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Egger K, Aicher HD, Cumming P, Scheidegger M. Neurobiological research on N,N-dimethyltryptamine (DMT) and its potentiation by monoamine oxidase (MAO) inhibition: from ayahuasca to synthetic combinations of DMT and MAO inhibitors. Cell Mol Life Sci 2024; 81:395. [PMID: 39254764 DOI: 10.1007/s00018-024-05353-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 06/19/2024] [Accepted: 07/04/2024] [Indexed: 09/11/2024]
Abstract
The potent hallucinogen N,N-dimethyltryptamine (DMT) has garnered significant interest in recent years due to its profound effects on consciousness and its therapeutic psychopotential. DMT is an integral (but not exclusive) psychoactive alkaloid in the Amazonian plant-based brew ayahuasca, in which admixture of several β-carboline monoamine oxidase A (MAO-A) inhibitors potentiate the activity of oral DMT, while possibly contributing in other respects to the complex psychopharmacology of ayahuasca. Irrespective of the route of administration, DMT alters perception, mood, and cognition, presumably through agonism at serotonin (5-HT) 1A/2A/2C receptors in brain, with additional actions at other receptor types possibly contributing to its overall psychoactive effects. Due to rapid first pass metabolism, DMT is nearly inactive orally, but co-administration with β-carbolines or synthetic MAO-A inhibitors (MAOIs) greatly increase its bioavailability and duration of action. The synergistic effects of DMT and MAOIs in ayahuasca or synthetic formulations may promote neuroplasticity, which presumably underlies their promising therapeutic efficacy in clinical trials for neuropsychiatric disorders, including depression, addiction, and post-traumatic stress disorder. Advances in neuroimaging techniques are elucidating the neural correlates of DMT-induced altered states of consciousness, revealing alterations in brain activity, functional connectivity, and network dynamics. In this comprehensive narrative review, we present a synthesis of current knowledge on the pharmacology and neuroscience of DMT, β-carbolines, and ayahuasca, which should inform future research aiming to harness their full therapeutic potential.
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Affiliation(s)
- Klemens Egger
- Department of Adult Psychiatry and Psychotherapy, Psychiatric University Clinic Zurich and University of Zurich, Zurich, Switzerland.
- Neuroscience Center Zurich, University of Zurich and Swiss Federal Institute of Technology Zurich, Zurich, Switzerland.
- Department of Nuclear Medicine, Bern University Hospital, Bern, Switzerland.
| | - Helena D Aicher
- Department of Adult Psychiatry and Psychotherapy, Psychiatric University Clinic Zurich and University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and Swiss Federal Institute of Technology Zurich, Zurich, Switzerland
- Department of Psychology, University of Zurich, Zurich, Switzerland
| | - Paul Cumming
- Department of Nuclear Medicine, Bern University Hospital, Bern, Switzerland
- School of Psychology and Counselling, Queensland University of Technology, Brisbane, Australia
| | - Milan Scheidegger
- Department of Adult Psychiatry and Psychotherapy, Psychiatric University Clinic Zurich and University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and Swiss Federal Institute of Technology Zurich, Zurich, Switzerland
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2
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Ait Bentaleb K, Boisvert M, Tourjman V, Potvin S. A Meta-Analysis of Functional Neuroimaging Studies of Ketamine Administration in Healthy Volunteers. J Psychoactive Drugs 2024; 56:211-224. [PMID: 36921026 DOI: 10.1080/02791072.2023.2190758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 02/22/2023] [Indexed: 03/17/2023]
Abstract
Ketamine administration leads to a psychotomimetic state when taken in large bolus doses, making it a valid model of psychosis. Therefore, understanding ketamine's effects on brain functioning is particularly relevant. This meta-analysis focused on neuroimaging studies that examined ketamine-induced brain activation at rest and during a task. Included are 10 resting-state studies and 23 task-based studies, 9 of which were measuring executive functions. Using a stringent statistical threshold (TFCE <0.05), the results showed increased activity at rest in the dorsal anterior cingulate cortex (ACC), and increased activation of the right Heschl's gyrus during executive tasks, following ketamine administration. Uncorrected results showed increased activation at rest in the right (anterior) insula and the right-fusiform gyrus, as well as increased activation during executive tasks in the rostral ACC. Rest-state studies highlighted alterations in core hubs of the salience network, while task-based studies suggested an impact on task-irrelevant brain regions. Increased activation in the rostral ACC may indicate a failure to deactivate the default mode network during executive tasks following ketamine administration. The results are coherent with alterations found in schizophrenia, which confer external validity to the ketamine model of psychosis. Studies investigating the neural mechanisms of ketamine's antidepressant action are warranted.
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Affiliation(s)
- Karim Ait Bentaleb
- Centre de recherche de l'Institut Universitaire en Santé Mentale de Montréal, Montréal, Canada
- Department of psychiatry and addiction, Université de Montréal, Montréal, Canada
| | - Mélanie Boisvert
- Centre de recherche de l'Institut Universitaire en Santé Mentale de Montréal, Montréal, Canada
- Department of psychiatry and addiction, Université de Montréal, Montréal, Canada
| | - Valérie Tourjman
- Centre de recherche de l'Institut Universitaire en Santé Mentale de Montréal, Montréal, Canada
- Department of psychiatry and addiction, Université de Montréal, Montréal, Canada
| | - Stéphane Potvin
- Centre de recherche de l'Institut Universitaire en Santé Mentale de Montréal, Montréal, Canada
- Department of psychiatry and addiction, Université de Montréal, Montréal, Canada
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3
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Scholkmann F, Vollenweider FX. Psychedelics and fNIRS neuroimaging: exploring new opportunities. NEUROPHOTONICS 2023; 10:013506. [PMID: 36474478 PMCID: PMC9717437 DOI: 10.1117/1.nph.10.1.013506] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 11/14/2022] [Indexed: 06/17/2023]
Abstract
In this Outlook paper, we explain to the optical neuroimaging community as well as the psychedelic research community the great potential of using optical neuroimaging with functional near-infrared spectroscopy (fNIRS) to further explore the changes in brain activity induced by psychedelics. We explain why we believe now is the time to exploit the momentum of the current resurgence of research on the effects of psychedelics and the momentum of the increasing progress and popularity of the fNIRS technique to establish fNIRS in psychedelic research. With this article, we hope to contribute to this development.
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Affiliation(s)
- Felix Scholkmann
- University Hospital Zurich, University of Zurich, Biomedical Optics Research Laboratory, Department of Neonatology, Zurich, Switzerland
- University of Bern, Institute of Complementary and Integrative Medicine, Bern, Switzerland
| | - Franz X. Vollenweider
- University Hospital of Psychiatry, University of Zurich, Neuropsychopharmacology and Brain Imaging, Department of Psychiatry, Psychotherapy and Psychosomatics, Zurich, Switzerland
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4
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Kurtz JS, Patel NA, Gendreau JL, Yang C, Brown N, Bui N, Picton B, Harris M, Hatter M, Beyer R, Sahyouni R, Diaz-Aguilar LD, Castellano J, Schuster N, Abraham ME. The Use of Psychedelics in the Treatment of Medical Conditions: An Analysis of Currently Registered Psychedelics Studies in the American Drug Trial Registry. Cureus 2022; 14:e29167. [PMID: 36259015 PMCID: PMC9567237 DOI: 10.7759/cureus.29167] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2022] [Indexed: 12/03/2022] Open
Abstract
Although early therapeutic research on psychedelics dates back to the 1940s, this field of investigation was met with many cultural and legal challenges in the 1970s. Over the past two decades, clinical trials using psychedelics have resumed. Therefore, the goal of this study was to (1) better characterize the recent uptrend in psychedelics in clinical trials and (2) identify areas where potentially new clinical trials could be initiated to help in the treatment of widely prevalent medical disorders. A systematic search was conducted on the clinicaltrials.gov database for all registered clinical trials examining the use of psychedelic drugs and was both qualitatively and quantitatively assessed. Analysis of recent studies registered in clinicaltrials.gov was performed using Pearson’s correlation coefficient testing. Statistical analysis and visualization were performed using R software. In totality, 105 clinical trials met this study’s inclusion criteria. The recent uptrend in registered clinical trials studying psychedelics (p = 0.002) was similar to the uptrend in total registered clinical trials in the registry (p < 0.001). All trials took place from 2007 to 2020, with 77.1% of studies starting in 2017 or later. A majority of clinical trials were in phase 1 (53.3%) or phase 2 (25.7%). Common disorders treated include substance addiction, post-traumatic stress disorder, and major depressive disorder. Potential research gaps include studying psychedelics as a potential option for symptomatic treatment during opioid tapering. There appears to be a recent uptrend in registered clinical trials studying psychedelics, which is similar to the recent increase in overall trials registered. Potentially, more studies could be performed to evaluate the potential of psychedelics for symptomatic treatment during opioid tapering and depression refractory to selective serotonin reuptake inhibitors.
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McCulloch DEW, Knudsen GM, Barrett FS, Doss MK, Carhart-Harris RL, Rosas FE, Deco G, Kringelbach ML, Preller KH, Ramaekers JG, Mason NL, Müller F, Fisher PM. Psychedelic resting-state neuroimaging: A review and perspective on balancing replication and novel analyses. Neurosci Biobehav Rev 2022; 138:104689. [PMID: 35588933 DOI: 10.1016/j.neubiorev.2022.104689] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 05/05/2022] [Accepted: 05/05/2022] [Indexed: 12/20/2022]
Abstract
Clinical research into serotonergic psychedelics is expanding rapidly, showing promising efficacy across myriad disorders. Resting-state functional magnetic resonance imaging (rs-fMRI) is a commonly used strategy to identify psychedelic-induced changes in neural pathways in clinical and healthy populations. Here we, a large group of psychedelic imaging researchers, review the 42 research articles published to date, based on the 17 unique studies evaluating psychedelic effects on rs-fMRI, focusing on methodological variation. Prominently, we observe that nearly all studies vary in data processing and analysis methodology, two datasets are the foundation of over half of the published literature, and there is lexical ambiguity in common outcome metric terminology. We offer guidelines for future studies that encourage coherence in the field. Psychedelic rs-fMRI will benefit from the development of novel methods that expand our understanding of the brain mechanisms mediating its intriguing effects; yet, this field is at a crossroads where we must also consider the critical importance of consistency and replicability to effectively converge on stable representations of the neural effects of psychedelics.
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Affiliation(s)
| | - Gitte Moos Knudsen
- Neurobiology Research Unit and NeuroPharm, Rigshospitalet, Copenhagen, Denmark; Institute of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Frederick Streeter Barrett
- Department of Psychiatry and Behavioral Sciences, Center for Psychedelic and Consciousness Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neuroscience and Department of Psychological and Brain Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Manoj K Doss
- Department of Psychiatry and Behavioral Sciences, Center for Psychedelic and Consciousness Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Robin Lester Carhart-Harris
- Neuroscape, Weill Institute for Neurosciences, University of California San Francisco, CA, USA; Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London, UK
| | - Fernando E Rosas
- Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London, UK; Data Science Institute, Imperial College London, London, UK; Centre for Complexity Science, Imperial College London, London, UK
| | - Gustavo Deco
- Center for Brain and Cognition, Computational Neuroscience Group, Universitat Pompeu Fabra, Barcelona, Spain; Department of Information and Communication Technologies, Universitat Pompeu Fabra, Barcelona, Spain; Institució Catalana de la Recerca i Estudis Avançats (ICREA), Barcelona, Spain; Department of Neuropsychology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; School of Psychological Sciences, Monash University, Melbourne, Australia
| | - Morten L Kringelbach
- Centre for Eudaimonia and Human Flourishing, Linacre College, University of Oxford, UK; Department of Psychiatry, University of Oxford, Oxford, UK; Center for Music in the Brain, Department of Clinical Medicine, Aarhus University, Denmark
| | - Katrin H Preller
- Pharmaco-Neuroimaging and Cognitive-Emotional Processing, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric University Hospital, University of Zurich, Zurich, Switzerland
| | | | - Natasha L Mason
- Faculty of Psychology and Neuroscience, Maastricht University, The Netherlands
| | - Felix Müller
- University of Basel, Department of Psychiatry (UPK), Basel, Switzerland
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Doss MK, Madden MB, Gaddis A, Nebel MB, Griffiths RR, Mathur BN, Barrett FS. Models of psychedelic drug action: modulation of cortical-subcortical circuits. Brain 2022; 145:441-456. [PMID: 34897383 PMCID: PMC9014750 DOI: 10.1093/brain/awab406] [Citation(s) in RCA: 55] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 08/10/2021] [Accepted: 10/05/2021] [Indexed: 12/15/2022] Open
Abstract
Classic psychedelic drugs such as psilocybin and lysergic acid diethylamide (LSD) have recaptured the imagination of both science and popular culture, and may have efficacy in treating a wide range of psychiatric disorders. Human and animal studies of psychedelic drug action in the brain have demonstrated the involvement of the serotonin 2A (5-HT2A) receptor and the cerebral cortex in acute psychedelic drug action, but different models have evolved to try to explain the impact of 5-HT2A activation on neural systems. Two prominent models of psychedelic drug action (the cortico-striatal thalamo-cortical, or CSTC, model and relaxed beliefs under psychedelics, or REBUS, model) have emphasized the role of different subcortical structures as crucial in mediating psychedelic drug effects. We describe these models and discuss gaps in knowledge, inconsistencies in the literature and extensions of both models. We then introduce a third circuit-level model involving the claustrum, a thin strip of grey matter between the insula and the external capsule that densely expresses 5-HT2A receptors (the cortico-claustro-cortical, or CCC, model). In this model, we propose that the claustrum entrains canonical cortical network states, and that psychedelic drugs disrupt 5-HT2A-mediated network coupling between the claustrum and the cortex, leading to attenuation of canonical cortical networks during psychedelic drug effects. Together, these three models may explain many phenomena of the psychedelic experience, and using this framework, future research may help to delineate the functional specificity of each circuit to the action of both serotonergic and non-serotonergic hallucinogens.
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Affiliation(s)
- Manoj K Doss
- Center for Psychedelic and Consciousness Research, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA
| | - Maxwell B Madden
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Andrew Gaddis
- Center for Psychedelic and Consciousness Research, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA
| | - Mary Beth Nebel
- Center for Neurodevelopmental and Imaging Research, Kennedy Krieger Institute, Baltimore, MD, 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA
| | - Roland R Griffiths
- Center for Psychedelic and Consciousness Research, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA
| | - Brian N Mathur
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Frederick S Barrett
- Center for Psychedelic and Consciousness Research, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
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7
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Castelhano J, Lima G, Teixeira M, Soares C, Pais M, Castelo-Branco M. The Effects of Tryptamine Psychedelics in the Brain: A meta-Analysis of Functional and Review of Molecular Imaging Studies. Front Pharmacol 2021; 12:739053. [PMID: 34658876 PMCID: PMC8511767 DOI: 10.3389/fphar.2021.739053] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 09/06/2021] [Indexed: 11/13/2022] Open
Abstract
There is an increasing interest in the neural effects of psychoactive drugs, in particular tryptamine psychedelics, which has been incremented by the proposal that they have potential therapeutic benefits, based on their molecular mimicry of serotonin. It is widely believed that they act mainly through 5HT2A receptors but their effects on neural activation of distinct brain systems are not fully understood. We performed a quantitative meta-analysis of brain imaging studies to investigate the effects of substances within this class (e.g., LSD, Psilocybin, DMT, Ayahuasca) in the brain from a molecular and functional point of view. We investigated the question whether the changes in activation patterns and connectivity map into regions with larger 5HT1A/5HT2A receptor binding, as expected from indolaemine hallucinogens (in spite of the often reported emphasis only on 5HT2AR). We did indeed find that regions with changed connectivity and/or activation patterns match regions with high density of 5HT2A receptors, namely visual BA19, visual fusiform regions in BA37, dorsal anterior and posterior cingulate cortex, medial prefrontal cortex, and regions involved in theory of mind such as the surpramarginal gyrus, and temporal cortex (rich in 5HT1A receptors). However, we also found relevant patterns in other brain regions such as dorsolateral prefrontal cortex. Moreover, many of the above-mentioned regions also have a significant density of both 5HT1A/5HT2A receptors, and available PET studies on the effects of psychedelics on receptor occupancy are still quite scarce, precluding a metanalytic approach. Finally, we found a robust neuromodulatory effect in the right amygdala. In sum, the available evidence points towards strong neuromodulatory effects of tryptamine psychedelics in key brain regions involved in mental imagery, theory of mind and affective regulation, pointing to potential therapeutic applications of this class of substances.
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Szabó Í, Varga VÉ, Dvorácskó S, Farkas AE, Körmöczi T, Berkecz R, Kecskés S, Menyhárt Á, Frank R, Hantosi D, Cozzi NV, Frecska E, Tömböly C, Krizbai IA, Bari F, Farkas E. N,N-Dimethyltryptamine attenuates spreading depolarization and restrains neurodegeneration by sigma-1 receptor activation in the ischemic rat brain. Neuropharmacology 2021; 192:108612. [PMID: 34023338 DOI: 10.1016/j.neuropharm.2021.108612] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 04/23/2021] [Accepted: 05/13/2021] [Indexed: 12/19/2022]
Abstract
Dimethyltryptamine (DMT), an endogenous ligand of sigma-1 receptors (Sig-1Rs), acts against systemic hypoxia, but whether DMT may prevent cerebral ischemic injury is unexplored. Here global forebrain ischemia was created in anesthetized rats and aggravated with the induction of spreading depolarizations (SDs) and subsequent short hypoxia before reperfusion. Drugs (DMT, the selective Sig-1R agonist PRE-084, the Sig-1R antagonist NE-100, or the serotonin receptor antagonist asenapine) were administered intravenously alone or in combination while physiological variables and local field potential from the cerebral cortex was recorded. Neuroprotection and the cellular localization of Sig-1R were evaluated with immunocytochemistry. Plasma and brain DMT content was measured by 2D-LC-HRMS/MS. The affinity of drugs for cerebral Sig-1R was evaluated with a radioligand binding assay. Both DMT and PRE-084 mitigated SDs, counteracted with NE-100. Further, DMT attenuated SD when co-administered with asenapine, compared to asenapine alone. DMT reduced the number of apoptotic and ferroptotic cells and supported astrocyte survival. The binding affinity of DMT to Sig-1R matched previously reported values. Sig-1Rs were associated with the perinuclear cytoplasm of neurons, astrocytes and microglia, and with glial processes. According to these data, DMT may be considered as adjuvant pharmacological therapy in the management of acute cerebral ischemia.
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Affiliation(s)
- Írisz Szabó
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged; Korányi Fasor 9, Szeged, 6720, Hungary.
| | - Viktória É Varga
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged; Korányi Fasor 9, Szeged, 6720, Hungary.
| | - Szabolcs Dvorácskó
- Laboratory of Chemical Biology, Institute of Biochemistry, Biological Research Centre, Temesvári Krt 62, Szeged, 6726, Hungary; Department of Medical Chemistry, Faculty of Medicine, University of Szeged, Dóm Tér 8, Szeged, 6720, Hungary.
| | - Attila E Farkas
- Neurovascular Unit Research Group, Molecular Neurobiology Research Unit, Institute of Biophysics, Biological Research Centre, Temesvári Krt 62, Szeged, 6726, Hungary.
| | - Tímea Körmöczi
- Department of Medical Chemistry, Faculty of Medicine, University of Szeged, Dóm Tér 8, Szeged, 6720, Hungary; Institute of Pharmaceutical Analysis, Faculty of Pharmacy, University of Szeged, Somogyi U 4, Szeged, 6720, Hungary.
| | - Róbert Berkecz
- Department of Medical Chemistry, Faculty of Medicine, University of Szeged, Dóm Tér 8, Szeged, 6720, Hungary; Institute of Pharmaceutical Analysis, Faculty of Pharmacy, University of Szeged, Somogyi U 4, Szeged, 6720, Hungary.
| | - Szilvia Kecskés
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged; Korányi Fasor 9, Szeged, 6720, Hungary.
| | - Ákos Menyhárt
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged; Korányi Fasor 9, Szeged, 6720, Hungary.
| | - Rita Frank
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged; Korányi Fasor 9, Szeged, 6720, Hungary.
| | - Dóra Hantosi
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged; Korányi Fasor 9, Szeged, 6720, Hungary.
| | - Nicholas V Cozzi
- Neuropharmacology Laboratory, University of Wisconsin School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA; Alexander Shulgin Research Institute, 1483 Shulgin Road, Lafayette, CA, 94549, USA.
| | - Ede Frecska
- Department of Psychiatry, Faculty of Medicine, University of Debrecen, Nagyerdei Krt 94, Debrecen, 4032, Hungary.
| | - Csaba Tömböly
- Laboratory of Chemical Biology, Institute of Biochemistry, Biological Research Centre, Temesvári Krt 62, Szeged, 6726, Hungary.
| | - István A Krizbai
- Neurovascular Unit Research Group, Molecular Neurobiology Research Unit, Institute of Biophysics, Biological Research Centre, Temesvári Krt 62, Szeged, 6726, Hungary; Institute of Life Sciences, UVVG, 94 Bulevardul Revoluției, Arad, 310025, Romania.
| | - Ferenc Bari
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged; Korányi Fasor 9, Szeged, 6720, Hungary.
| | - Eszter Farkas
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged; Korányi Fasor 9, Szeged, 6720, Hungary.
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9
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Kitson A, Chirico A, Gaggioli A, Riecke BE. A Review on Research and Evaluation Methods for Investigating Self-Transcendence. Front Psychol 2020; 11:547687. [PMID: 33312147 PMCID: PMC7701337 DOI: 10.3389/fpsyg.2020.547687] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 09/30/2020] [Indexed: 12/15/2022] Open
Abstract
Self-transcendence has been characterized as a decrease in self-saliency (ego disillusionment) and increased connection, and has been growing in research interest in the past decade. Several measures have been developed and published with some degree of psychometric validity and reliability. However, to date, there has been no review systematically describing, contrasting, and evaluating the different methodological approaches toward measuring self-transcendence including questionnaires, neurological and physiological measures, and qualitative methods. To address this gap, we conducted a review to describe existing methods of measuring self-transcendence, evaluate the strengths and weaknesses of these methods, and discuss research avenues to advance assessment of self-transcendence, including recommendations for suitability of methods given research contexts.
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Affiliation(s)
- Alexandra Kitson
- School of Interactive Arts and Technology, Simon Fraser University, Burnaby, BC, Canada
| | - Alice Chirico
- Department of Psychology, Catholic University of the Sacred Heart, Milan, Italy
| | - Andrea Gaggioli
- Department of Psychology, Catholic University of the Sacred Heart, Milan, Italy.,ATN-P Lab, Istituto Auxologico Italiano, Milan, Italy
| | - Bernhard E Riecke
- School of Interactive Arts and Technology, Simon Fraser University, Burnaby, BC, Canada
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10
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Alamia A, Timmermann C, Nutt DJ, VanRullen R, Carhart-Harris RL. DMT alters cortical travelling waves. eLife 2020; 9:e59784. [PMID: 33043883 PMCID: PMC7577737 DOI: 10.7554/elife.59784] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 10/11/2020] [Indexed: 12/25/2022] Open
Abstract
Psychedelic drugs are potent modulators of conscious states and therefore powerful tools for investigating their neurobiology. N,N, Dimethyltryptamine (DMT) can rapidly induce an extremely immersive state of consciousness characterized by vivid and elaborate visual imagery. Here, we investigated the electrophysiological correlates of the DMT-induced altered state from a pool of participants receiving DMT and (separately) placebo (saline) while instructed to keep their eyes closed. Consistent with our hypotheses, results revealed a spatio-temporal pattern of cortical activation (i.e. travelling waves) similar to that elicited by visual stimulation. Moreover, the typical top-down alpha-band rhythms of closed-eyes rest were significantly decreased, while the bottom-up forward wave was significantly increased. These results support a recent model proposing that psychedelics reduce the 'precision-weighting of priors', thus altering the balance of top-down versus bottom-up information passing. The robust hypothesis-confirming nature of these findings imply the discovery of an important mechanistic principle underpinning psychedelic-induced altered states.
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Affiliation(s)
| | - Christopher Timmermann
- Computational, Cognitive and Clinical Neuroscience Laboratory (C3NL), Faculty of Medicine, Imperial CollegeLondonUnited Kingdom
- Centre for Psychedelic Research, Division of Psychiatry, Department of Brain Sciences, Imperial College LondonLondonUnited Kingdom
| | - David J Nutt
- Centre for Psychedelic Research, Division of Psychiatry, Department of Brain Sciences, Imperial College LondonLondonUnited Kingdom
| | - Rufin VanRullen
- Cerco, CNRS Université de ToulouseToulouseFrance
- Artificial and Natural Intelligence Toulouse Institute (ANITI)ToulouseFrance
| | - Robin L Carhart-Harris
- Centre for Psychedelic Research, Division of Psychiatry, Department of Brain Sciences, Imperial College LondonLondonUnited Kingdom
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Barrett FS, Krimmel SR, Griffiths RR, Seminowicz DA, Mathur BN. Psilocybin acutely alters the functional connectivity of the claustrum with brain networks that support perception, memory, and attention. Neuroimage 2020; 218:116980. [PMID: 32454209 PMCID: PMC10792549 DOI: 10.1016/j.neuroimage.2020.116980] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 05/18/2020] [Indexed: 02/06/2023] Open
Abstract
Psychedelic drugs, including the serotonin 2a (5-HT2A) receptor partial agonist psilocybin, are receiving renewed attention for their possible efficacy in treating a variety of neuropsychiatric disorders. Psilocybin induces widespread dysregulation of cortical activity, but circuit-level mechanisms underlying this effect are unclear. The claustrum is a subcortical nucleus that highly expresses 5-HT2A receptors and provides glutamatergic inputs to arguably all areas of the cerebral cortex. We therefore tested the hypothesis that psilocybin modulates claustrum function in humans. Fifteen healthy participants (10M, 5F) completed this within-subjects study in which whole-brain resting-state blood-oxygenation level-dependent (BOLD) signal was measured 100 min after blinded oral administration of placebo and 10 mg/70 kg psilocybin. Left and right claustrum signal was isolated using small region confound correction. Psilocybin significantly decreased both the amplitude of low frequency fluctuations as well as the variance of BOLD signal in the left and right claustrum. Psilocybin also significantly decreased functional connectivity of the right claustrum with auditory and default mode networks (DMN), increased right claustrum connectivity with the fronto-parietal task control network (FPTC), and decreased left claustrum connectivity with the FPTC. DMN integrity was associated with right-claustrum connectivity with the DMN, while FPTC integrity and modularity were associated with right claustrum and left claustrum connectivity with the FPTC, respectively. Subjective effects of psilocybin predicted changes in the amplitude of low frequency fluctuations and the variance of BOLD signal in the left and right claustrum. Observed effects were specific to claustrum, compared to flanking regions of interest (the left and right insula and putamen). This study used a pharmacological intervention to provide the first empirical evidence in any species for a significant role of 5-HT2A receptor signaling in claustrum functioning, and supports a possible role of the claustrum in the subjective and therapeutic effects of psilocybin.
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Affiliation(s)
- Frederick S Barrett
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA; Center for Psychedelic and Consciousness Research, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA.
| | - Samuel R Krimmel
- Department of Neural and Pain Sciences, School of Dentistry, and Center to Advance Chronic Pain Research, University of Maryland, Baltimore, MD, 21201, USA
| | - Roland R Griffiths
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA; Center for Psychedelic and Consciousness Research, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA; Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21224, USA
| | - David A Seminowicz
- Department of Neural and Pain Sciences, School of Dentistry, and Center to Advance Chronic Pain Research, University of Maryland, Baltimore, MD, 21201, USA
| | - Brian N Mathur
- Department of Pharmacology, School of Medicine, University of Maryland, Baltimore, MD, 21201, USA
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Pallavicini C, Vilas MG, Villarreal M, Zamberlan F, Muthukumaraswamy S, Nutt D, Carhart-Harris R, Tagliazucchi E. Spectral signatures of serotonergic psychedelics and glutamatergic dissociatives. Neuroimage 2019; 200:281-291. [DOI: 10.1016/j.neuroimage.2019.06.053] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/19/2019] [Accepted: 06/21/2019] [Indexed: 01/23/2023] Open
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13
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Rodrigues AVSL, Almeida FJ, Vieira-Coelho MA. Dimethyltryptamine: Endogenous Role and Therapeutic Potential. J Psychoactive Drugs 2019; 51:299-310. [DOI: 10.1080/02791072.2019.1602291] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Alexandra VSL Rodrigues
- Department of Biomedicine-Pharmacology and Therapeutics unit, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Francisco Jcg Almeida
- Department of Biomedicine-Pharmacology and Therapeutics unit, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Maria A Vieira-Coelho
- Department of Biomedicine-Pharmacology and Therapeutics unit, Faculty of Medicine, University of Porto, Porto, Portugal
- Psychiatry and Mental Health Clinic, Hospital de São João, Porto, Portugal
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14
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Haaf M, Leicht G, Curic S, Mulert C. Glutamatergic Deficits in Schizophrenia - Biomarkers and Pharmacological Interventions within the Ketamine Model. Curr Pharm Biotechnol 2018; 19:293-307. [PMID: 29929462 PMCID: PMC6142413 DOI: 10.2174/1389201019666180620112528] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 05/12/2018] [Accepted: 05/26/2018] [Indexed: 11/30/2022]
Abstract
Background: The observation that N-methyl-D-aspartate glutamate receptor (NMDAR) antagonists such as ketamine transiently induce schizophrenia-like positive, negative and cognitive symptoms has led to a paradigm shift from dopaminergic to glutamatergic dysfunction in pharmacological models of schizophrenia. NMDAR hypofunction can explain many schizophrenia symptoms directly due to excitatory-to-inhibitory (E/I) imbalance, but also dopaminergic dysfunction itself. However, so far no new drug targeting the NMDAR has been successfully approved. In the search for possible biomarkers it is interesting that ketamine-induced psychopathological changes in healthy participants were accompanied by altered electro-(EEG), magnetoencephalographic (MEG) and functional magnetic resonance imaging (fMRI) signals. Methods: We systematically searched PubMed/Medline and Web of Knowledge databases (January 2006 to July 2017) to identify EEG/MEG and fMRI studies of the ketamine model of schizophrenia with human subjects. The search strategy identified 209 citations of which 46 articles met specified eligibility criteria. Results: In EEG/MEG studies, ketamine induced changes of event-related potentials, such as the P300 potential and the mismatch negativity, similar to alterations observed in schizophrenia patients. In fMRI studies, alterations of activation were observed in different brain regions, most prominently within the anterior cingulate cortex and limbic structures as well as task-relevant brain regions. These alterations were accompanied by changes in functional connectivity, indicating a balance shift of the underlying brain networks. Pharmacological treatments did alter ketamine-induced changes in EEG/MEG and fMRI studies to different extents. Conclusion: This review highlights the potential applicability of the ketamine model for schizophrenia drug development by offering the possibility to assess the effect of pharmacological agents on schizophrenia-like symptoms and to find relevant neurophysiological and neuroimaging biomarkers.
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Affiliation(s)
- Moritz Haaf
- Psychiatry Neuroimaging Branch (PNB), Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Gregor Leicht
- Psychiatry Neuroimaging Branch (PNB), Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Stjepan Curic
- Psychiatry Neuroimaging Branch (PNB), Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christoph Mulert
- Psychiatry Neuroimaging Branch (PNB), Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Department of Psychiatry and Psychotherapy, UKGM, Justus-Liebig University Giessen, Giessen, Germany
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15
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Cameron LP, Olson DE. Dark Classics in Chemical Neuroscience: N, N-Dimethyltryptamine (DMT). ACS Chem Neurosci 2018; 9:2344-2357. [PMID: 30036036 DOI: 10.1021/acschemneuro.8b00101] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Though relatively obscure, N, N-dimethyltryptamine (DMT) is an important molecule in psychopharmacology as it is the archetype for all indole-containing serotonergic psychedelics. Its structure can be found embedded within those of better-known molecules such as lysergic acid diethylamide (LSD) and psilocybin. Unlike the latter two compounds, DMT is ubiquitous, being produced by a wide variety of plant and animal species. It is one of the principal psychoactive components of ayahuasca, a tisane made from various plant sources that has been used for centuries. Furthermore, DMT is one of the few psychedelic compounds produced endogenously by mammals, and its biological function in human physiology remains a mystery. In this review, we cover the synthesis of DMT as well as its pharmacology, metabolism, adverse effects, and potential use in medicine. Finally, we discuss the history of DMT in chemical neuroscience and why this underappreciated molecule is so important to the field of psychedelic science.
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Affiliation(s)
- Lindsay P. Cameron
- Neuroscience Graduate Program, University of California, Davis, 1544 Newton Ct., Davis, California 95618, United States
| | - David E. Olson
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
- Department of Biochemistry & Molecular Medicine, School of Medicine, University of California, Davis, 2700 Stockton Blvd., Suite 2102, Sacramento, California 95817, United States
- Center for Neuroscience, University of California, Davis, 1544 Newton Ct., Davis, California 95618, United States
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Barrett FS, Carbonaro TM, Hurwitz E, Johnson MW, Griffiths RR. Double-blind comparison of the two hallucinogens psilocybin and dextromethorphan: effects on cognition. Psychopharmacology (Berl) 2018; 235:2915-2927. [PMID: 30062577 PMCID: PMC6162157 DOI: 10.1007/s00213-018-4981-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 07/23/2018] [Indexed: 01/30/2023]
Abstract
OBJECTIVES Classic psychedelics (serotonin 2A receptor agonists) and dissociative hallucinogens (NMDA receptor antagonists), though differing in pharmacology, may share neuropsychological effects. These drugs, however, have undergone limited direct comparison. This report presents data from a double-blind, placebo-controlled within-subjects study comparing the neuropsychological effects of multiple doses of the classic psychedelic psilocybin with the effects of a single high dose of the dissociative hallucinogen dextromethorphan (DXM). METHODS Twenty hallucinogen users (11 females) completed neurocognitive assessments during five blinded drug administration sessions (10, 20, and 30 mg/70 kg psilocybin; 400 mg/70 kg DXM; and placebo) in which participants and study staff were informed that a large range of possible drug conditions may have been administered. RESULTS Global cognitive impairment, assessed using the Mini-Mental State Examination during peak drug effects, was not observed with psilocybin or DXM. Orderly and dose-dependent effects of psilocybin were observed on psychomotor performance, working memory, episodic memory, associative learning, and visual perception. Effects of DXM on psychomotor performance, visual perception, and associative learning were in the range of effects of a moderate to high dose (20 to 30 mg/70 kg) of psilocybin. CONCLUSIONS This was the first study of the dose effects of psilocybin on a large battery of neurocognitive assessments. Evidence of delirium or global cognitive impairment was not observed with either psilocybin or DXM. Psilocybin had greater effects than DXM on working memory. DXM had greater effects than all psilocybin doses on balance, episodic memory, response inhibition, and executive control.
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Affiliation(s)
- Frederick S Barrett
- Behavioral Pharmacology Research Unit, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 5510 Nathan Shock Dr., Baltimore, MD, 21224, USA.
| | - Theresa M Carbonaro
- Behavioral Pharmacology Research Unit, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 5510 Nathan Shock Dr., Baltimore, MD, 21224, USA
| | - Ethan Hurwitz
- Behavioral Pharmacology Research Unit, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 5510 Nathan Shock Dr., Baltimore, MD, 21224, USA
| | - Matthew W Johnson
- Behavioral Pharmacology Research Unit, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 5510 Nathan Shock Dr., Baltimore, MD, 21224, USA
| | - Roland R Griffiths
- Behavioral Pharmacology Research Unit, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 5510 Nathan Shock Dr., Baltimore, MD, 21224, USA
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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17
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Müller F, Liechti ME, Lang UE, Borgwardt S. Advances and challenges in neuroimaging studies on the effects of serotonergic hallucinogens: Contributions of the resting brain. PROGRESS IN BRAIN RESEARCH 2018; 242:159-177. [PMID: 30471679 DOI: 10.1016/bs.pbr.2018.08.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The effects of hallucinogenic drugs on the human brain have been studied since the earliest days of neuroimaging in the 1990s. However, approaches are often hard to compare and results are heterogeneous. In this chapter, we summarize studies investigating the effects of hallucinogens on the resting brain, with a special emphasis on replicability and limitations. In previous studies, similarities were observed between psilocybin, LSD, and ayahuasca, with respect to decreases in cerebral blood flow and increases in global functional connectivity in the precuneus and thalamus. Additionally, LSD consistently decreased functional connectivity within distinct resting state networks. Little convergence was observed for connectivity between networks and for blood flow in other brain regions. Although these studies are limited by small sample sizes and might be biased by unspecific drug effects on physiological parameters and the vascular system, current results indicate that neuroimaging could be a useful tool to elucidate the neuronal correlates of hallucinogenic effects.
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Affiliation(s)
- Felix Müller
- Department of Psychiatry (UPK), University of Basel, Basel, Switzerland
| | - Matthias E Liechti
- Division of Clinical Pharmacology and Toxicology, Department of Biomedicine and Department of Clinical Research, University Hospital Basel, University of Basel, Basel, Switzerland
| | - Undine E Lang
- Department of Psychiatry (UPK), University of Basel, Basel, Switzerland
| | - Stefan Borgwardt
- Department of Psychiatry (UPK), University of Basel, Basel, Switzerland.
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Barker SA. N, N-Dimethyltryptamine (DMT), an Endogenous Hallucinogen: Past, Present, and Future Research to Determine Its Role and Function. Front Neurosci 2018; 12:536. [PMID: 30127713 PMCID: PMC6088236 DOI: 10.3389/fnins.2018.00536] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 07/17/2018] [Indexed: 01/12/2023] Open
Abstract
This report provides a historical overview of research concerning the endogenous hallucinogen N, N-dimethyltryptamine (DMT), focusing on data regarding its biosynthesis and metabolism in the brain and peripheral tissues, methods and results for DMT detection in body fluids and brain, new sites of action for DMT, and new data regarding its possible physiological and therapeutic roles. Research that further elaborates its consideration as a putative neurotransmitter is also addressed. Taking these studies together, the report proposes several new directions and experiments to ascertain the role of DMT in the brain, including brain mapping of enzymes responsible for the biosynthesis of DMT, further studies to elaborate its presence and role in the pineal gland, a reconsideration of binding site data, and new administration and imaging studies. The need to resolve the "natural" role of an endogenous hallucinogen from the effects observed from peripheral administration are also emphasized.
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Affiliation(s)
- Steven A. Barker
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, United States
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19
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Nagels A, Cabanis M, Oppel A, Kirner-Veselinovic A, Schales C, Kircher T. S-Ketamine-Induced NMDA Receptor Blockade during Natural Speech Production and Its Implications for Formal Thought Disorder in Schizophrenia: A Pharmaco-fMRI Study. Neuropsychopharmacology 2018; 43:1324-1333. [PMID: 29105665 PMCID: PMC5916352 DOI: 10.1038/npp.2017.270] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 09/14/2017] [Accepted: 10/16/2017] [Indexed: 02/04/2023]
Abstract
Structural and functional changes in the lateral temporal language areas have been related to formal thought disorder (FTD) in schizophrenia. Continuous, natural speech production activates the right lateral temporal lobe in schizophrenia, as opposed to the left in healthy subjects. Positive and negative FTD can be elicited in healthy subjects by glutamatergic NMDA blockade with ketamine. It is unclear whether the glutamate system is related to the reversed hemispheric lateralization during speaking in patients. In a double-blind, crossover, placebo-controlled study, 15 healthy, male, right-handed volunteers overtly described 7 pictures for 3 min each while BOLD signal changes were acquired with fMRI. As a measure of linguistic demand, the number of words within 20 s epochs was correlated with BOLD responses. Participants developed S-ketamine-induced psychotic symptoms, particularly positive FTD. Ketamine vs placebo was associated with enhanced neural responses in the right middle and inferior temporal gyri. Similar to a previous fMRI study in schizophrenia patients vs healthy controls applying the same design, S-ketamine reversed functional lateralization during speech production in healthy subjects. Results demonstrate an association between glutamatergic imbalance, dysactivations in lateral temporal brain areas, and FTD symptom formation.
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Affiliation(s)
- Arne Nagels
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany
- Department of English and Linguistics, Johannes Gutenberg University, Mainz, Germany
| | - Maurice Cabanis
- Department of Psychiatry and Psychotherapy, Social Neuroscience Lab, University of Lübeck, Lübeck, Germany
- Clinic for Addiction Medicine and Addictive Behaviour, Centre for Mental Health, Stuttgart, Germany
| | - Andrea Oppel
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany
| | | | - Christian Schales
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany
| | - Tilo Kircher
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany
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20
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Rucker JJH, Iliff J, Nutt DJ. Psychiatry & the psychedelic drugs. Past, present & future. Neuropharmacology 2017; 142:200-218. [PMID: 29284138 DOI: 10.1016/j.neuropharm.2017.12.040] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 11/26/2017] [Accepted: 12/22/2017] [Indexed: 12/17/2022]
Abstract
The classical psychedelic drugs, including psilocybin, lysergic acid diethylamide and mescaline, were used extensively in psychiatry before they were placed in Schedule I of the UN Convention on Drugs in 1967. Experimentation and clinical trials undertaken prior to legal sanction suggest that they are not helpful for those with established psychotic disorders and should be avoided in those liable to develop them. However, those with so-called 'psychoneurotic' disorders sometimes benefited considerably from their tendency to 'loosen' otherwise fixed, maladaptive patterns of cognition and behaviour, particularly when given in a supportive, therapeutic setting. Pre-prohibition studies in this area were sub-optimal, although a recent systematic review in unipolar mood disorder and a meta-analysis in alcoholism have both suggested efficacy. The incidence of serious adverse events appears to be low. Since 2006, there have been several pilot trials and randomised controlled trials using psychedelics (mostly psilocybin) in various non-psychotic psychiatric disorders. These have provided encouraging results that provide initial evidence of safety and efficacy, however the regulatory and legal hurdles to licensing psychedelics as medicines are formidable. This paper summarises clinical trials using psychedelics pre and post prohibition, discusses the methodological challenges of performing good quality trials in this area and considers a strategic approach to the legal and regulatory barriers to licensing psychedelics as a treatment in mainstream psychiatry. This article is part of the Special Issue entitled 'Psychedelics: New Doors, Altered Perceptions'.
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Affiliation(s)
- James J H Rucker
- The Institute of Psychiatry, Psychology & Neuroscience, King's College London, 16 De Crespigny Park, London, SE5 8AF, United Kingdom; South West London & St George's Mental Health NHS Trust, Glenburnie Road, London, SW17 7DJ, United Kingdom; Centre for Psychiatry, Division of Brain Sciences, Imperial College London, Burlington Danes Building, Hammersmith Campus, 160 Du Cane Road, London, W12 0NN, United Kingdom.
| | - Jonathan Iliff
- University College London Medical School, 19 Gordon Square, London, WC1H 0AW, United Kingdom
| | - David J Nutt
- Centre for Psychiatry, Division of Brain Sciences, Imperial College London, Burlington Danes Building, Hammersmith Campus, 160 Du Cane Road, London, W12 0NN, United Kingdom
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21
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Carhart-Harris RL, Goodwin GM. The Therapeutic Potential of Psychedelic Drugs: Past, Present, and Future. Neuropsychopharmacology 2017; 42:2105-2113. [PMID: 28443617 PMCID: PMC5603818 DOI: 10.1038/npp.2017.84] [Citation(s) in RCA: 266] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 04/10/2017] [Accepted: 04/20/2017] [Indexed: 01/25/2023]
Abstract
Plant-based psychedelics, such as psilocybin, have an ancient history of medicinal use. After the first English language report on LSD in 1950, psychedelics enjoyed a short-lived relationship with psychology and psychiatry. Used most notably as aids to psychotherapy for the treatment of mood disorders and alcohol dependence, drugs such as LSD showed initial therapeutic promise before prohibitive legislature in the mid-1960s effectively ended all major psychedelic research programs. Since the early 1990s, there has been a steady revival of human psychedelic research: last year saw reports on the first modern brain imaging study with LSD and three separate clinical trials of psilocybin for depressive symptoms. In this circumspective piece, RLC-H and GMG share their opinions on the promises and pitfalls of renewed psychedelic research, with a focus on the development of psilocybin as a treatment for depression.
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Affiliation(s)
- Robin L Carhart-Harris
- Psychedelic Research Group, Centre for Psychiatry, Division of Brain Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Guy M Goodwin
- University of Oxford Department of Psychiatry and Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
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22
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Bøhling F. Psychedelic pleasures: An affective understanding of the joys of tripping. THE INTERNATIONAL JOURNAL OF DRUG POLICY 2017; 49:133-143. [PMID: 28918193 DOI: 10.1016/j.drugpo.2017.07.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 06/22/2017] [Accepted: 07/23/2017] [Indexed: 11/24/2022]
Abstract
BACKGROUND This paper considers the pleasures of psychedelic drugs and proposes a Deleuzian understanding of drugged pleasures as affects. In spite of a large body of work on psychedelics, not least on their therapeutic potentials, the literature is almost completely devoid of discussions of the recreational practices and pleasures of entheogenic drugs. Yet, most people do not use psychedelics because of their curative powers, but because they are fun and enjoyable ways to alter the experience of reality. METHODS In the analytical part of the paper, I examine 100 trip reports from an internet forum in order to explore the pleasures of tripping. RESULTS The analyses map out how drugs such as LSD and mushrooms - in combination with contextual factors such as other people, music and nature - give rise to a set of affective modifications of the drug user's capacities to feel, sense and act. CONCLUSION In conclusion it is argued that taking seriously the large group of recreational users of hallucinogens is important not only because it broadens our understanding of how entheogenic drugs work in different bodies and settings, but also because it may enable a more productive and harm reductive transmission of knowledge between the scientific and recreational psychedelic communities.
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Affiliation(s)
- Frederik Bøhling
- Copenhagen Business School (CBS), Department of Organization, Denmark.
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23
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Dos Santos RG, Bouso JC, Hallak JEC. Ayahuasca, dimethyltryptamine, and psychosis: a systematic review of human studies. Ther Adv Psychopharmacol 2017; 7:141-157. [PMID: 28540034 PMCID: PMC5433617 DOI: 10.1177/2045125316689030] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Ayahuasca is a hallucinogen brew traditionally used for ritual and therapeutic purposes in Northwestern Amazon. It is rich in the tryptamine hallucinogens dimethyltryptamine (DMT), which acts as a serotonin 5-HT2A agonist. This mechanism of action is similar to other compounds such as lysergic acid diethylamide (LSD) and psilocybin. The controlled use of LSD and psilocybin in experimental settings is associated with a low incidence of psychotic episodes, and population studies corroborate these findings. Both the controlled use of DMT in experimental settings and the use of ayahuasca in experimental and ritual settings are not usually associated with psychotic episodes, but little is known regarding ayahuasca or DMT use outside these controlled contexts. Thus, we performed a systematic review of the published case reports describing psychotic episodes associated with ayahuasca and DMT intake. We found three case series and two case reports describing psychotic episodes associated with ayahuasca intake, and three case reports describing psychotic episodes associated with DMT. Several reports describe subjects with a personal and possibly a family history of psychosis (including schizophrenia, schizophreniform disorders, psychotic mania, psychotic depression), nonpsychotic mania, or concomitant use of other drugs. However, some cases also described psychotic episodes in subjects without these previous characteristics. Overall, the incidence of such episodes appears to be rare in both the ritual and the recreational/noncontrolled settings. Performance of a psychiatric screening before administration of these drugs, and other hallucinogens, in controlled settings seems to significantly reduce the possibility of adverse reactions with psychotic symptomatology. Individuals with a personal or family history of any psychotic illness or nonpsychotic mania should avoid hallucinogen intake.
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Affiliation(s)
- Rafael G Dos Santos
- Department of Neurosciences and Behavior, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil; National Institute for Translational Medicine (INCT-TM), CNPq, Ribeirão Preto, Brazil; International Center for Ethnobotanical Education, Research and Service, ICEERS, Barcelona, Spain
| | - José Carlos Bouso
- International Center for Ethnobotanical Education, Research and Service, ICEERS, Barcelona, Spain
| | - Jaime E C Hallak
- Department of Neurosciences and Behavior, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil; National Institute for Translational Medicine (INCT-TM), CNPq, Ribeirão Preto, Brazil
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24
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Dos Santos RG, Balthazar FM, Bouso JC, Hallak JE. The current state of research on ayahuasca: A systematic review of human studies assessing psychiatric symptoms, neuropsychological functioning, and neuroimaging. J Psychopharmacol 2016; 30:1230-1247. [PMID: 27287824 DOI: 10.1177/0269881116652578] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
RATIONALE In recent decades, the use of ayahuasca (AYA) - a β-carboline- and dimethyltryptamine-rich hallucinogenic botanical preparation traditionally used by Northwestern Amazonian tribes for ritual and therapeutic purposes - has spread from South America to Europe and the USA, raising concerns about its possible toxicity and hopes of its therapeutic potential. Thus, it is important to analyze the acute, subacute, and long-term effects of AYA to assess its safety and toxicity. OBJECTIVES The purpose of this study was to conduct a systematic review of human studies assessing AYA effects on psychiatric symptoms, neuropsychological functioning, and neuroimaging. METHODS Papers published until 16 December 2015 were included from PubMed, LILACS and SciELO databases following a comprehensive search strategy and pre-determined set of criteria for article selection. RESULTS The review included 28 full-text articles. Acute AYA administration was well tolerated, increased introspection and positive mood, altered visual perceptions, activated frontal and paralimbic regions and decreased default mode network activity. It also improved planning and inhibitory control and impaired working memory, and showed antidepressive and antiaddictive potentials. Long-term AYA use was associated with increased cortical thickness of the anterior cingulate cortex and cortical thinning of the posterior cingulate cortex, which was inversely correlated to age of onset, intensity of prior AYA use, and spirituality. Subacute and long-term AYA use was not associated with increased psychopathology or cognitive deficits, being associated with enhanced mood and cognition, increased spirituality, and reduced impulsivity. CONCLUSIONS Acute, subacute, and long-term AYA use seems to have low toxicity. Preliminary studies about potential therapeutic effects of AYA need replication due to their methodological limitations.
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Affiliation(s)
- Rafael G Dos Santos
- Department of Neurosciences and Behavior, University of São Paulo, Ribeirão Preto, Brazil .,International Center for Ethnobotanical Education, Research and Service, Barcelona, Spain
| | - Fermanda M Balthazar
- Federal Institute of Education, Science and Technology of São Paulo, São Paulo, Brazil
| | - José C Bouso
- International Center for Ethnobotanical Education, Research and Service, Barcelona, Spain
| | - Jaime Ec Hallak
- Department of Neurosciences and Behavior, University of São Paulo, Ribeirão Preto, Brazil.,National Institute of Science and Technology - Translational Medicine, Ribeirão Preto, Brazil
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25
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Steffens M, Becker B, Neumann C, Kasparbauer AM, Meyhöfer I, Weber B, Mehta MA, Hurlemann R, Ettinger U. Effects of ketamine on brain function during smooth pursuit eye movements. Hum Brain Mapp 2016; 37:4047-4060. [PMID: 27342447 PMCID: PMC6867533 DOI: 10.1002/hbm.23294] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 05/18/2016] [Accepted: 06/13/2016] [Indexed: 11/07/2022] Open
Abstract
The uncompetitive NMDA receptor antagonist ketamine has been proposed to model symptoms of psychosis. Smooth pursuit eye movements (SPEM) are an established biomarker of schizophrenia. SPEM performance has been shown to be impaired in the schizophrenia spectrum and during ketamine administration in healthy volunteers. However, the neural mechanisms mediating SPEM impairments during ketamine administration are unknown. In a counter-balanced, placebo-controlled, double-blind, within-subjects design, 27 healthy participants received intravenous racemic ketamine (100 ng/mL target plasma concentration) on one of two assessment days and placebo (intravenous saline) on the other. Participants performed a block-design SPEM task during functional magnetic resonance imaging (fMRI) at 3 Tesla field strength. Self-ratings of psychosis-like experiences were obtained using the Psychotomimetic States Inventory (PSI). Ketamine administration induced psychosis-like symptoms, during ketamine infusion, participants showed increased ratings on the PSI dimensions cognitive disorganization, delusional thinking, perceptual distortion and mania. Ketamine led to robust deficits in SPEM performance, which were accompanied by reduced blood oxygen level dependent (BOLD) signal in the SPEM network including primary visual cortex, area V5 and the right frontal eye field (FEF), compared to placebo. A measure of connectivity with V5 and FEF as seed regions, however, was not significantly affected by ketamine. These results are similar to the deviations found in schizophrenia patients. Our findings support the role of glutamate dysfunction in impaired smooth pursuit performance and the use of ketamine as a pharmacological model of psychosis, especially when combined with oculomotor biomarkers. Hum Brain Mapp 37:4047-4060, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- M Steffens
- Department of Psychology, University of Bonn, Bonn, Germany
| | - B Becker
- Department of Psychiatry and Division of Medical Psychology, University of Bonn, Bonn, Germany
| | - C Neumann
- Department of Anesthesiology, University of Bonn, Bonn, Germany
| | | | - I Meyhöfer
- Department of Psychology, University of Bonn, Bonn, Germany
| | - B Weber
- Center for Economics and Neuroscience, University of Bonn, Bonn, Germany
- Department of Epileptology, University Hospital Bonn, Bonn, Germany
- Department of NeuroCognition/Imaging, Life&Brain Research Center, Bonn, Germany
| | - M A Mehta
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom
| | - R Hurlemann
- Department of Psychiatry and Division of Medical Psychology, University of Bonn, Bonn, Germany
| | - U Ettinger
- Department of Psychology, University of Bonn, Bonn, Germany.
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Dos Santos RG, Osório FL, Crippa JAS, Hallak JEC. Classical hallucinogens and neuroimaging: A systematic review of human studies: Hallucinogens and neuroimaging. Neurosci Biobehav Rev 2016; 71:715-728. [PMID: 27810345 DOI: 10.1016/j.neubiorev.2016.10.026] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/29/2016] [Accepted: 10/27/2016] [Indexed: 01/07/2023]
Abstract
Serotonergic hallucinogens produce alterations of perceptions, mood, and cognition, and have anxiolytic, antidepressant, and antiaddictive properties. These drugs act as agonists of frontocortical 5-HT2A receptors, but the neural basis of their effects are not well understood. Thus, we conducted a systematic review of neuroimaging studies analyzing the effects of serotonergic hallucinogens in man. Studies published in the PubMed, Lilacs, and SciELO databases until 12 April 2016 were included using the following keywords: "ayahuasca", "DMT", "psilocybin", "LSD", "mescaline" crossed one by one with the terms "mri", "fmri", "pet", "spect", "imaging" and "neuroimaging". Of 279 studies identified, 25 were included. Acute effects included excitation of frontolateral/frontomedial cortex, medial temporal lobe, and occipital cortex, and inhibition of the default mode network. Long-term use was associated with thinning of the posterior cingulate cortex, thickening of the anterior cingulate cortex, and decreased neocortical 5-HT2A receptor binding. Despite the high methodological heterogeneity and the small sample sizes, the results suggest that hallucinogens increase introspection and positive mood by modulating brain activity in the fronto-temporo-parieto-occipital cortex.
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Affiliation(s)
- Rafael G Dos Santos
- Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo, SP, Brazil.
| | - Flávia L Osório
- Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo, SP, Brazil; National Institute for Translational Medicine (INCT-TM), CNPq, Brazil
| | - José Alexandre S Crippa
- Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo, SP, Brazil; National Institute for Translational Medicine (INCT-TM), CNPq, Brazil
| | - Jaime E C Hallak
- Department of Neuroscience and Behavior, Ribeirão Preto Medical School, University of São Paulo, SP, Brazil; National Institute for Translational Medicine (INCT-TM), CNPq, Brazil
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Carbonaro TM, Gatch MB. Neuropharmacology of N,N-dimethyltryptamine. Brain Res Bull 2016; 126:74-88. [PMID: 27126737 PMCID: PMC5048497 DOI: 10.1016/j.brainresbull.2016.04.016] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 12/20/2022]
Abstract
N,N-dimethyltryptamine (DMT) is an indole alkaloid widely found in plants and animals. It is best known for producing brief and intense psychedelic effects when ingested. Increasing evidence suggests that endogenous DMT plays important roles for a number of processes in the periphery and central nervous system, and may act as a neurotransmitter. This paper reviews the current literature of both the recreational use of DMT and its potential roles as an endogenous neurotransmitter. Pharmacokinetics, mechanisms of action in the periphery and central nervous system, clinical uses and adverse effects are also reviewed. DMT appears to have limited neurotoxicity and other adverse effects except for intense cardiovascular effects when administered intravenously in large doses. Because of its role in nervous system signaling, DMT may be a useful experimental tool in exploring how the brain works, and may also be a useful clinical tool for treatment of anxiety and psychosis.
