Psilocybin microdosing does not affect emotion-related symptoms and processing: A preregistered field and lab-based study

Journal of Psychopharmacology, vol. 36, pp. 97–113

Abstract

BACKGROUND: Microdoses of psychedelics (i.e. a sub-hallucinogenic dose taken every third day) can reduce symptoms of depression, anxiety and stress according to anecdotal reports and observational studies. Research with medium to high doses of psilocybin points towards potential underlying mechanisms, including the modulation of emotion and interoceptive processing. AIMS: In this preregistered study, we investigated whether psilocybin microdoses alter self-reported interoceptive awareness and whether repeated microdosing over 3 weeks modulates emotion processing and reduces symptoms of anxiety and depression. METHODS: We used a double-blind, placebo-controlled, within-subject crossover design. Participants completed the Multidimensional Assessment of Interoceptive Awareness Questionnaire 1½ h after self-administering their second dose (or placebo), and the emotional go/no-go task and the shortened Depression Anxiety Stress Scale 1½ h after self-administering their seventh dose. RESULTS: Our confirmatory analyses revealed that psilocybin microdosing did not affect emotion processing or symptoms of anxiety and depression compared with placebo. Our exploratory analyses revealed that psilocybin microdosing did not affect self-reported interoceptive awareness, that symptoms of depression and stress were significantly reduced in the first block compared with baseline, that participants broke blind in the second block and that there was no effect of expectations. Further research in a substance-naïve population with clinical range anxiety and depressive symptoms is needed to substantiate the potential beneficial effects of microdosing.

Authors 7

1. Josephine Marschall

   University of Amsterdam

   Affiliation as printed

   Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands

2. George Fejer

   University of Amsterdam

   Affiliation as printed

   Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands

3. Pascal Lempe

   University of Amsterdam

   Affiliation as printed

   Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands

4. Luisa Prochazkova Aachen Department of Psychology, Leiden University

   Leiden University

   Affiliation as printed

   Department of Psychology, Leiden University, Leiden, The Netherlands

5. Martin Kuchař

   National Institute of Mental Health · University of Chemistry and Technology, Prague

   Affiliation as printed

   Department of Experimental Neurobiology, National Institute of Mental Health, Klecany, Czech Republic

   Forensic Laboratory of Biologically Active Substances, Department of Chemistry of Natural Compounds, University of Chemistry and Technology Prague, Prague, Czech Republic

6. Kateřina Hájková

   National Institute of Mental Health · University of Chemistry and Technology, Prague

   Affiliation as printed

   Department of Experimental Neurobiology, National Institute of Mental Health, Klecany, Czech Republic

   Forensic Laboratory of Biologically Active Substances, Department of Chemistry of Natural Compounds, University of Chemistry and Technology Prague, Prague, Czech Republic

7. Michiel van Elk corresponding

   University of Amsterdam

   Affiliation as printed

   Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands