Anxiety DisordersDepressive DisordersMicrodosingInterpersonal Functioning & Social Connectedness

Positive expectations predict improved mental-health outcomes linked to psychedelic microdosing

In a prospective web-based study of 81 participants following a four-week psychedelic microdosing regimen, self-reported psychological well‑being, emotional stability, resilience and reductions in anxiety and depressive symptoms were observed. However, baseline positive expectancies strongly predicted these improvements, indicating a substantial placebo contribution and cautioning against strong therapeutic claims.

Authors

  • Robin Carhart-Harris
  • Christopher Timmermann
  • Leor Roseman

Published

Scientific Reports
individual Study

Abstract

Psychedelic microdosing describes the ingestion of near-threshold perceptible doses of classic psychedelic substances. Anecdotal reports and observational studies suggest that microdosing may promote positive mood and well-being, but recent placebo-controlled studies failed to find compelling evidence for this. The present study collected web-based mental health and related data using a prospective (before, during and after) design. Individuals planning a weekly microdosing regimen completed surveys at strategic timepoints, spanning a core four-week test period. Eighty-one participants completed the primary study endpoint. Results revealed increased self-reported psychological well-being, emotional stability and reductions in state anxiety and depressive symptoms at the four-week primary endpoint, plus increases in psychological resilience, social connectedness, agreeableness, nature relatedness and aspects of psychological flexibility. However, positive expectancy scores at baseline predicted subsequent improvements in well-being, suggestive of a significant placebo response. This study highlights a role for positive expectancy in predicting positive outcomes following psychedelic microdosing and cautions against zealous inferences on its putative therapeutic value.

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Study Details

References (40)

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The neurobiology of psychedelic drugs: implications for the treatment of mood disorders

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The pharmacology of lysergic acid diethylamide: a review

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Hutten, N. P. W., Mason, N. L., Dolder, P. C. et al. · International Journal of Neuropsychopharmacology (2019)

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Carhart-Harris, R. L., Roseman, L., Bolstridge, M. et al. · Scientific Reports (2017)

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Show all 40 references
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Predicting responses to psychedelics: a prospective study

Haijen, E. C. H. M., Kaelen, M., Roseman, L. et al. · Frontiers in Pharmacology (2018)

339 cited
Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance

Griffiths, R. R., Richards, W. A., Mccann, U. et al. · Journal of Psychopharmacology (2006)

Mystical experiences occasioned by the hallucinogen psilocybin lead to increases in the personality domain of openness

Maclean, K. A., Johnson, M. W., Griffiths, R. R. · Journal of Psychopharmacology (2011)

The paradoxical psychological effects of lysergic acid diethylamide (LSD)

Carhart-Harris, R. L., Kaelen, M., Bolstridge, M. et al. · Psychological Medicine (2016)

253 cited
Pilot study of psilocybin treatment for anxiety in patients with advanced-stage cancer

Grob, C. S., Danforth, A. L., Chopra, G. S. et al. · JAMA Psychiatry (2011)

Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: A randomized controlled trial

Ross, S., Bossis, A. P., Guss, J. et al. · Journal of Psychopharmacology (2016)

Psilocybin-assisted treatment for alcohol dependence: a proof-of-concept study

Bogenschutz, M. P., Forcehimes, A. A., Pommy, J. A. et al. · Journal of Psychopharmacology (2015)

Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder

Davis, A. K., Barrett, F. S., May, D. G. et al. · JAMA Psychiatry (2021)

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Taking Psychedelics Seriously

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Modern clinical research on LSD

Liechti, M. E. · Neuropsychopharmacology (2017)

Human hallucinogen research: guidelines for safety

Johnson, M. W., Richards, W. A., Griffiths, R. R. · Journal of Psychopharmacology (2008)

Survey study of challenging experiences after ingesting psilocybin mushrooms: Acute and enduring positive and negative consequences

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Microdosing psychedelics: Demographics, practices, and psychiatric comorbidities.

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Prochazkova, L., Lippelt, D. P., Colzato, L. S. et al. · Psychopharmacology (2018)

The effects of microdose LSD on time perception: a randomised, double-blind, placebo-controlled trial

Yanakieva, S., Polychroni, N., Family, N. et al. · Psychopharmacology (2018)

Acute Subjective and Behavioral Effects of Microdoses of Lysergic Acid Diethylamide in Healthy Human Volunteers

Bershad, A. K., Schepers, S. T., Bremmer, M. P. et al. · Biological Psychiatry (2019)

Safety, tolerability, pharmacokinetics, and pharmacodynamics of low dose lysergic acid diethylamide (LSD) in healthy older volunteers

Family, N., Maillet, E. L., Williams, L. T. J. et al. · Psychopharmacology (2019)

The Meaning-Enhancing Properties of Psychedelics and Their Mediator Role in Psychedelic Therapy, Spirituality, and Creativity

Hartogsohn, I. · Frontiers in Human Neuroscience (2018)

Psychometric evaluation of the altered states of consciousness rating scale (OAV)

Studerus, E., Gamma, A., Vollenweider, F. X. · PLOS ONE (2010)

Ego-dissolution and psychedelics: validation of the ego-dissolution inventory (EDI)

Nour, M. R., Evans, J., Nutt, D. J. et al. · Frontiers in Human Neuroscience (2016)

Constructing drug effects: a history of set and setting

Hartogsohn, I. · Drug Science Policy and Law (2017)

389 cited
LSD enhances suggestibility in healthy volunteers

Carhart-Harris, R. L., Kaelen, M., Whalley, M. G. et al. · Psychopharmacology (2014)

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Ramaekers, J. G., Hutten, N. P. W., Mason, N. L. et al. · Journal of Psychopharmacology (2020)

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Psychedelic effects of psilocybin correlate with serotonin 2A receptor occupancy and plasma psilocin levels

Madsen, M. K., Fisher, P. M., Burmester, D. et al. · Neuropsychopharmacology (2019)

Serotonin and brain function: a tale of two receptors

Carhart-Harris, R. L., Nutt, D. J. · Journal of Psychopharmacology (2017)

Low Doses of LSD Acutely Increase BDNF Blood Plasma Levels in Healthy Volunteers

Hutten, N. R. P. W., Mason, N. L., Dolder, P. C. et al. · ACS Pharmacology and Translational Science (2020)

Psychedelics promote structural and functional neural plasticity

Ly, C., Greb, A. C., Cameron, L. P. et al. · Cell Reports (2018)

REBUS and the Anarchic Brain: Toward a Unified Model of the Brain Action of Psychedelics

Carhart-Harris, R. L., Friston, K. J. · Pharmacological Reviews (2019)

Psychedelic microdosing benefits and challenges: an empirical codebook

Anderson, T., Petranker, R., Christopher, A. et al. · Harm Reduction Journal (2019)

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