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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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Chang X, Zhao W, Kang J, Xiang S, Xie C, Corona-Hernández H, Palaniyappan L, Feng J. Language abnormalities in schizophrenia: binding core symptoms through contemporary empirical evidence. SCHIZOPHRENIA (HEIDELBERG, GERMANY) 2022; 8:95. [PMID: 36371445 PMCID: PMC9653408 DOI: 10.1038/s41537-022-00308-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
Both the ability to speak and to infer complex linguistic messages from sounds have been claimed as uniquely human phenomena. In schizophrenia, formal thought disorder (FTD) and auditory verbal hallucinations (AVHs) are manifestations respectively relating to concrete disruptions of those abilities. From an evolutionary perspective, Crow (1997) proposed that "schizophrenia is the price that Homo sapiens pays for the faculty of language". Epidemiological and experimental evidence points to an overlap between FTD and AVHs, yet a thorough investigation examining their shared neural mechanism in schizophrenia is lacking. In this review, we synthesize observations from three key domains. First, neuroanatomical evidence indicates substantial shared abnormalities in language-processing regions between FTD and AVHs, even in the early phases of schizophrenia. Second, neurochemical studies point to a glutamate-related dysfunction in these language-processing brain regions, contributing to verbal production deficits. Third, genetic findings further show how genes that overlap between schizophrenia and language disorders influence neurodevelopment and neurotransmission. We argue that these observations converge into the possibility that a glutamatergic dysfunction in language-processing brain regions might be a shared neural basis of both FTD and AVHs. Investigations of language pathology in schizophrenia could facilitate the development of diagnostic tools and treatments, so we call for multilevel confirmatory analyses focused on modulations of the language network as a therapeutic goal in schizophrenia.
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Affiliation(s)
- Xiao Chang
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China
- Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Fudan University, Ministry of Education, Shanghai, China
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
- Zhangjiang Fudan International Innovation Center, Shanghai, China
| | - Wei Zhao
- MOE-LCSM, School of Mathematics and Statistics, Hunan Normal University, Changsha, PR China
| | - Jujiao Kang
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China
- Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Fudan University, Ministry of Education, Shanghai, China
- Shanghai Center for Mathematical Sciences, Shanghai, China
| | - Shitong Xiang
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China
- Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Fudan University, Ministry of Education, Shanghai, China
| | - Chao Xie
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China
- Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Fudan University, Ministry of Education, Shanghai, China
| | - Hugo Corona-Hernández
- Department of Biomedical Sciences of Cells & Systems, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Lena Palaniyappan
- Douglas Mental Health University Institute, Department of Psychiatry, McGill University, Montreal, Quebec, Canada.
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.
- Lawson Health Research Institute, London, Ontario, Canada.
| | - Jianfeng Feng
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China.
- Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Fudan University, Ministry of Education, Shanghai, China.
- MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China.
- Zhangjiang Fudan International Innovation Center, Shanghai, China.
- Shanghai Center for Mathematical Sciences, Shanghai, China.
- Department of Computer Science, University of Warwick, Coventry, UK.
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Zhornitsky S, Tourjman V, Pelletier J, Assaf R, Li CSR, Potvin S. Acute effects of ketamine and esketamine on cognition in healthy subjects: A meta-analysis. Prog Neuropsychopharmacol Biol Psychiatry 2022; 118:110575. [PMID: 35568275 DOI: 10.1016/j.pnpbp.2022.110575] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 05/04/2022] [Accepted: 05/09/2022] [Indexed: 11/27/2022]
Abstract
BACKGROUND Impairment in cognition is frequently associated with acute ketamine administration. However, some questions remain unanswered as to which deficits are most prominent and what variables modulate these effects. METHODS A literature search yielded 56 experimental studies of acute ketamine administration that assessed cognition in 1041 healthy volunteers. A multivariate meta-analysis was performed, and effect sizes were estimated for eleven cognitive domains: attention, executive function, response inhibition, social cognition, speed of processing, verbal / language, verbal learning, verbal memory, visual learning & memory, visuospatial abilities, and working memory. RESULTS There were small-to-moderate impairments across all cognitive domains. Deficits in verbal learning / memory were most prominent, whereas response inhibition was the least affected. Meta-regression analysis revealed that the negative effects of ketamine on cognition are dependent on infusion dose and plasma level, but unaffected by enantiomer type, route of administration, sex or age. A publication bias was observed. DISCUSSION Acute ketamine broadly impairs cognition across all domains among healthy individuals. Verbal learning and memory figures most prominently in cognitive impairment elicited by acute ketamine administration.
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Affiliation(s)
- Simon Zhornitsky
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Valérie Tourjman
- Department of Psychiatry, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada; Centre de recherche de l'Institut Universitaire en Santé Mentale de Montréal, Montreal, QC, Canada
| | - Julie Pelletier
- Department of Psychiatry, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Roxane Assaf
- Department of Psychiatry, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada; Centre de recherche de l'Institut Universitaire en Santé Mentale de Montréal, Montreal, QC, Canada
| | - Chiang-Shan R Li
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA; Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA; Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT, USA
| | - Stéphane Potvin
- Department of Psychiatry, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada; Centre de recherche de l'Institut Universitaire en Santé Mentale de Montréal, Montreal, QC, Canada.
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Chen S, Tang Y, Fan X, Qiao Y, Wang J, Wen H, Wang W, Wang H, Yang F, Sheng J. The role of white matter abnormality in the left anterior corona radiata: In relation to formal thought disorder in patients with schizophrenia. Psychiatry Res 2022; 307:114302. [PMID: 34890908 DOI: 10.1016/j.psychres.2021.114302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 11/17/2021] [Accepted: 11/19/2021] [Indexed: 12/27/2022]
Abstract
White matter abnormality has been widely reported in patients with schizophrenia (Sz). However, few studies have focused on the relationship between the white matter deficit and formal thought disorder (FTD). Moreover, the role of genetic high risk in FTD-related white matter deficit remains unclear. The present study recruited 46 Sz patients, 18 unaffected first-degree relatives of Sz patients, and 29 healthy controls. There was a widespread fractional anisotropy (FA) reduction in Sz. In addition, reduced FA in the left anterior corona radiata was related to more severe FTD symptoms in Sz. However, the genetic high-risk group only showed lower mean FA in the left anterior limb of the internal capsule than healthy controls. Our findings suggest that abnormality in the left anterior corona radiata may only occur in Sz but not in the genetic high-risk group. Such an abnormality might be associated with the severity of FTD symptoms. Meanwhile, genetic vulnerability may contribute to the abnormality in the left anterior limb of the internal capsule. Better analytical methods are needed to validate our results.
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Affiliation(s)
- Shan Chen
- Department of Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 600 Wan Ping Nan Road, Shanghai 200030, China
| | - Yingying Tang
- Shanghai Key Laboratory of Psychotic Disorders,Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, China; Department of EEG and Imaging, Shanghai Mental Health Center, Shanghai JiaoTong University School of Medicine, Shanghai 200030, China
| | - Xiaoduo Fan
- UMass Memorial Health Care & University of Massachusetts Medical School, Worcester, MA 01605, United States
| | - Yi Qiao
- Department of Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 600 Wan Ping Nan Road, Shanghai 200030, China
| | - Jijun Wang
- Shanghai Key Laboratory of Psychotic Disorders,Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, China; Department of EEG and Imaging, Shanghai Mental Health Center, Shanghai JiaoTong University School of Medicine, Shanghai 200030, China
| | - Hun Wen
- Department of Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 600 Wan Ping Nan Road, Shanghai 200030, China
| | - Wenzheng Wang
- Department of Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 600 Wan Ping Nan Road, Shanghai 200030, China
| | - Hongyan Wang
- Department of Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 600 Wan Ping Nan Road, Shanghai 200030, China
| | - Fuzhong Yang
- Department of Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 600 Wan Ping Nan Road, Shanghai 200030, China.
| | - Jianhua Sheng
- Department of Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 600 Wan Ping Nan Road, Shanghai 200030, China.
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Fiorentini A, Cantù F, Crisanti C, Cereda G, Oldani L, Brambilla P. Substance-Induced Psychoses: An Updated Literature Review. Front Psychiatry 2021; 12:694863. [PMID: 35002789 PMCID: PMC8732862 DOI: 10.3389/fpsyt.2021.694863] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 11/17/2021] [Indexed: 01/22/2023] Open
Abstract
Background: On the current psychopharmacological panorama, the variety of substances able to provoke an episode of acute psychosis is rapidly increasing. Such psychotic episodes are classified according to the major category of symptoms: positive, negative, or cognitive psychotic episodes. On one hand, the abuse of methamphetamines, cannabis, and cocaine plays a big role in increasing the incidence of episodes resembling a psychotic disorder. On the other hand, the progress in terms of pharmacodynamics knowledge has led to the synthesis of new drugs, such as cannabinoids and cathinone's, which have rapidly entered into the common pool of abusers' habits. Regarding these newly synthesized substances of abuse, further clinical studies are needed to understand their psychogenic properties. The topic of this review is complicated due to the frequent abuse of psychotomimetic drugs by patients affected by psychotic disorders, a fact that makes it extremely difficult to distinguish between an induced psychosis and a re-exacerbation of a previously diagnosed disorder. Methods: The present narrative review summarizes results from clinical studies, thus investigating the psychotogenic properties of abused substances and the psychotic symptoms they can give rise to. It also discusses the association between substance abuse and psychosis, especially with regards to the differential diagnosis between a primary vs. a substance-induced psychotic disorder. Findings: Our findings support the theory that psychosis due to substance abuse is commonly observed in clinical practice. The propensity to develop psychosis seems to be a function of the severity of use and addiction. Of note, from a phenomenological point of view, it is possible to identify some elements that may help clinicians involved in differential diagnoses between primary and substance-induced psychoses. There remains a striking paucity of information on the outcomes, treatments, and best practices of substance-induced psychotic episodes.
