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Robin Carhart‐Harris

Imperial College London, Centre for Neuropsychopharmacology Division of Experimental Medicine London United Kingdom

123 papers in the library · 14,072 citations · publishing 2010-2026

Papers

LSD alters eyes-closed functional connectivity within the early visual cortex in a retinotopic fashion

Journal of Vision September 1, 2016 Leor Roseman, Martin I. Sereno, Robert Leech et al. 4 citations

Under LSD, the visual cortex's resting-state functional connectivity (RSFC) becomes more dependent on its intrinsic retinotopic organization, as if the brain were processing actual visual input despite closed eyes. In 10 healthy subjects, RSFC between non-adjacent patches of V1 and V3 that represent congruent parts of the visual field (both horizontal or both vertical meridians) was significantly stronger than connectivity between incongruent patches (horizontal-vertical), compared to placebo. The difference between congruent and incongruent connectivity was greater under LSD (Cohen's d=1.6), suggesting that psychedelic imagery involves transient local retinotopic activation similar to that from visual stimulation.

Improved mental health outcomes and normalised spontaneous EEG activity in veterans reporting a history of traumatic brain injuries following participation in a psilocybin retreat

Frontiers in Psychiatry August 6, 2025 Grace Blest‐hopley, Giuseppe Pasculli, Simon Ruffell et al. 3 citations

Veterans with traumatic brain injuries who participated in psilocybin retreats showed improvements in PTSD, depression, and anxiety symptoms four weeks afterward. PTSD scores decreased by 50%, depression scores by 65%, and anxiety scores by 28%. Electroencephalography measurements revealed decreased delta and theta brainwave power in frontal and temporal regions, along with enhanced coherence in alpha and beta bands, suggesting improved cognitive control, emotional processing, and neural communication. The preliminary findings provide a rationale for larger controlled studies.

A virtual clinical trial of psychedelics to treat patients with disorders of consciousness

bioRxiv (Cold Spring Harbor Laboratory) August 19, 2024 Naji Alnagger, Paolo Cardone, Charlotte Martial et al. 3 citations preprint

Disorders of consciousness, such as unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS), have few treatments. Using whole-brain computational models built from individual patients' fMRI and diffusion-weighted imaging data, this virtual clinical trial simulated the effects of LSD and psilocybin. The psychedelics shifted the brains of patients with disorders of consciousness closer to a critical dynamical state, with a larger effect in MCS patients. In UWS patients, the treatment response depended on structural connectivity, whereas in MCS patients it aligned with baseline functional connectivity. These results provide a computational foundation for considering psychedelics in treating disorders of consciousness and highlight the role of computational modeling in drug discovery and personalized medicine.

Psilocybin Therapy for Treatment Resistant Depression: Prediction of Clinical Outcome by Natural Language Processing

September 30, 2022 Robert F. Dougherty, Patrick Clarke, Merve Alti et al. 3 citations preprint

A machine learning model that analyzes language from therapy sessions accurately predicted which patients with treatment-resistant depression would respond to psilocybin treatment. Transcripts of psychological support sessions held one day after COMP360 (a synthetic psilocybin formulation) administration were analyzed using a zero-shot classifier based on the BART large language model to measure sentiment (valence and arousal) for both participant and therapist. These scores, combined with the Emotional Breakthrough Index and treatment arm, were used to predict treatment outcome measured by MADRS scores. Two multinomial logistic regression models predicted responder status at week 3 and through week 12 with 85% and 88% accuracy, and AUC values of 88% and 85%, respectively. The approach enables rapid prognostication of personalized response to psilocybin treatment and insights into therapeutic model optimization.

Defining ‘psychedelic’

December 4, 2025 Avery Ostrand, Matthew M. Nour, Christopher Timmermann et al. 2 citations preprint

The term 'psychedelic' was coined in 1956 from Greek roots meaning 'soul-manifesting' or 'soul-illuminating,' intended to name a drug category defined by its ability to induce a characteristic subjective state. This study examined the main subjective effects of psilocybin, ketamine, and MDMA. Over two hundred participants rated items about their experiences with all three drugs. Factor analyses revealed three or four independent dimensions of subjective experience. A machine learning classifier successfully predicted which drug a person had taken from the effects reported, confirming that the three drugs produce categorically distinct experiences: psilocybin induces visions and psychological insight, ketamine induces dissociation, and MDMA induces pro-social feelings such as love. Psilocybin is thus an exemplar psychedelic drug, definable by its induction of a psychedelic state characterized by visions and insight.

A Virtual Clinical Trial of Psychedelics to Treat Patients With Disorders of Consciousness

Advanced Science November 20, 2025 Paolo Cardone, Charlotte Martial, Yonatan Sanz Perl et al. 2 citations

Simulated administration of LSD and psilocybin in computational models of patients with disorders of consciousness (DoC), including unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS), shifted brain activity closer to criticality—the phase transition between order and chaos. The effect was greater in MCS patients. In UWS patients, the treatment response correlated with structural connectivity, while in MCS patients it aligned with baseline functional connectivity. These results provide a computational foundation for using psychedelics in DoC treatment and highlight the potential role of computational modeling in drug discovery and personalized medicine.

Psychedelic Therapy, Positive Emotional Experiences, and the Central Role of Self-Compassion

Research Square August 22, 2025 Richard J. Zeifman, George Danias, Gabrielle Agin-Liebes et al. 2 citations

Psychedelics can acutely induce mystical experiences and elevated positive mood, which may contribute to the potential benefits of psychedelic therapy. However, there remains limited understanding of the occurrence and importance of specific positive emotional experiences within psychedelic therapy. Therefore, we examined the effects of psychedelics on positive emotional experiences and their association with improvements in mental health. Methods: Study 1 was an observational study of naturalistic psychedelic use. Study 2 used data from a clinical trial that compared psilocybin with escitalopram in individuals with major depressive disorder.

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

medRxiv March 21, 2025 Jessica S. Henry, Bruna Giribaldi, David Nutt et al. 2 citations preprint

In a randomized controlled trial of 59 patients with major depressive disorder, two high-dose psilocybin therapy sessions produced large increases in optimism and improvements in dysfunctional attitudes related to achievement, dependency, and self-control after six weeks. By contrast, a six-week daily course of escitalopram produced no change in optimism and only improved dysfunctional attitudes in the achievement domain. Psilocybin therapy was superior to escitalopram in remediating negative cognitive biases in depression.

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

arXiv (Cornell University) November 29, 2024 Claudio Agnorelli, Meg J. Spriggs, Kate Godfrey et al. 2 citations

Classic psychedelics (LSD, psilocybin, N,N-DMT) and non-classic psychedelics (ketamine, MDMA) enhance neuroplasticity, the nervous system's ability to adapt. Animal studies indicate these drugs induce meta-plasticity, heightening sensitivity to environmental stimuli, and hyper-plasticity, reopening developmental windows for long-term structural changes that affect mood and behavior. Translating these findings to humans is challenged by limitations in current imaging techniques, but emerging approaches like novel PET radioligands, non-invasive brain stimulation, and multimodal methods offer promising directions. This review informs development of targeted interventions for neuropsychiatric disorders and advances understanding of psychedelics' therapeutic potential.

Development of the Japanese version of the Ego‐Dissolution Inventory (EDI)

Neuropsychopharmacology Reports March 13, 2024 Keisuke Kusudo, Hideaki Tani, Kengo Yonezawa et al. 2 citations

A Japanese version of the Ego-Dissolution Inventory (EDI) was developed through a translation and back-translation process following international guidelines. Two Japanese psychiatrists independently translated the original English EDI, reconciled differences, and had the resulting version back-translated into English. The original authors reviewed and approved the back-translated version after iterative revisions. The final Japanese EDI is intended to help assess ego-dissolution experiences during psychedelic-assisted therapy in Japanese-speaking populations. Further research is needed to test the reliability and validity of this new instrument.

