A Phase 2 interventional study of Psilocybin (drug) and Psilocybin (drug) in Depression and Parkinson's Disease (PD), sponsored by Yale University. Recruiting at 1 site in United States. Open to participants aged 40 Years to 80 Years. Per ClinicalTrials.gov, last updated 2026-09-28.
Sponsored by Yale University · Phase 2, Interventional, and Treatment
The purpose of this study is to understand whether people with Parkinson's Disease and depression have improvement in their symptoms after psilocybin therapy.
This is a randomized controlled trial of oral psilocybin therapy for depression in people with Parkinson's disease (PD). The primary goal is to examine efficacy of psilocybin therapy in this patient population. Investigators will enroll participants with clinically diagnosed early to moderate stage Parkinson's disease (Hoehn and Yahr Stage 1-3 during an "on" period), who meet criteria for moderate or greater depression severity and meet all other inclusion and exclusion criteria at screening. Participants will complete two drug administration sessions where they will each receive a dose of oral psilocybin ranging from low ("microdose") to high in a medically monitored setting with psychotherapeutic support. Participants will also complete a series of psychotherapy sessions before and after each drug administration session. Clinical assessments will be used to quantify changes in depression as well as other relevant outcomes (non-motor and motor symptoms of PD, cognitive performance, quality of life). Follow-up will continue to 3 months after the second session. Endpoints will evaluate efficacy, safety, and tolerability of study procedures.
After posting of these trial results, this data will be combined with the data from the trial at UCSF (NCT06455293) for publication purposes.
8,577 studies on the registry are indexed under Depression; 1,720 are open to participants now.
This study's planned enrollment of 40 is below the median of 81 across 7,063 interventional studies indexed under Depression.
Browse Depression studies →Yale University is the lead sponsor of 1,770 studies on the registry; 294 are open to participants now.
Of its 221 completed or terminated interventional studies of FDA-regulated products, 129 (58%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Cardiovascular conditions, including:
Hepatic dysfunction as indicated by any of the following laboratory values:
Use of any of the following concomitant medications AND inability/unwillingness to discontinue for at least 5 times the elimination half-life of the agent (specific exceptions are noted) prior to psilocybin administration, including:
Agents that may be associated with serotonin syndrome:
Agents that may interact with psilocybin metabolism/effects:
Agents that may increase the risk of psychotic symptoms:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Short tests of memory and thinking, each scored out of 30. Lower scores suggest more difficulty; criteria give a range, either to include people with memory problems or to leave them out.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
MMSE and MoCA
Short tests of memory and thinking, each scored out of 30. Lower scores suggest more difficulty; criteria give a range, either to include people with memory problems or to leave them out.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
DSM diagnostic criteria
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Creatinine clearance (CrCl)
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive one dose of psilocybin ranging from low ("microdose") to high in a monitored setting with preparation sessions before and integration sessions after.
Drug: Psilocybin (drug)
Participants will receive one dose of psilocybin ranging from low ("microdose") to high in a monitored setting with preparation sessions before and integration sessions after.
Drug: Psilocybin (drug)
Single dose of psilocybin ranging from low ("microdose") to high delivered orally with psychological support and monitoring
Also known as: 4-phosphoryloxy- N, N-dimethyltryptamine
Single dose of psilocybin ranging from low ("microdose") to high delivered orally with psychological support and monitoring
Also known as: 4-phosphoryloxy- N, N-dimethyltryptamine
Change in depression as measured by the Montgomery-Asberg Depression Rating Scale (MADRS)
MADRS is a 10-item clinician-administered scale used to measure the severity of depressive symptoms. Total scores range from 0 to 60 with higher scores indicating more severe depression.
Time frame: Baseline to 30 days after first drug dose
Adverse Events
Incidence, severity, and frequency of all Adverse Events (AEs) including Treatment-Emergent AEs (TEAEs) and Serious AEs (SAEs)
Time frame: Baseline to 90 days after second drug dose
Changes in clinician-rated psychotic symptoms as measured by the Enhanced Scale for the Assessment of Positive Symptoms for Parkinson's Disease (eSAPS-PD)
The eSAPS-PD is a clinician-administered scale used to track Parkinson's Disease symptom severity. Scores range from 25 to 125, where higher scores indicate more impairment.
Time frame: Baseline to 90 days after second drug dose
Subjective effects of psilocybin as measured by the 5-Dimensional Altered States of Consciousness Rating Scale (5D-ASC)
The 5D-ASC is a patient-reported scale used to measure the intensity of an experience during altered states of conciousness. Scores range from 0 to 100, where higher scores indicate more intense psychedelic effects.
Time frame: Up to 30 and 60 days after Baseline
Suicidality as measured using the Columbia Suicide Severity Rating Scale (C-SSRS)
The C-SSRS is a clinician-administered scale used to assess suicide risk. Scores range from 0 to 6, where higher scores indicate more severe suicide risk.
Time frame: Baseline to 90 days after second drug dose
Participant -reported acceptability of study procedures as measured by the study-specific Treatment Satisfaction Questionnaire-Participant (TSQ-P)
TSQ-P is a patient-reported 7-point scale used to measure patients' satisfaction with their medication. Scores range from 0 to 7, where higher scores indicate greater satisfaction.
Time frame: 30 days after second drug dose
Changes in depression severity as measured by Montgomery-Asberg Depression Rating Scale (MADRS)
MADRS is a 10-item clinician-administered scale used to measure the severity of depression symptoms. Overall score ranges from 0 to 60, where higher scores indicate more severe depression.