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Affiliation(s)
- Alessio Fiorentini
- Department of Neurosciences and Mental Health, Fondazione Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS) Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Filippo Cantù
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Camilla Crisanti
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Guido Cereda
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Lucio Oldani
- Department of Neurosciences and Mental Health, Fondazione Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS) Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Paolo Brambilla
- Department of Neurosciences and Mental Health, Fondazione Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS) Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
- Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
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Beck K, Hindley G, Borgan F, Ginestet C, McCutcheon R, Brugger S, Driesen N, Ranganathan M, D’Souza DC, Taylor M, Krystal JH, Howes OD. Association of Ketamine With Psychiatric Symptoms and Implications for Its Therapeutic Use and for Understanding Schizophrenia: A Systematic Review and Meta-analysis. JAMA Netw Open 2020; 3:e204693. [PMID: 32437573 PMCID: PMC7243091 DOI: 10.1001/jamanetworkopen.2020.4693] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 02/29/2020] [Indexed: 12/16/2022] Open
Abstract
Importance Ketamine hydrochloride is increasingly used to treat depression and other psychiatric disorders but can induce schizophrenia-like or psychotomimetic symptoms. Despite this risk, the consistency and magnitude of symptoms induced by ketamine or what factors are associated with these symptoms remain unknown. Objective To conduct a meta-analysis of the psychopathological outcomes associated with ketamine in healthy volunteers and patients with schizophrenia and the experimental factors associated with these outcomes. Data Sources MEDLINE, Embase, and PsychINFO databases were searched for within-participant, placebo-controlled studies reporting symptoms using the Brief Psychiatric Rating Scale (BPRS) or the Positive and Negative Syndrome Scale (PANSS) in response to an acute ketamine challenge in healthy participants or patients with schizophrenia. Study Selection Of 8464 citations retrieved, 36 studies involving healthy participants were included. Inclusion criteria were studies (1) including healthy participants; (2) reporting symptoms occurring in response to acute administration of subanesthetic doses of ketamine (racemic ketamine, s-ketamine, r-ketamine) intravenously; (3) containing a placebo condition with a within-subject, crossover design; (4) measuring total positive or negative symptoms using BPRS or PANSS; and (5) providing data allowing the estimation of the mean difference and deviation between the ketamine and placebo condition. Data Extraction and Synthesis Two independent investigators extracted study-level data for a random-effects meta-analysis. Total, positive, and negative BPRS and PANSS scores were extracted. Subgroup analyses were conducted examining the effects of blinding status, ketamine preparation, infusion method, and time between ketamine and placebo conditions. The Meta-analysis of Observational Studies in Epidemiology (MOOSE) and Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed. Main Outcomes and Measures Standardized mean differences (SMDs) were used as effect sizes for individual studies. Standardized mean differences between ketamine and placebo conditions were calculated for total, positive, and negative BPRS and PANSS scores. Results The overall sample included 725 healthy volunteers (mean [SD] age, 28.3 [3.6] years; 533 [73.6%] male) exposed to the ketamine and placebo conditions. Racemic ketamine or S-ketamine was associated with a statistically significant increase in transient psychopathology in healthy participants for total (SMD = 1.50 [95% CI, 1.23-1.77]; P < .001), positive (SMD = 1.55 [95% CI, 1.29-1.81]; P < .001), and negative (SMD = 1.16 [95% CI, 0.96-1.35]; P < .001) symptom ratings relative to the placebo condition. The effect size for this association was significantly greater for positive than negative symptoms of psychosis (estimate, 0.36 [95% CI, 0.12-0.61]; P = .004). There was significant inconsistency in outcomes between studies (I2 range, 77%-83%). Bolus followed by constant infusion increased ketamine's association with positive symptoms relative to infusion alone (effect size, 1.63 [95% CI, 1.36-1.90] vs 0.84 [95% CI, 0.35-1.33]; P = .006). Single-day study design increased ketamine's ability to generate total symptoms (effect size, 2.29 [95% CI, 1.69-2.89] vs 1.39 [95% CI, 1.12-1.66]; P = .007), but age and sex did not moderate outcomes. Insufficient studies were available for meta-analysis of studies in schizophrenia. Of these studies, 2 found a statistically significant increase in symptoms with ketamine administration in total and positive symptoms. Only 1 study found an increase in negative symptom severity with ketamine. Conclusions and Relevance This study found that acute ketamine administration was associated with schizophrenia-like or psychotomimetic symptoms with large effect sizes, but there was a greater increase in positive than negative symptoms and when a bolus was used. These findings suggest that bolus doses should be avoided in the therapeutic use of ketamine to minimize the risk of inducing transient positive (psychotic) symptoms.
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Affiliation(s)
- Katherine Beck
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
- Psychiatric Imaging Group, MRC (Medical Research Council) London Institute of Medical Sciences, Hammersmith Hospital, London, United Kingdom
- South London and Maudsley NHS (National Health Service) Foundation Trust, London, United Kingdom
| | - Guy Hindley
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Faith Borgan
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Cedric Ginestet
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
- Department of Biostatistics and Health Informatics, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Robert McCutcheon
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
- Psychiatric Imaging Group, MRC (Medical Research Council) London Institute of Medical Sciences, Hammersmith Hospital, London, United Kingdom
- South London and Maudsley NHS (National Health Service) Foundation Trust, London, United Kingdom
| | - Stefan Brugger
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
- Division of Psychiatry, University College London, London, United Kingdom
- Cardiff University Brain Research Imaging Centre, Cardiff, United Kingdom
| | - Naomi Driesen
- Yale University Medical School, Veterans Affairs Connecticut Health Care System, West Haven
| | - Mohini Ranganathan
- Yale University Medical School, Veterans Affairs Connecticut Health Care System, West Haven
- Department of Psychiatry and National Center for Posttraumatic Stress Disorder (PTSD), Veterans Affairs Connecticut Healthcare System, West Haven
| | - Deepak Cyril D’Souza
- Yale University Medical School, Veterans Affairs Connecticut Health Care System, West Haven
- Department of Psychiatry and National Center for Posttraumatic Stress Disorder (PTSD), Veterans Affairs Connecticut Healthcare System, West Haven
| | - Matthew Taylor
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
- University Department of Psychiatry, Warneford Hospital, Oxford, United Kingdom
| | - John H. Krystal
- Yale University Medical School, Veterans Affairs Connecticut Health Care System, West Haven
- Department of Veteran Affairs National Center for Posttraumatic Stress Disorder, Clinical Neurosciences Division, Veterans Affairs Connecticut Healthcare System, West Haven
| | - Oliver D. Howes
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
- Psychiatric Imaging Group, MRC (Medical Research Council) London Institute of Medical Sciences, Hammersmith Hospital, London, United Kingdom
- South London and Maudsley NHS (National Health Service) Foundation Trust, London, United Kingdom
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
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Paek EJ, Murray LL, Newman SD. Neural Correlates of Verb Fluency Performance in Cognitively Healthy Older Adults and Individuals With Dementia: A Pilot fMRI Study. Front Aging Neurosci 2020; 12:73. [PMID: 32265685 PMCID: PMC7100367 DOI: 10.3389/fnagi.2020.00073] [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: 10/08/2019] [Accepted: 02/28/2020] [Indexed: 12/14/2022] Open
Abstract
Currently there are ~6 million Americans who are affected by dementia. Verbal fluency tasks have been commonly and frequently utilized to document the disease progression in many forms of dementia. Verb fluency has been found to display substantial potential to detect and monitor the cognitive declines of individuals with dementia who have fronto-striatal involvement. The neural substrates underlying verb fluency task performance, however, have remained unclear so far, especially in individuals with dementia. Therefore, in the current study, brain activation patterns of seven individuals with dementia and nine healthy older adults were investigated using functional MRI. The participants performed in the scanner an overt, subject-paced verb fluency task, representative of fluency tasks used in clinical settings. The brain activation patterns during the verb fluency task were compared between the two groups, and a correlational analysis was conducted to determine the neural correlates of verb fluency performance. The results suggest that compared to healthy older adults, individuals with dementia demonstrated poorer verb fluency performance and showed higher activation in specific neural regions, such as the bilateral frontal lobe. In addition, the correlational analysis revealed that poorer verb fluency performance lead to increased activation in certain cortical and subcortical areas, including left hippocampus and right supramarginal gyrus. The current findings are consistent with previous neurophysiological findings related to semantic (noun) fluency performance in older adults and individuals with dementia and add to the empirical evidence that supports the role of the frontal lobe and hippocampus in verb retrieval and search. Declines in verb fluency performance cannot only be used as a cognitive marker, but also represent neuropathological changes due to the neurodegenerative disease.
