Psilocybin beat placebo on depression scores in an NHS trial — by a lot

Key Findings

🍄 Psilocybin Was Tolerable for Phantom Limb Pain — a First

• A placebo-controlled pilot randomized 9 people with phantom limb pain to a single 25 mg dose of psilocybin or a niacin control. No serious adverse events or emergent suicidality occurred.
• Two participants reported nausea, three reported headache, and blood pressure bumps resolved before discharge. Exploratory pain ratings trended downward at 2 and 4 weeks post-dose, though the tiny sample makes those signals hard to interpret.

🧬 LSD Slowed Colorectal Tumor Growth in Mice — Without Entering the Brain

• Researchers found that LSD activates serotonin receptors on enteric glial cells in the gut, triggering chemical signals that recruit cancer-killing CD8+ T cells into colorectal tumors. They then built a compound designed to hit only peripheral receptors — skipping the brain entirely.
• In mouse models, that compound suppressed tumor growth and made tumors more responsive to a standard checkpoint immunotherapy. The psychedelic effect was not required for the antitumor activity.

🐭 New Engineered Mice Will Help Decode How Psychedelics Actually Work

• A research team published a suite of genetically modified mouse lines designed to map exactly which brain cells carry the serotonin receptor that psychedelics activate, and what those cells do when stimulated.
• In brain slice recordings, a psychedelic compound drove robust increases in firing of genetically identified pyramidal neurons — the kind of direct, cell-type-specific evidence that standard pharmacology can't easily produce.

💊 Most Veterans with PTSD Have at Least One Complication for MDMA Therapy

• A national study of over 300,000 U.S. veterans treated for PTSD each year found that 15–17% had at least one outright contraindication to MDMA-assisted therapy, and 55–58% had at least one conditional risk factor requiring evaluation.
• More striking: 86–88% were already taking a medication that could interact with MDMA. Many risk factors are modifiable, but the scale of the management challenge is larger than earlier trial populations suggested.

🧪 The Molecular Pathway Hyped for Psychedelic Plasticity Has a Complicated Report Card

• A mouse study tested whether β-arrestin2 — a signaling protein increasingly cited as key to psychedelics' therapeutic effects — actually drives the behaviors and brain changes researchers care about.
• Knocking out the protein had no clear effect on the head-twitch response (a proxy for hallucinogenic activity) or plasticity-related gene expression. It did reduce psilocybin- and DOI-induced dendrite growth in cultured neurons, suggesting the pathway may matter for structural plasticity but not for the acute psychedelic signature.

🌙 Hormonal Cycles May Shift How Women Respond to Psychedelics

• A narrative review synthesized evidence that estradiol and progesterone influence the liver enzymes that break down psilocybin and LSD, and also modulate the density of the serotonin receptor those drugs primarily target — with receptor availability appearing higher in low-progesterone states.
• No clinical trials have directly tested psychedelic dosing across menstrual phases, so the review is raising a question rather than answering one: current trial designs may be averaging over a meaningful source of variability.