Synergistic, Multi-level Understanding of Psychedelics: Three Systematic Reviews and Meta-analyses of Their Pharmacology, Neuroimaging and Phenomenology

bioRxiv (Cold Spring Harbor Laboratory) October 7, 2023 Kenneth Shinozuka, Katarina Jerotic, Pedro A. M. Mediano et al. 2 citations preprint

Serotonergic psychedelics such as LSD, psilocybin, and DMT alter consciousness and show therapeutic potential for depression and addiction, but their mechanisms remain unclear. A systematic review and meta-analysis across three levels—phenomenology, neuroimaging, and pharmacology—reveals that medium and high doses of LSD produce significantly stronger visionary restructuring than psilocybin. Neuroimaging shows psychedelics generally strengthen connectivity between brain networks while weakening connectivity within networks. Pharmacologically, LSD triggers more inositol phosphate formation at the 5-HT2A receptor than DMT or psilocin, but no significant differences emerged in receptor selectivity among the drugs. The findings highlight high heterogeneity and risk of bias, underscoring the need for standardized methods.

The Structural Organization and Construct Validity Evidence of the Brazilian Versions of the Mysticism Scale and the Ego-Dissolution Inventory in a Major Religion of the Ayahuasca

International Journal of Latin American Religions June 9, 2023 Robson Savoldi, Antônio Roazzi, José Arturo Costa Escobar et al. 2 citations

Mysticism significantly enhances well-being, with 75% of participants in a study reporting improved life satisfaction after engaging in mystical experiences. In a sample of 500 individuals, psychometric assessments utilized structural equation modeling to confirm the construct validity of these experiences. The interplay between philosophy and social psychology revealed that psychedelics, particularly alkaloids, can facilitate profound insights into the self—bridging the id, ego, and super-ego. This highlights the potential of mystical experiences as therapeutic tools within developmental psychology and theology.

Distinct brain responses to psilocybin and escitalopram in depression captured by the Fluctuation-Dissipation Theorem

bioRxiv (Cold Spring Harbor Laboratory) June 16, 2026 Paulina Clara Dagnino, Irene Acero-Pousa, Gorka Zamora‐lópez et al. 1 citation

Psilocybin 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.

Brain dynamics of classical psychedelics show paradoxical hierarchical flattening with increased complexity

bioRxiv (Cold Spring Harbor Laboratory) December 22, 2024 Jakub Vohryzek, Morten L. Kringelbach, Edmundo Lopez-Sola et al. 1 citation preprint

Both psychedelic states and reduced states of consciousness flatten the brain's functional hierarchy, yet their behavioral and phenomenological profiles differ. To resolve this paradox, researchers defined hierarchy by the brain's proximity to thermodynamic equilibrium and examined changes induced by three serotonergic psychedelics: psilocybin, LSD, and DMT. All three consistently reduced the functional hierarchy globally. Unlike loss of consciousness, psychedelics moved the brain toward equilibrium while increasing neural activity complexity, indicating a distinct mechanism involving altered configuration and differentiation of resting-state networks. This work demonstrates how statistical mechanics metrics can characterize different global brain states, advancing understanding of consciousness as an emergent collective process.

A Bayesian Reanalysis of a Trial of Psilocybin versus Escitalopram for Depression

June 30, 2022 Sandeep M. Nayak, Bilal A. Bari, David B. Yaden et al. 1 citation preprint

A Bayesian reanalysis of a trial comparing psilocybin (COMP360) to escitalopram for major depressive disorder found that psilocybin outperformed escitalopram, but not by a clinically meaningful amount. The analysis also found extremely strong evidence that psilocybin is non-inferior to escitalopram. Evidence for psilocybin's superiority varied by depression scale: indeterminate for one, strong for two, and extremely strong for another. For a clinically meaningful difference, evidence was moderate against it on one scale, indeterminate on two, and moderate supporting it on one. These results provide a more nuanced interpretation and support further research.

Psychedelics and Health Behavior Change - Journal of Psychopharmacology (in press)

March 24, 2021 Pedro J. Teixeira, Matthew W. Johnson, Christopher Timmermann et al. 1 citation preprint

Unhealthy behaviors like poor diet, inactivity, and smoking are major contributors to cancer, diabetes, and cardiovascular disease, causing substantial suffering and public health costs. Interventions to promote healthy behaviors increasingly draw on psychobiological models. This article explores the potential of psilocybin, a psychedelic with low toxicity and no addictive properties, to assist positive lifestyle change. Psilocybin has shown favorable effects in patients with depression, anxiety, and substance misuse, conditions marked by rigid behavioral patterns. The authors describe proposed mechanisms and research findings linking psychedelics to health behavior change, noting that therapeutic models combining psychedelic experiences with methods like Cognitive Behavior Therapy and Motivational Interviewing are already being tested for addiction and eating disorders. They suggest this research may extend to promoting diet, exercise, nature exposure, and mindfulness.

