CSF galanin and noradrenaline downregulation by psilocybin therapy in major depressive disorder.

Psilocybin is a rapid-acting antidepressant, but its mechanism of action in major depressive disorder remains unclear. In this secondary analysis of randomized, placebo-controlled trial with multimodal CSF and blood biomarker measurements, psilocybin selectively reduced CSF galanin and noradrenaline, implicating that normalization of these co-transmitters is a key pharmacodynamic signature.