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Singer P, Yee BK. The adenosine hypothesis of schizophrenia into its third decade: From neurochemical imbalance to early life etiological risks. Front Cell Neurosci 2023; 17:1120532. [PMID: 36998267 PMCID: PMC10043328 DOI: 10.3389/fncel.2023.1120532] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Accepted: 02/15/2023] [Indexed: 03/17/2023] Open
Abstract
The adenosine hypothesis of schizophrenia was conceptualized about two decades ago in an attempt to integrate two prominent theories of neurochemical imbalance that attribute the pathogenesis of schizophrenia to hyperfunction of the mesocorticolimbic dopamine neurotransmission and hypofunction of cortical glutamate neurotransmission. Given its unique position as an endogenous modulator of both dopamine and glutamate signaling in the brain, adenosine was postulated as a potential new drug target to achieve multiple antipsychotic actions. This new strategy may offer hope for improving treatment, especially in alleviating negative symptoms and cognitive deficits of schizophrenia that do not respond to current medications. To date, however, the adenosine hypothesis has yet led to any significant therapeutic breakthroughs. Here, we address two possible reasons for the impasse. First, neither the presence of adenosine functional deficiency in people with schizophrenia nor its causal relationship to symptom production has been satisfactorily examined. Second, the lack of novel adenosine-based drugs also impedes progress. This review updates the latest preclinical and clinical data pertinent to the construct validity of the adenosine hypothesis and explores novel molecular processes whereby dysregulation of adenosine signaling could be linked to the etiology of schizophrenia. It is intended to stimulate and revitalize research into the adenosine hypothesis towards the development of a new and improved generation of antipsychotic drugs that has eluded us for decades.
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Affiliation(s)
- Philipp Singer
- Roche Diagnostics International AG, Rotkreuz, Switzerland
- *Correspondence: Philipp Singer Benjamin K. Yee
| | - Benjamin K. Yee
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
- Mental Health Research Centre, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China
- *Correspondence: Philipp Singer Benjamin K. Yee
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2
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Li J, Tang F, Si S, Wang B, Xue F. Integration analysis of GWAS and expression quantitative trait loci to identify candidate genes and pathways for clozapine-related neutropaenia. Br J Clin Pharmacol 2021; 88:1904-1912. [PMID: 34409637 DOI: 10.1111/bcp.15043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 07/30/2021] [Accepted: 08/06/2021] [Indexed: 12/23/2022] Open
Abstract
AIMS Little is known about the genetic basis of clozapine-related neutropaenia. This study aims to explore candidate genes and pathways involved in clozapine-related neutropaenia. METHODS This study conducted a two-stage integrative analysis of the summary statistics from the genome-wide association study (GWAS, n = 552) of the lowest absolute neutrophil count (ANC) during clozapine treatment and the summary data of the expressed quantitative trait locus (eQTL). First, we use the probabilistic Mendelian randomization (PMR-Egger) to identify genes whose expression is causally related to ANC, and then use Bayesian co-localization analysis to investigate whether there are shared causal variants between them [posterior probability for hypotheses 4 (PP.H4) > 0.80]. Finally, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were conducted to explore the pathways that may be associated with ANC during clozapine treatment. RESULTS PMR-Egger analysis identified 146 genes that may be causally associated with ANC after Bonferroni correction (P-value < 3.25e-6). Bayesian co-localization analysis identified six further genes whose gene expression shared common variants with ANC, including NT5E (PP.H4 = 0.96), GLDC (PP.H4 = 0.82), NUDT17 (PP.H4 = 0.88), MSH4 (PP.H4 = 0.88), PTER (PP.H4 = 0.89) and SERPINB6 (PP.H4 = 0.83). Enrichment analysis identified 52 GO terms and seven pathways associated with ANC, such as NAD metabolic process, drug catabolic process and glyoxylate and dicarboxylate metabolism. CONCLUSION This study identified multiple candidate genes and pathways that may be involved in clozapine-related neutropaenia, providing novel clues for the mechanism of clozapine-related neutropaenia.
