Skip to Main Content
Phase II

A Study of Psilocybin for Major Depressive Disorder (MDD)

  • Study HIC#:2000025986
  • Last Updated:01/05/2022

Eighty participants, ages 21 to 65, who meet Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria for major depressive disorder (MDD) will be stratified by study site and randomized with a 1-to-1 allocation under double-blind conditions to receive a single 25 mg oral dose of psilocybin or a single 100 mg oral dose of niacin. Niacin will serve as an active placebo.

The purpose of this study is to evaluate the potential efficacy of a single 25 mg oral dose of psilocybin for MDD compared to the active placebo in otherwise medically-healthy participants, assessed as the difference between groups in changes in depressive symptoms from Baseline to Day 8 post-dose.

To learn more contact: Jane Wanyiri, RN at, 203-764-9131 and/or Elizabeth Cooper at, 203-764-9182.

  • Age21 years - 65 years
  • GenderBoth
  • Start Date11/04/2019
  • End Date03/31/2022

Trial Purpose and Description

The overarching purpose of this study is to conduct an initial examination of the safety, efficacy and tolerability of single-dose therapy with the psychedelic medication, psilocybin, in otherwise medically healthy patients with Major Depressive Disorder (MDD). The overall objectives of this study are to examine the potential efficacy of a single, fixed, 25 mg oral dose of psilocybin in reducing depressive and anxious symptoms and improving functional disability and quality of life in 56 medically healthy patients with MDD when compared to active placebo; and to collect safety and tolerability data on single-dose psilocybin treatment in medically healthy patients with MDD. Of note, this study represents the first randomized, double-blind, placebo-controlled study of single-dose psilocybin in a general-population (i.e. medically healthy) MDD sample (prior studies of depression have either used an open design or occurred in patients with a concomitant medical illness).

To learn more contact: Jane Wanyiri, RN at, 203-764-9131 and/or Elizabeth Cooper at, 203-764-9182.

Eligibility Criteria

Inclusion Criteria: 

21 to 65 years old
Able to swallow capsules
If of childbearing potential, agree to practice an effective means of birth control throughout the duration of the study
Have an identified support person and agree to be accompanied home by that person following dosing
Have sustained moderate-severe depression symptoms at Screening and Baseline
Meet DSM-5 criteria for a diagnosis of major depressive disorder and are currently experiencing a major depressive episode of at least a 60-day duration at the time of screening

Exclusion Criteria:
Women who are pregnant or who intend to become pregnant during the study or who are currently nursing
Have any of the following cardiovascular conditions: uncontrolled hypertension, coronary artery disease, congenital long QT syndrome, cardiac hypertrophy, cardiac ischemia, congestive heart failure, myocardial infarction, tachycardia, artificial heart valve, a clinically significant screening ECG abnormality, or any other significant cardiovascular condition
Have a history of stroke or Transient Ischemic Attack (TIA)
Have moderate to severe hepatic impairment
Have epilepsy
Have insulin-dependent diabetes
Have a positive urine drug test
Nicotine dependence that would disallow an individual to be nicotine free for the 7-10 hours during the dosing period
Meet DSM-5 criteria for schizophrenia spectrum or other psychotic disorders, including major depressive disorder with psychotic features, or Bipolar I or Bipolar II Disorder
Meet DSM-5 criteria for antisocial personality disorder
Meet DSM-5 criteria for a moderate or severe alcohol or drug use disorder

Principal Investigator


For more information about this study, contact:

Or contact the Help us Discover team on: