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David Erritzoe

Perceptive Inc. (formerly Invicro LLC), Hammersmith Hospital, London (Wall, Demetriou, Ertl); Department of Metabolism, Digestion, and Reproduction (Wall, Ertl) and Centre for Psychedelic Research, Division of Psychiatry, Department of Brain Sciences, Faculty of Medicine (Wall, Ertl, Giribaldi, Roseman, Erritzoe, Nutt, Carhart-Harris), Imperial College London; Nuffield Department of Women's and Reproductive Health, University of Oxford, Oxford, UK (Demetriou); Department of Neurology, University of California, San Francisco (Carhart-Harris).

37 papers in the library · 1,039 citations · publishing 2017-2026

Papers

Perturbing whole‐brain models of brain hierarchy: An application for depression following pharmacological treatment

Annals of the New York Academy of Sciences July 21, 2025 Marcel Socoró-garrigosa, Yonatan Sanz Perl, Morten L Kringelbach et al. 3 citations

The scale at which the brain represents information remains a key question in neuroscience. Evidence shows that information is encoded not just in localized areas but across distributed, hierarchical networks. The hierarchy of causal influences shaping brain activity patterns is a signature of different brain states, relevant to neuropsychiatric disorders. Using whole-brain models guided by the thermodynamics of mind framework, researchers estimated brain hierarchy and studied in-silico transitions in static functional connectivity. Applying this to major depressive disorder, they built resting-state whole-brain models of depressed patients before and after treatment with psilocybin or escitalopram.

How to set up a psychedelic study: Unique considerations for research involving human participants.

Neuroscience and biobehavioral reviews July 1, 2026 Marcus J Glennon, Catherine I V Bird, Prateek Yadav et al. 2 citations

Setting up a psychedelic research study involves a long, arduous, and Kafkaesque process with many unstandardised challenges. These complexities challenge existing assumptions about psychiatric prescribing, the placebo effect, and definitions of selfhood. This review brings together major UK psychedelic research teams to formalise these unique considerations, addressing sociocultural, political, legal, pharmacological, safety, study design, and experiential facets. It identifies continuing areas of debate and provides a practical, experience-based guide with recommendations for policymakers and future researchers intending to set up a psychedelic study or clinical trial.

Study Protocol for ‘PsilOCD: A Pharmacological Challenge Study Evaluating the Effects of the 5-HT2A Agonist Psilocybin on the Neurocognitive and Clinical Correlates of Compulsivity’

Cureus January 29, 2025 Sorcha O'Connor, Kate Godfrey, Sara Reed et al. 2 citations

The study aims to uncover the neural mechanisms by which psilocybin-assisted therapy affects obsessive-compulsive disorder (OCD) and whether those brain changes align with improvements in cognitive symptoms. A secondary goal is to test whether a low, tolerable dose is both practical and effective as a clinical treatment. The results will provide essential data for designing a future randomized controlled trial.

Knowledge gaps in psychedelic medicalisation: Preclinical and neuroimaging mechanisms.

Neuroscience applied January 1, 2024 Drummond E-Wen Mcculloch, Juan Pablo Lopez, Christina Dalla et al. 2 citations

Classical psychedelic drugs like psilocybin and LSD stimulate the serotonin 2A receptor and are being investigated for clinical effects in brain disorders. Experts at the ECNP 'New Frontiers meeting' in March 2023 identified key knowledge gaps in psychedelic mechanisms, including the need for appropriate behavioral models, dose optimization, molecular mechanisms, sex differences, and effects on neurotransmitter release and brain activity. The meeting highlighted the importance of preclinical and neuroimaging research to address these gaps.

Evidence for tolerance in psychedelic microdosing from the self-blinding microdose trial

October 19, 2022 Stefan Baumann, Robin Carhart-Harris, David Nutt et al. 2 citations preprint

In a placebo-controlled citizen science trial with 240 participants, microdosing tolerance was assessed by tracking whether correct guesses of receiving a microdose decreased with more doses taken. Correct guess probability declined overall, indicating tolerance developed. This tolerance was specific to LSD and LSD-analogue microdoses, not psilocybin microdoses. The findings suggest that microdosers may need to periodically suspend their routine to avoid tolerance and that psilocybin may be better suited for long-term protocols.

The effects of psilocybin therapy versus escitalopram on cognitive bias: A secondary analysis of a randomized controlled trial.

European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology June 23, 2025 Jessica Henry, Bruna Giribaldi, David J Nutt et al. 1 citation

In patients with major depressive disorder, two high-dose psilocybin therapy sessions produced large increases in optimism and improvements in all three domains of dysfunctional attitudes (achievement, dependency, self-control) at six weeks, while a six-week daily course of escitalopram improved only the achievement domain and did not change optimism. Psilocybin also made patients more optimistic about desirable life events, whereas escitalopram reduced pessimism about negative life events. The findings suggest psilocybin therapy is superior to escitalopram for remediating negative cognitive biases in depression.