Time frame: Baseline to 90 days after second drug dose
Proportion of participants with a response (defined as a >/=50% decrease in MADRS total score) as measured by the Montgomery-Asberg Depression Rating Scale (MADRS)
MADRS is a 10-item clinician-administered scale used to measure the severity of depression symptoms. Overall score ranges from 0 to 60, where higher scores indicate more severe depression.
Time frame: 7 days after first drug dose and up to 90 days after second drug dose
Changes in participant reported depression as measured by the Beck Depression Inventory (BDI-II)
BDI-II is a 21-item patient-reported questionnaire used to assess the severity of depressive symptoms. Total scores range from 0 to 63, with higher scores indicating more severe depression.
Time frame: Baseline up to 90 days after second drug dose
Changes in anxiety as measured by the Parkinson Anxiety Scale (PAS)
PAS is a 12-item, PD-specific scale used to assess anxiety in adults with Parkinson's disease. Total scores range from 0 to 50 with higher scores indicating more severe anxiety.
Time frame: Baseline to 90 days after second drug dose
Changes in PD symptom severity as measured by the Movement Disorder Society revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS)
MDS-UPDRS is a 50-item scale used for assessing both motor and non-motor aspects of Parkinson's disease. Total scores range from 0 to 176 with higher scores indicating more severe disease.
Time frame: Baseline to 90 days after second drug dose
Changes in cognitive performance as measured by multi-task assessments to include Probabilistic Reversal Task, Category Switch Task, Simon Task, Delay Discounting Task, California Verbal Learning Test-II, Digit span forward and backward
Probabilistic Reversal Task measures flexible learning, Category Switch Task measures mental set shifting, Simon Task measures selective attention, Delay Discounting Task measures impulse control/waiting for rewards, California Verbal Learning Test (CVLT-II) measures short- and long-term memory, Digit Span Forward and Backward measures working memory.
Time frame: Baseline to 90 days after second drug dose
Changes in Quality of Life as measured by the 36-item Short Form survey (SF-36)
SF-36 is a patient-reported 36-item scale used to measure health-related quality of life. Total scores range from 0 to 100 with higher scores indicating better health.
Time frame: Baseline to 90 days after second drug dose
Changes in sleep parameters as measured using passive sensing via an Oura ring (exploratory)
The Oura ring is a wearable device that synchronizes with a smartphone application. It records sleep by combining infrared photoplethysmography (PPG) sensors, a sensitive accelerometer, and temperature monitoring to track heart rate, movement, and body temperature, which are analyzed by machine learning algorithms to determine sleep stages and patterns.
Time frame: Baseline to 30 days after the second drug dose
Changes in physical activity as measured using passive sensing via an Oura ring (exploratory)
The Oura ring is a wearable device that synchronizes with a smartphone application. It records physical activity using using a combination of a 3D accelerometer, heart rate sensors, and activity algorithms to track movement, steps, calories burned, and exercise intensity.
Time frame: Baseline to 30 days after the second drug dose
Changes in body temperature as measured using passive sensing via an Oura ring (exploratory)
The Oura ring is a wearable device that synchronizes with a smartphone application. It records average nighttime skin temperature to track deviations from personal baseline, providing insights into readiness, health changes, and menstrual cycle trends.
Time frame: Baseline to 30 days after the second drug dose
Changes in heart rate as measured using passive sensing via an Oura ring (exploratory)
The Oura ring is a wearable device that synchronizes with a smartphone application. It records resting heart rate and heart rate variability, primarily during sleep and select daytime sessions.
Time frame: Baseline to 30 days after the second drug dose
Changes in participant-reported sleep as measured by the Parkinson's Disease Sleep Scale-2 (exploratory)
The PDSS-2 is a scale used to assess sleep disturbances in individuals with Parkinson's disease, with scores indicating the severity of sleep problems ranging from 0 to 60. Higher scores reflect more severe sleep issues.
Time frame: Baseline to 90 days after second drug dose
Evaluation of treatment expectancy as measured by the Treatment Expectancy Questionnaire (TEQ) (exploratory)
The TEQ is a patient-reported scale used to measure and compare patients' expectations across diverse treatment contexts. Scores range from 0 to 75, where higher scores indicate stronger overall treatment expectations.
Time frame: Baseline
Evaluation of masking procedures as measured by a study-specific Masking Questionnaire (exploratory)
The Masking Questionnaire is completed by participants and facilitators/clinical assessors to formally define, document, and evidence the blinding (masking) strategy for the study.
Time frame: At first and second drug dose
Plan to share: Yes — Any data, code and software needed for independent verification of research results will be shared freely and publicly per the funder's open access publication policy.
Supporting information: Study protocol
Time frame: The IPD will be shared at the end of the research project and for 1 year after that.
Access criteria: The public will be able to access the IPD and supporting information, the IPD accessed will be data and code generated from the project and they will be able to access it from a community-recognized repository.
Data sharing details ↗ · www.michaeljfox.org
No publications or documents are linked to this record.
Started Jul 2026 (actual). Primary completion is estimated for Jul 2030, 48 months after the start.
Of 143 non-industry phase 2 interventional studies under Depression, half reached primary completion within 38 months of starting (the median), counting those still running; a quarter within 27 and three quarters within 57. This study's planned 48 months is above that.
Counting every sponsor, half of 196 studies reached it within 31 months; a quarter within 18 and three quarters within 47.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
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Studies of the drug tested here: Psilocybin