RCT · 2026
Psilocybin lowered two stress-related brain chemicals in spinal fluid in depression trial
- Original title
- CSF galanin and noradrenaline downregulation by psilocybin therapy in major depressive disorder.
- Authors
- Paslawski W, Doyon D, Ekman CJ, et al.
- Journal
- Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 2026
- Molecules
- Psilocybin
- Conditions
- Depression
- Evidence grade
- Low
- Source
- Read the original paper
The question
How does psilocybin work in the brain in major depressive disorder? The researchers looked for chemical signals that change after psilocybin therapy.
What they did
This was a secondary analysis of a randomized, placebo-controlled trial in people with major depressive disorder. Alongside the main trial, the researchers collected cerebrospinal fluid (the fluid that surrounds the brain and spinal cord) and blood, and measured a range of biological markers. They then compared what changed after psilocybin versus placebo.
What they found
Psilocybin selectively lowered two substances in cerebrospinal fluid: galanin, a signalling molecule linked to stress responses, and noradrenaline, a chemical messenger involved in arousal and alertness. The authors suggest that bringing these two co-transmitters back toward normal levels is a key part of how psilocybin acts in the body. The abstract does not report participant numbers, doses, effect sizes or mood outcomes.
The fine print
This is a secondary analysis, meaning it was not the trial’s main question, so the findings are exploratory and need confirmation. The abstract gives no sample size, no measured values and no statistics, so the strength of the effect cannot be judged. Biological markers in spinal fluid are not the same as feeling better, and the abstract does not link these changes to symptom improvement. This summary is based on the abstract only.
What it means
The study points to specific brain chemical changes that may accompany psilocybin therapy for depression, but it describes a possible mechanism rather than showing a clinical benefit.
Evidence grade: Low. This is a secondary biomarker analysis of a randomized placebo-controlled trial, and the abstract gives no sample size or numerical results.
This summary is based on the study’s published abstract.