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Affiliation(s)
- Jiqing Li
- Department of Biostatistics, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.,Healthcare Big Data Research Institute, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Fang Tang
- Center for Big Data Research in Health and Medicine, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Jinan, China.,Shandong Qianfoshan Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Shucheng Si
- Department of Biostatistics, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.,Healthcare Big Data Research Institute, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Bojie Wang
- Department of Biostatistics, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.,Healthcare Big Data Research Institute, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
| | - Fuzhong Xue
- Department of Biostatistics, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.,Healthcare Big Data Research Institute, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China
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3
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Jones R, MacCabe JH, Price MJ, Liu X, Upthegrove R. Effect of age on the relative efficacy of clozapine in schizophrenia. Acta Psychiatr Scand 2020; 142:109-120. [PMID: 31977065 DOI: 10.1111/acps.13156] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/19/2020] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Early treatment of schizophrenia improves outcomes. Clozapine appears to have unique benefit when other antipsychotic medication has failed. This systematic review and meta-analysis aims to assess clozapine's superiority over alternative antipsychotic medication and examine whether earlier use is associated with additional benefit. METHOD Systematic retrieval of blinded, randomized controlled trials comparing clozapine with alternative antipsychotics in adults with schizophrenia. The effect of mean age on relative clozapine response was examined using random effects meta-regression, and multiple linear regression on available patient data. RESULTS A total of 276 studies were retrieved. Thirty-four studies were included in the meta-analysis. Clozapine was significantly more effective than alternative antipsychotics in reducing psychotic symptoms and increasing response. However, meta-regression failed to show a more significant effect in younger patients (age on effect size (total psychotic symptoms) 0.00, P = 0.79 CI -0.03 to 0.03). Individual patient data were available for two studies, the larger of which showed a significant interaction between younger age and superiority of clozapine. CONCLUSION The results support clozapine's superiority over other antipsychotics. A convincing effect of age on this effect was not demonstrated, although this was suggested in one study. In view of the age of many of the included studies, and changes in reporting practice over time, new clozapine RCTs, which include age of illness onset as well as age at trial time, would be welcome in order to provide meta-analysable data for future use.
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Affiliation(s)
- R Jones
- Institute for Mental Health, University of Birmingham, Birmingham, UK.,Birmingham and Solihull Mental Health Foundation Trust, Birmingham, UK
| | - J H MacCabe
- Department of Psychosis Studies, King's College London, and South London and Maudsley NHS Foundation Trust, London, UK
| | - M J Price
- NIHR Birmingham Biomedical Research Centre, University Hospitals Birmingham NHS Foundation Trust and University of Birmingham, Birmingham, UK.,Institute of Applied Health Research, University of Birmingham, Birmingham, UK
| | - X Liu
- Guangdong Mental Health Center, Guangdong Provincial People's Hospital & Guangdong Academy of Medical Sciences, Affliated School of Medicine of South China University of Technology, Guangzhou, China
| | - R Upthegrove
- Institute for Mental Health, University of Birmingham, Birmingham, UK.,Birmingham Early Intervention Service, Birmingham Womens and Childrens NHS trust, Birmingham, UK
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4
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Mizuno Y, McCutcheon RA, Brugger SP, Howes OD. Heterogeneity and efficacy of antipsychotic treatment for schizophrenia with or without treatment resistance: a meta-analysis. Neuropsychopharmacology 2020; 45:622-631. [PMID: 31766049 PMCID: PMC7021799 DOI: 10.1038/s41386-019-0577-3] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 10/30/2019] [Accepted: 11/08/2019] [Indexed: 01/08/2023]
Abstract
Two important clinical questions are whether there is a subtype of schizophrenia which responds differently to clozapine relative to other antipsychotics, and whether greater efficacy of clozapine is dependent on the degree of treatment-resistance. The authors address this by examining both variability and magnitude of response in patients treated with clozapine and other antipsychotics for both treatment-resistant schizophrenia (TRS) and non-resistant schizophrenia. Double-blind randomised controlled trials comparing clozapine with other antipsychotics in patients with schizophrenia were identified using five databases. Standard deviations and means of change in total, positive, and negative symptoms were extracted. Variability ratio (VR) and coefficient of variation ratio (CVR) were used to quantify relative variability in symptom change. Hedges' g was used to quantify mean differences. Ten TRS studies (n = 822) and 29 non-TRS studies (n = 2566) were meta-analysed. Relative variability in change of total symptoms did not differ significantly between clozapine and other antipsychotics in TRS studies (VR = 1.84; 95%CI, 0.85-4.02). These findings were similar with CVR, and for positive and negative symptoms. Clozapine was superior to other antipsychotics in improving total symptoms in both TRS (g = 0.34; 95%CI, 0.13-0.56) and non-TRS (g = 0.20; 95%CI, 0.08-0.32) studies. Furthermore, clozapine was superior in improving positive symptoms in both study groups, but not for negative symptoms. Pooled effect sizes showed no significant difference between TRS and non-TRS studies. These findings do not support a subtype of schizophrenia which responds specifically to clozapine. Clozapine is more effective than other antipsychotics irrespective of treatment-resistance, arguing for its use more generally in schizophrenia. PROSPERO CRD42018086507.
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Affiliation(s)
- Yuya Mizuno
- 0000 0001 2322 6764grid.13097.3cDepartment of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, London, SE5 8AF UK ,0000 0004 1936 9959grid.26091.3cDepartment of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan
| | - Robert A. McCutcheon
- 0000 0001 2322 6764grid.13097.3cDepartment of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, London, SE5 8AF UK ,0000 0001 0705 4923grid.413629.bPsychiatric Imaging Group, MRC London Institute of Medical Sciences, Hammersmith Hospital, London, UK ,0000 0001 2113 8111grid.7445.2Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, UK
| | - Stefan P. Brugger
- 0000 0001 0705 4923grid.413629.bPsychiatric Imaging Group, MRC London Institute of Medical Sciences, Hammersmith Hospital, London, UK ,0000 0001 2113 8111grid.7445.2Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, UK ,0000 0004 1936 7603grid.5337.2Centre for Academic Mental Health, University of Bristol, Bristol, UK ,0000000121901201grid.83440.3bDivision of Psychiatry, University College London, London, UK ,0000 0001 0807 5670grid.5600.3Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Cardiff, UK
| | - Oliver D. Howes
- 0000 0001 2322 6764grid.13097.3cDepartment of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, London, SE5 8AF UK ,0000 0001 0705 4923grid.413629.bPsychiatric Imaging Group, MRC London Institute of Medical Sciences, Hammersmith Hospital, London, UK ,0000 0001 2113 8111grid.7445.2Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, UK
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5
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Tiihonen J, Koskuvi M, Storvik M, Hyötyläinen I, Gao Y, Puttonen KA, Giniatullina R, Poguzhelskaya E, Ojansuu I, Vaurio O, Cannon TD, Lönnqvist J, Therman S, Suvisaari J, Kaprio J, Cheng L, Hill AF, Lähteenvuo M, Tohka J, Giniatullin R, Lehtonen Š, Koistinaho J. Sex-specific transcriptional and proteomic signatures in schizophrenia. Nat Commun 2019; 10:3933. [PMID: 31477693 PMCID: PMC6718673 DOI: 10.1038/s41467-019-11797-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 08/01/2019] [Indexed: 12/15/2022] Open
Abstract
It has remained unclear why schizophrenia typically manifests after adolescence and which neurobiological mechanisms are underlying the cascade leading to the actual onset of the illness. Here we show that the use of induced pluripotent stem cell-derived neurons of monozygotic twins from pairs discordant for schizophrenia enhances disease-specific signal by minimizing genetic heterogeneity. In proteomic and pathway analyses, clinical illness is associated especially with altered glycosaminoglycan, GABAergic synapse, sialylation, and purine metabolism pathways. Although only 12% of all 19,462 genes are expressed differentially between healthy males and females, up to 61% of the illness-related genes are sex specific. These results on sex-specific genes are replicated in another dataset. This implies that the pathophysiology differs between males and females, and may explain why symptoms appear after adolescence when the expression of many sex-specific genes change, and suggests the need for sex-specific treatments.
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Affiliation(s)
- Jari Tiihonen
- Department of Clinical Neuroscience, Karolinska Institutet, Byggnad R5, SE-171 76, Stockholm, Sweden. .,Department of Forensic Psychiatry, University of Eastern Finland, Niuvanniemi Hospital, Niuvankuja 65, FI-70240, Kuopio, Finland.
| | - Marja Koskuvi
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FI-70211, Kuopio, Finland.,Neuroscience Center, University of Helsinki, PO Box 63, FI-00271, Helsinki, Finland
| | - Markus Storvik
- Department of Pharmacology, University of Eastern Finland, PO Box 1627, FI-70211, Kuopio, Finland
| | - Ida Hyötyläinen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FI-70211, Kuopio, Finland
| | - Yanyan Gao
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FI-70211, Kuopio, Finland
| | - Katja A Puttonen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FI-70211, Kuopio, Finland
| | - Raisa Giniatullina
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FI-70211, Kuopio, Finland
| | - Ekaterina Poguzhelskaya
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FI-70211, Kuopio, Finland
| | - Ilkka Ojansuu
- Department of Forensic Psychiatry, University of Eastern Finland, Niuvanniemi Hospital, Niuvankuja 65, FI-70240, Kuopio, Finland
| | - Olli Vaurio
- Department of Forensic Psychiatry, University of Eastern Finland, Niuvanniemi Hospital, Niuvankuja 65, FI-70240, Kuopio, Finland
| | - Tyrone D Cannon
- Department of Psychology and Psychiatry, Yale University, 1 Prospect Street, New Haven, Connecticut, 06511, USA
| | - Jouko Lönnqvist
- Mental Health Unit, Department of Public Health Solutions, National Institute for Health and Welfare, PO Box 30, FI-00271, Helsinki, Finland.,Department of Psychiatry, University of Helsinki, PO Box 22, FI-00014, Helsinki, Finland
| | - Sebastian Therman
- Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, PO Box 30, FI-00271, Helsinki, Finland
| | - Jaana Suvisaari
- Mental Health Unit, Department of Public Health Solutions, National Institute for Health and Welfare, PO Box 30, FI-00271, Helsinki, Finland
| | - Jaakko Kaprio
- Department of Public Health, University of Helsinki, PO Box 20, FI-00014, Helsinki, Finland.,Institute for Molecular Medicine FIMM, University of Helsinki, PO Box 20, FI-00014, Helsinki, Finland
| | - Lesley Cheng
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Science Drive, Bundoora, VIC, 3083, Australia
| | - Andrew F Hill
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Science Drive, Bundoora, VIC, 3083, Australia
| | - Markku Lähteenvuo
- Department of Forensic Psychiatry, University of Eastern Finland, Niuvanniemi Hospital, Niuvankuja 65, FI-70240, Kuopio, Finland.,Institute for Molecular Medicine FIMM, University of Helsinki, PO Box 20, FI-00014, Helsinki, Finland
| | - Jussi Tohka
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FI-70211, Kuopio, Finland
| | - Rashid Giniatullin
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FI-70211, Kuopio, Finland
| | - Šárka Lehtonen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FI-70211, Kuopio, Finland. .,Neuroscience Center, University of Helsinki, PO Box 63, FI-00271, Helsinki, Finland.
| | - Jari Koistinaho
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FI-70211, Kuopio, Finland. .,Neuroscience Center, University of Helsinki, PO Box 63, FI-00271, Helsinki, Finland.
