Obsessive-Compulsive DisorderPhase 1NCT03356483
Efficacy of Psilocybin in OCD: a Double-Blind, Placebo-Controlled Study.
A Phase 1 study testing Psilocybin (0.25mg/kg) and Niacin (250mg) in people with Obsessive-Compulsive Disorder, run by Yale University at 1 site in United States.
Trial summary
This study aims to investigate the effects of oral psilocybin on OCD symptomatology and provide the first evidence of the neural mechanism that may mediate psilocybin's purported therapeutic effects on OCD. Read more about this study
- Who is it for?
- Ages 21 to 65 years
- Conditions the study is for
- Obsessive-Compulsive Disorder
- What is being tested?
- Psilocybin (0.25mg/kg) and Niacin (250mg)
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 28 participants
- Where
- 1 siteUnited States
- Study dates
- 13 Nov 2018to 25 Jul 2024
- Phase
- Phase 1
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
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 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Primary DSM-5 diagnosis of OCD
- Y-BOCS score of 19 or greater
- Failure of at least one trial of standard care treatment (medication and/or psychotherapy [CBT/ERP]) for OCD
- English proficiency and fluency, and ability to understand the consent process and provide written informed consent
- Willingness to sign a medical release for direct communication between research staff and external provider(s) about the participant's treatment and medical histories
- Non-consumption of SSRIs for at least 8 weeks at the time of randomization
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- Willingness to refrain from psychiatric medications (e.g., antidepressants, first- and second-generation antipsychotics, mood stabilizers) during the study period, as well as certain other medications (e.g., anti-seizure medications, cardiovascular medications, and aldomet specifically) during the day of dosing
- Willingness to abstain from THC-containing products for study duration. A negative urinary drug screen is also required at baseline and the day of dosing.
- A negative urinary pregnancy screen at study entry and day of dosing if of childbearing potential, and willingness to use adequate birth control for study duration
- Having a contact person who is willing and able to be reached by the study team in the event of an emergency/crisis, and who is able to transport the participant home at the end of the inpatient stay/dosing week
- Willingness to commit to all study procedures and visits, including inpatient stay, assessments and self-reports, neuroimaging, and being medically cleared to be discharged and transported home at the end of the dosing week
Who cannot join
- Personal or immediate family history of schizophrenia spectrum and other psychotic disorders, bipolar I or II disorder, or major depressive disorder with psychotic features
- Active suicidal intent
- Unremitted Tourette syndrome
- Autism spectrum disorder
- OCPD or BPD
- Current substance use disorder (except mild alcohol use disorder)
Show all 10Show fewer
- Unstable neurological or medical condition(s) that may render study procedures unsafe, including poorly managed diabetes, hypertension, or cardiovascular conditions, or history of seizure(s) or chronic/severe headaches
- Any history of head injury with loss of consciousness for more than 30 minutes
- Any contraindications to undergoing an MRI scan, including having metal implants or metal fragments in the body
- Any use of psychedelic substances within the prior 12 months
Trial locations and contacts
1 site in 1 country.
United States1 site
Enact Research Collaborative
New Haven, Connecticut, 06510
About this study
Official title: Psilocybin Treatment in Obsessive-Compulsive Disorder: a Preliminary Efficacy Study and Exploratory Investigation of Neural Correlates.
This study aims to investigate the effects of oral psilocybin on OCD symptomatology and provide the first evidence of the neural mechanism that may mediate psilocybin's purported therapeutic effects on OCD.
Read the detailed description
Aim 1: To investigate the effects of psilocybin on OCD symptomatology. OCD symptom severity will be assessed before treatment and 24 and 48 hours after treatment, one week after treatment, two weeks, one month, and three months after treatment. Hypothesis: We hypothesize that 0.25mg/kg of psilocybin will lead to greater symptom improvement than niacin (as the active-placebo-control agent) at the primary endpoint of 48 hours post-dosing and at all other assessment points.
Aim 2: To explore the relationship between the psilocybin-induced brain connectivity changes and symptom change in OCD. Resting-state brain connectivity will be assessed before and 48 hours after treatment. Hypothesis: We hypothesize that (i) psilocybin will normalize abnormal fronto-striatal functional connectivity in patients with OCD; and (ii) normalization of these abnormalities will correlate with improvement in symptomatology after psilocybin treatment.
This study will pilot a single-center, randomized, active-placebo-controlled, double-blind design to examine the clinical and neural effects on OCD, of either 0.25mg/kg of psilocybin or active placebo-control agent (niacin 250mg), given along with non-drug preparatory and follow-up support appointments to 30 study participants. The duration of the randomized study phase is from consent until two weeks after drug administration. Participants will be followed for 12 weeks (3 months) post-study drug administration.
