Psychedelic ExperiencesPhase 1i2NCT05698511
Neural and Physiological Correlates of Psychedelic Sub-states
A Phase 1 study testing Psilocybin in people with Psychedelic Experiences and Neuroimaging, run by Robin Carhart-Harris, PhD, MA at 1 site in United States.
Trial summary
The main purpose of this study is to gain a better understanding of the distinct mental states and physical reactions that can arise during a psychedelic experience. By repeatedly assessing the same participants in an MRI while under the effects of psilocybin, the investigators want to identify reliable brain and body… Read more about this study
- Who is it for?
- Ages 21 to 70 yearsHealthy volunteers can take part
- Conditions the study is for
- Psychedelic Experiences, Neuroimaging, Healthy Volunteers
- What is being tested?
- Psilocybin
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 12 participants
- Where
- 1 siteUnited States
- Study dates
- 31 Jul 2023to 30 Jan 2027
- 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 to 70 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Have had previous experiences with psychedelic substances
- Mentally and physically healthy
- Have had prior experiences with MRI machines (optional but preferred)
- Flexible schedule- able to commit to scans once or twice per week for 4 weeks in a row
- Are between 21 and 70 years of age
- Are fluent in speaking and reading English
Show all 11Show fewer
- Can swallow pills/capsules
- If able to become pregnant, must be non-lactating, have a negative pregnancy test at study entry and prior to each Experimental Session and must agree to an adequate form of birth control and contraception over the course of the study. Adequate forms of birth control or contraception include intrauterine device (IUD), injected, implanted, intravaginal, or transdermal hormonal methods, abstinence, oral hormones plus a barrier contraception, vasectomized sole partner, or double barrier contraception. Two forms of contraception are required with any barrier method or oral hormones (i.e. condom plus diaphragm, condom or diaphragm plus spermicide, oral hormonal contraceptives plus spermicide or condom). Not of childbearing potential is defined as documented hysterectomy, bilateral salpingectomy, bilateral oophorectomy, and/or tubal ligation), permanently sterile by medical device such as Essure, postmenopausal, or male by birth. Contraception applies to males as well as females and male participants must not be planning sperm donation within the study period.
- Able and willing to provide informed consent
- Able and willing to use computers and tablets or phones to enter electronic data
- Agree to inform the investigators within 48 hours of any new or changed medical conditions.
Who cannot join
None listed.
Trial locations and contacts
1 site in 1 country.
United States1 site
University of California, San Francisco
San Francisco, California, 94158
About this study
Official title: Multivariate Neural and Physiological Correlates of Psychedelic Sub-states: a Within-subjects, Healthy Volunteer Study With Experience-sampling
The main purpose of this study is to gain a better understanding of the distinct mental states and physical reactions that can arise during a psychedelic experience. By repeatedly assessing the same participants in an MRI while under the effects of psilocybin, the investigators want to identify reliable brain and body reactions arising during these psychedelic experiences. It is hoped that this will provide an insight to inspire future research on psilocybin and related psychedelics as well as inform on their therapeutic action. This study will involve up to 12 healthy volunteers with previous psychedelic experience. Participants in this study will be given four doses of psilocybin, with breaks of at least seven days in between dosing visits. The first dosing visit will feature a 10 mg dose of psilocybin, which can be considerate a low to moderate dose, whereas the remaining three dosing visits will feature 25 mg psilocybin, a high dose that is consistent with the dosage chosen for several modern clinical trials with psilocybin. From the initial in-person screening visit to the final follow-up, participants will be in this study for approximately 6-12 weeks and visit the research site 5 times. The first visit will be an in-person screening visit, during which the investigators will assess participants' eligibility to be enrolled. There will be 4 subsequent visits to the scan center for dosing and magnetic resonance imaging (MRI) scanning, and there will be a final remote follow up. Each of the four dosing visits will include four periods of lying within the MRI scanner for scanning, each of these 'in-scanner' sessions will last for ~ 45 minutes. Actual scans, which are also called 'runs' last for ~ 12 mins. During these 'runs', the investigators will ask participants two brief questions about how positive or negative their current experience is every 100 seconds. They will be able to record their answers using a button box which they will be operating with their hand. One day after each dosing visit, the investigators will schedule a phone call with the participant to check how they are doing and perform an informal interview focused on their experience while under the effects of psilocybin.
- Conditions
- Psychedelic Experiences, Neuroimaging, Healthy Volunteers
- Being tested
- Psilocybin
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
PsilocybinDrug
Multiple dosing of healthy volunteers with up to 25 mg psilocybin separated from each other by at least one week. Participants will be scanned before and after receiving psilocybin on each dosing day. Surveys will be performed on dosing days and after dosing.
| Study group | Role | What they receive |
|---|---|---|
| Psilocybin | Experimental | Healthy volunteers will receive up to four doses of psilocybin separated from each other by at least one week. The first dosing session will involve 10 mg psilocybin, the remaining three dosing sessions will receive up to 25mg psilocybin. Receives: Drug: Psilocybin |
What is being measured
The primary outcome is the main question the study is designed to answer.
