GlossaryNon-inferiority (trial design)

Non-inferiority (trial design)

A clinical trial design that tests whether a new treatment is no worse than an active comparator by more than a pre-defined margin — rather than testing whether it is better (superiority). The 2021 NEJM psilocybin vs escitalopram trial was a non-inferiority study: psilocybin was found non-inferior to the SSRI on the primary QIDS-SR outcome, meaning it performed at least as well. This is a meaningful finding — not a consolation. Non-inferiority with fewer side effects and a shorter treatment course represents a clinically significant advantage.

Full Explanation

Non-inferiority is a clinical trial design that tests whether a new treatment is no worse than an active comparator by more than a pre-defined margin — rather than testing whether it is better (superiority). The 2021 NEJM psilocybin vs escitalopram trial was a non-inferiority study: psilocybin was found non-inferior to the SSRI on the primary QIDS-SR outcome, meaning it performed at least as well. This is a meaningful finding — not a consolation. Non-inferiority with fewer side effects and a shorter treatment course represents a clinically significant advantage.

See: Psilocybin vs SSRIs (/guides/psilocybin-vs-ssris).

Why It Matters

Understanding non-inferiority helps you read the NEJM trial correctly: psilocybin "as good as" escitalopram is a strong result, especially with a shorter course and different side-effect profile.

Related Guides

Psilocybin vs SSRIs

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Pulse regimen

A dosing schedule used in cluster headache and migraine trials — typically three doses of psilocybin (~10 mg each), administered approximately five days apart, over a two-week period. Distinct from the single high-dose sessions used in depression and PTSD protocols. The therapeutic effect in headache disorders does not correlate with the intensity of the psychedelic experience, suggesting a direct neurological mechanism rather than a psychotherapy-mediated one. (Schindler et al., Journal of Neurological Sciences, 2024)

SSRI discontinuation syndrome

A cluster of symptoms occurring when SSRIs are stopped abruptly or tapered too quickly. Symptoms include dizziness, nausea, flu-like sensations, irritability, insomnia, and "brain zaps" — brief electric shock-like sensations in the head or extremities. Severity varies by drug: highest risk with paroxetine and venlafaxine; lowest with fluoxetine (despite its long washout time). Always requires a clinician-supervised taper. Relevant for anyone considering transitioning from SSRIs to psilocybin therapy.

Afterglow

The period of heightened mood, openness, and mental flexibility that commonly follows a full-dose psilocybin session — typically lasting 24 hours to several weeks. During the afterglow, neuroplasticity is elevated, default mode network activity is altered, and emotional and cognitive patterns are unusually open to change. Considered the critical integration window: therapeutic insights translate into lasting behavior change most effectively during this period. (Majić et al., 2015)

Spores

Reproductive cells produced by mushrooms, used to start new cultures and legal to possess in most US states.

Set and Setting

The combination of mindset (set) and environment (setting) that shapes a psychedelic experience.

Integration

The process of making meaning from a psychedelic experience and applying insights to daily life.