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Affiliation(s)
- Theresa M Carbonaro
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Michael B Gatch
- Center for Neuroscience Discovery University of North Texas Health Science Center Fort Worth, TX, United States.
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28
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Kleinloog D, Rombouts S, Zoethout R, Klumpers L, Niesters M, Khalili-Mahani N, Dahan A, van Gerven J. Subjective Effects of Ethanol, Morphine, Δ(9)-Tetrahydrocannabinol, and Ketamine Following a Pharmacological Challenge Are Related to Functional Brain Connectivity. Brain Connect 2015; 5:641-8. [PMID: 26390148 DOI: 10.1089/brain.2014.0314] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This analysis examines the neuronal foundation of drug-induced psychomimetic symptoms by relating the severity of these symptoms to changes in functional connectivity for a range of different psychoactive compounds with varying degrees of psychomimetic effects. The repeated measures design included 323 resting-state functional magnetic resonance imaging time series and measures of subjective effects in 36 healthy male volunteers. Four different pharmacological challenges with ethanol, morphine, Δ(9)-tetrahydrocannabinol, and ketamine (12 subjects per drug) were applied. A set of 10 "template" resting-state networks was used to determine individual connectivity maps. Linear regression was used for each individual subject to relate these connectivity maps to three clusters of drug-induced subjective psychomimetic effects ("perception," "relaxation," and "dysphoria") as measured with visual analogue scales. Group analysis showed that the subjective effects of perception correlated significantly across drugs with the connectivity of the posterior cingulate cortex and precentral gyrus with the sensorimotor network (p < 0.005, corrected). No significant correlations were found for relaxation or dysphoria. The posterior cingulate cortex has a role in visuospatial evaluation and the precentral gyrus has been associated with auditory hallucinations. Both the posterior cingulate cortex and the precentral gyrus show changes in activation in patients with schizophrenia, which can be related to the severity of positive symptoms (i.e., hallucinations and delusions), and have previously been related to changes induced by psychoactive drugs. The similarity of functional connectivity changes for drug-induced psychomimetic effects and symptoms of psychosis provides further support for the use of pharmacological challenges with psychomimetic drugs as models for psychosis.
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Affiliation(s)
- Daniël Kleinloog
- 1 Centre for Human Drug Research , Leiden, The Netherlands .,2 Leiden Institute for Brain and Cognition , Leiden, The Netherlands .,3 Leiden University Medical Centre , Leiden, The Netherlands
| | - Serge Rombouts
- 2 Leiden Institute for Brain and Cognition , Leiden, The Netherlands .,3 Leiden University Medical Centre , Leiden, The Netherlands .,4 Institute of Psychology, Leiden University , Leiden, The Netherlands
| | - Remco Zoethout
- 1 Centre for Human Drug Research , Leiden, The Netherlands
| | - Linda Klumpers
- 1 Centre for Human Drug Research , Leiden, The Netherlands
| | | | - Najmeh Khalili-Mahani
- 2 Leiden Institute for Brain and Cognition , Leiden, The Netherlands .,3 Leiden University Medical Centre , Leiden, The Netherlands
| | - Albert Dahan
- 3 Leiden University Medical Centre , Leiden, The Netherlands
| | - Joop van Gerven
- 1 Centre for Human Drug Research , Leiden, The Netherlands .,3 Leiden University Medical Centre , Leiden, The Netherlands
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29
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Alonso JF, Romero S, Mañanas MÀ, Riba J. Serotonergic psychedelics temporarily modify information transfer in humans. Int J Neuropsychopharmacol 2015; 18:pyv039. [PMID: 25820842 PMCID: PMC4571623 DOI: 10.1093/ijnp/pyv039] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 03/18/2015] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Psychedelics induce intense modifications in the sensorium, the sense of "self," and the experience of reality. Despite advances in our understanding of the molecular and cellular level mechanisms of these drugs, knowledge of their actions on global brain dynamics is still incomplete. Recent imaging studies have found changes in functional coupling between frontal and parietal brain structures, suggesting a modification in information flow between brain regions during acute effects. METHODS Here we assessed the psychedelic-induced changes in directionality of information flow during the acute effects of a psychedelic in humans. We measured modifications in connectivity of brain oscillations using transfer entropy, a nonlinear measure of directed functional connectivity based on information theory. Ten healthy male volunteers with prior experience with psychedelics participated in 2 experimental sessions. They received a placebo or a dose of ayahuasca, a psychedelic preparation containing the serotonergic 5-HT2A agonist N,N-dimethyltryptamine. RESULTS The analysis showed significant changes in the coupling of brain oscillations between anterior and posterior recording sites. Transfer entropy analysis showed that frontal sources decreased their influence over central, parietal, and occipital sites. Conversely, sources in posterior locations increased their influence over signals measured at anterior locations. Exploratory correlations found that anterior-to-posterior transfer entropy decreases were correlated with the intensity of subjective effects, while the imbalance between anterior-to-posterior and posterior-to-anterior transfer entropy correlated with the degree of incapacitation experienced. CONCLUSIONS These results suggest that psychedelics induce a temporary disruption of neural hierarchies by reducing top-down control and increasing bottom-up information transfer in the human brain.
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Affiliation(s)
| | | | | | - Jordi Riba
- Biomedical Engineering Research Centre, Department of Automatic Control (Drs Alonso, Romero, and Mañanas), and Barcelona College of Industrial Engineering (Drs Alonso and Mañanas), Universitat Politècnica de Catalunya, Barcelona, Spain; CIBER de Bioingeniería, Biomateriales y Nanomedicina, Spain (Drs Romero and Mañanas); Human Neuropsychopharmacology Group, Sant Pau Institute of Biomedical Research, Barcelona, Spain (Dr Riba); Department of Pharmacology and Therapeutics, Universitat Autònoma de Barcelona, Barcelona, Spain (Dr Riba); Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Spain (Dr Riba).
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30
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Höflich A, Hahn A, Küblböck M, Kranz GS, Vanicek T, Windischberger C, Saria A, Kasper S, Winkler D, Lanzenberger R. Ketamine-Induced Modulation of the Thalamo-Cortical Network in Healthy Volunteers As a Model for Schizophrenia. Int J Neuropsychopharmacol 2015; 18:pyv040. [PMID: 25896256 PMCID: PMC4576520 DOI: 10.1093/ijnp/pyv040] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2014] [Accepted: 04/03/2015] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Schizophrenia has been associated with disturbances of thalamic functioning. In light of recent evidence suggesting a significant impact of the glutamatergic system on key symptoms of schizophrenia, we assessed whether modulation of the glutamatergic system via blockage of the N-methyl-D-aspartate (NMDA)-receptor might lead to changes of thalamic functional connectivity. METHODS Based on the ketamine model of psychosis, we investigated changes in cortico-thalamic functional connectivity by intravenous ketamine challenge during a 55-minute resting-state scan. Thirty healthy volunteers were measured with pharmacological functional magnetic resonance imaging using a double-blind, randomized, placebo-controlled, crossover design. RESULTS Functional connectivity analysis revealed significant ketamine-specific changes within the thalamus hub network, more precisely, an increase of cortico-thalamic connectivity of the somatosensory and temporal cortex. CONCLUSIONS Our results indicate that changes of thalamic functioning as described for schizophrenia can be partly mimicked by NMDA-receptor blockage. This adds substantial knowledge about the neurobiological mechanisms underlying the profound changes of perception and behavior during the application of NMDA-receptor antagonists.
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Affiliation(s)
- Anna Höflich
- Department of Psychiatry and Psychotherapy (Drs Höflich, Hahn, Kranz, Vanicek, Kasper, Winkler, and Lanzenberger), and MR Center of Excellence and Center for Biomedical Engineering and Physics (Mr Küblböck and Dr Windischberger), Medical University of Vienna, Vienna, Austria; Experimental Psychiatry Unit, Center for Psychiatry and Psychotherapy, Medical University of Innsbruck, Innsbruck, Austria (Dr Saria)
| | - Andreas Hahn
- Department of Psychiatry and Psychotherapy (Drs Höflich, Hahn, Kranz, Vanicek, Kasper, Winkler, and Lanzenberger), and MR Center of Excellence and Center for Biomedical Engineering and Physics (Mr Küblböck and Dr Windischberger), Medical University of Vienna, Vienna, Austria; Experimental Psychiatry Unit, Center for Psychiatry and Psychotherapy, Medical University of Innsbruck, Innsbruck, Austria (Dr Saria)
| | - Martin Küblböck
- Department of Psychiatry and Psychotherapy (Drs Höflich, Hahn, Kranz, Vanicek, Kasper, Winkler, and Lanzenberger), and MR Center of Excellence and Center for Biomedical Engineering and Physics (Mr Küblböck and Dr Windischberger), Medical University of Vienna, Vienna, Austria; Experimental Psychiatry Unit, Center for Psychiatry and Psychotherapy, Medical University of Innsbruck, Innsbruck, Austria (Dr Saria)
| | - Georg S Kranz
- Department of Psychiatry and Psychotherapy (Drs Höflich, Hahn, Kranz, Vanicek, Kasper, Winkler, and Lanzenberger), and MR Center of Excellence and Center for Biomedical Engineering and Physics (Mr Küblböck and Dr Windischberger), Medical University of Vienna, Vienna, Austria; Experimental Psychiatry Unit, Center for Psychiatry and Psychotherapy, Medical University of Innsbruck, Innsbruck, Austria (Dr Saria)
| | - Thomas Vanicek
- Department of Psychiatry and Psychotherapy (Drs Höflich, Hahn, Kranz, Vanicek, Kasper, Winkler, and Lanzenberger), and MR Center of Excellence and Center for Biomedical Engineering and Physics (Mr Küblböck and Dr Windischberger), Medical University of Vienna, Vienna, Austria; Experimental Psychiatry Unit, Center for Psychiatry and Psychotherapy, Medical University of Innsbruck, Innsbruck, Austria (Dr Saria)
| | - Christian Windischberger
- Department of Psychiatry and Psychotherapy (Drs Höflich, Hahn, Kranz, Vanicek, Kasper, Winkler, and Lanzenberger), and MR Center of Excellence and Center for Biomedical Engineering and Physics (Mr Küblböck and Dr Windischberger), Medical University of Vienna, Vienna, Austria; Experimental Psychiatry Unit, Center for Psychiatry and Psychotherapy, Medical University of Innsbruck, Innsbruck, Austria (Dr Saria)
| | - Alois Saria
- Department of Psychiatry and Psychotherapy (Drs Höflich, Hahn, Kranz, Vanicek, Kasper, Winkler, and Lanzenberger), and MR Center of Excellence and Center for Biomedical Engineering and Physics (Mr Küblböck and Dr Windischberger), Medical University of Vienna, Vienna, Austria; Experimental Psychiatry Unit, Center for Psychiatry and Psychotherapy, Medical University of Innsbruck, Innsbruck, Austria (Dr Saria)
| | - Siegfried Kasper
- Department of Psychiatry and Psychotherapy (Drs Höflich, Hahn, Kranz, Vanicek, Kasper, Winkler, and Lanzenberger), and MR Center of Excellence and Center for Biomedical Engineering and Physics (Mr Küblböck and Dr Windischberger), Medical University of Vienna, Vienna, Austria; Experimental Psychiatry Unit, Center for Psychiatry and Psychotherapy, Medical University of Innsbruck, Innsbruck, Austria (Dr Saria)
| | - Dietmar Winkler
- Department of Psychiatry and Psychotherapy (Drs Höflich, Hahn, Kranz, Vanicek, Kasper, Winkler, and Lanzenberger), and MR Center of Excellence and Center for Biomedical Engineering and Physics (Mr Küblböck and Dr Windischberger), Medical University of Vienna, Vienna, Austria; Experimental Psychiatry Unit, Center for Psychiatry and Psychotherapy, Medical University of Innsbruck, Innsbruck, Austria (Dr Saria)
| | - Rupert Lanzenberger
- Department of Psychiatry and Psychotherapy (Drs Höflich, Hahn, Kranz, Vanicek, Kasper, Winkler, and Lanzenberger), and MR Center of Excellence and Center for Biomedical Engineering and Physics (Mr Küblböck and Dr Windischberger), Medical University of Vienna, Vienna, Austria; Experimental Psychiatry Unit, Center for Psychiatry and Psychotherapy, Medical University of Innsbruck, Innsbruck, Austria (Dr Saria).
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Powers AR, Gancsos MG, Finn ES, Morgan PT, Corlett PR. Ketamine-Induced Hallucinations. Psychopathology 2015; 48:376-85. [PMID: 26361209 PMCID: PMC4684980 DOI: 10.1159/000438675] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 07/11/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND Ketamine, the NMDA glutamate receptor antagonist drug, is increasingly employed as an experimental model of psychosis in healthy volunteers. At subanesthetic doses, it safely and reversibly causes delusion-like ideas, amotivation and perceptual disruptions reminiscent of the aberrant salience experiences that characterize first-episode psychosis. However, auditory verbal hallucinations, a hallmark symptom of schizophrenia, have not been reported consistently in healthy volunteers even at high doses of ketamine. SAMPLING AND METHODS Here we present data from a set of healthy participants who received moderately dosed, placebo-controlled ketamine infusions in the reduced stimulation environment of the magnetic resonance imaging (MRI) scanner. We highlight the phenomenological experiences of 3 participants who experienced particularly vivid hallucinations. RESULTS Participants in this series reported auditory verbal and musical hallucinations at a ketamine dose that does not induce auditory hallucination outside of the scanner. CONCLUSIONS We interpret the observation of ketamine-induced auditory verbal hallucinations in the context of the reduced perceptual environment of the MRI scanner and offer an explanation grounded in predictive coding models of perception and psychosis - the brain fills in expected perceptual inputs, and it does so more in situations of altered perceptual input. The altered perceptual input of the MRI scanner creates a mismatch between top-down perceptual expectations and the heightened bottom-up signals induced by ketamine. Such circumstances induce aberrant percepts, including musical and auditory verbal hallucinations. We suggest that these circumstances might represent a useful experimental model of auditory verbal hallucinations and highlight the impact of ambient sensory stimuli on psychopathology.
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Affiliation(s)
- Albert R Powers
- Department of Psychiatry, Yale School of Medicine, Yale University, New Haven, Conn., USA
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Gomes MM, Coimbra JB, Clara RO, Dörr FA, Moreno ACR, Chagas JR, Tufik S, Pinto E, Catalani LH, Campa A. Biosynthesis of N,N-dimethyltryptamine (DMT) in a melanoma cell line and its metabolization by peroxidases. Biochem Pharmacol 2014; 88:393-401. [PMID: 24508833 DOI: 10.1016/j.bcp.2014.01.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 01/23/2014] [Accepted: 01/24/2014] [Indexed: 01/19/2023]
Abstract
Tryptophan (TRP) is essential for many physiological processes, and its metabolism changes in some diseases such as infection and cancer. The most studied aspects of TRP metabolism are the kynurenine and serotonin pathways. A minor metabolic route, tryptamine and N,N-dimethyltryptamine (DMT) biosynthesis, has received far less attention, probably because of the very low amounts of these compounds detected only in some tissues, which has led them to be collectively considered as trace amines. In a previous study, we showed a metabolic interrelationship for TRP in melanoma cell lines. Here, we identified DMT and N,N-dimethyl-N-formyl-kynuramine (DMFK) in the supernatant of cultured SK-Mel-147 cells. Furthermore, when we added DMT to the cell culture, we found hydroxy-DMT (OH-DMT) and indole acetic acid (IAA) in the cell supernatant at 24 h. We found that SK-Mel-147 cells expressed mRNA for myeloperoxidase (MPO) and also had peroxidase activity. We further found that DMT oxidation was catalyzed by peroxidases. DMT oxidation by horseradish peroxidase, H2O2 and MPO from PMA-activated neutrophils produced DMFK, N,N-dimethyl-kynuramine (DMK) and OH-DMT. Oxidation of DMT by peroxidases apparently uses the common peroxidase cycle involving the native enzyme, compound I and compound II. In conclusion, this study describes a possible alternative metabolic pathway for DMT involving peroxidases that has not previously been described in humans and identifies DMT and metabolites in a melanoma cell line. The extension of these findings to other cell types and the biological effects of DMT and its metabolites on cell proliferation and function are key questions for future studies.
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Affiliation(s)
- Melissa M Gomes
- Department of Clinical Chemistry and Toxicology, Universidade de São Paulo, São Paulo, Brazil
| | - Janine B Coimbra
- Department of Clinical Chemistry and Toxicology, Universidade de São Paulo, São Paulo, Brazil
| | - Renan O Clara
- Department of Clinical Chemistry and Toxicology, Universidade de São Paulo, São Paulo, Brazil
| | - Felipe A Dörr
- Department of Clinical Chemistry and Toxicology, Universidade de São Paulo, São Paulo, Brazil
| | - Ana Carolina R Moreno
- Department of Clinical Chemistry and Toxicology, Universidade de São Paulo, São Paulo, Brazil
| | - Jair R Chagas
- Department of Psychobiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Sérgio Tufik
- Department of Psychobiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Ernani Pinto
- Department of Clinical Chemistry and Toxicology, Universidade de São Paulo, São Paulo, Brazil
| | - Luiz H Catalani
- Department of Fundamental Chemistry, Universidade de Sao Paulo, São Paulo, Brazil
| | - Ana Campa
- Department of Clinical Chemistry and Toxicology, Universidade de São Paulo, São Paulo, Brazil.
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Acute effects of ayahuasca on neuropsychological performance: differences in executive function between experienced and occasional users. Psychopharmacology (Berl) 2013; 230:415-24. [PMID: 23793226 DOI: 10.1007/s00213-013-3167-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 05/29/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Ayahuasca, a South American psychotropic plant tea containing the psychedelic 5-HT2A receptor agonist N,N-dimethyltryptamine, has been shown to increase regional cerebral blood flow in prefrontal brain regions after acute administration to humans. Despite interactions at this level, neuropsychological studies have not found cognitive deficits in abstinent long-term users. OBJECTIVES Here, we wished to investigate the effects of acute ayahuasca intake on neuropsychological performance, specifically on working memory and executive function. METHODS Twenty-four ayahuasca users (11 long-term experienced users and 13 occasional users) were assessed in their habitual setting using the Stroop, Sternberg, and Tower of London tasks prior to and following ayahuasca intake. RESULTS Errors in the Sternberg task increased, whereas reaction times in the Stroop task decreased and accuracy was maintained for the whole sample following ayahuasca intake. Interestingly, results in the Tower of London showed significantly increased execution and resolution times and number of movements for the occasional but not the experienced users. Additionally, a correlation analysis including all subjects showed that impaired performance in the Tower of London was inversely correlated with lifetime ayahuasca use. CONCLUSIONS Acute ayahuasca administration impaired working memory but decreased stimulus-response interference. Interestingly, detrimental effects on higher cognition were only observed in the less experienced group. Rather than leading to increased impairment, greater prior exposure to ayahuasca was associated with reduced incapacitation. Compensatory or neuromodulatory effects associated with long-term ayahuasca intake could underlie preserved executive function in experienced users.
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Frecska E, Szabo A, Winkelman MJ, Luna LE, McKenna DJ. A possibly sigma-1 receptor mediated role of dimethyltryptamine in tissue protection, regeneration, and immunity. J Neural Transm (Vienna) 2013; 120:1295-303. [PMID: 23619992 DOI: 10.1007/s00702-013-1024-y] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 04/01/2013] [Indexed: 01/20/2023]
Abstract
N,N-dimethyltryptamine (DMT) is classified as a naturally occurring serotonergic hallucinogen of plant origin. It has also been found in animal tissues and regarded as an endogenous trace amine transmitter. The vast majority of research on DMT has targeted its psychotropic/psychedelic properties with less focus on its effects beyond the nervous system. The recent discovery that DMT is an endogenous ligand of the sigma-1 receptor may shed light on yet undiscovered physiological mechanisms of DMT activity and reveal some of its putative biological functions. A three-step active uptake process of DMT from peripheral sources to neurons underscores a presumed physiological significance of this endogenous hallucinogen. In this paper, we overview the literature on the effects of sigma-1 receptor ligands on cellular bioenergetics, the role of serotonin, and serotoninergic analogues in immunoregulation and the data regarding gene expression of the DMT synthesizing enzyme indolethylamine-N-methyltransferase in carcinogenesis. We conclude that the function of DMT may extend central nervous activity and involve a more universal role in cellular protective mechanisms. Suggestions are offered for future directions of indole alkaloid research in the general medical field. We provide converging evidence that while DMT is a substance which produces powerful psychedelic experiences, it is better understood not as a hallucinogenic drug of abuse, but rather an agent of significant adaptive mechanisms that can also serve as a promising tool in the development of future medical therapies.
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Affiliation(s)
- Ede Frecska
- Department of Psychiatry, Medical and Health Science Center, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary.
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Nagels A, Kirner-Veselinovic A, Wiese R, Paulus FM, Kircher T, Krach S. Effects of ketamine-induced psychopathological symptoms on continuous overt rhyme fluency. Eur Arch Psychiatry Clin Neurosci 2012; 262:403-14. [PMID: 22189657 DOI: 10.1007/s00406-011-0281-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 12/03/2011] [Indexed: 11/29/2022]
Abstract
The N-methyl-D-aspartate receptor (NMDAR) has been implicated in the pathophysiology of schizophrenia. Administered to healthy individuals, a subanesthetic dose of the noncompetitive NMDAR antagonist ketamine reproduces several psychopathological symptoms commonly observed in patients with schizophrenia. In a counterbalanced, placebo-controlled, double-blind, within-participants study, fifteen healthy subjects were administered a continuous subanesthetic S-ketamine infusion while cortical activation was measured using functional magnetic resonance imaging. While being scanned, subjects performed an overt word generation task. Ketamine-induced psychopathological symptoms were assessed with the Positive and Negative Syndrome Scale (PANSS). Ketamine administration elicited effects on psychopathology, including difficulties in abstract thinking, lack of spontaneity and flow of conversation as well as formal thought disorder. On a behavioral level, verbal fluency performance was unaffected. The PANSS score for formal thought disorder positively correlated with activation measures encompassing the left superior temporal gyrus, the right middle and inferior frontal gyrus and the precuneus. Difficulty in abstract thinking was correlated with pronounced activations in prefrontal as well as in anterior cingulate regions, whereas hyperactivations in the left superior temporal gyrus were found in association with a lack of spontaneity and flow of conversation. In the absence of behavioral impairments during verbal fluency, NMDAR blocking evoked psychopathological symptoms and cortical activations in regions previously reported in schizophrenia patients. The results provide further support for the hypothesis of an NMDAR dysfunction in the pathophysiology of schizophrenia.
