> In a phase 2, double-blind, randomized, controlled trial

It seems like you can't blind the participants in this case? It should be obvious if you're getting the treatment because psilocybin is a hallucinogen, unless they're giving such a small dose that it reliably doesn't cause any hallucinations?

This is important because most (70-80%) of the effect of existing anti-depressants is known to be placebo, and there's already concern that you can't blind in regular anti-depressant trials because the participant might know they receive treatment due to feeling the side effects of the drug (e.g. insomnia). The problem of being unable to blind participants would seem to be magnified in a psilocybin trial.