European Journal of Pharmacology
August 1, 2026
Erik Kaadt, Rolf Søkilde, Hanne Demant Garling et al.
Novel treatment strategies are needed to address treatment resistance and delayed onset of action in psychiatry. Psilocybin has shown promise as a treatment for major depressive disorder, but the molecular changes associated with its effects remain incompletely understood. In parallel, microRNAs (miRNAs) have been implicated in depression and in responses to antidepressant interventions. Here,...
Translational Psychiatry
July 15, 2026
Annette Johansen, Pontus Plavén-sigray, Martin K Madsen et al.
Psychedelics such as psilocybin have been linked to enhanced neuroplasticity and symptom relief in affective disorders, but the neurobiological mechanisms and impact of environmental context remain unclear. Here, we tested whether a single dose of psilocybin (0.3 mg/kg) alters synaptic density in healthy individuals and whether setting-dependent subjective experience shapes this effect. Fifteen...
Molecular Psychiatry
July 8, 2026
Granville J. Matheson, Johan Lundberg, Martin Gärde et al.
The serotonin 1B receptor can be studied in vivo with PET using [^11C]AZ10419369, and has been linked to both the pathophysiology and treatment of major depressive disorder (MDD). Ketamine and electroconvulsive therapy (ECT) both exert rapid and potent antidepressive effects, and although these treatments may not act directly on the serotonin system, they both cause dose-dependent increases in...
Nature Communications
June 24, 2026
Drummond E-Wen Mcculloch, Anders S. Olsen, Brice Ozenne et al.
A prominent theory of psychedelics is that they increase brain entropy. Thirteen studies have evaluated psychedelic effects on fMRI brain entropy, each applying a distinct measure. Here we evaluated these metrics in an independent 28-participant healthy cohort with 121 pre- and post-psilocybin fMRI scans. We assessed relations between brain entropy and objective and subjective psychedelic drug...
Journal of psychopharmacology (Oxford, England)
May 29, 2026
Kristoffer Brendstrup‐brix, Brice Ozenne, Patrick M. Fisher et al.
Patients with chronic cluster headache (CCH) suffer from poor sleep, which may impact their brain microstructure and parenchymal clearance of waste products. Psilocybin has shown promise for the treatment of CCH and has been linked to increased neuroplasticity with possible influences on brain microstructure. To investigate the effects of psilocybin on sleep, brain water diffusivity, and...
bioRxiv
April 13, 2026
Anders S. Olsen, Kristian Larsen, Drummond E. Mcculloch et al.
Abstract Psilocybin and other serotonergic drugs acutely alter human brain function and large-scale connectivity as measured with BOLD fMRI, but whether these effects are frequency-specific remains unknown. We applied multitaper spectral and cross-spectral analyses to resting-state fMRI data from 28 healthy volunteers scanned multiple times acutely following oral psilocybin administration (0.2...
Neuroscience Applied
2026
CA Madsen, M. Navarro, E. Kolesnik et al.
Background: Serotonergic psychedelics induce their psychoactive effects by stimulating the brain’s serotonin 2A receptor (5-HT2AR). In humans, a cerebral 5-HT2AR occupancy of ≥60% is required to elicit a profound psychedelic experience with psilocybin [1] and for pigs, a dose corresponding to ∼65% 5-HT2AR occupancy elicits headshakes [2]. We posit that in order to assess biochemical and...
Research Square
October 10, 2025
Gitte M. Knudsen, Annette Johansen, Pontus Plavén-sigray et al.
Abstract Psychedelics such as psilocybin have been linked to enhanced neuroplasticity and symptom relief in affective disorders, but the neurobiological mechanisms and impact of environmen-tal context remain unclear. Here, we tested whether a single dose of psilocybin alters synap-tic density in healthy individuals and whether setting-dependent subjective experience shapes this effect. Fifteen...
Nature Neuroscience
September 1, 2025
Isak K Aarrestad, Lindsay P. Cameron, Ethan M Fenton et al.