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6
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Gadelha A, Zugman A, Calzavara MB, de Mendonça Furtado RH, Scorza FA, Bressan RA. Is adenosine associated with sudden death in schizophrenia? A new framework linking the adenosine pathway to risk of sudden death. Neurosci Biobehav Rev 2018; 84:29-34. [DOI: 10.1016/j.neubiorev.2017.10.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 09/25/2017] [Accepted: 10/22/2017] [Indexed: 11/29/2022]
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7
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Sasidharan A, Kumar S, John JP, Philip M, Subramanian S, Jain S, Kutty BM. Elevated serum adenosine deaminase levels in neuroleptic-naïve patients with recent-onset schizophrenia. Asian J Psychiatr 2017; 29:13-15. [PMID: 29061410 DOI: 10.1016/j.ajp.2017.03.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Revised: 03/12/2017] [Accepted: 03/13/2017] [Indexed: 12/18/2022]
Abstract
The present study examined serum levels of adenosine deaminase (ADA), an adenosine metabolizing enzyme, in neuroleptic-naive patients with recent-onset schizophrenia and age-matched healthy comparison subjects. ADA levels were found to be higher among patients, and revealed a possible link between evening rise and severity of auditory hallucinations as well as morning rise and severity of avolition-apathy in patients with schizophrenia. These findings suggest the potential utility of serum ADA as a peripheral biomarker of schizophrenia.
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Affiliation(s)
- Arun Sasidharan
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India; Multimodal Brain Image Analysis Laboratory (MBIAL), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India
| | - Sunil Kumar
- Multimodal Brain Image Analysis Laboratory (MBIAL), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India; Department of Psychiatry, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India
| | - John P John
- Multimodal Brain Image Analysis Laboratory (MBIAL), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India; Department of Psychiatry, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India; Department of Clinical Neuroscience, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India.
| | - Mariamma Philip
- Department of Biostatistics, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India
| | - Sarada Subramanian
- Department of Neurochemistry, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India
| | - Sanjeev Jain
- Department of Psychiatry, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India; Molecular Genetics Laboratory, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India
| | - Bindu M Kutty
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India
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8
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Sasidharan A, Kumar S, Nair AK, Lukose A, Marigowda V, John JP, Kutty BM. Further evidences for sleep instability and impaired spindle-delta dynamics in schizophrenia: a whole-night polysomnography study with neuroloop-gain and sleep-cycle analysis. Sleep Med 2017; 38:1-13. [DOI: 10.1016/j.sleep.2017.02.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Revised: 02/03/2017] [Accepted: 02/09/2017] [Indexed: 02/04/2023]
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Rutherford BR, Pott E, Tandler JM, Wall MM, Roose SP, Lieberman JA. Placebo response in antipsychotic clinical trials: a meta-analysis. JAMA Psychiatry 2014; 71:1409-21. [PMID: 25321611 PMCID: PMC4256120 DOI: 10.1001/jamapsychiatry.2014.1319] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Because increasing placebo response rates decrease drug-placebo differences and increase the number of failed trials, it is imperative to determine what is causing this trend. OBJECTIVES To investigate the relationship between antipsychotic medication and placebo response by publication year, and to identify associated study design and implementation variables. DATA SOURCES MEDLINE, PsycINFO, and PubMed were searched to identify randomized clinical trials of antipsychotic medications published from 1960 to July 2013. STUDY SELECTION Included were randomized clinical trials lasting 4 to 24 weeks, contrasting antipsychotic medication with placebo or an active comparator, and enrolling patients 18 years of age or older with schizophrenia or schizoaffective disorder. DATA EXTRACTION AND SYNTHESIS Standardized mean change scores were calculated for each