Psilocybin microdosing did not change emotion processing or anxiety and depression in a preregistered trial
75 people microdosed psilocybin truffles or placebo in a blinded crossover over two months. Confirmatory tests found no effect on emotion processing, anxiety or depression. Participants broke blind in the second block.
Well-supported by good-quality research. how we score evidence
Caveat on this rating: Crossover with heavy dropout; participants broke blind in the second block; experienced, non-clinical sample.
A preregistered, placebo-controlled test of the claim most often made for psilocybin microdosing: that it eases anxiety and low mood.
Significant findings
Marschall and colleagues (Journal of Psychopharmacology, 2022) used a double-blind, placebo-controlled, within-subject crossover design: each participant spent one block on psilocybin microdoses and one on placebo, about three weeks each. Of 75 initial participants, 56 completed the final session. The authors' confirmatory analyses "revealed that psilocybin microdosing did not affect emotion processing or symptoms of anxiety and depression compared with placebo." Exploratory analyses found no effect on interoceptive awareness either.
The other direction
Two findings cut the other way, and the authors report both. Symptoms of depression and stress "were significantly reduced in the first block compared with baseline", in both conditions, which is what a placebo or an expectation effect looks like. And "participants broke blind in the second block", which means the second half was no longer a clean test. Dropout was large and the authors say the study may have been underpowered. Participants were experienced users who chose to microdose, not people with clinical anxiety or depression, and the authors call for that trial next. The authors declared no conflicts and no external funding.
What this does not show
It does not show microdosing is harmful, and it does not show it works. Psilocybin is a Schedule I substance with no approved use.
Worth asking
If I felt better while microdosing, how would I know whether it was the dose or the expectation?
Source
Psilocybin microdosing does not affect emotion-related symptoms and processing: A preregistered field and lab-based study — Marschall J, Fejer G, Lempe P, Prochazkova L, Kuchar M, Hajkova K, van Elk M (2022)
Reputable peer-reviewed journal
Read the source: https://doi.org/10.1177/02698811211050556
DOI: 10.1177/02698811211050556
How this was scored
- Study design
- Randomised controlled trial
- Funding
- No external funding
- Published in
- Reputable peer-reviewed journal
- Sample size
- 75
- Preregistered
- Yes
- Conflicts disclosed
- Yes
- Independent of proponent
- not recorded
- Retracted
- No
Read the full scoring rubric, including what it can't tell you.
Published October 21, 2026.
Questions
How strong is the evidence behind this?
veisund rates this source "strong evidence". Well-supported by good-quality research. It scores 79 out of 100 on our published rubric. One caveat travels with that badge: Crossover with heavy dropout; participants broke blind in the second block; experienced, non-clinical sample. The score is calculated from recorded facts about the source — study design, funding, publication venue, sample size, preregistration — not typed in by an editor.
What is the source for this?
Psilocybin microdosing does not affect emotion-related symptoms and processing: A preregistered field and lab-based study — Marschall J, Fejer G, Lempe P, Prochazkova L, Kuchar M, Hajkova K, van Elk M (2022). Published in: Reputable peer-reviewed journal. DOI: 10.1177/02698811211050556. The full source is linked on this page so you can read it yourself.
Who paid for this research, and does that matter?
Study design: Randomised controlled trial. Funding: No external funding. Independence from the proponent is not recorded. Industry sponsorship is one of the most reliably measured biases in medicine, which is why funding carries real weight in the score rather than sitting in a footnote.
Is this medical advice?
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.