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Affiliation(s)
- Eun Jin Paek
- Department of Audiology and Speech Pathology, The University of Tennessee Health Science Center, Knoxville, TN, United States
| | - Laura L. Murray
- School of Communication Sciences and Disorders, Western University London, London, ON, Canada
| | - Sharlene D. Newman
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
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8
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Using proton magnetic resonance spectroscopic imaging to study glutamatergic alterations in patients with schizophrenia: A systematic review. Schizophr Res 2019; 210:13-20. [PMID: 31272905 DOI: 10.1016/j.schres.2019.06.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 06/05/2019] [Accepted: 06/16/2019] [Indexed: 12/21/2022]
Abstract
The glutamate hypothesis of schizophrenia posits aberrant glutamatergic activity in patients with schizophrenia. Levels of glutamate and glutamine can be detected and quantified in vivo by proton magnetic resonance spectroscopy. A related technique, proton magnetic resonance spectroscopic imaging (1H-MRSI), is particularly useful as it simultaneously collects multiple spectra, across multiple voxels, from a single acquisition. The primary aim of this study was to review and discuss the use of 1H-MRSI to measure levels of glutamate and glutamine in patients with schizophrenia. Additionally, the advantages and disadvantages of using 1H-MRSI to examine schizophrenia pathophysiology are discussed. A literature search was conducted through Ovid. English language studies utilizing 1H-MRSI to measure glutamate and glutamine in patients with schizophrenia were identified. Six studies met the inclusion criteria. The included studies provide inconclusive support for glutamatergic elevations within frontal brain regions in patients with schizophrenia. The key benefit of employing 1H-MRSI to examine schizophrenia pathophysiology appears to be its broader spatial coverage. Future 1H-MRSI studies utilizing large sample sizes and longitudinal study designs are necessitated to further our understanding of glutamatergic alterations in patients with schizophrenia.
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Ionescu DF, Felicione JM, Gosai A, Cusin C, Shin P, Shapero BG, Deckersbach T. Ketamine-Associated Brain Changes: A Review of the Neuroimaging Literature. Harv Rev Psychiatry 2019; 26:320-339. [PMID: 29465479 PMCID: PMC6102096 DOI: 10.1097/hrp.0000000000000179] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Major depressive disorder (MDD) is one of the most prevalent conditions in psychiatry. Patients who do not respond to traditional monoaminergic antidepressant treatments have an especially difficult-to-treat type of MDD termed treatment-resistant depression. Subanesthetic doses of ketamine-a glutamatergic modulator-have shown great promise for rapidly treating patients with the most severe forms of depression. As such, ketamine represents a promising probe for understanding the pathophysiology of depression and treatment response. Through neuroimaging, ketamine's mechanism may be elucidated in humans. Here, we review 47 articles of ketamine's effects as revealed by neuroimaging studies. Some important brain areas emerge, especially the subgenual anterior cingulate cortex. Furthermore, ketamine may decrease the ability to self-monitor, may increase emotional blunting, and may increase activity in reward processing. Further studies are needed, however, to elucidate ketamine's mechanism of antidepressant action.
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Affiliation(s)
- Dawn F. Ionescu
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA
- Harvard Medical School, Boston, MA
| | | | - Aishwarya Gosai
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA
| | - Cristina Cusin
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA
- Harvard Medical School, Boston, MA
| | - Philip Shin
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA
| | - Benjamin G. Shapero
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA
- Harvard Medical School, Boston, MA
| | - Thilo Deckersbach
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA
- Harvard Medical School, Boston, MA
- Athinoula A. Martinos Center for Biomedical Imaging, Boston, MA
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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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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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12
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Kircher T, Bröhl H, Meier F, Engelen J. Formal thought disorders: from phenomenology to neurobiology. Lancet Psychiatry 2018; 5:515-526. [PMID: 29678679 DOI: 10.1016/s2215-0366(18)30059-2] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 11/27/2017] [Accepted: 12/07/2017] [Indexed: 01/15/2023]
Abstract
Formal thought disorder (FTD) is present in most psychiatric disorders and in some healthy individuals. In this Review, we present a comprehensive, integrative, and multilevel account of what is known about FTD, covering genetic, cellular, and neurotransmitter effects, environmental influences, experimental psychology and neuropsychology, brain imaging, phenomenology, linguistics, and treatment. FTD is a dimensional, phenomenologically defined construct, which can be clinically subdivided into positive versus negative and objective versus subjective symptom clusters. Because FTDs have been traditionally linked to schizophrenia, studies in other diagnoses are scarce. Aetiologically, FTD is the only symptom under genetic influence in schizophrenia as shown in linkage studies, but familial communication patterns (allusive thinking) have also been associated with the condition. Positive FTDs are related to synaptic rarefication in the glutamate system of the superior and middle lateral temporal cortices. Cortical volume of the left superior temporal gyrus is decreased in patients with schizophrenia who have positive FTD in structural MRI studies and shows reversed hemispheric (right more than left) activation in functional MRI experiments during speech production. Semantic network dysfunction in positive FTD has been demonstrated in experiments of indirect semantic hyperpriming (reaction time). In acute positive FTD, antipsychotics are effective, but a subgroup of patients have treatment-resistant, chronic, positive or negative FTD. Specific psychotherapy as treatment for FTD has not yet been developed. With this solid data on the pathogenesis of FTD, we can now implement clinical studies to treat this condition.
