What we mean when we say a drug "works"
Psychedelic trials report dramatic numbers. Understanding what those numbers measure — and what they quietly leave out — is the first step to reading them honestly.
Every few months a headline announces that a psychedelic compound has produced "unprecedented" results for depression, addiction or trauma. The effect sizes are often genuinely large. They are also frequently misunderstood — by readers, by reporters, and sometimes by the people running the studies.
This is not an argument that the research is weak. Much of it is careful and promising. It is an argument that promising is a specific, limited claim, and that learning to hear it precisely is the most useful skill a curious person can bring to this field.
A result is a sentence with hidden clauses
When a trial reports that a single dose "reduced depression scores by 50 per cent at six weeks", several quieter facts travel underneath that sentence: how many people were studied, who they were, what the comparison group received, how long anyone was followed, and how many dropped out before the end.
A number without its denominator is a rumour with a decimal point.
Small early-phase studies exist to detect whether an effect is plausible, not to measure it accurately. The honest reading of an exciting Phase 2 result is not "this works" but "this is worth the expense and risk of finding out properly".
The unblinding problem
Psychedelics present researchers with an awkward fact: people generally know whether they have taken one. That breaks the blind that ordinary drug trials rely on, and expectation is a powerful medicine in its own right. Good teams now design around this — active placebos, independent raters, careful measurement of what participants believed they received — but a study that ignores it should be read with that gap in mind.
What good evidence will look like
- Larger samples that include the people clinicians actually treat, not only the unusually well and unusually motivated.
- Longer follow-up, because durability is the whole question for a one- or two-dose treatment.
- Honest accounting of harms, including the difficult or destabilising experiences that averages tend to hide.
None of this is a reason for despair, and none of it is a reason for hype. The field is young. The most respectful thing we can do for it — and for the people waiting on it — is to describe it accurately while it grows up.