Detecting neuroplastic effects induced by ketamine in healthy human subjects: a multimodal approach

bioRxiv Preprint Server May 1, 2025 Claudio Agnorelli, Joseph Peill, Gabriela Sawicka et al. preprint

A single psychedelic dose of ketamine (1 mg/kg, intravenous) alters brain chemistry and connectivity in healthy people for at least one to eight days. After the dose, glutamate levels in the anterior cingulate cortex rose significantly. Functional connectivity decreased within high-order networks such as the default mode network, while integration between low- and high-order networks increased. Increases in a PET marker of synaptic plasticity correlated with reduced intrinsic activity in default mode network regions and a diminished influence of the posterior cingulate cortex on global network dynamics. The posterior cingulate cortex appears to be a central hub through which ketamine may reshape brain hierarchies over the long term.

Correction: Study Protocol for 'PsilOCD: A Pharmacological Challenge Study Evaluating the Effects of the 5-HT2A Agonist Psilocybin on the Neurocognitive and Clinical Correlates of Compulsivity'.

Cureus January 1, 2025 Sorcha O'Connor, Kate Godfrey, Sara Reed et al. correction

A protocol describes a planned study testing whether a low-moderate dose of psilocybin (10 mg), combined with non-interventional therapy, can improve cognitive flexibility and neuroplasticity in people with obsessive-compulsive disorder (OCD). Twenty blinded participants will receive an active placebo (1 mg psilocybin) in a first session and 10 mg in a second session four weeks later. Cognitive flexibility will be measured with the intradimensional-extradimensional shift task two days after each session, and neuroplasticity will be assessed via electroencephalography immediately after each session. Secondary outcomes include OCD symptom severity and patient-reported measures. The results are expected to clarify neural mechanisms and guide a future randomized controlled trial.

Membrane Permeation of Psychedelic Compounds

ChemRxiv Vito Federico Palmisano, Claudio Agnorelli, Andrea Fagiolini et al.

The ability of classic psychedelics to permeate neuronal membranes and reach intracellular 5-HT2A receptors is critical for their therapeutic effects. Using molecular dynamics simulations, this computational study examined how structural modifications to tryptamines affect membrane permeability. Dimethylation of the primary amine group and adding a methoxy group at position 5 increased permeability. In contrast, substitutions at other positions on the indole ring and protonation of the molecules raised the energy barrier at the bilayer center, making the compounds highly impermeable. These findings can guide future drug design to develop psychedelics with enhanced activity.

Micro-phenomenology of immersion and perceived presences under DMT.

Neuroscience of consciousness January 1, 2026 James W Sanders, Raphaël Millière, Ema Demšar et al.

The psychedelic compound DMT induces highly immersive experiences that often include encounters with seemingly sentient presences. Using micro-phenomenology, immersion under DMT was characterized as a structured continuum from subtle to gross forms. Twenty-three participants received 20 mg intravenous DMT during fMRI-EEG, followed by detailed interviews. Analysis yielded 125 phenomenological categories describing structural dimensions like sensory faculties, spatial organization, and self-world configuration. Bodily effects typically preceded visual and auditory ones, and perceived presences emerged only after multisensory integration and 3D spatial characteristics had developed, illustrating a hierarchical relationship between subtle and gross immersion. Perceived presences varied widely in sensory modality, semantic complexity, and relational mode, showing immersion as a dynamic, constructive process.

How to set up a psychedelic study: Unique considerations for research involving human participants

arXiv Preprint Archive March 28, 2025 Marcus J. Glennon, Catherine I. V. Bird, Prateek Yadav et al.

Setting up a psychedelic study is a long and complex process that presents unique challenges not yet standardized. This review brings together major UK research teams to formalize these considerations, identify ongoing debates, and provide a practical guide for researchers and policymakers. It addresses challenges to existing assumptions about psychiatric prescribing, the placebo effect, and definitions of selfhood. The paper can be read end-to-end or used as a manual with sections for specific needs.

Neuroplasticity and Psychedelics: a comprehensive examination of classic and non-classic compounds in pre and clinical models

arXiv Preprint Archive November 29, 2024 Claudio Agnorelli, Meg Spriggs, Kate Godfrey et al.

Psychedelics like LSD and psilocybin can rewire brain connections after just one dose, unlike traditional psychiatric medications. These compounds boost the brain's natural plasticity, helping neurons form new pathways and adapt to change. Studies show they create a window of enhanced learning and adaptation, leading to lasting improvements in mood and behavior.