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Affiliation(s)
- Tilo Kircher
- Department of Psychiatry and Psychotherapy, Marburg University, Marburg, Germany.
| | - Henrike Bröhl
- Department of Psychiatry and Psychotherapy, Marburg University, Marburg, Germany
| | - Felicitas Meier
- Department of Psychiatry and Psychotherapy, Marburg University, Marburg, Germany
| | - Jennifer Engelen
- Department of Psychiatry and Psychotherapy, Marburg University, Marburg, Germany
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13
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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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14
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Thiebes S, Leicht G, Curic S, Steinmann S, Polomac N, Andreou C, Eichler I, Eichler L, Zöllner C, Gallinat J, Hanganu-Opatz I, Mulert C. Glutamatergic deficit and schizophrenia-like negative symptoms: new evidence from ketamine-induced mismatch negativity alterations in healthy male humans. J Psychiatry Neurosci 2017; 42:273-283. [PMID: 28556775 PMCID: PMC5487274 DOI: 10.1503/jpn.160187] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Targeting the N-methyl-D-aspartate receptor (NMDAR) is a major translational approach for treating negative symptoms of schizophrenia. Ketamine comprehensively produces schizophrenia-like symptoms, such as positive, cognitive and negative symptoms in healthy volunteers. The amplitude of the mismatch negativity (MMN) is known to be significantly reduced not only in patients with schizophrenia, but also in healthy controls receiving ketamine. Accordingly, it was the aim of the present study to investigate whether changes of MMN amplitudes during ketamine administration are associated with the emergence of schizophrenia-like negative symptoms in healthy volunteers. METHODS We examined the impact of ketamine during an MMN paradigm with 64-channel electroencephalography (EEG) and assessed the psychopathological status using the Positive and Negative Syndrome Scale (PANSS) in healthy male volunteers using a single-blind, randomized, placebo-controlled crossover design. Low-resolution brain electromagnetic tomography was used for source localization. RESULTS Twenty-four men were included in our analysis. Significant reductions of MMN amplitudes and an increase in all PANSS scores were identified under the ketamine condition. Smaller MMN amplitudes were specifically associated with more pronounced negative symptoms. Source analysis of MMN generators indicated a significantly reduced current source density (CSD) under the ketamine condition in the primary auditory cortex, the posterior cingulate and the middle frontal gyrus. LIMITATIONS The sample included only men within a tight age range of 20-32 years. CONCLUSION The MMN might represent a biomarker for negative symptoms in schizophrenia related to an insufficient NMDAR system and could be used to identify patients with schizophrenia with negative symptoms due to NMDAR dysfunction.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Christoph Mulert
- Correspondence to: C. Mulert, Martinistr. 52, D-20246 Hamburg, Germany;
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15
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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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16
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Alfimova MV, Golimbet VE, Korovaitseva GI, Abramova LI, Lezheiko TV, Aksenova EV. [The association between the GRIN2B gene and verbal fluency and impairment of abstract thinking in schizophrenia]. Zh Nevrol Psikhiatr Im S S Korsakova 2016; 116:42-46. [PMID: 27240047 DOI: 10.17116/jnevro20161164142-46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To search for the association between the GRIN2B gene and signs of thought and speech disorders which may be the result of decreased accessibility to the mental lexicon. MATERIAL AND METHODS The association between the GRIN2B polymorphism rs7301328 with semantic verbal fluency and five symptoms of thought and speech disorders, as assessed with the PANSS, was studied in 552 patients with schizophrenia-spectrum disorders. RESULTS AND CONCLUSION There was the association of the GRIN2B gene with verbal fluency and the PANSS item «Difficulty in Abstract Thinking». The association was not modified by verbal fluency. The results suggest that the GRIN2B gene may modify the linguistic processes involved in the retrieval of information from the mental lexicon on the basis of semantic traits and, moreover, contribute to the variability of clinical symptoms of impairment of abstract thinking in patients with schizophrenia. The heterozygous genotype may be protective against the development of thought and speech disorders.
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17
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Kleinloog D, Uit den Boogaard A, Dahan A, Mooren R, Klaassen E, Stevens J, Freijer J, van Gerven J. Optimizing the glutamatergic challenge model for psychosis, using S+ -ketamine to induce psychomimetic symptoms in healthy volunteers. J Psychopharmacol 2015; 29:401-13. [PMID: 25693889 DOI: 10.1177/0269881115570082] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The psychomimetic effects that occur after acute administration of ketamine can constitute a model of psychosis and antipsychotic drug action. However, the optimal dose/concentration has not been established and there is a large variety in outcome measures. In this study, 36 healthy volunteers (21 males and 15 females) received infusions of S(+)-ketamine or placebo to achieve pseudo-steady state concentrations of 180 and 360 ng/mL during two hours. The target of 360 ng/mL induced increasingly more intensive effects than expected, and the targets were subsequently reduced to 120 and 240 ng/mL, which were considered tolerable. There was a clear, concentration-dependent psychomimetic effect as shown on all subscales of the positive and negative syndrome scale (e.g. positive subscale +43.7%, 95%CI 34.4-53.7%, p < 0.0001 for 120 ng/mL and +70.5%, 95%CI 59.0-82.8%, p < 0.0001 for 240 ng/mL) and different visual analogue scales. The startle reflex was inhibited (prepulse inhibition) by both main target concentrations to a similar extent, suggesting a maximum effect. Ketamine was found to constitute a robust model for induction of psychomimetic symptoms and the optimal concentration range for a drug interaction study would be between 100 and 200 ng/mL.
