Clinical TrialHealthy VolunteersPsilocybinPlaceboNot yet recruiting

The Acute Effects of Psilocybin on Cognition, Memory, and Brain Function

This double-blind, placebo-controlled, crossover trial (n=48) will study the effects of psilocybin (15 mg) on memory, cognition, and brain function in healthy adults.

Target Enrollment
48 participants
Study Type
Phase I/II interventional
Design
Randomized, quadruple Blind

Detailed Description

Randomised, quadruple-masked, placebo-controlled crossover in healthy adults using two single-dose sessions (psilocybin 15 mg and placebo) with counterbalanced order.

Outcomes include computerised cognitive tasks and MRI/fMRI measures to characterise acute effects on memory, cognition and brain function; basic-science aim to inform safety and therapeutic mechanistic work.

Study Protocol

Preparation

sessions

Dosing

2 sessions

Integration

sessions

Study Arms & Interventions

Psilocybin 15 mg

experimental

Single 15 mg oral psilocybin capsule

Interventions

  • Psilocybin15 mg
    via Oral• single dose• 1 doses total

Placebo

inactive

Capsule containing microcrystalline cellulose

Interventions

  • Placebo
    via Oral• single dose• 1 doses total

    Microcrystalline cellulose placebo capsule

Participants

Ages
21 – 45
Sexes
Male & Female

Inclusion Criteria

  • Inclusion Criteria:
  • 21 to 45 years old.
  • 3–30 lifetime psychedelic uses.
  • English as a first language.
  • High school education (or equivalent).
  • Psychiatrically healthy (as assessed by the SCID-5).
  • Medically healthy (as assessed by a physical examination and ECG).
  • Willingness to attend all study sessions and complete all procedures.
  • BMI between 19 and 30.

Exclusion Criteria

  • Exclusion Criteria:
  • Current or past diagnosis of psychiatric disorders except panic attacks, depressive disorder, or anxiety disorder from ≥1 year prior.
  • Current or past medical conditions that might interfere with study participation or be contraindicated for psilocybin administration (e.g., hypertension, history of stroke, cardiovascular disease, etc.).
  • Current daily medications except birth control (females).
  • Pregnant, nursing, or planning to become pregnant (assessed with urine pregnancy test).
  • Ingestion of a psychedelic <2 months prior to an experimental session (with the exception of psilocybin administered in the context of the current study's repeated measures design).
  • History of serious adverse event with a psychedelic and/or self-reported hypersensitivity to psychedelics.
  • Inability to abstain from alcohol 48 hours prior to an experimental session.
  • Use of other psychoactive drugs (other than caffeine or nicotine) 1 week prior to an experimental session.
  • Positive urine drug screening for drugs of abuse during experimental sessions.
  • Self-reported ferrous metal, metallic implants, or implanted medical devices that would preclude participation in MRI procedures, including but not limited to cochlear implants, implanted brain stimulators, and aneurysm clips.
  • Self-reported past penetrating brain injury or any head injury resulting in a loss of consciousness for 30 minutes or more or post-concussive symptoms for more than seven days following a head injury.
  • Self-reported claustrophobia (prohibiting MRI acquisition).
  • Any other factors such as unstable housing or life-threatening circumstances, erratic behaviour, etc. that are judged by the investigators to be a significant barrier to participation in the study protocol and/or to establishing rapport necessary for safe administration of psilocybin.
  • Participant unwillingness to not ingest or use additional serotonergic psychedelics outside the context of study procedures for the duration of the study.
  • Resting blood pressure >140/90 mm Hg at study entry.
  • Lifetime history of cardiomyopathy, stroke, heart disease, heart attack, tachycardia, elongated QT-interval corrected by Fridericia (>450 ms for men and >470 ms for women); clinically significant cardiac arrhythmia within 1 year of study entry; and/or abnormal electrocardiogram on study entry.
  • Left-handedness (given that functional lateralizations may differ from those of right-handed individuals).

Study Details

  • Status
    Not yet recruiting
  • Phase
    Phase IPhase II
  • Type
    interventional
  • Design
    Randomizedquadruple Blind
  • Target Enrollment48 participants
  • Timeline
    Start: 2025-09-01
    End: 2027-08-01
  • Compounds
    PsilocybinPlacebo
  • Topic
    Healthy Volunteers

Locations

The University of Texas at Austin Dell Medical School — Austin, Texas, United States

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