Nonhallucinogenic psychoplastogens, such as tabernanthalog (TBG), are being developed as potentially safer, more scalable alternatives to psychedelics for promoting neuronal growth and treating various brain conditions. Currently, it is unclear whether 5-hydroxytryptamine 2A (5-HT2A) receptors and immediate early gene (IEG) activation have a role in the neuroplasticity-promoting effects of...
medRxiv
June 18, 2025
Drummond E-Wen Mcculloch, Kristian Larsen, Annette Johansen et al.
preprint
In this study, we provide the first study to integrate molecular and functional neuroimaging during psychedelic drug effects in humans. Using simultaneous PET-MRI technology, we describe multiple brain actions of lysergic acid diethylamide (LSD) in healthy volunteers. We quantify the occupancy of LSD at cerebral serotonin 2A receptors and show that LSD increases global cerebral blood flow and...
Journal of Psychopharmacology
February 28, 2025
Dea Siggaard Stenbæk, Emil Deleuran Poulsen, Marie Katrine Klose Nielsen et al.
15 citations
Background: Psilocybin, a serotonin 2A receptor agonist with psychedelic properties, shows promise as a novel treatment for alcohol use disorder (AUD). While current studies involve two dosing sessions, the effects of a single dose have not been investigated. Aims: To investigate the pharmacokinetics, feasibility, safety and efficacy of single-dose psilocybin therapy in AUD. Methods: This...
Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism
February 26, 2025
Kristian Larsen, Ulrich Lindberg, Brice Ozenne et al.
9 citations
Psilocin, the active metabolite of psilocybin, is a psychedelic and agonist at the serotonin 2A receptor (5-HT2AR) that has shown positive therapeutic effects for brain disorders such as depression. To elucidate the brain effects of psilocybin, we directly compared the acute effects of 5-HT2AR agonist (psilocybin) and antagonist (ketanserin) on cerebral blood flow (CBF) using pseudo-continuous...
International review of neurobiology
2025
Paul Cumming, Klemens Egger, Gitte M. Knudsen
2 citations
Molecular brain imaging by positron emission tomography (PET) and single photon emission computer-tomography (SPECT) entails the mapping of the cerebral distribution of radiopharmaceuticals that track physiological processes such as blood perfusion and glucose metabolism, or the abundance in brain of specific molecular targets such as neuroreceptors. PET and SPECT emerged as useful in vivo...
The British Journal of Psychiatry
December 5, 2024
Emma S Høgsted, Vincent Beliveau, Brice Ozenne et al.
4 citations
Background Using [ 18 F]altanserin, a serotonin 2A receptor (5-HT 2A R) antagonist Positron Emission Tomography (PET) tracer, a positive association between cortical 5-HT 2A R binding and the inward-directed facets of neuroticism has been demonstrated in healthy individuals. Psilocybin, a 5-HT 2A R agonist, shows promise for the treatment of depression, reducing neuroticism and mood symptoms...
Research Square
August 23, 2024
Mathias E. Jensen, Dea Siggaard Stenbæk, Catharina Messell et al.
1 citation
Abstract Background Psilocybin, a serotonin 2A receptor agonist with psychedelic properties, shows promise as a novel treatment for alcohol use disorder (AUD). While current studies involve two dosing sessions, the effects a single dose have not been investigated. Aims To investigate the pharmacokinetics, feasibility, safety, and efficacy of single-dose psilocybin therapy in AUD. Methods This...
European Neuropsychopharmacology
August 9, 2024
Friederike Holze, M. Madsen, Claus Svarer et al.
16 citations
The serotonin 2A (5-HT2A) receptor is an important target for drug development and the main receptor through which classical psychedelics elucidate their hallucinogenic effects. The 5-HT2A receptor antagonist ketanserin has frequently been used as a tool to block the receptor. Here, we establish the dose-occupancy relation of ketanserin and the cerebral 5-HT2A receptor in healthy participants...
Research Square
January 12, 2024
Erik Kaadt, Rolf Søkilde, Hanne D. Hansen et al.
