Clinical TrialParallelHealthy VolunteersPsilocybinRecruiting

Changes in Self-awareness Induced by Psychoactive Substances: an Experimental Study With Psilocybin.

This early Phase I, randomised, triple-masked, crossover trial (n=100) will evaluate the effects of a single 15 mg dose of psilocybin on components of self-awareness in healthy adults aged 21–60 years. The primary outcome is change in global metacognitive judgement, assessed using a computerised success–failure manipulation paradigm from baseline to 1 week after dosing. Participants will receive either 15 mg of psilocybin, provided as 3 × 5 mg capsules, or a sham comparator comprising 100 mg of niacin with 2 × 25 mg inert placebo capsules. Tasks and questionnaires measuring self-awareness will be completed 1 week before dosing, immediately after dosing and 1 week afterwards. Neural correlates of self-awareness will also be examined before and after substance administration using near-infrared spectroscopy. Participants in the placebo group may be offered an open-label psilocybin extension when the substance is available.

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Target Enrollment
100 participants
Study Type
Phase I interventional
Design
Randomized, triple Blind

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Compound research: PsilocybinTopic research: Healthy VolunteersResearch in Brazil

Detailed Description

Self-awareness, the capacity of becoming the object of one's own awareness, is a frontier of scientific knowledge. Over centuries, distinct philosophical and religious traditions have grappled with the subject, but only recently has the importance of self-awareness been established as a central concept for scientific investigation, to which scientific methods can be applied to explore and characterize this phenomenon. Self-awareness has important implications, notably from a clinical perspective. Psychedelics can affect the sense of self, with 'ego dissolution' being an essential feature of the experience of substances such as psilocybin and dimethyltryptamine. Recent evidence indicates that psychedelics can rearrange brain connectivity, with these changes being linked to alterations in self-awareness. Nevertheless, the extent to which specific components of self-awareness are modified by these substances has not been fully explored. It is possible that part of the clinical benefits of psychedelics, for conditions such as depression, OCD, and anxiety, is mediated by changes in self-awareness. Given this clinical potential, the current study aims to examine the effects of psilocybin on various components of self-awareness in healthy participants. 100 participants will be allocated to receive either 15mg of psilocybin (n=50) or an active placebo (100mg niacin; n=50). Participants will be assessed one week before, immediately after, and one week after the administration of the substances, performing tasks and completing questionnaires measuring self-awareness at these time points. The neural correlates of self-awareness, before and after substance effects, will be investigated using near-infrared spectroscopy. Participants allocated to the placebo group will be invited to an open-label extension with psilocybin upon availability of the substance. It is expected that the results of the study will elucidate the brain regions involved in self-awareness, as well as the alterations induced by psilocybin in this process, opening the possibility of new therapeutic interventions for different clinical groups.

Study Arms & Interventions

Psilocybin (15 mg)

experimental

Interventions

  • Psilocybin15 mg

Niacin 100 mg (active placebo)

inactive

Interventions

  • Compound100 mg

    Unmatched intervention: Niacin 100 mg

Participants

Ages
21 – 60
Sexes
Male & Female

Inclusion Criteria

  • Minimum age of 21 and maximum age of 60;
  • Minimum of eight years of schooling;
  • Fluency in Portuguese;
  • Agree, one week before the experiment, to abstain from:
  • * Using any herbal supplements (except with prior approval from the researchers);
  • * Using any non-prescribed medication (except non-steroidal anti-inflammatory drugs or paracetamol, provided they have prior approval from the research team);
  • * Using any prescribed medication (except birth control pills, thyroid hormones, or other medications, provided they have prior approval from the research team);
  • * Using recreational psychoactive substances;
  • Agree to abstain, 24 hours before the experiment, from:
  • * Consuming beverages with high caffeine content (e.g., coffee, mate, cola);
  • * Consuming alcoholic beverages;
  • Agreeing not to use caffeine or nicotine for two and six hours, respectively, after the experiment;
  • Agree not to drive a motor vehicle or operate machinery for 24 hours after the experiment;
  • Be available to be contacted by telephone for all planned stages;
  • Agree to use effective contraception throughout the study;
  • Agree to inform researchers of any medical condition or procedure that may arise prior to the experiment;
  • Agree not to participate in any other interventional clinical trial for the duration of this study.

Exclusion Criteria

  • History of traumatic brain injury, stroke, epilepsy, neurological disease, or cardiovascular disease;
  • Evidence or history of coronary or cerebral artery disease, peripheral vascular disease, liver disease with altered liver enzymes, or any other medical condition that the researchers, including the responsible physician, deem to significantly increase the risk of administering any substance;
  • Pregnant or breastfeeding women, or women who could potentially become pregnant and are not using any effective contraceptive method;
  • Women who, at the screening stage, do not have a negative pregnancy test.
  • Having a history of or currently having a primary psychotic disorder, schizophrenia spectrum disorder, bipolar affective disorder (type 1 and 2), dissociative identity disorder, major depressive disorder;
  • History of psychotic disorders in a first-degree relative;
  • Have resting blood pressure that does not exceed 140 mmHg (systolic) and 90 mmHg (diastolic) - measured in four assessments on at least two different days;
  • Have resting blood pressure below 90 mmHg (systolic) and 60 mmHg (diastolic) - measured in four assessments on at least two different days;
  • Weigh less than 48 kg;
  • Require therapy with psychiatric medications concurrently with the study;
  • Have a history of or present with gastrointestinal disease;
  • Previous use of psilocybin or similar substances;
  • Frequent use (at least once a month) of any other psychoactive substance in the last year, except for nicotine, caffeine and alcohol;
  • Have a history of disorders or problems related to the use of psychoactive substances;
  • Not be able to provide adequate informed consent;
  • Any other condition that may compromise the results or that represents any risk to the participant, according to the assessment of the research team and the responsible physician.

Study Protocol, Arms & Participants

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Study Details

  • Status
    Recruiting
  • Phase
    Phase I
  • Type
    interventional
  • Design
    Randomizedtriple Blind
  • Target Enrollment100 participants
  • Timeline
    Start: 2026-04-01
    End: 2027-12-01
  • Compound
    Psilocybin
  • Topic
    Healthy Volunteers

Locations

Centro de Pesquisas Matteo Ricci — Rio de Janeiro, Rio de Janeiro, Brazil

Recent activity

  • StartedChanges in Self-awareness Induced by Psychoactive Substances: an Experimental Study With Psilocybin. (NCT07732166, psilocybin)

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