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Affiliation(s)
| | | | - Albert Dahan
- Leiden University Medical Centre, Leiden, The Netherlands
| | - René Mooren
- Leiden University Medical Centre, Leiden, The Netherlands
| | | | | | - Jan Freijer
- Centre for Human Drug Research, Leiden, The Netherlands
| | - Joop van Gerven
- Centre for Human Drug Research, Leiden, The Netherlands Leiden University Medical Centre, Leiden, The Netherlands
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18
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Kircher T, Krug A, Stratmann M, Ghazi S, Schales C, Frauenheim M, Turner L, Fährmann P, Hornig T, Katzev M, Grosvald M, Müller-Isberner R, Nagels A. A rating scale for the assessment of objective and subjective formal Thought and Language Disorder (TALD). Schizophr Res 2014; 160:216-21. [PMID: 25458572 DOI: 10.1016/j.schres.2014.10.024] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 10/13/2014] [Accepted: 10/19/2014] [Indexed: 11/26/2022]
Abstract
Formal thought disorder (FTD) is a core syndrome of schizophrenia. However, patients with other diagnoses, such as mania and depression amongst others, also present with FTD. We introduce a novel, comprehensive clinical rating scale, capturing the full variety of FTD phenomenology including subjective experiences. The 30-item Thought and Language Disorder (TALD) scale is based on a detailed review of the literature, encompassing all formal thought disorder symptoms reported from the early 20th century onwards. Objectively observable symptoms as well as subjective phenomena were included. Two hundred and ten participants (146 patients ICD-10 diagnoses: depression n=63, schizophrenia n=63, mania n=20; 64 healthy control subjects) were interviewed and symptoms rated with the TALD, TLC, HAMD, YMRS and SAPS/SANS. A principal component analyses was performed for the TALD to differentiate sub-syndromes. The principal component analysis revealed four FTD factors; objective and subjective as well as positive and negative factor dimensions. The correlation analyses with the TLC and the SAPS/SANS FTD sub-scores demonstrated the factor validity for the objective factors. The different diagnoses showed a distinct pattern of symptom severity in each of the factors, with mania patients exhibiting the highest value in the positive, objective dimension. The scale showed good psychometric results, which makes it a practicable, nosologically-open instrument for the detailed assessment of all FTD dimensions. The results strengthen the importance of subjective symptom assessment reported by the patient.
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Affiliation(s)
- Tilo Kircher
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Str. 8, 35039 Marburg, Germany.
| | - Axel Krug
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Str. 8, 35039 Marburg, Germany
| | - Mirjam Stratmann
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Str. 8, 35039 Marburg, Germany
| | - Sayed Ghazi
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Str. 8, 35039 Marburg, Germany
| | - Christian Schales
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Str. 8, 35039 Marburg, Germany
| | - Michael Frauenheim
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Str. 8, 35039 Marburg, Germany
| | - Lena Turner
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Str. 8, 35039 Marburg, Germany
| | - Paul Fährmann
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Str. 8, 35039 Marburg, Germany
| | - Tobias Hornig
- Department of Neurology, University of Freiburg, Hauptstr. 5, 79104 Freiburg, Germany
| | - Michael Katzev
- Department of Neurology, University of Freiburg, Hauptstr. 5, 79104 Freiburg, Germany
| | - Michael Grosvald
- Department of English Literature & Linguistics, College of Arts & Sciences, Qatar University, PO Box 2713, Doha, Qatar
| | | | - Arne Nagels
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Str. 8, 35039 Marburg, Germany
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19
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Increased neural activity during overt and continuous semantic verbal fluency in major depression: mainly a failure to deactivate. Eur Arch Psychiatry Clin Neurosci 2014; 264:631-45. [PMID: 24557502 DOI: 10.1007/s00406-014-0491-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 02/07/2014] [Indexed: 12/15/2022]
Abstract
Major depression is associated with impairments in semantic verbal fluency (VF). However, the neural correlates underlying dysfunctional cognitive processing in depressed subjects during the production of semantic category members still remain unclear. In the current study, an overt and continuous semantic VF paradigm was used to examine these mechanisms in a representative sample of 33 patients diagnosed with a current episode of unipolar depression and 33 statistically matched healthy controls. Subjects articulated words in response to semantic category cues while brain activity was measured with functional magnetic resonance imaging (fMRI). Compared to controls, patients showed poorer task performance. On the neural level, a group by condition interaction analysis, corrected for task performance, revealed a reduced task-related deactivation in patients in the right parahippocampal gyrus, the right fusiform gyrus, and the right supplementary motor area. An additional and an increased task-related activation in patients were observed in the right precentral gyrus and the left cerebellum, respectively. These results indicate that a failure to suppress potentially interfering activity from inferior temporal regions involved in default-mode network functions and visual imagery, accompanied by an enhanced recruitment of areas implicated in speech initiation and higher-order language processes, may underlie dysfunctional cognitive processing during semantic VF in depression. The finding that patients with depression demonstrated both decreased performance and aberrant brain activation during the current semantic VF task demonstrates that this paradigm is a sensitive tool for assessing brain dysfunctions in clinical populations.