Abstract Novel treatment strategies are needed to overcome some of the current challenges related to treatment resistance and treatment latency within the psychiatric field. Recently, psilocybin has shown promise as a novel treatment of major depressive disorder. A single dose of psilocybin is associated with lasting changes in personality and mood. In parallel, various studies have indicated...
Neurosci Appl
January 11, 2024
Drummond E-Wen Mcculloch, Matthias E. Liechti, Kim Pc Kuypers et al.
10 citations
Psychedelic drugs including psilocybin and LSD are undergoing clinical trials for a range of psychiatric and neurological conditions, and have particularly shown substantial promise in phase 2 studies of depression. In this article we outline key knowledge gaps that may be imperative for a successful implementation of psychedelic drugs as medicines as identified by members of the European...
Headache The Journal of Head and Face Pain
2024
Anja Sofie Petersen, Inger Marie Sørensen, Harald Schiønning et al.
29 citations
Abstract Objective To evaluate the feasibility and prophylactic effect of psilocybin as well as its effects on hypothalamic functional connectivity (FC) in patients with chronic cluster headache (CCH). Background CCH is an excruciating and difficult‐to‐treat disorder with incompletely understood pathophysiology, although hypothalamic dysfunction has been implicated. Psilocybin may have...
Neuroscience Applied
December 30, 2023
Sophia Armand, Kristian Larsen, Martin K Madsen et al.
7 citations
The serotonergic psychedelic psilocybin acutely induces changes in emotional states. However, it remains unresolved whether psilocybin acutely modulates amygdala reactivity to emotions, a brain region critically involved in emotion processing. Using functional magnetic resonance imaging (fMRI), we examined in 26 healthy individuals whether amygdala responses to angry, fearful and neutral faces...
medRxiv
July 3, 2023
Drummond E-Wen Mcculloch, Anders S. Olsen, Brice Ozenne et al.
20 citations
preprint
A prominent theory of psychedelics is that they increase brain entropy. Twelve studies have evaluated psychedelic effects on fMRI brain entropy quantifications, no findings have been replicated. Here we evaluated these metrics in an independent 28-participant healthy cohort with 121 pre- and post-psilocybin fMRI scans. We assessed relations between brain entropy and plasma psilocin, brain...
J Neurosci
November 1, 2022
Steven F. Grieco, Eero Castrén, Gitte M. Knudsen et al.
83 citations
Psychedelic drugs have reemerged as tools to treat several brain disorders. Cultural attitudes toward them are changing, and scientists are once again investigating the neural mechanisms through which these drugs impact brain function. The significance of this research direction is reflected by recent work, including work presented by these authors at the 2022 meeting of the Society for...
Neuroimage
October 27, 2022
Anders Lykkebo-Valløe, Brice Ozenne, Sophia Armand et al.
44 citations
Our findings suggest that the acute perceptual psychedelic effects induced by psilocybin may stem from drug-level associated decreases in the occurrence and duration of lateral and medial frontoparietal connectivity motifs. We apply and argue for a modified approach to modeling eigenvectors produced by LEiDA that more fully acknowledges their underlying structure. Together these findings...
Frontiers in Psychology
October 5, 2022
Anna Søndergaard, Brice Ozenne, Sophia Armand et al.
35 citations
Background Psilocybin-induced mystical-type experiences are associated with lasting positive psychological outcomes. Recent studies indicate that trait mindfulness is increased 3 months after psilocybin intake, preceded by decreases in neocortical serotonin 2A receptor (5-HT 2A R) binding. However, the association between psilocybin-induced mystical-type experiences and subsequent changes in...
Translational Psychiatry
August 11, 2022
Nicole Fadahunsi, Jens Lund, Alberte Wollesen Breum et al.
47 citations
Abstract Psilocybin and other serotonergic psychedelics have re-emerged as therapeutics for neuropsychiatric disorders, including addiction. Psilocybin induces long-lasting effects on behavior, likely due to its profound ability to alter consciousness and augment neural connectivity and plasticity. Impaired synaptic plasticity in obesity contributes to ‘addictive-like’ behaviors, including...