The aim of this study is to elucidate if the anti-depressive effect of N,N-dimethyltryptamine (DMT) is based on a biological mechanisms including neuroplasticity and anti-inflammatory effect or due to the subjective psychedelic experience.
Major depressive disorder (MDD) affects nearly 20% of people, but current treatments-both pharmacological and psychotherapeutic-have limited efficacy, especially for mild to severe cases. Psychedelics like LSD, psilocybin, and DMT are being explored as alternative therapies, with studies showing promising antidepressant effects. However, it is unclear whether these benefits stem from their acute subjective (psychedelic) experience or from biological mechanisms like neuroplasticity and anti-inflammatory effects. This study aims to determine if the antidepressant effects of DMT occur independently of its psychedelic experience. To test this, DMT will be administered under sedation (with propofol) to mask subjective effects, as well as without sedation.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
112
University Hospital Basel
Basel, Switzerland
RECRUITINGlong term changes in depressive symptoms (MADRS)
Changes in depressive symptoms will be assessed using Montgomery-Asberg-Depression Rating Scale (MADRS). The MADRS is a ten-item questionnaire widely used to measure severity of depressive symptoms during the last week. Total score (range 0-60); higher scores indicate greater depression severity.
Time frame: baseline (before intervention) and on day 14 post-intervention
Short term changes in depressive symptoms (MADRS)
Changes in depressive symptoms will be assessed using Montgomery-Asberg-Depression Rating Scale (MADRS). The MADRS is a ten-item questionnaire widely used to measure severity of depressive symptoms during the last week. Total score (range 0-60); higher scores indicate greater depression severity.
Time frame: Baseline (before intervention) and on day 1, 3 and 7 post-intervention
Changes in depressive symptoms (BDI)
Changes in depressive symptoms will be assessed using Beck Depression Inventory (BDI) questionnaire. Total score (range 0-63); higher scores indicate more severe depressive symptoms.
Time frame: Baseline (before intervention) and on day 1, 3, 7 and 14 post-intervention
Changes in anxiety (STAI)
Changes in anxiety will be assessed using the self-reported State-Trait Anxiety Inventory (STAI) questionnaire. Separate total scores for State Anxiety (S-Anxiety) and Trait Anxiety (T-Anxiety) (each range 20-80); higher scores indicate greater anxiety.
Time frame: Baseline (before intervention) and on day 1, 3, 7 and 14 post-intervention
Changes of clinical global impression (CGI-S)
The clinical global impression (CGI) is an instrument for the assessment of the patient's overall functioning both before and after starting the treatment. Severity of Illness (CGI-S): Rated on a 7-point scale (1 = normal, 7 = among the most extremely ill).
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
no sedation
Time frame: Baseline (before intervention) and on day 1, 3, 7 and 14 post-intervention
Changes of clinical global impression (CGI-I)
The clinical global impression (CGI) is an instrument for the assessment of the patient's overall functioning both before and after starting the treatment. Improvement (CGI-I): Rated on a 7-point scale (1 = very much improved, 7 = very much worse).
Time frame: Baseline (before intervention) and on day 1, 3, 7 and 14 post-intervention
Changes in quality of life (WHOQOL-bref)
Changes in quality of life will be assessed by World Health Organization Quality of life scale (WHOQOL-bref). The WHOQOL-bref is one of the most commonly used self-rating instruments for the assessment of the quality of life and covers different domains of quality of life (physical, psychological, level of independence, social relationships, and environment, and spirituality). Domain scores (Physical, Psychological, Social, Environmental), scaled from 0 to 100; higher scores indicate better quality of life.
Time frame: Baseline (before intervention) and on day 1, 3, 7 and 14 post-intervention
Persisting positive and negative effects (PEQ)
Psychedelics have been shown to produce persisting effects on well-being and appreciation of social relationships on the PEQ.This questionnaire will be used at the EOS visit to assess similar persisting effects of the DMT experience in addition to any effects on depressive symptomatology. Subscale scores (e.g., positive attitudes, mood changes, spirituality), typically rated 0-5 or 0-6; higher scores indicate stronger persisting effects.
