Distinct brain responses to psilocybin and escitalopram in depression captured by the Fluctuation-Dissipation Theorem
Paulina Clara Dagnino, Irene Acero-Pousa, Gorka Zamora‐lópez, Anira Escrichs, David Erritzøe, David Nutt, Robin Carhart‐Harris, Yonatan Sanz Perl, Morten L. Kringelbach, Gustavo Deco
bioRxiv (Cold Spring Harbor Laboratory) June 16, 2026 DOI: 10.64898/2026.06.12.731811 via OpenAlex
Summary
AI-generated from the abstractPsilocybin and the conventional antidepressant escitalopram produce opposite changes in the brain's hierarchical non-equilibrium dynamics when treating major depressive disorder. Using resting-state fMRI before and after treatment, researchers built whole-brain models and measured how much each patient's brain activity deviated from the fluctuation-dissipation theorem. Baseline measures distinguished treatment responders from non-responders within each group. The deviation from the fluctuation-dissipation theorem may serve as a marker to differentiate the brain effects of psilocybin and escitalopram, contributing to understanding how these treatments work for depression.
Study at a glance
| Characteristics | Double-blind randomised controlled trial Randomized Peer reviewed |
|---|---|
| Population | Patients with major depressive disorder |
| Interventions | Psilocybin Escitalopram |
| Topics | Default mode network Depression Psilocybin |
| Keywords | Escitalopram Depression economics Hallucinogen |
| Citations | 1 |
| Registration | NCT03429075 |
| Key finding | Psilocybin and escitalopram produce opposite reconfigurations of hierarchical non-equilibrium brain dynamics in major depressive disorder treatment. |
Abstract
Abstract In recent decades, the psychedelic psilocybin has been studied as a potential treatment for major depressive disorder (MDD), offering an alternative to traditional antidepressants. However, the brain changes underlying the clinical effects of different interventions remain unclear. Here, we investigated the effects of psilocybin and a conventional antidepressant, escitalopram, from the double-blind randomised controlled trial (DB-RCT) - NCT03429075 - on the brain’s hierarchical organisation. Using pre- and post-treatment resting-state functional magnetic resonance imaging (fMRI) we built whole-brain models and obtained a generative effective connectivity (GEC) matrix for each patient. Based on the GEC, we measured the level of non-equilibrium brain dynamics by quantifying the deviation from the fluctuation-dissipation theorem (FDT) and performed complementary analysis on brain segregation and asymmetry. Our results showed opposite reconfigurations of the hierarchical non-equilibrium brain dynamics following each treatment. Additionally, baseline measures effectively distinguished responders from non-responders within each treatment. These findings suggest that the deviation of the FDT may serve as a marker for differentiating the effects of psilocybin and escitalopram in MDD treatment, overall, contributing to the understanding of therapeutic mechanisms of depression.