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Completed

NCT Number: NCT03321136

Role of the Serotonin 5-HT2A Receptor in LSD-induced Altered States of Consciousness (LDR-Study)

Serotonin receptors, especially the 5HT2A receptor, are thought to be involved in the effects of various recreationally used psychedelic substances such as LSD. LSD potently stimulates the 5-HT2A receptor but also 5-HT2B/C, 5-HT1 and dopaminergic receptors. LSD induces acute transient alterations in waking consciousness including visual perceptual alterations, audio-visual synesthesia, derealization and depersonalization. LSD has therefore been used as experimental tool ("psychotomimetic") in modern psychiatric research to study psychotic-like states and model psychosis in healthy subjects [1-5]. However, the dose-effects of 5-HT2A receptor stimulation by LSD has not yet been studied. Additionally, there is still very limited data to what extent the 5HT2A receptor contributes to LSD's effects and its role in the mediation of the full response to LSD at a high dose is unclear. A recent experimental human study showed the 5-HT2A receptor antagonist ketanserin fully blocked the subjective effects of a moderate dose of 100 µg of LSD [6]. But, whether the effects of a high 200 µg oral dose of LSD can be blocked by the selective pharmacological 5-HT2A antagonist ketanserin remains to be tested to confirm the critical role of the 5-HT2A receptor in more pronounced alterations of consciousness and perception. The present study therefore explores the role the 5-HT2A receptor in LSD-induced altered states of consciousness using escalating doses of LSD and the 5-HT2A receptor blocker ketanserin administered before a high dose of LSD.

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Key information

Conditions

Healthy

Age range

25 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Early Phase 1

Primary location

University Hospital

Basel, 4031, Switzerland

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age between 25 and 65 years.
  • Understanding of the German language.
  • Understanding the procedures and the risks associated with the study.
  • Participants must be willing to adhere to the protocol and sign the consent form.
  • Participants must be willing to refrain from taking illicit psychoactive substances during the study.
  • Participants must be willing to drink only alcohol-free liquids and no coffee, black or green tea, or energy drink after midnight of the evening before the study session, as well as during the study day.
  • Participants must be willing not to drive a traffic vehicle or to operate machines within 48 h after substance administration.
  • Women of childbearing potential must have a negative pregnancy test at the beginning of the study. Pregnancy tests are repeated before each study session.
  • Women of childbearing potential must be willing to use double-barrier birth control
  • Body mass index 18-29 kg/m2.

Exclusion criteria

  • Chronic or acute medical condition
  • Current or previous major psychiatric disorder
  • Psychotic disorder in first-degree relatives
  • Illicit substance use (with the exception of cannabis) more than 10 times or any time within the previous two months.
  • Pregnant or nursing women.
  • Participation in another clinical trial (currently or within the last 30 days)
  • Use of medications that may interfere with the effects of the study medications (any psychiatric medications)
  • Tobacco smoking (>10 cigarettes/day)
  • Consumption of alcoholic drinks (>10/week)

Treatment and study plan

LSD

Drug

0.025 mg LSD per os, single dose

Other names: Lysergic Acid Diethylamide

Placebo

Drug

Capsules containing mannitol looking identical to the other drugs.

Primary outcomes

  1. Altered states of consciousness

    Time frame: 18 months

    total 5D-ASC score (5-Dimensional Altered States of Consciousness Rating Scale)

Secondary outcomes

  1. Subjective effects

    Time frame: 18 months

    VAS (Visual analog scales)

  2. Subjective effects

    Time frame: 18 months

    AMRS scales (Adjective mood rating scale)

  3. Psychotomimetic effects

    Time frame: 18 months

    ESI scale (Eppendorf Schizophrenia Inventory)

  4. Mystical-type experiences

    Time frame: 18 months

    MS scales (Mysticism scale)

  5. Mystical-type experiences

    Time frame: 18 months

    SCQ scales (States of consciousness questionnaire)

  6. Autonomic effects

    Time frame: 18 months

    Blood pressure

  7. Autonomic effects

    Time frame: 18 months

    Heart Rate

  8. Autonomic effects

    Time frame: 18 months

    Body temperature

Sponsors and collaborators

Lead sponsor

University Hospital, Basel, Switzerland

Other

Registry information

Acronym: LDR

Important dates

Study start
2017
Primary completion
2019
Study completion
2019
First posted
Oct 25, 2017
Registry last updated
Aug 28, 2019

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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