months
- unwilling or unable to stop using cannabis a minimum of one week prior to enrollment and to refrain from cannabis use for the duration of the study enrollment, to be tested with urine drug screens
- currently pregnant (as indicated by a positive urine pregnancy test assessed at intake and before the drug session), nursing, intending to become pregnant within 3 months of enrollment, intending to father a child within 3 months of enrollment, intending to donate sperm or eggs within 3 months of enrollment, or not practicing a highly effective means of birth control as noted in the Inclusion Criteria.
- history of traumatic brain injury, or history of seizure disorder in adulthood
- history of any clinically significant cardiovascular condition, or condition that could make receiving the study drug harmful because of increases in blood pressure and heart rate. This includes, but is not limited to, uncontrolled hypertension, coronary artery disease, heart failure, stroke, myocardial infarction, artificial heart valve, aneurism, or clinically significant arrhythmia. Uncontrolled hypertension is defined here as repeated blood pressure readings of >= 140 mmHg systolic or >= 90 mmHg diastolic.
- baseline QTc > 450 milliseconds (QTc is defined as the QT interval corrected for heart rate, either machine-read or manually over-read)
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- current poorly controlled or insulin dependent diabetes mellitus (type I or type II)
- current clinically significant respiratory condition (supplemental oxygen requirement, or requiring hospitalization within the last year)
- current clinically significant liver or biliary disease, including recent laboratory abnormalities (AST or ALT > 3x institutional upper limit of normal (ULN); total bilirubin > 1.5 x ULN or direct bilirubin < 35%), or based on the presence of ascites, encephalopathy, jaundice, esophageal varices, or coagulopathy
- clinically significant renal disease, including but not limited to CKD stage 3 or greater
- history of ever meeting Diagnostic and Statistical Manual, version 5 (DSM-5) criteria for any schizophrenia spectrum disorder, bipolar spectrum disorder, major depressive disorder with psychotic features, or any other psychotic disorder, including substance-induced psychotic disorders ever in lifetime
- have a first or second-degree relative with history of schizophrenia spectrum disorder, bipolar spectrum disorder, major depressive disorder with psychotic features, or other psychotic disorder including substance-induced psychotic disorders ever in lifetime
- clinically significant suicide risk, as determined by clinician judgment and the C-SSRS. Participants will be excluded if any current active suicidal ideation, including intent to kill oneself or preparatory behavior, or a lifetime history of suicide attempts including aborted or interrupted.
- history within last 5 years of inpatient psychiatric hospitalization for any reason
- lifetime history of hallucinogen persisting perception disorder
- current or history within the last 1 year of meeting DSM-5 criteria for an alcohol or substance use disorder, excluding caffeine and nicotine; or a lifetime history of hallucinogen use disorder
- a positive urine drug screen or alcohol breathalyzer test result on any study visit, or unwillingness to provide these tests
- history of antisocial personality disorder, borderline personality disorder, or narcissistic personality disorder
- taking a primary psychoactive medication on a regular basis within 3 months of study participation, including but not limited to antidepressants (SSRIs, SNRIs, NDRIs, MAOIs, TCAs), antipsychotics, mood stabilizers, anxiolytics, stimulants, or sedative-hypnotics
- current clinically significant episode of any other psychiatric disorder, including but not limited to a current episode of major depressive disorder, anxiety disorder, trauma- or stressor-related disorder, obsessive-compulsive disorder, neurodevelopmental disorder, and personality disorder that is not in full remission
- any other current problem which, in the opinion of study clinicians, might pose an unacceptable risk to participant or staff safety and/or significantly interfere with study participation
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Brown University School of Public Health
Providence, Rhode Island, 02903
Eric A. Miller, M.D., (401) 903-0752, eric_miller@brown.edu
About this study
The primary aim of this phase I mechanistic pilot study is to evaluate the effects of psilocybin on aspects of cognition in healthy adult volunteers. Up to 24 participants will receive a single dose of either psilocybin or inert placebo, and they will be asked to complete several computer-based behavioral tasks measuring features of learning, belief updating, and abstraction. Participants will also complete measures of subjective experience and expectancy, as well as semi-structured interviews at follow up, to assess whether experience correlates with behavior. This is a Voluntary Submission.