Eligible participants will be admitted as an inpatient for at least 3 nights / 4 days surrounding the initial drug administration (or more, at the option of the subject and the investigator). Participants will be randomized into active medication and active-placebo-control groups, and will be blinded as to their study condition. This admission 2 nights prior to the drug administration will allow the participant to adjust to sleeping on the unit and allow them to settle in to the research unit routine. A return for an fMRI scan (48 hours after the administration session) will be scheduled. The participants who received active-placebo-control will be offered the option to receive open-label psilocybin.
- Conditions
- Obsessive-Compulsive Disorder
- Being tested
- Psilocybin (0.25mg/kg), Niacin (250mg)
- Keywords
- Psilocybin
- Medical subject headings
- Obsessive-Compulsive Disorder
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Psilocybin (0.25mg/kg)Drug
Also called "Magic Mushrooms"
Psilocybin is a naturally occurring hallucinogenic ingredient found in some varieties of mushrooms that can be produced synthetically. It is considered to be a serotonergic psychedelic.
Niacin (250mg)Drug
Also called Nicotinic acid
A medication used to treat high cholesterol, triglyceride levels, and niacin deficiency.
| Study group | Role | What they receive |
|---|---|---|
| Psilocybin | Experimental | Psilocybin (0.25mg/kg) Receives: Drug: Psilocybin (0.25mg/kg) |
| Niacin | Placebo comparator | Niacin (250mg) Receives: Drug: Niacin (250mg) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Changes in Severity of OCD Symptoms, Which Will be Measured by The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). The Primary Outcome Measure Will be Collected at Baseline and 48 Hours, Assessing Change From Baseline at 48 Hours.
Assesses severity and types of OCD symptoms over the past seven days. Consists of two parts: 1- symptom checklist, 2- symptom severity scale. The most prominent obsessions and compulsions are identified by the checklist and then rated by the symptom severity scale. The symptom severity scale consists of 11 items (3 items are not included in the total score) and uses a 0 to 4 severity scale. Total Y-BOCS scores range from 0 to 40, with higher scores indicating greater severity of OCD symptoms.
Measured: Baseline, weeks: 1, 2, 4, 12 post-drug
Changes in Severity of OCD Symptoms, Measured by Acute Yale-Brown Obsessive-Compulsive Scale (A-YBOCS)
A clinician-administered measure of specific participant OCD symptoms over prior 24 hours. The most prominent obsessions and compulsions that were previously identified by the checklist are rated by the symptom severity scale. The symptom severity scale consists of 11 items (3 items are not included in the total score) and uses a 0 to 4 severity scale. Total A-YBOCS scores range from 0 to 40, with higher scores indicating greater severity of OCD symptoms. Data presented here is the mean change from baseline to 48 hours post-drug.
Measured: Day 1 (drug treatment), 24 hours post-drug, 48 hours post-drug
Changes in Severity of OCD Symptoms, Measured by Visual Analog Scale (VAS) for OCD Symptoms
A self-report measure of severity of and distress related to OCD symptoms over the past 24 hours. Consists of 5 items assessing compulsive urges, obsessions, anxiety, mood, and discomfort, each on a 0-100 VAS, with higher scores on each item indicating greater severity.
Measured: 24 hours post-drug, 48 hours post-drug
Changes in Suicidality, Measured by the Columbia-Suicide Severity Rating Scale (C-SSRS) Since Last Visit Version
A clinician-administered measure of suicidality since the last visit. Consists of 5 items assessing suicidal ideation and 6 items assessing suicidal and non-suicidal self-injurious behaviors. Higher scores on either scale indicate more severe suicidal ideation and suicidal or non-suicidal behaviors since the last study visit. Data presented here is the number of participants with new suicidal ideation cases, number of participants with Suicide attempts and number of participants with completed Suicides
Measured: Up to 12 weeks post-drug
Secondary outcomes (2)
Changes in Functional Impairment, Which Will be Measured by The Sheehan Disability Scale (SDS).
Assesses functional impairment in three inter-related domains; work/school, social and family life. Impairment of each domain is rated from 0 (not at all) to 10 (extremely). The 3 items are summed into a single dimensional measure of global functional impairment that rages from 0 (unimpaired) to 30 (highly impaired). Mean difference presented here.
Measured: Baseline & 12 weeks post-drug
Changes in Depression Symptoms, Which Will be Measured by The Montgomery-Asberg Depression Scale (MADRS).
