Perception DisordersPhase 1NCT05265546
Investigating the Mechanisms of the Effects of Psilocybin on Visual Perception and Visual Representations in the Brain
A Phase 1 study testing Psilocybin in people with Perception Disorders, run by University of California, Berkeley at 1 site in United States.
Trial summary
The long-term objective of this project is to characterize how psilocybin affects visual perception and the brain's representation of the visual environment. It is known that psilocybin alters aspects of visual perception, but the underlying brain mechanisms contributing to these effects are poorly understood. Read more about this study
- Who is it for?
- Ages 21 years and olderHealthy volunteers can take part
- Conditions the study is for
- Perception Disorders
- What is being tested?
- Psilocybin
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 80 participants
- Where
- 1 siteUnited States
- Study dates
- 8 Mar 2024to 31 Dec 2028
- Phase
- Phase 1
- Are there results?
- Not yet: the study is under way
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 21 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Are ≥21 years of age at time of Informed Consent Form signing
- Are able and willing to adhere to study requirements, including attending all study visits, preparatory and follow-up sessions, and completing all study evaluations.
- Are able to swallow capsules.
- Women of childbearing potential (WOCBP) must agree to practice an effective means of birth control throughout the duration of the study.
- Written informed consent obtained from and ability for subject to comply with the requirements of the study.
- Have an identified support person and agree to be accompanied home (or to an otherwise safe destination) by the support person, or another responsible party, following dosing.
- Agree to inform the investigators within 48 hours of any new or changed medical conditions during the course of their study participation.
Who cannot join
- Breastfeeding, have a positive pregnancy test at screening or at any point during the course of the study, or unwilling to practice birth control during participation in the study.
- Have a current psychiatric disorder, general medical condition, or other problem or abnormality that, in the opinion of the study clinician or PI, could compromise safety, render them unsuitable for the study, or would make them unable to comply with study activities.
- Have MRI contraindications (e.g., metal implants, pacemakers, claustrophobia etc.) as determined by an MRI contraindications questionnaire.
- Uncontrolled hypertension (Systolic BP>139mmHG or Diastolic BP>89mmHG) or tachycardia (average HR>90bpm) averaged over at least two measurements.
- Clinically significant cardiovascular disease (e.g., history of myocardial infarction or congestive heart failure); or baseline QT/QTc>500msec; or baseline QT/QTc 451-500msec with repeat QT/QTc >500msec.
- Inadequate hepatic function as determined by total bilirubin or alkaline phosphatase >3x institutional upper limit of normal; or AST or ALT >6x institutional upper limit of normal. However, participants with Gilbert syndrome are allowed to enroll.
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- Inadequate renal function as determined by eGFR < 30 mL/min/1.73 m2 (based on the MDRD equation) or CrCl < 30 mL/min (based on the C-G equation).
- The regular use of psychotropic medications, such as antidepressants (i.e., SSRIs, tricyclic antidepressants, and monoamine oxidase inhibitors), antipsychotics, and mood stabilizers.
- Concomitant dosing of psilocybin with known UGT1A10 and UGT1A9 inhibitors (e.g., diclofenac and probenecid) will be avoided. [There is no exclusion criterion based on the use of medications or substances that are inhibitors or inducers of CYP450 enzymes.]
- The use of Prohibited Medications:
- Serotonin Reuptake Inhibitors (SSRIs and SNRIs) Tricyclic Antidepressants (TCAs) Monoamine Oxidase Inhibitors (MAOIs) Atypical antidepressants (e.g., mirtazapine, trazodone, buspar) Antipsychotics/Neuroleptics (typical and atypical) Anti-epileptics or mood stabilizers (e.g., lithium, valproate) (does not include gabapentin used for non-epilepsy conditions) Efavirenz (Sustiva, in Atripla) Lorcaserin Over-the-counter supplements intended to affect mood or anxiety (e.g., 5HT-P, SAMe or St. John's Wort).
- Other drugs associated with the serotonin syndrome (e.g., ondansetron) used within 48 hours of study drug administration (70).