- Conditions
- Phase I
- Being tested
- Psilocybin (Usona Institute), Inactive Placebo (Usona Institute)
- Keywords
- psilocybin, psychedelic, cognition, learning, healthy volunteers
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Psilocybin (Usona Institute)Drug
1 dose of psilocybin 25 mg oral capsule
Inactive Placebo (Usona Institute)Drug
1 dose of Microcrystalline Cellulose (MCC) 25 mg capsule
| Study group | Role | What they receive |
|---|---|---|
| Psilocybin | Experimental | Psilocybin 25 mg oral capsule Receives: Drug: Psilocybin (Usona Institute) |
| Inert Placebo | Placebo comparator | Microcrystalline cellulose 25 mg oral capsule Receives: Drug: Inactive Placebo (Usona Institute) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Reinforcement Learning and Abstraction Task
Custom computer-based behavioral task requiring participants to complete a series of puzzles to complete game levels. This task requires working memory and reinforcement learning, and it also includes a measure of state abstraction.
Measured: During dosing session and 1 day after the dosing session
Belief Updating Task
Custom computer-based behavioral task in which participants must dynamically adjust predictions on each trial. This task measures trial to trial belief updating.
Measured: 1 day before dosing, during dosing, and 1 day after the dosing session
Secondary outcomes (18)
Altered States of Consciousness Questionnaire (ASC)
Measure of subjective experience.
Measured: During dosing session
Mystical Experience Questionnaire (MEQ)
Measure of mystical type experiences
Measured: During dosing session
Psychological Insight Questionnaire (PIQ)
Measure of psychological insight
Measured: During dosing session
Emotional Breakthrough Inventory (EBI)
Measure of emotional breakthrough
Measured: During dosing session
Challenging Experience Questionnaire (CEQ)
Measure of challenging subjective experiences
Measured: During dosing session
Warwick-Edinburgh Mental Wellbeing Scale (WEMWBS)
Measure of general wellbeing
Measured: 1 day before dosing, 1 day after dosing, and 1 week after dosing
Clinician Administered Dissociative States Scale (CADSS)
Measure of dissociative experiences
Measured: 1 day before dosing, during dosing, 1 day after dosing, 3 days after dosing, and 1 week after dosing
Barcelona Music Reward Questionnaire (BMRQ)
Measure of music reward experiences
Measured: From baseline to 1 week after dosing
Geneva Emotional Music Scale, 9-item version (GEMS-9)
Measure of music experiences
Measured: During dosing session, 1 day after dosing
Modified Stanford Expectations of Treatment Scale (SETS)
Measure of expectancy about psychological changes from psilocybin
Measured: 1 day before dosing session
Bang Blinding Index
Measure of blinding integrity
Measured: 1 day after dosing
Custom Rapport Questions
Measure of rapport with study team
Measured: 1 day after dosing
Subjective intensity and valence
Periodic measurements of subjective intensity and valence
Measured: During dosing session
Subjective insight
Participant-triggered measurements of subjective insight experiences
Measured: During dosing session
Semi-structured interviews
Brief semi-structured interviews exploring several pre-specified themes, including tolerability, changes in cognition, subjective insight experiences, experience of music, and other subjective experiences from the dosing session.
Measured: 1 day after dosing session
Columbia Suicide Severity Rating Scale (C-SSRS)
Measure of suicidal ideation during every study visit
Measured: From baseline to 1 week after dosing
Incidence of Adverse Events
Monitoring for adverse events, including misuse monitoring
Measured: From baseline to 1 week follow up
Feasibility and Acceptability
Percentage of full study completion; percentage of tasks and questionnaires completed per participant; semi-structured interview questions to assess tolerability of the study procedures
Measured: From baseline to 1 week after dosing
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Sep 2026
- Study startNov 2026 (estimated)
- Primary completionNov 2027 (estimated)
- Study completionNov 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for Phase IStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 1
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 24 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Brown University
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07818564
- Sponsor's protocol ID
- STUDY00001310
- Status last verified
- Oct 2026
- First submitted
- 8 Sep 2026
- Last updated
- 8 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Publications
Lehnert L, Littman ML, Frank MJ. Reward-predictive representations generalize across tasks in reinforcement learning. PLoS Comput Biol. 2020 Oct 15;16(10):e1008317. doi: 10.1371/journal.pcbi.1008317. eCollection 2020 Oct.
PubMed 33057329Nassar MR, Wilson RC, Heasly B, Gold JI. An approximately Bayesian delta-rule model explains the dynamics of belief updating in a changing environment. J Neurosci. 2010 Sep 15;30(37):12366-78. doi: 10.1523/JNEUROSCI.0822-10.2010.
PubMed 20844132