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20
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Plitman E, Nakajima S, de la Fuente-Sandoval C, Gerretsen P, Chakravarty MM, Kobylianskii J, Chung JK, Caravaggio F, Iwata Y, Remington G, Graff-Guerrero A. Glutamate-mediated excitotoxicity in schizophrenia: a review. Eur Neuropsychopharmacol 2014; 24:1591-605. [PMID: 25159198 PMCID: PMC4470624 DOI: 10.1016/j.euroneuro.2014.07.015] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 07/22/2014] [Accepted: 07/26/2014] [Indexed: 12/16/2022]
Abstract
Findings from neuroimaging studies in patients with schizophrenia suggest widespread structural changes although the mechanisms through which these changes occur are currently unknown. Glutamatergic activity appears to be increased in the early phases of schizophrenia and may contribute to these structural alterations through an excitotoxic effect. The primary aim of this review was to describe the possible role of glutamate-mediated excitotoxicity in explaining the presence of neuroanatomical changes within schizophrenia. A Medline(®) literature search was conducted, identifying English language studies on the topic of glutamate-mediated excitotoxicity in schizophrenia, using the terms "schizophreni" and "glutam" and (("MRS" or "MRI" or "magnetic resonance") or ("computed tomography" or "CT")). Studies concomitantly investigating glutamatergic activity and brain structure in patients with schizophrenia were included. Results are discussed in the context of findings from preclinical studies. Seven studies were identified that met the inclusion criteria. These studies provide inconclusive support for the role of glutamate-mediated excitotoxicity in the occurrence of structural changes within schizophrenia, with the caveat that there is a paucity of human studies investigating this topic. Preclinical data suggest that an excitotoxic effect may occur as a result of a paradoxical increase in glutamatergic activity following N-methyl-D-aspartate receptor hypofunction. Based on animal literature, glutamate-mediated excitotoxicity may account for certain structural changes present in schizophrenia, but additional human studies are required to substantiate these findings. Future studies should adopt a longitudinal design and employ magnetic resonance imaging techniques to investigate whether an association between glutamatergic activity and structural changes exists in patients with schizophrenia.
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Affiliation(s)
- Eric Plitman
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Shinichiro Nakajima
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada; Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan; Geriatric Mental Health Division, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Camilo de la Fuente-Sandoval
- Experimental Psychiatry Laboratory, Instituto Nacional de Neurología y Neurocirugía, Mexico City, Mexico; Neuropsychiatry Department, Instituto Nacional de Neurología y Neurocirugía, Mexico City, Mexico
| | - Philip Gerretsen
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Geriatric Mental Health Division, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - M Mallar Chakravarty
- Cerebral Imaging Centre, Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada; Departments of Psychiatry and Biomedical Engineering, McGill University, Montreal, Quebec, Canada
| | - Jane Kobylianskii
- Department of Medicine, Queen׳s University, Kingston, Ontario, Canada
| | - Jun Ku Chung
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Fernando Caravaggio
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Yusuke Iwata
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada; Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan
| | - Gary Remington
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada; Campbell Institute Research Program, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada; Schizophrenia Program, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada
| | - Ariel Graff-Guerrero
- Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Geriatric Mental Health Division, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada; Campbell Institute Research Program, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada.
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Bredlau AL, Thakur R, Korones DN, Dworkin RH. Ketamine for pain in adults and children with cancer: a systematic review and synthesis of the literature. PAIN MEDICINE 2013; 14:1505-17. [PMID: 23915253 DOI: 10.1111/pme.12182] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Chronic cancer pain is often refractory and difficult to treat. Ketamine is a medication with evidence of efficacy in the treatment of chronic pain. DESIGN This article presents a synthesis of the data on ketamine for refractory cancer pain in adults and children. RESULTS There are five randomized, double-blind, controlled trials of ketamine use in cancer pain that demonstrate improvement in pain for some patients. There are six prospective, uncontrolled trials in cancer pain that also demonstrate improvement in pain scores for some patients. There are no randomized, controlled trials in children with cancer pain, although there are a few studies reflecting improved pain control with ketamine for children with cancer pain. Adverse events for adults on ketamine are most commonly somnolence, feelings of insobriety, nausea/vomiting, hallucinations, depersonalization/derealization, and drowsiness. However, when ketamine is combined with benzodiazepines, feelings of insobriety, hallucinations, and depersonalization/derealization are not reported. Children on ketamine have had few reported adverse effects, which include sedation, anorexia, urinary retention, and myoclonic movements. Recommended ketamine infusion dosages are from 0.05 to 0.5 mg/kg/h (intravenous or subcutaneous). Recommended oral dosages of ketamine are 0.2-0.5 mg/kg/dose two to three times daily with a maximum of 50 mg/dose three times daily. CONCLUSIONS Despite limitations in the breadth and depth of data available, there is evidence that ketamine may be a viable option for treatment-refractory cancer pain.
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Affiliation(s)
- Amy Lee Bredlau
- Departments of Pediatrics and Neurosciences, Medical University of South Carolina, Charleston, South Carolina
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Vulnerability to psychotogenic effects of ketamine is associated with elevated D2/3-receptor availability. Int J Neuropsychopharmacol 2013; 16:745-54. [PMID: 22906553 DOI: 10.1017/s1461145712000764] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Previous positron emission tomography (PET) studies employing competition paradigms have shown either no change or substantial declines in striatal [(11)C]-raclopride binding after challenge with psychotogenic doses of the N-methyl-D-aspartate antagonist ketamine. We sought to probe the relationship between the severity of ketamine-induced psychotic symptoms and altered dopamine D(2/3) receptor availability throughout brain using the high affinity ligand [(18)F]-fallypride (FP). PET recordings were obtained in a group of 10 healthy, young male volunteers, in a placebo condition, and in the course of an infusion with ketamine at a psychotomimetic dose. Administration of the Positive and Negative Syndrome Scale and the Thought and Language Index in both conditions revealed a substantial emergence of mainly negative symptoms of schizophrenia, persisting until the end of the 3 h PET recordings. The baseline FP binding in cortex, caudate nucleus and other brain regions was highly predictive of the individual severity of psychotic symptoms in the ketamine condition. However, there was no evidence of ketamine-evoked reductions in FP binding. In the context of earlier findings, we speculate that high baseline D(2/3)-receptor availability may impart benefits with regard to cognitive flexibility, but increases the risk of maladaptive information processing in the face of environmental stresses and challenges.