Time frame: On day 14 post-intervention
Acute subjective effects (5D-ASC)
The 5 Dimensions of Altered States of Consciousness (5D-ASC) Scale is a questionnaire containing visual analog scales for 94 items. The instrument contains five scales assessing mood, anxiety, derealization, depersonalization, changes in perception, auditory alterations, and reduced vigilance. Each item of the scale is scored on a 0-100 mm VAS. Scores for 5 dimensions (e.g., Oceanic Boundlessness, Anxious Ego Dissolution), range typically 0-100%; higher scores indicate more intense altered states.
Time frame: On day 0 post-intervention
Subjective Effects Rating (SES)
Participants will be asked by the investigator to repeatedly rate their subjective effects verbally on a Likert scale from 0 to 10 for: "any drug effect", "good drug effect", "bad drug effect", and "fear". Ratings will be performed before and repeatedly after substance administration and will take approximately 30 sec to complete. The time course and maximal ratings (Emax, 0-10) are defined for each rating and Emax values compared between treatments using analysis of variance (ANOVAs). Total and subscale scores (range and subscales vary by implementation); higher scores indicate more intense subjective effects.
Time frame: On day 0 pre- and post-intervention
Psychedelic Experience Scale (PES)
In the PES, 100-items are rated on a six-point scale. The PES represents a revalidation of the original 100-item States of Consciousness Questionnaire (SOCQ)
Time frame: On day 0 post-intervention
Emotional breakthrough inventory (EBI)
The Emotional breakthrough inventory (EBI) is a validated instrument with 6 items to assess the degree of emotional breakthrough as a distinct component of the acute psychedelic experience. Total score (range varies); higher scores indicate stronger emotional breakthrough experiences.
Time frame: On day 0 post-intervention
Acute adverse effects
Acute adverse effects wil be assessed by the List of complaints (LC). LC is a self-reporting tool to assess physical and general discomfort. A revised version is used which consists of a 40-item list covering a wide variety of symptoms and complaints that are answered with a four-point intensity-scoring ranging from "not at all" to "strong". Total number or severity of reported somatic and psychological complaints will be evaluated.
Time frame: On day 0 post-intervention
Safety events
Adverse events will be assessed over the whole study period.
Time frame: From day 0 to day 14 post-intervention
Neuroplasticity
brain-derived neurotrophic factor (BDNF), a biomarker for neurogenesis will be quantified in blood samples collected before and 14 days after intervention
Time frame: Baseline (before intervention) and on day 14 post-intervention
Inflammation
Interleukin-1 beta (IL-1β) an immunological factor linked to depression will be quantified in blood samples collected before and 14 days after intervention
Time frame: Baseline (before intervention) and on day 14 post-intervention
DMT plasma concentration
Plasma levels of DMT will be measured once shortly before the end of the perfusion
Time frame: On day 0 shortly before the end of the perfusion
Expectancy (CEQ)
Expectancy will be assessed before the first drug administration. Thus, patients will know at this timepoint whether they get the treatment with or without propofol. To measure expectancy, a modified 2-item version of the Credibility / Expectancy Questionnaire (CEQ) is used. Credibility score (range 3-27).
Time frame: At Baseline before intervention
Expectancy
The Stanford Expectations of Treatment Scale (SETS) will evaluate positive and negative expectancies. Expectancy score (range 3-27 or expressed as a probability %).
Time frame: At Baseline before intervention
Mood
The Adjective Mood Rating Scale (AMRS) is a self-rating scale assessing current mood states. The AMRS will be used to assess mood before the DMT experience. Positive mood and greater acute well-being is expected to positively enhance the acute DMT effects as similarly shown for other psychedelics. Scores for multiple mood dimensions (e.g., energy, mood, agitation); higher scores reflect greater expression of that dimension.
Time frame: At day 0 directly before administration of the study drug
Personality (NEO-FFI)
Personality traits are known to affect subjective responses to psychoactive substances. The NEO Five Factor Inventory (NEO-FFI) will be used during screening to self-assess personality traits. Scores for five domains (Neuroticism, Extraversion, Openness, Agreeableness, Conscientiousness); raw or standardized T-scores.
Time frame: At Baseline before intervention
Personality (TAS)
Personality traits are known to affect subjective responses to psychoactive substances. The Tellegen Absorption Scale (TAS) will be used during screening to self-assess personality traits. Total score (range 0-34 or 0-136, depending on version); higher scores indicate greater trait absorption.
Time frame: At Baseline before intervention