Investigating the effects of psilocybin on consciousness

Role of the Serotonin 2A Receptor in Psilocybin-induced Altered States of Consciousness (PDR-Study)

Phase 1 Interventional University Hospital, Basel, Switzerland · NCT06796361

This study is testing how different doses of psilocybin affect the way healthy people experience consciousness to better understand its effects.

Quick facts

PhasePhase 1
Study typeInterventional
Enrollment16 (estimated)
Ages25 Years to 75 Years
SexAll
SponsorUniversity Hospital, Basel, Switzerland Academic / other
Locations1 site (Basel, Canton of Basel-City)
Trial IDNCT06796361 on ClinicalTrials.gov

What this trial studies

This study aims to explore the dose-response relationship of psilocybin, a psychedelic compound, by administering varying doses (5mg to 40mg) to healthy participants. The research will utilize modern psychometric instruments to assess the subjective effects of psilocybin and examine the role of the serotonin 2A receptor in these altered states of consciousness. Participants will receive both psilocybin and placebo treatments in a randomized order, with a focus on understanding the pharmacological effects of psilocybin and its metabolite psilocin. The study seeks to fill a knowledge gap regarding the physiological and psychological impacts of psilocybin at different dosages.

Who should consider this trial

Good fit: Ideal candidates for this study are healthy adults aged 25 to 75 who can understand German and are willing to comply with the study protocols.

Not a fit: Patients with chronic medical conditions, major psychiatric disorders, or those with a body mass index outside the specified range may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could enhance our understanding of psilocybin's effects, potentially informing future therapeutic applications for neuropsychiatric disorders.

How similar studies have performed: While psilocybin has been studied for its therapeutic potential, this specific investigation into its dose-response relationship is novel and has not been extensively tested.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

1. Age between 25 and 75 years.
2. Sufficient understanding of the German language.
3. Understanding the procedures and the risks that are associated with the study.
4. Participants must be willing to adhere to the protocol and sign the consent form.
5. Participants must be willing to refrain from taking illicit psychoactive substances during the study (not including cannabis).
6. Participants must be willing not to drive a traffic vehicle or to operate machines within 48 h after substance administration.
7. Women of childbearing potential must be willing to use effective birth-control throughout study participation

Exclusion Criteria:

1. Chronic or acute medical condition, including a history of seizures.
2. Body mass index 18-29.9 kg/m2
3. Current or previous major psychiatric disorder (e.g. psychotic disorders, mania / hypomania, anxiety disorders).
4. Psychotic or bipolar disorder in first-degree relatives, not including psychotic disorders secondary to an apparent medical reason, e.g., brain injury, dementia, or lesions of the brain.
5. Hypertension (SBP\>140/90 mmHg) or hypotension (SBP\<85 mmHg)
6. Psychedelic substance use (with the exception of cannabis) more than 20 times or any time within the previous two months
7. Pregnant or nursing women.
8. Participation in another clinical trial (currently or within the last 30 days).
9. Use of medications that may interfere with the effects of the study medications (any psychiatric medications and any medication with known to interact with the study substances).
10. Tobacco smoking (\>10 cigarettes/day).
11. Consumption of alcoholic drinks (\>15 drinks / week).
12. Body weight \< 45 kg.

Where this trial is running

Basel, Canton of Basel-City

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions HealthyHallucinogensPhysiological Effects of DrugsPsychotropic DrugsSerotonin AntagonistsSerotonin AgentsNeurotransmitter AgentsMolecular Mechanisms of Pharmacological Action
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.