FDA will publicly reference functional-unblinding methodology when discussing COMPASS-class psilocybin data this fall, tempering approval expectations.

When people take psilocybin in a clinical trial, they almost always know they got the real drug — not a placebo — because the effects are so obvious. Regulators at the FDA are expected to formally flag this problem when reviewing data from COMPASS Pathways' psilocybin trials for treatment-resistant depression. This is a big deal because if patients know they got the drug, their improvement might partly come from expectation rather than the drug itself, making results harder to trust.

Regulators must address expectancy bias before any classic psychedelic label; the TRD readouts force the issue.