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Affiliation(s)
- Arne Nagels
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Germany.
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N-methyl-D-aspartate receptor 2B subunit (GRIN2B) gene variation is associated with alerting, but not with orienting and conflicting in the Attention Network Test. Neuropharmacology 2012; 63:259-65. [PMID: 22484476 DOI: 10.1016/j.neuropharm.2012.02.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 02/22/2012] [Accepted: 02/23/2012] [Indexed: 01/27/2023]
Abstract
Appropriate attention levels are pivotal for cognitive processes, and individual differences in attentional functioning are related to variations in the interplay of neurotransmitters. The attention network theory reflects attention as a non-homogenous set of separate neural networks: alerting, orienting and conflicting. In the present study, the role of variations in GRIN2B, which encodes the NR2B subunit of N-methyl-d-aspartate (NMDA) receptors, was explored with regard to the regulation of arousal and attention by comparing the efficiency of the three attentional networks as measured with the Attention Network Test (ANT). Two synonymous SNPs in GRIN2B, rs1806201 (T888T) and rs1806191 (H1178H) were genotyped in 324 young Caucasian adults. Results revealed a highly specific modulatory influence of SNP rs1806201 on alerting processes with subjects homozygous for the frequent C allele displaying higher alerting network scores as compared to the other two genotype groups (CT and TT). This effect is due to the fact that in the no cue condition faster reaction times were evident in participants carrying at least one of the rare T alleles, possibly as a result of more effective glutamatergic neurotransmission. The results might be further explained by a dissociation between tonic and phasic alertness modulated by the GRIN2B genotype and by a ceiling effect, meaning that subjects cannot be phasicly alert in excess to a certain level. Altogether, the results show that variations in GRIN2B have to be taken into consideration when examining attentional processes.
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Barker SA, McIlhenny EH, Strassman R. A critical review of reports of endogenous psychedelic N, N-dimethyltryptamines in humans: 1955-2010. Drug Test Anal 2012; 4:617-35. [DOI: 10.1002/dta.422] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 01/03/2012] [Accepted: 01/03/2012] [Indexed: 11/11/2022]
Affiliation(s)
- Steven A. Barker
- School of Veterinary Medicine; Louisiana State University; Baton Rouge; LA; USA
| | - Ethan H. McIlhenny
- School of Veterinary Medicine; Louisiana State University; Baton Rouge; LA; USA
| | - Rick Strassman
- School of Medicine, University of New Mexico; Albuquerque, and Cottonwood Research Foundation; Taos; New Mexico; USA
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Abstract
BACKGROUND Based on the glutamatergic NMDA receptor hypofunction theory of schizophrenia, NMDA receptor modulators (NMDARMs) may have therapeutic potential in the treatment of schizophrenia. OBJECTIVE This meta-analysis aimed to evaluate the potential of modulators of the NMDA receptor as adjunctive therapy for schizophrenia, using the results from published trials. DATA SOURCES A primary electronic search for controlled clinical trials using NMDARMs in schizophrenia was conducted on the PubMed, Cochrane Library, EMBASE, CINAHL® and PsycINFO databases. A secondary manual search of references from primary publications was also performed. STUDY SELECTION Inclusion criteria were the application of an established method of diagnosis, randomized case assignment, comparison of NMDARM add-on therapy with placebo, and double-blind assessment of symptoms in chronic schizophrenia using standardized rating scales. Results were based on a total sample size of 1253 cases from 29 trials that fulfilled the specified criteria. DATA EXTRACTION Scores on rating scales or on their relevant subscales were obtained for all selected studies from published results for the minimum dataset to compute the difference between post- and pre-trial scores and their pooled standard deviation for NMDARM add-on therapy and placebo groups for negative, positive and total symptoms. RESULTS A negative standardized mean difference (SMD) indicates therapeutic benefit in favour of NMDARM add-on therapy and all SMD results mentioned here are statistically significant. The overall effect size for NMDARMs as a group was small for negative (SMD -0.27) and medium for total (SMD -0.40) symptoms of chronic schizophrenia. Subgroup analysis revealed medium effect sizes for D-serine and N-acetyl-cysteine (NAC) for negative (SMD -0.53 and -0.45, respectively) and total (SMD -0.40 and -0.64, respectively) symptoms, and for glycine (SMD -0.66) and sarcosine (SMD -0.41) for total symptoms. As adjuvants to non-clozapine antipsychotics, additional therapeutic benefits were observed for NMDARM as a group (SMD -0.14) and glycine (SMD -0.54) for positive symptoms; D-serine (SMD -0.54), NAC (SMD -0.45) and sarcosine (SMD -0.39) for negative symptoms; and NMDARM as a group (SMD -0.38), D-serine (SMD -0.40), glycine (SMD -1.12), NAC (SMD -0.64) and sarcosine (SMD -0.53) for total symptoms. When added to clozapine, none of the drugs demonstrated therapeutic potential, while addition of glycine (SMD +0.56) worsened positive symptoms. CONCLUSIONS Taking into consideration the number of trials and sample size in subgroup analyses, D-serine, NAC and sarcosine as adjuncts to non-clozapine antipsychotics have therapeutic benefit in the treatment of negative and total symptoms of chronic schizophrenia. While glycine improves positive and total symptoms as an adjuvant to non-clozapine antipsychotics, it worsens them when added to clozapine.
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Affiliation(s)
- Surendra P Singh
- General Adult Psychiatry, Mental Health Directorate, Wolverhampton City Primary Care Trust, Wolverhampton, West Midlands, UK
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Alertness can be improved by an interaction between orienting attention and alerting attention in schizophrenia. Behav Brain Funct 2011; 7:24. [PMID: 21729299 PMCID: PMC3156722 DOI: 10.1186/1744-9081-7-24] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Accepted: 07/05/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Attention is impaired in schizophrenia. Early attention components include orienting and alerting, as well as executive control networks. Previous studies have shown mainly executive control deficits, while few of them found orienting and alerting abnormalities. Here we explore the different attentive networks, their modulation and interactions in patients with schizophrenia. METHODS Twenty-one schizophrenic patients (DSMIV), compared to 21 controls, performed a modified version of the Attention Network Task, in which an orienting paradigm (with valid, invalid and no cues) was combined with a flanker task (congruent/incongruent) and an alerting signal (tone/no tone), to assess orienting, executive control and alerting networks independently. RESULTS Patients showed an abnormal alerting effect and slower overall reaction time compared to controls. Moreover, there was an interaction between orienting and alerting: patients are helped more than controls by the alerting signal in a valid orientation to solve the incongruent condition. CONCLUSION These results suggest that patients with schizophrenia have altered alerting abilities. However, the orienting and alerting cues interact to improve their attention performance in the resolution of conflict, creating possibilities for cognitive remediation strategies.
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Musso F, Brinkmeyer J, Ecker D, London MK, Thieme G, Warbrick T, Wittsack HJ, Saleh A, Greb W, de Boer P, Winterer G. Ketamine effects on brain function--simultaneous fMRI/EEG during a visual oddball task. Neuroimage 2011; 58:508-25. [PMID: 21723949 DOI: 10.1016/j.neuroimage.2011.06.045] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 06/09/2011] [Accepted: 06/17/2011] [Indexed: 10/18/2022] Open
Abstract
BACKGROUND Behavioral and electrophysiological human ketamine models of schizophrenia are used for testing compounds that target the glutamatergic system. However, corresponding functional neuroimaging models are difficult to reconcile with functional imaging and electrophysiological findings in schizophrenia. Resolving the discrepancies between different observational levels is critical to understand the complex pharmacological ketamine action and its usefulness for modeling schizophrenia pathophysiology. METHODS We conducted a within-subject, randomized, placebo-controlled pharmacoimaging study in twenty-four male volunteers. Subjects were given low-dose S-ketamine (bolus prior to functional imaging: 0.1mg/kg during 5min, thereafter continuous infusion: 0.015625mg/kg/min reduced by 10% every ten minutes) or placebo while performing a visual oddball task during simultaneous functional magnetic resonance imaging (fMRI) with continuous recording of event-related potentials (P300) and electrodermal activity (EDA). Before and after intervention, psychopathological status was assessed using the Positive and Negative Syndrome Scale (PANSS) and the Altered State of Consciousness (5D-ASC) Rating Scale. RESULTS P300 amplitude and corresponding BOLD responses were diminished in the ketamine condition in cortical regions being involved in sensory processing/selective attention. In both measurement modalities separation of drug conditions was achieved with area under the curve (AUC) values of up to 0.8-0.9. Ketamine effects were also observed in the clinical, behavioral and peripheral physiological domains (Positive and Negative Syndrome Scale, reaction hit and false alarm rate, electrodermal activity and heart rate) which were in part related to the P300/fMRI measures. CONCLUSION The findings from our ketamine experiment are consistent across modalities and directly related to observations in schizophrenia supporting the validity of the model. Our investigation provides the first prototypic example of a pharmacoimaging study using simultaneously acquired fMRI/EEG.
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Affiliation(s)
- Francesco Musso
- Institute of Neurosciences and Medicine, Helmholtz Research Center, Jülich, Germany
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Langner R, Kellermann T, Eickhoff SB, Boers F, Chatterjee A, Willmes K, Sturm W. Staying responsive to the world: modality-specific and -nonspecific contributions to speeded auditory, tactile, and visual stimulus detection. Hum Brain Mapp 2011; 33:398-418. [PMID: 21438078 DOI: 10.1002/hbm.21220] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 10/17/2010] [Accepted: 11/08/2010] [Indexed: 12/30/2022] Open
Abstract
Sustained responsiveness to external stimulation is fundamental to many time-critical interactions with the outside world. We used functional magnetic resonance imaging during speeded stimulus detection to identify convergent and divergent neural correlates of maintaining the readiness to respond to auditory, tactile, and visual stimuli. In addition, using a multimodal condition, we investigated the effect of making stimulus modality unpredictable. Relative to sensorimotor control tasks, all three unimodal detection tasks elicited stronger activity in the right temporo-parietal junction, inferior frontal cortex, anterior insula, dorsal premotor cortex, and anterior cingulate cortex as well as bilateral mid-cingulum, midbrain, brainstem, and medial cerebellum. The multimodal detection condition additionally activated left dorsal premotor cortex and bilateral precuneus. Modality-specific modulations were confined to respective sensory areas: we found activity increases in relevant, and decreases in irrelevant sensory cortices. Our findings corroborate the modality independence of a predominantly right-lateralized core network for maintaining an alert (i.e., highly responsive) state and extend previous results to the somatosensory modality. Monitoring multiple sensory channels appears to induce additional processing, possibly related to stimulus-driven shifts of intermodal attention. The results further suggest that directing attention to a given sensory modality selectively enhances and suppresses sensory processing-even in simple detection tasks, which do not require inter- or intra-modal selection.
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Affiliation(s)
- Robert Langner
- Department of Neurology, Neuropsychology Section, RWTH Aachen University, Aachen, Germany.
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