- Vasoactive drugs (e.g., sildenafil, sumatriptan, calcium channel blockers) used within 48 hours of study drug administration.
- Unable to agree to the following required Lifestyle Modifications: Patients will be asked to refrain from consuming alcohol, cannabinoids, prescription analgesics/stimulants/benzodiazepines, and any recreational drugs for 48 hours before, the day of, and for 48 hours after study drug administration. Participants will be advised to consume their usual amount of coffee, tea, or other caffeine-containing beverages on the morning of their Medication Visits.
- Have a recent history of suicidal ideation or attempted suicide that, in the opinion of the study clinician or PI, may present a risk of suicidal or self-injurious behavior.
- Have received an investigational drug or taken a psychedelic within 30 days of the screening visit.
- Have an allergy or intolerance to any of the materials contained in the investigational drug product.
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
University of California, Berkeley
Berkeley, California, 94720
BCSP Research Staff, (415) 874-1308, BCSPresearchsubjects@berkeley.edu
About this study
The long-term objective of this project is to characterize how psilocybin affects visual perception and the brain's representation of the visual environment. It is known that psilocybin alters aspects of visual perception, but the underlying brain mechanisms contributing to these effects are poorly understood. The proposed work will address these questions in a large, diverse sample of healthy human subjects by using functional magnetic resonance imaging (fMRI) to measure the brain's responses to visual stimuli. The proposed research will document which brain areas mediate the effects of psilocybin. The technique of fMRI will be employed to measure brain activity in different brain areas while subjects are performing a visual perceptual task.
- Conditions
- Perception Disorders
- Being tested
- Psilocybin
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
PsilocybinDrug
The effects of different doses of psilocybin (0 - 14 mg) will be compared.
| Study group | Role | What they receive |
|---|---|---|
| Experimental | Experimental | Psilocybin 0-14 mg, before fMRI measurement Receives: Drug: Psilocybin |
| Comparator | Other | Psilocybin 0-14 mg, before fMRI measurement Receives: Drug: Psilocybin |
What is being measured
The primary outcome is the main question the study is designed to answer.
Amplitude and pattern of fMRI cortical responses
Functional magnetic resonance imaging (fMRI) responses to visual stimuli will be recorded.
Measured: Functional MRI recordings will begin approximately 30 minutes after oral administration of experimental or comparator arm treatment and will continue for up to two hours.
Secondary outcomes (3)
Perceptual measurements
Within-subject inferential statistical testing will be used to assess the effects of doses of psilocybin (0-14 mg) on participants' abilities to update prior expectations based on new information. Specifically, paired t-tests will be used to contrast perceptual measures collected at MRI scan sessions.
Measured: Statistical tests will be performed after all data collection is complete.
Voxelwise modeling
Voxelwise modeling results will be quantified by measuring the amount of variance in fMRI responses to presentation of stimuli that is accounted for by the model in each voxel. Cross-validation using held-out data will be used to assess possible overfitting and to facilitate unbiased interpretations. Model weights associated with each parameter will be contrasted between the effects of doses of psilocybin (0-14 mg) and quantified for individual brain areas using paired t-tests and appropriate corrections for multiple comparisons.
Measured: Modeling of fMRI data will be performed within subjects after experiment data collection is complete.
Participant-reported Subjective Effects
Within-subject inferential statistical testing will be used to assess the effects of doses of psilocybin (0 - 14 mg) on subjective effects. Specifically, paired t-tests and between-group effect sizes with 95% confidence intervals will be used to contrast patient-reported outcomes (MEQ-30, ChEQ, 11D-ASC and POMS-SF), corrected for multiple comparisons.
