One psilocybin dose alters brain structure

FDA Commissioner Makary resigned; acting Commissioner Kyle Diamantas — a lawyer with no scientific background — has taken over with an unknown stance on CNPV implementation, Right to Try rulemaking, and the June 2023 psychedelic trial guidance still awaiting finalization, per The Microdose. Makary had cited "new guidance to advance psychedelics" among his accomplishments.
Tracy Beth Høeg, acting CDER director, was fired alongside CBER leadership on May 18 in the broadest concurrent FDA scientific leadership removal of the current cycle, raising continuity questions for COMPASS and Usona psilocybin NDA reviews advancing under CNPV acceleration (previously reported: FDA had publicly targeted late summer or fall 2026 for first approval decisions).

A Karolinska Phase 2 RCT (JAMA Network Open; n=35) of 25 mg psilocybin plus 5 psychotherapy sessions found 53% full remission vs. 6% placebo at 6 weeks (MADRS gap of 7.3 points by day 8; effect detectable by day 2). The study enrolled common recurrent MDD — not treatment-resistant — the first psilocybin RCT to do so, extending the potential indication beyond COMPASS's TRD focus. Blinding failed in nearly all participants; 2 of 35 had severe persistent anxiety requiring medical attention.
Cambridge/KCL researchers presented PsiFUND open-label pilot data (n=20) on psilocybin for functional neurological disorder, an indication with no approved pharmacotherapy. Average CDI severity dropped from 4.4 to 3.4; 3 of 20 participants reached near-complete symptom cessation at 3 months. Two had prolonged functional seizures during dosing, consistent with pre-existing FND rather than drug effects. Blinding and expectancy did not predict symptom change; fMRI analysis ongoing.
Filament Health confirmed PEX010 botanical psilocybin shipments for three new Canadian RCTs: a UBC trial in Bipolar II treatment-resistant depression (the first psilocybin RCT targeting this historically excluded population); a Bruyère multi-site Phase 3 in palliative care psychological distress; and a University of Calgary trial using risperidone to block the subjective experience and directly test whether ego dissolution is required for lasting benefit.

A Stanford observational study (Biol. Psychiatry: CNNI; n=30 male Special Ops veterans) found single-dose ibogaine associated with cerebral blood flow increases sustained at 1 month (anterior cingulate cortex and left insula, correlating with improved functioning), reduced amygdala–medial prefrontal connectivity, and a new hippocampus–dorsal attention network pathway. Limitations: observational, no placebo, male-only, veteran-specific population.
Michigan Rep. Jaime Greene (R), a Navy veteran and military sexual trauma survivor, introduced a bill to fund ibogaine research for veterans and opioid addiction treatment — the first such legislation in Michigan, joining Texas, Tennessee, Oklahoma, Arizona, and Mississippi in state-level ibogaine research activity.

An attorney for AIMS Institute formally urged DEA to advance a 2022 petition to reschedule psilocybin from Schedule I to II for terminally ill palliative care patients — forwarded to HHS in August 2025 with no public update since. The letter invokes Trump's EO and FDA's two psilocybin Breakthrough designations as grounds for prompt action.
A International Journal of Molecular Sciences review makes the mechanistic case for 5-HT2A agonism modulating the dopaminergic and noradrenergic circuits implicated in ADHD, but no controlled ADHD trials have been published and the indication holds no FDA Breakthrough Therapy designation for any psychedelic compound.

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