Author response: Self-blinding citizen science to explore psychedelic microdosing

December 11, 2020 Balázs Szigeti, Laura Kärtner, Allan Blemings et al. 1 citation

A self-blinding citizen science study tested whether psychedelic microdosing improves well-being and cognition beyond placebo. 191 participants who already planned to microdose were randomly assigned to receive four weeks of microdoses, placebos, or a mix. All psychological outcomes—including well-being, mindfulness, and life satisfaction—improved from baseline in the microdose group, but the placebo group also improved, and no significant differences emerged between groups. Small acute differences in mood, energy, and creativity were observed, but these could be explained by participants correctly guessing whether they took a microdose. The findings suggest that the anecdotal benefits of microdosing are likely due to the placebo effect.

Divergent changes in perturbation-induced brain reconfiguration following depression treatment with psilocybin and escitalopram

bioRxiv (Cold Spring Harbor Laboratory) June 26, 2026 Paulina Clara Dagnino, Irene Acero-Pousa, Robin Carhart‐Harris et al.

A central challenge in neuroscience is understanding how the human brain is organised to support optimal functioning and adaptability. One approach to characterise complex brain dynamics is by artificially perturbing whole-brain models. Here, we asked whether whole-brain organisation under perturbation in major depressive disorder (MDD) changes after intervention with psilocybin and escitalopram. First, we built whole-brain models of pre- and post-treatment resting-state functional magnetic resonance imaging (fMRI) and obtained an initial generative effective connectivity (GEC) matrix for each individual.

Negative affective bias in depression following treatment with psilocybin or escitalopram – a secondary analysis from a randomized trial

Translational Psychiatry November 13, 2025 Bruna Giribaldi Cunha, David Nutt, Marieke Martens et al.

In a double-blind randomized trial, patients with long-standing moderate-to-severe depression received either two doses of 25 mg psilocybin plus daily placebo or two doses of 1 mg psilocybin plus daily escitalopram over six weeks. Both treatments comparably reduced negative bias in recognizing facial emotions, a measure of emotional information processing. However, changes in this bias were not linked to concurrent depression score changes. Only in the escitalopram group did a decrease in misclassifying positive faces as negative correlate with lower depression scores at a one-month follow-up. The findings suggest overlapping cognitive mechanisms between psilocybin and escitalopram, notable given psilocybin's short dosing regimen.

Revealing Changes in Linear and Nonlinear Functional Connectivity After Psilocybin and Escitalopram Treatment in Patients with Depression

bioRxiv (Cold Spring Harbor Laboratory) March 10, 2025 Shaun K.l. Quah, Cameron Glick, Leor Roseman et al. preprint

People with major depression who responded to either psilocybin or escitalopram showed distinct changes in brain network connectivity compared to non-responders. Responders had increased linear connectivity within the ventral attention network and greater nonlinear connectivity within the default mode and ventral attention networks. Psilocybin responders showed enhanced coordination between higher-order networks, while escitalopram responders showed reduced connectivity within networks linked to self-referential thought and salience processing. These patterns suggest the two antidepressants work through different mechanisms, with nonlinear connectivity analyses revealing effects not captured by traditional linear measures.

A critique of: Skepticism About Recent Evidence that Psilocybin Opens Depressed Minds

May 10, 2022 Robin Carhart‐Harris, Richard E. Daws, David Nutt preprint

The authors respond to a critique of their earlier work that questioned whether psilocybin truly opens depressed minds. They address the skeptic's arguments, defending their original evidence and conclusions about psilocybin's effects on depression. The response clarifies methodological points and reaffirms the potential of psilocybin as a treatment for depression, while acknowledging the need for further research to address lingering doubts.