Measured: Statistical tests will be performed after all data collection is complete.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Mar 2022
- Study start8 Mar 2024
- Primary completion31 Dec 2028 (estimated)
- Study completion31 Dec 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Perception DisordersStudies 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
- Crossover
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 80 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of California, Berkeley
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05265546
- Sponsor's protocol ID
- 2021-11-14799
- Status last verified
- Jul 2026
- First submitted
- 22 Feb 2022
- Last updated
- 10 Jul 2026
- Results posted
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 10 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Investigating the Mechanisms of the Effects of Psilocybin on Visual Perception and Visual Representations in the Brain
- ClinicalTrials.gov ID
- NCT05265546
- Acronym / sponsor ID
- 2021-11-14799
- Conditions
- Perception Disorders
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 80 participants (estimated)
- Lead sponsor
- University of California, BerkeleyUniversity, hospital or other
- Study start
- 8 Mar 2024 (actual)
- Primary completion
- 31 Dec 2028 (estimated)
- Study completion
- 31 Dec 2028 (estimated)
- First posted
- 3 Mar 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The long-term objective of this project is to characterize how psilocybin affects visual perception and the brain's representation of the visual environment. It is known that psilocybin alters aspects of visual perception, but the underlying brain mechanisms contributing to these effects are poorly understood. The proposed work will address these questions in a large, diverse sample of healthy human subjects by using functional magnetic resonance imaging (fMRI) to measure the brain's responses to visual stimuli. The proposed research will document which brain areas mediate the effects of psilocybin. The technique of fMRI will be employed to measure brain activity in different brain areas while subjects are performing a visual perceptual task.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Experimental | Experimental | Drug: PsilocybinPsilocybin 0-14 mg, before fMRI measurement |
| Comparator | Other | Drug: PsilocybinPsilocybin 0-14 mg, before fMRI measurement |
Who may qualify
- Ages
- 21 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- Are ≥21 years of age at time of Informed Consent Form signing
- Are able and willing to adhere to study requirements, including attending all study visits, preparatory and follow-up sessions, and completing all study evaluations.
- Are able to swallow capsules.
- Women of childbearing potential (WOCBP) must agree to practice an effective means of birth control throughout the duration of the study.
- Written informed consent obtained from and ability for subject to comply with the requirements of the study.
Key exclusion criteria (17 listed)
- Breastfeeding, have a positive pregnancy test at screening or at any point during the course of the study, or unwilling to practice birth control during participation in the study.
- Have a current psychiatric disorder, general medical condition, or other problem or abnormality that, in the opinion of the study clinician or PI, could compromise safety, render them unsuitable for the study, or would make them unable to comply with study activities.
- Have MRI contraindications (e.g., metal implants, pacemakers, claustrophobia etc.) as determined by an MRI contraindications questionnaire.
- Uncontrolled hypertension (Systolic BP>139mmHG or Diastolic BP>89mmHG) or tachycardia (average HR>90bpm) averaged over at least two measurements.
- Clinically significant cardiovascular disease (e.g., history of myocardial infarction or congestive heart failure); or baseline QT/QTc>500msec; or baseline QT/QTc 451-500msec with repeat QT/QTc >500msec.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| PsilocybinThe effects of different doses of psilocybin (0 - 14 mg) will be compared. | Drug | Comparator, Experimental |
Primary outcome
Amplitude and pattern of fMRI cortical responses
Time frame: Functional MRI recordings will begin approximately 30 minutes after oral administration of experimental or comparator arm treatment and will continue for up to two hours.
Functional magnetic resonance imaging (fMRI) responses to visual stimuli will be recorded.
3 secondary outcomes
Perceptual measurements
Time frame: Statistical tests will be performed after all data collection is complete.
Voxelwise modeling
Time frame: Modeling of fMRI data will be performed within subjects after experiment data collection is complete.
Participant-reported Subjective Effects
Time frame: Statistical tests will be performed after all data collection is complete.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 10 Jul 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing Psilocybin in people with Perception Disorders, run by University of California, Berkeley at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 17 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 10 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact BCSP Staff ((669) 244-2436, bcspresearchsubjects@berkeley.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Amplitude and pattern of fMRI cortical responses (time frame: Functional MRI recordings will begin approximately 30 minutes after oral administration of experimental or comparator arm treatment and will continue for up to two hours.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 10 Jul 2026.