Assesses depression symptoms. Consists of 10 items and uses a 0 to 6 severity scale. Total scores range from 0 to 60, with higher scores indicating more severe depression.
Measured: Baseline, 48 hours post-drug, weeks: 1, 2 post-drug
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Nov 2017
- Study start13 Nov 2018
- Primary completion25 Jul 2024
- Study completion25 Jul 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (5)Papers the sponsor has linked to this study.
- Other trials for Obsessive-Compulsive DisorderStudies of the same condition, open and under way.
- More trials run by Yale UniversityThe sponsor's other registered studies.
- 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
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- In the study, half of the participants will be randomized to receive psilocybin (n=15) or the active-placebo-control, niacin (n=15). Following the first treatment session of either the active agent or active-placebo-control, participants who were randomized to receive active-placebo-control will be offered the option to receive open-label psilocybin. The blind will be broken at 48-hours to make this determination.
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 28 participants (actual)
Sponsor and investigators
- Lead sponsor
- Yale University
- Sponsor type
- University, hospital or other
- Collaborators
- Heffter Research Institute, National Institute of Mental Health (NIMH)
- Responsible party
- Principal investigator, Benjamin Kelmendi, MD, Yale University
- Investigators
- Benjamin Kelmendi, MD, Principal investigator, Yale University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03356483
- Sponsor's protocol ID
- 2000020355
- Other IDs
- 1K23MH122777-01A1
- Status last verified
- Aug 2025
- First submitted
- 6 Nov 2017
- Last updated
- 16 Oct 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Moreno FA, Wiegand CB, Taitano EK, Delgado PL. Safety, tolerability, and efficacy of psilocybin in 9 patients with obsessive-compulsive disorder. J Clin Psychiatry. 2006 Nov;67(11):1735-40. doi: 10.4088/jcp.v67n1110.
PubMed 17196053Ross S, Bossis A, Guss J, Agin-Liebes G, Malone T, Cohen B, Mennenga SE, Belser A, Kalliontzi K, Babb J, Su Z, Corby P, Schmidt BL. Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: a randomized controlled trial. J Psychopharmacol. 2016 Dec;30(12):1165-1180. doi: 10.1177/0269881116675512.
PubMed 27909164Griffiths RR, Johnson MW, Carducci MA, Umbricht A, Richards WA, Richards BD, Cosimano MP, Klinedinst MA. Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial. J Psychopharmacol. 2016 Dec;30(12):1181-1197. doi: 10.1177/0269881116675513.
PubMed 27909165Carhart-Harris RL, Erritzoe D, Williams T, Stone JM, Reed LJ, Colasanti A, Tyacke RJ, Leech R, Malizia AL, Murphy K, Hobden P, Evans J, Feilding A, Wise RG, Nutt DJ. Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin. Proc Natl Acad Sci U S A. 2012 Feb 7;109(6):2138-43. doi: 10.1073/pnas.1119598109. Epub 2012 Jan 23.
PubMed 22308440Ching THW, Grazioplene R, Bohner C, Kichuk SA, DePalmer G, D'Amico E, Eilbott J, Jankovsky A, Burke M, Hokanson J, Martins B, Witherow C, Patel P, Amoroso L, Schaer H, Pittenger C, Kelmendi B. Safety, tolerability, and clinical and neural effects of single-dose psilocybin in obsessive-compulsive disorder: protocol for a randomized, double-blind, placebo-controlled, non-crossover trial. Front Psychiatry. 2023 Apr 25;14:1178529. doi: 10.3389/fpsyt.2023.1178529. eCollection 2023.
PubMed 37181888
Study at a glance
From the registry record, last updated by the sponsor on 16 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Psilocybin Treatment in Obsessive-Compulsive Disorder: a Preliminary Efficacy Study and Exploratory Investigation of Neural Correlates.
- ClinicalTrials.gov ID
- NCT03356483
- Acronym / sponsor ID
- 2000020355
- Conditions
- Obsessive-Compulsive Disorder
- Keywords
- Psilocybin
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 28 participants (actual)
- Lead sponsor
- Yale UniversityUniversity, hospital or other
- Collaborators
- Heffter Research Institute, National Institute of Mental Health (NIMH)
- Study start
- 13 Nov 2018 (actual)
- Primary completion
- 25 Jul 2024 (actual)
- Study completion
- 25 Jul 2024 (actual)
- First posted
- 29 Nov 2017 (actual)
- Results
- Posted 16 Oct 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study aims to investigate the effects of oral psilocybin on OCD symptomatology and provide the first evidence of the neural mechanism that may mediate psilocybin's purported therapeutic effects on OCD.
