Psilocybin-Assisted Psychotherapy for Treatment-Resistant Depression: Comparing One Versus Two Doses of Psilocybin
Recruiting · Toronto, Ontario
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Voluntary — you can stop anytime
What is this study?
The purpose of this study is to see if one or two doses of psilocybin is more effective in relieving depressive symptoms in patients with treatment-resistant depression (TRD). Researchers also want to know if a second dose of psilocybin is safe and well-tolerated.
It is , overseen by an independent and licensed medical staff.
Read the full clinical description
The purpose of this study is to see if one or two doses of psilocybin is more effective in relieving depressive symptoms in patients with treatment-resistant depression (TRD). Researchers also want to know if a second dose of psilocybin is safe and well-tolerated. This study will see if psilocybin is effective, safe, and well-tolerated by tracking changes in depressive symptoms, suicidality, and side effects. This study will also see if a second dose of psilocybin has an effect on quality of life, functioning, cognition (thinking, reasoning, remembering), and how long depressive symptoms improve (or worsen) after psilocybin is administered.
Who this study is looking for
In plain language, from the study's own rules. The study team confirms the full details with you — this isn't a final yes or no.
✅ You may be able to join if…
- •Adults age 18 to 65.
- •The study team confirms you can give informed consent.
- •You have major depressive disorder (MDD) with a current major depressive episode (MDE) without psychosis, confirmed with the MINI interview.
- •Your current depression is moderate to severe (MADRS score greater than 21).
- •You have not improved after at least two antidepressant trials at adequate dose and time.
🚫 You may not be able to join if…
- •You have ever had mania, hypomania, or psychosis.
- •Right now you have mania, hypomania, or mixed symptoms (YMRS score greater than 12).
- •You have had substance (including cannabis or alcohol) use disorder in the past 3 months, or lifetime hallucinogen use disorder.
- •You have active suicidal ideation/suicidality that makes you need urgent or inpatient treatment, or a suicide attempt in the past 3 months.
- •You are pregnant, planning pregnancy, or breastfeeding.
Are you a good fit?
Simplified highlights. The study team always confirms the full details with you.
- ✓Adults roughly 18–65
- ✓Have Depression
- !Some conditions may not be a fit: Heart / cardiovascular disease, High blood pressure
- !Not for people who are pregnant or breastfeeding
What to expect, step by step
- 1
Usually a few weeks
The study team checks whether the study is a good fit for you, with a visit and sometimes lab tests. You can ask any questions before deciding.
- 2
Treatment
If you join and choose to continue, you receive the study treatment and are watched closely by medical staff.
- 3
Follow-up
After treatment, the team checks on your health and confirms the visit schedule with you. You can leave the study at any point.
Has this treatment been tested before?
Yes. This treatment has already been through earlier human studies for safety before reaching this stage.
What you need to know before you apply
What is this study testing?+
The purpose of this study is to see if one or two doses of psilocybin is more effective in relieving depressive symptoms in patients with treatment-resistant depression (TRD). Researchers also want to know if a second dose of psilocybin is safe and well-tolerated.
Is it safe? Who makes sure of that?+
This is a mid-stage study (Phase 2), looking at safety and whether the treatment works. Every study is reviewed and monitored by an independent ethics board (called an IRB) whose job is to protect participants, and care is overseen by licensed medical staff. You'll be told the known risks before you agree to anything, and you can stop at any time.
Will I get a placebo instead of the real treatment?+
Some studies compare a treatment against a placebo (an inactive version), and some don't. If this one does, the study team will explain your chances of receiving the active treatment before you decide. Nothing is hidden from you.
Do I have to stop taking my current medications?+
It depends on the study. Some let you stay on your current medications and some ask you to adjust them. Never stop a medication on your own — the study team will review everything with you first.
Does it cost anything? Will I be paid?+
The study treatment and study-related visits are provided at no cost to you. Some studies also pay for your time; the coordinator can tell you if this one does. You should never be asked to pay to take part.
Do I need insurance? Will anyone ask about my immigration status?+
No. You do not need health insurance to take part in a research study, and you will not be asked about your immigration status to join. Taking part is about whether you're a medical fit for the study.
What if English isn't my first language?+
You have the right to understand everything before you agree. Study sites can often provide materials or an interpreter in your language — you can ask the coordinator for one.
Is my information private?+
Yes. Your health information is only shared with the study sites you choose to be contacted by, and only to help match and enroll you. It is never sold, and you can ask us to delete it at any time.
Source: ClinicalTrials.gov · NCT06341426 · Locations: Ontario