Brain-averaged normalized global signal complexity
Signal complexity of brain activity derived from resting-state fMRI
Measured: Peak effects (120 min post dosing) vs pre-dose
Secondary outcomes (2)
EEG-derived signal complexity of brain activity
Measure of brain complexity derived from EEG
Measured: Peak effects (120 min post-dose) vs pre-dose fMRI runs
Psychological insight
Measure of psychological insight
Measured: Peak effects (120-min post-dose) vs predose
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted26 Jan 2023
- Study start31 Jul 2023
- Primary completion30 Jan 2026
- Study completion30 Jan 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Psychedelic ExperiencesStudies 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
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 12 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Robin Carhart-Harris, PhD, MA
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor-investigator, Robin Carhart-Harris, PhD, MA, University of California, San Francisco
- Investigators
- Robin Carhart-Harris, PhD, Principal investigator, University of California, San Francisco
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05698511
- Sponsor's protocol ID
- 21-35696
- Other IDs
- 157762
- Acronym
- i2
- Status last verified
- Mar 2026
- First submitted
- 13 Dec 2022
- Last updated
- 5 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 5 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Multivariate Neural and Physiological Correlates of Psychedelic Sub-states: a Within-subjects, Healthy Volunteer Study With Experience-sampling
- ClinicalTrials.gov ID
- NCT05698511
- Acronym / sponsor ID
- i2 / 21-35696
- Conditions
- Psychedelic Experiences, Neuroimaging, Healthy Volunteers
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 12 participants (estimated)
- Lead sponsor
- Robin Carhart-Harris, PhD, MAUniversity, hospital or other
- Study start
- 31 Jul 2023 (actual)
- Primary completion
- 30 Jan 2026 (actual)
- Study completion
- 30 Jan 2027 (estimated)
- First posted
- 26 Jan 2023 (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 main purpose of this study is to gain a better understanding of the distinct mental states and physical reactions that can arise during a psychedelic experience. By repeatedly assessing the same participants in an MRI while under the effects of psilocybin, the investigators want to identify reliable brain and body reactions arising during these psychedelic experiences. It is hoped that this will provide an insight to inspire future research on psilocybin and related psychedelics as well as inform on their therapeutic action. This study will involve up to 12 healthy volunteers with previous psychedelic experience. Participants in this study will be given four doses of psilocybin, with breaks of at least seven days in between dosing visits. The first dosing visit will feature a 10 mg dose of psilocybin, which can be considerate a low to moderate dose, whereas the remaining three dosing visits will feature 25 mg psilocybin, a high dose that is consistent with the dosage chosen for several modern clinical trials with psilocybin. From the initial in-person screening visit to the final follow-up, participants will be in this study for approximately 6-12 weeks and visit the research site 5 times. The first visit will be an in-person screening visit, during which the investigators will assess participants' eligibility to be enrolled. There will be 4 subsequent visits to the scan center for dosing and magnetic resonance imaging (MRI) scanning, and there will be a final remote follow up. Each of the four dosing visits will include four periods of lying within the MRI scanner for scanning, each of these 'in-scanner' sessions will last for ~ 45 minutes. Actual scans, which are also called 'runs' last for ~ 12 mins. During these 'runs', the investigators will ask participants two brief questions about how positive or negative their current experience is every 100 seconds. They will be able to record their answers using a button box which they will be operating with their hand. One day after each dosing visit, the investigators will schedule a phone call with the participant to check how they are doing and perform an informal interview focused on their experience while under the effects of psilocybin.
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Psilocybin | Experimental | Drug: PsilocybinHealthy volunteers will receive up to four doses of psilocybin separated from each other by at least one week. The first dosing session will involve 10 mg psilocybin, the remaining three dosing sessions will receive up to 25mg psilocybin. |
Who may qualify
- Ages
- 21 to 70 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (11 listed)
- Have had previous experiences with psychedelic substances
- Mentally and physically healthy
- Have had prior experiences with MRI machines (optional but preferred)
- Flexible schedule- able to commit to scans once or twice per week for 4 weeks in a row
- Are between 21 and 70 years of age
Key exclusion criteria (0 listed)
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 |
|---|---|---|
| PsilocybinMultiple dosing of healthy volunteers with up to 25 mg psilocybin separated from each other by at least one week. Participants will be scanned before and after receiving psilocybin on each dosing day. Surveys will be performed on dosing days and after dosing. | Drug | Psilocybin |
Primary outcome
Brain-averaged normalized global signal complexity
Time frame: Peak effects (120 min post dosing) vs pre-dose
Signal complexity of brain activity derived from resting-state fMRI
2 secondary outcomes
EEG-derived signal complexity of brain activity
Time frame: Peak effects (120 min post-dose) vs pre-dose fMRI runs
Psychological insight
Time frame: Peak effects (120-min post-dose) vs predose
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 5 Jun 2026.
- Individual participant dataSharing planned: No
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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. This study is not recruiting at the moment.
Robin Carhart-Harris, PhD principal investigator
University of California, San Francisco
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 Psychedelic Experiences and Neuroimaging, run by Robin Carhart-Harris, PhD, MA 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 11 inclusion and 0 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: under way, not looking for participants, as of the sponsor's last update on 5 Jun 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?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Brain-averaged normalized global signal complexity (time frame: Peak effects (120 min post dosing) vs pre-dose). 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 5 Jun 2026.