Detailed description
Aim 1: To investigate the effects of psilocybin on OCD symptomatology. OCD symptom severity will be assessed before treatment and 24 and 48 hours after treatment, one week after treatment, two weeks, one month, and three months after treatment. Hypothesis: We hypothesize that 0.25mg/kg of psilocybin will lead to greater symptom improvement than niacin (as the active-placebo-control agent) at the primary endpoint of 48 hours post-dosing and at all other assessment points.
Aim 2: To explore the relationship between the psilocybin-induced brain connectivity changes and symptom change in OCD. Resting-state brain connectivity will be assessed before and 48 hours after treatment. Hypothesis: We hypothesize that (i) psilocybin will normalize abnormal fronto-striatal functional connectivity in patients with OCD; and (ii) normalization of these abnormalities will correlate with improvement in symptomatology after psilocybin treatment.
This study will pilot a single-center, randomized, active-placebo-controlled, double-blind design to examine the clinical and neural effects on OCD, of either 0.25mg/kg of psilocybin or active placebo-control agent (niacin 250mg), given along with non-drug preparatory and follow-up support appointments to 30 study participants. The duration of the randomized study phase is from consent until two weeks after drug administration. Participants will be followed for 12 weeks (3 months) post-study drug administration.
Eligible participants will be admitted as an inpatient for at least 3 nights / 4 days surrounding the initial drug administration (or more, at the option of the subject and the investigator). Participants will be randomized into active medication and active-placebo-control groups, and will be blinded as to their study condition. This admission 2 nights prior to the drug administration will allow the participant to adjust to sleeping on the unit and allow them to settle in to the research unit routine. A return for an fMRI scan (48 hours after the administration session) will be scheduled. The participants who received active-placebo-control will be offered the option to receive open-label psilocybin.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- In the study, half of the participants will be randomized to receive psilocybin (n=15) or the active-placebo-control, niacin (n=15). Following the first treatment session of either the active agent or active-placebo-control, participants who were randomized to receive active-placebo-control will be offered the option to receive open-label psilocybin. The blind will be broken at 48-hours to make this determination.
| Arm | Type | Receives |
|---|---|---|
| Psilocybin | Experimental | Drug: Psilocybin (0.25mg/kg)Psilocybin (0.25mg/kg) |
| Niacin | Placebo comparator | Drug: Niacin (250mg)Niacin (250mg) |
Who may qualify
- Ages
- 21 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (11 listed)
- Primary DSM-5 diagnosis of OCD
- Y-BOCS score of 19 or greater
- Failure of at least one trial of standard care treatment (medication and/or psychotherapy [CBT/ERP]) for OCD
- English proficiency and fluency, and ability to understand the consent process and provide written informed consent
- Willingness to sign a medical release for direct communication between research staff and external provider(s) about the participant's treatment and medical histories
Key exclusion criteria (10 listed)
- Personal or immediate family history of schizophrenia spectrum and other psychotic disorders, bipolar I or II disorder, or major depressive disorder with psychotic features
- Active suicidal intent
- Unremitted Tourette syndrome
- Autism spectrum disorder
- OCPD or BPD
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 |
|---|---|---|
| Psilocybin (0.25mg/kg)Also: "Magic Mushrooms"Psilocybin is a naturally occurring hallucinogenic ingredient found in some varieties of mushrooms that can be produced synthetically. It is considered to be a serotonergic psychedelic. | Drug | Psilocybin |
| Niacin (250mg)Also: Nicotinic acidA medication used to treat high cholesterol, triglyceride levels, and niacin deficiency. | Drug | Niacin |
Primary outcome
Changes in Severity of OCD Symptoms, Which Will be Measured by The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). The Primary Outcome Measure Will be Collected at Baseline and 48 Hours, Assessing Change From Baseline at 48 Hours.
Time frame: Baseline, weeks: 1, 2, 4, 12 post-drug
Assesses severity and types of OCD symptoms over the past seven days. Consists of two parts: 1- symptom checklist, 2- symptom severity scale. The most prominent obsessions and compulsions are identified by the checklist and then rated by the symptom severity scale. The symptom severity scale consists of 11 items (3 items are not included in the total score) and uses a 0 to 4 severity scale. Total Y-BOCS scores range from 0 to 40, with higher scores indicating greater severity of OCD symptoms.
Changes in Severity of OCD Symptoms, Measured by Acute Yale-Brown Obsessive-Compulsive Scale (A-YBOCS)
Time frame: Day 1 (drug treatment), 24 hours post-drug, 48 hours post-drug
A clinician-administered measure of specific participant OCD symptoms over prior 24 hours. The most prominent obsessions and compulsions that were previously identified by the checklist are rated by the symptom severity scale. The symptom severity scale consists of 11 items (3 items are not included in the total score) and uses a 0 to 4 severity scale. Total A-YBOCS scores range from 0 to 40, with higher scores indicating greater severity of OCD symptoms. Data presented here is the mean change from baseline to 48 hours post-drug.
Changes in Severity of OCD Symptoms, Measured by Visual Analog Scale (VAS) for OCD Symptoms
Time frame: 24 hours post-drug, 48 hours post-drug
A self-report measure of severity of and distress related to OCD symptoms over the past 24 hours. Consists of 5 items assessing compulsive urges, obsessions, anxiety, mood, and discomfort, each on a 0-100 VAS, with higher scores on each item indicating greater severity.
Changes in Suicidality, Measured by the Columbia-Suicide Severity Rating Scale (C-SSRS) Since Last Visit Version
Time frame: Up to 12 weeks post-drug
A clinician-administered measure of suicidality since the last visit. Consists of 5 items assessing suicidal ideation and 6 items assessing suicidal and non-suicidal self-injurious behaviors. Higher scores on either scale indicate more severe suicidal ideation and suicidal or non-suicidal behaviors since the last study visit. Data presented here is the number of participants with new suicidal ideation cases, number of participants with Suicide attempts and number of participants with completed Suicides
2 secondary outcomes
Changes in Functional Impairment, Which Will be Measured by The Sheehan Disability Scale (SDS).
Time frame: Baseline & 12 weeks post-drug
Changes in Depression Symptoms, Which Will be Measured by The Montgomery-Asberg Depression Scale (MADRS).
Time frame: Baseline, 48 hours post-drug, weeks: 1, 2 post-drug
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Oct 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Background: PubMed 17196053Moreno FA, Wiegand CB, Taitano EK, Delgado PL. Safety, tolerability, and efficacy of psilocybin in 9 patients with obsessive-compulsive disorder. J Clin Psychiatry. 2006 Nov;67(11):1735-40. doi: 10.4088/jcp.v67n1110.
- Background: PubMed 27909164Ross S, Bossis A, Guss J, Agin-Liebes G, Malone T, Cohen B, Mennenga SE, Belser A, Kalliontzi K, Babb J, Su Z, Corby P, Schmidt BL. Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: a randomized controlled trial. J Psychopharmacol. 2016 Dec;30(12):1165-1180. doi: 10.1177/0269881116675512.
- Background: PubMed 27909165Griffiths RR, Johnson MW, Carducci MA, Umbricht A, Richards WA, Richards BD, Cosimano MP, Klinedinst MA. Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial. J Psychopharmacol. 2016 Dec;30(12):1181-1197. doi: 10.1177/0269881116675513.
- Background: PubMed 22308440Carhart-Harris RL, Erritzoe D, Williams T, Stone JM, Reed LJ, Colasanti A, Tyacke RJ, Leech R, Malizia AL, Murphy K, Hobden P, Evans J, Feilding A, Wise RG, Nutt DJ. Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin. Proc Natl Acad Sci U S A. 2012 Feb 7;109(6):2138-43. doi: 10.1073/pnas.1119598109. Epub 2012 Jan 23.
- Derived from this study: PubMed 37181888Ching THW, Grazioplene R, Bohner C, Kichuk SA, DePalmer G, D'Amico E, Eilbott J, Jankovsky A, Burke M, Hokanson J, Martins B, Witherow C, Patel P, Amoroso L, Schaer H, Pittenger C, Kelmendi B. Safety, tolerability, and clinical and neural effects of single-dose psilocybin in obsessive-compulsive disorder: protocol for a randomized, double-blind, placebo-controlled, non-crossover trial. Front Psychiatry. 2023 Apr 25;14:1178529. doi: 10.3389/fpsyt.2023.1178529. eCollection 2023.
- 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.
Benjamin Kelmendi, MD principal investigator
Yale University
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 (0.25mg/kg) and Niacin (250mg) in people with Obsessive-Compulsive Disorder, run by Yale University 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 10 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: finished, as of the sponsor's last update on 16 Oct 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. Some participants in this study may receive a placebo. 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?
Yes. Results are posted in the registry (first posted 16 Oct 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
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?
Changes in Severity of OCD Symptoms, Which Will be Measured by The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). The Primary Outcome Measure Will be Collected at Baseline and 48 Hours, Assessing Change From Baseline at 48 Hours. (time frame: Baseline, weeks: 1, 2, 4, 12 post-drug). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT03356483, which also lists 5 linked publications.
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 16 Oct 2026.