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Scheidegger M, Walter M, Lehmann M, Metzger C, Grimm S, Boeker H, Boesiger P, Henning A, Seifritz E. Ketamine decreases resting state functional network connectivity in healthy subjects: implications for antidepressant drug action. PLoS One 2012; 7:e44799. [PMID: 23049758 PMCID: PMC3461985 DOI: 10.1371/journal.pone.0044799] [Citation(s) in RCA: 186] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 08/14/2012] [Indexed: 12/22/2022] Open
Abstract
Increasing preclinical and clinical evidence underscores the strong and rapid antidepressant properties of the glutamate-modulating NMDA receptor antagonist ketamine. Targeting the glutamatergic system might thus provide a novel molecular strategy for antidepressant treatment. Since glutamate is the most abundant and major excitatory neurotransmitter in the brain, pathophysiological changes in glutamatergic signaling are likely to affect neurobehavioral plasticity, information processing and large-scale changes in functional brain connectivity underlying certain symptoms of major depressive disorder. Using resting state functional magnetic resonance imaging (rsfMRI), the „dorsal nexus “(DN) was recently identified as a bilateral dorsal medial prefrontal cortex region showing dramatically increased depression-associated functional connectivity with large portions of a cognitive control network (CCN), the default mode network (DMN), and a rostral affective network (AN). Hence, Sheline and colleagues (2010) proposed that reducing increased connectivity of the DN might play a critical role in reducing depression symptomatology and thus represent a potential therapy target for affective disorders. Here, using a randomized, placebo-controlled, double-blind, crossover rsfMRI challenge in healthy subjects we demonstrate that ketamine decreases functional connectivity of the DMN to the DN and to the pregenual anterior cingulate (PACC) and medioprefrontal cortex (MPFC) via its representative hub, the posterior cingulate cortex (PCC). These findings in healthy subjects may serve as a model to elucidate potential biomechanisms that are addressed by successful treatment of major depression. This notion is further supported by the temporal overlap of our observation of subacute functional network modulation after 24 hours with the peak of efficacy following an intravenous ketamine administration in treatment-resistant depression.
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Affiliation(s)
- Milan Scheidegger
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
- Clinic of Affective Disorders and General Psychiatry, Psychiatric University Hospital, Zurich, Switzerland
- * E-mail: (MS); (MW)
| | - Martin Walter
- Department of Psychiatry, Otto-von-Guericke University, Magdeburg, Germany
- Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Clinical Affective Neuroimaging Laboratory (CANLAB), Center for Behavioral and Brain Sciences, CBBS, Magdeburg, Germany
- * E-mail: (MS); (MW)
| | - Mick Lehmann
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Coraline Metzger
- Department of Psychiatry, Otto-von-Guericke University, Magdeburg, Germany
- Clinical Affective Neuroimaging Laboratory (CANLAB), Center for Behavioral and Brain Sciences, CBBS, Magdeburg, Germany
| | - Simone Grimm
- Clinic of Affective Disorders and General Psychiatry, Psychiatric University Hospital, Zurich, Switzerland
- Cluster Languages of Emotion, Freie Universität Berlin, Berlin, Germany
- Department of Psychiatry, Charité, CBF, Berlin, Germany
| | - Heinz Boeker
- Clinic of Affective Disorders and General Psychiatry, Psychiatric University Hospital, Zurich, Switzerland
| | - Peter Boesiger
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Anke Henning
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Erich Seifritz
- Clinic of Affective Disorders and General Psychiatry, Psychiatric University Hospital, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
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Wende KC, Straube B, Stratmann M, Sommer J, Kircher T, Nagels A. Neural correlates of continuous causal word generation. Neuroimage 2012; 62:1399-407. [DOI: 10.1016/j.neuroimage.2012.06.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 05/29/2012] [Accepted: 06/03/2012] [Indexed: 11/24/2022] Open
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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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Nagels A, Kircher T, Dietsche B, Backes H, Marquetand J, Krug A. Neural processing of overt word generation in healthy individuals: the effect of age and word knowledge. Neuroimage 2012; 61:832-40. [PMID: 22521476 DOI: 10.1016/j.neuroimage.2012.04.019] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 04/04/2012] [Accepted: 04/07/2012] [Indexed: 11/17/2022] Open
Abstract
Verbal fluency is a classical and widely used neuropsychological instrument to assess cognitive abilities. Results of previous studies indicate an influence on verbal fluency performance of both, age and word knowledge. So far, no imaging study has investigated the neural mechanisms underlying an age and word knowledge related decline on the quantitative verbal output in a highly demanding overt and continuous semantic fluency task. Fifty healthy volunteers (age 22-56 years, verbal IQ 95-143) overtly and continuously articulated words in response to ten visually presented semantic categories while BOLD signal was measured with fMRI. Verbal responses were recorded with an MRI compatible microphone and transcribed after the scanning session. The number of produced words as well as age, word knowledge and level of education was implemented in the design matrix enabling a separate analysis of these factors on both, neural responses and behavioral differences. There was a significant correlation of level of education and number of generated words, but no significant correlations of generated words and age or word knowledge were observed. On the neural level, a widespread network was found for the word production task as contrasted with the resting condition, encompassing the bilateral superior temporal gyri, the cerebellum and the SMA. An age related positive correlation was found in the bilateral inferior and middle frontal gyri, the anterior cingulate gyrus, the left precentral gyrus and the right insula. A lower word knowledge resulted in enhanced BOLD responses in the right superior temporal gyrus and the left superior frontal gyrus. Results are interpreted in terms of compensation mechanisms countervailing potential age and word knowledge related effects.
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Affiliation(s)
- Arne Nagels
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Rudolf-Bultmann-Str. 8, 35039 Marburg, Germany
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