treatment arm, plotted against publication year, and tested with Spearman rank correlation coefficients. Hierarchical linear modeling identified factors associated with the standardized mean change across medication and placebo treatment arms. MAIN OUTCOMES AND MEASURES We hypothesized that the mean change in placebo-treated patients would significantly increase from 1960 to the present, that a greater change would be observed in active comparator vs placebo-controlled trials, and that more protocol visits would increase the symptom change observed. RESULTS In the 105 trials examined, the mean change observed in placebo arms increased significantly with year of publication (n=39, r=0.52, P=.001), while the mean change in effective dose medication arms decreased significantly (n=208, r=-0.26, P<.001). Significant interactions were found between assignment to effective dose medication and publication year (t260=-5.55, P<.001), baseline severity (t260=5.08, P<.001), and study duration (t260=-3.76, P<.001), indicating that the average drug-placebo difference significantly decreased over time, with decreasing baseline severity and with increasing study duration. Medication treatment in comparator studies was associated with significantly more improvement than medication treatment in placebo-controlled trials (t93=2.73, P=.008). CONCLUSIONS AND RELEVANCE The average treatment change associated with placebo treatment in antipsychotic trials increased since 1960, while the change associated with medication treatment decreased. Changes in randomized clinical trials leading to inflation of baseline scores, enrollment of less severely ill participants, and higher expectations of patients may all be responsible.
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Affiliation(s)
- Bret R Rutherford
- Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute ,1051 Riverside Drive, Box 98, New York, NY 10032, 646 774 8660 (telephone)
| | | | | | - Melanie M. Wall
- Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute
| | - Steven P. Roose
- Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute
| | - Jeffrey A. Lieberman
- Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute
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10
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Wonodi I, Gopinath HV, Liu J, Adami H, Hong LE, Allen-Emerson R, McMahon RP, Thaker GK. Dipyridamole monotherapy in schizophrenia: pilot of a novel treatment approach by modulation of purinergic signaling. Psychopharmacology (Berl) 2011; 218:341-5. [PMID: 21537940 PMCID: PMC4009981 DOI: 10.1007/s00213-011-2315-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Accepted: 04/15/2011] [Indexed: 01/24/2023]
Abstract
BACKGROUND Emerging data indicate the neuromodulator adenosine may play a role in the therapeutics of schizophrenia. Adenosine A(2A) receptor stimulation exerts a functional antagonism at postsynaptic D(2) receptors. Data from animal models relevant to schizophrenia support a therapeutic effect of modulating adenosinergic transmission in the ventral striatum. One previous clinical trial showed superiority of adjunctive dipyridamole, an adenosine reuptake inhibitor, compared to placebo in ameliorating positive symptoms in schizophrenia patients. OBJECTIVES The aim of this study was to examine the effects of dipyridamole monotherapy of 200 mg/day on positive and negative symptoms, with the goal of determining dosing for future adjunctive studies in schizophrenia. METHODS Twenty symptomatic schizophrenia participants were randomized to a 6-week double-blind trial comparing olanzapine (20 mg/day) to dipyridamole monotherapy (200 mg/day). Thirteen participants completed the treatment phase (eight on dipyridamole; five on olanzapine). RESULTS The olanzapine group showed a trend (p = 0.08) for superiority on BPRS total scores (mean ± SD: total BPRS score decreasing from 36.8 ± 2.3 at week 1, to 33.2 ± 5.5 at the end of the study). The mean total BPRS scores decreased from 36.4 ± 5.3 to 34.0 ± 7.7 in the dipyridamole group. CONCLUSIONS Although these pilot data do not support a significant antipsychotic effect of dipyridamole monotherapy, the results provide some evidence for examining dipyridamole (200 mg/day) as adjunct to symptomatic antipsychotic-treated schizophrenia patients.
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Affiliation(s)
- Ikwunga Wonodi
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, P.O. Box 21247, Baltimore, MD 21228, USA.
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