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Chye Y, Solowij N, Suo C, Batalla A, Cousijn J, Goudriaan AE, Martin-Santos R, Whittle S, Lorenzetti V, Yücel M. Orbitofrontal and caudate volumes in cannabis users: a multi-site mega-analysis comparing dependent versus non-dependent users. Psychopharmacology (Berl) 2017; 234:1985-1995. [PMID: 28364340 DOI: 10.1007/s00213-017-4606-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 03/13/2017] [Indexed: 11/25/2022]
Abstract
RATIONALE Cannabis (CB) use and dependence are associated with regionally specific alterations to brain circuitry and substantial psychosocial impairment. OBJECTIVES The objective of this study was to investigate the association between CB use and dependence, and the volumes of brain regions critically involved in goal-directed learning and behaviour-the orbitofrontal cortex (OFC) and caudate. METHODS In the largest multi-site structural imaging study of CB users vs healthy controls (HC), 140 CB users and 121 HC were recruited from four research sites. Group differences in OFC and caudate volumes were investigated between HC and CB users and between 70 dependent (CB-dep) and 50 non-dependent (CB-nondep) users. The relationship between quantity of CB use and age of onset of use and caudate and OFC volumes was explored. RESULTS CB users (consisting of CB-dep and CB-nondep) did not significantly differ from HC in OFC or caudate volume. CB-dep compared to CB-nondep users exhibited significantly smaller volume in the medial and the lateral OFC. Lateral OFC volume was particularly smaller in CB-dep females, and reduced volume in the CB-dep group was associated with higher monthly cannabis dosage. CONCLUSIONS Smaller medial OFC volume may be driven by CB dependence-related mechanisms, while smaller lateral OFC volume may be due to ongoing exposure to cannabinoid compounds. The results highlight a distinction between cannabis use and dependence and warrant examination of gender-specific effects in studies of CB dependence.
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Affiliation(s)
- Yann Chye
- Brain and Mental Health Laboratory, Monash Institute of Cognitive and Clinical Neurosciences, School of Psychological Sciences, Monash University, Melbourne, Australia
| | - Nadia Solowij
- School of Psychology and Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - Chao Suo
- Brain and Mental Health Laboratory, Monash Institute of Cognitive and Clinical Neurosciences, School of Psychological Sciences, Monash University, Melbourne, Australia
| | - Albert Batalla
- Department of Psychiatry, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands
- Department of Psychiatry and Psychology, Hospital Clinic, IDIBAPS, CIBERSAM and Institute of Neuroscience, University of Barcelona, Barcelona, Spain
| | - Janna Cousijn
- Department of Developmental Psychology, University of Amsterdam, Amsterdam, The Netherlands
| | - Anna E Goudriaan
- Department of Psychiatry, Amsterdam Institute for Addiction Research, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
- Arkin Mental Health Care, Amsterdam, The Netherlands
| | - Rocio Martin-Santos
- Department of Psychiatry and Psychology, Hospital Clinic, IDIBAPS, CIBERSAM and Institute of Neuroscience, University of Barcelona, Barcelona, Spain
| | - Sarah Whittle
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Melbourne Health, Melbourne, Australia
| | - Valentina Lorenzetti
- Brain and Mental Health Laboratory, Monash Institute of Cognitive and Clinical Neurosciences, School of Psychological Sciences, Monash University, Melbourne, Australia.
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Melbourne Health, Melbourne, Australia.
- School of Psychological Sciences, Institute of Psychology, Health and Society, The University of Liverpool, Liverpool, UK.
| | - Murat Yücel
- Brain and Mental Health Laboratory, Monash Institute of Cognitive and Clinical Neurosciences, School of Psychological Sciences, Monash University, Melbourne, Australia.
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Motivation deficits and use of alcohol and illicit drugs among individuals with schizophrenia. Psychiatry Res 2017; 253:391-397. [PMID: 28441618 PMCID: PMC5503109 DOI: 10.1016/j.psychres.2017.04.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 03/13/2017] [Accepted: 04/04/2017] [Indexed: 11/23/2022]
Abstract
This study examined the impact of substance use on intrinsic motivation and evaluated the association between intrinsic motivation and substance use recovery among individuals with schizophrenia. Alcohol and illicit drug use and intrinsic motivation were evaluated at baseline and 6-months for 1434 individuals with schizophrenia from the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) using self-rated substance use assessments and a derived motivation measure from the Heinrichs-Carpenter Quality of Life Scale. Results revealed patients had moderate motivation deficits overall and a considerable number were using alcohol or illicit drugs at baseline (n=576; 40.2%). Regression models at baseline showed patients with low levels of motivation had higher odds of substance use and those who were using substances had greater motivation deficits. At 6-months, substance using patients continued to demonstrate greater motivation deficits; however, those with high levels of motivation exhibited a greater reduction in their use of substances. Findings remained significant after adjusting for clinical confounds and were consistent across any substance, alcohol, and cannabis use. Our results emphasize concerns about substance use compounding motivation deficits in schizophrenia, and suggest that disentangling the motivation-substance use relationship in schizophrenia may facilitate efforts aimed at ameliorating these challenges and improving outcomes.
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103
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New Repeat Polymorphism in the AKT1 Gene Predicts Striatal Dopamine D2/D3 Receptor Availability and Stimulant-Induced Dopamine Release in the Healthy Human Brain. J Neurosci 2017; 37:4982-4991. [PMID: 28416594 DOI: 10.1523/jneurosci.3155-16.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 03/31/2017] [Accepted: 04/05/2017] [Indexed: 12/21/2022] Open
Abstract
The role of the protein kinase Akt1 in dopamine neurotransmission is well recognized and has been implicated in schizophrenia and psychosis. However, the extent to which variants in the AKT1 gene influence dopamine neurotransmission is not well understood. Here we investigated the effect of a newly characterized variant number tandem repeat (VNTR) polymorphism in AKT1 [major alleles: L- (eight repeats) and H- (nine repeats)] on striatal dopamine D2/D3 receptor (DRD2) availability and on dopamine release in healthy volunteers. We used PET and [11C]raclopride to assess baseline DRD2 availability in 91 participants. In 54 of these participants, we also measured intravenous methylphenidate-induced dopamine release to measure dopamine release. Dopamine release was quantified as the difference in specific binding of [11C]raclopride (nondisplaceable binding potential) between baseline values and values following methylphenidate injection. There was an effect of AKT1 genotype on DRD2 availability at baseline for the caudate (F(2,90) = 8.2, p = 0.001) and putamen (F(2,90) = 6.6, p = 0.002), but not the ventral striatum (p = 0.3). For the caudate and putamen, LL showed higher DRD2 availability than HH; HL were in between. There was also a significant effect of AKT1 genotype on dopamine increases in the ventral striatum (F(2,53) = 5.3, p = 0.009), with increases being stronger in HH > HL > LL. However, no dopamine increases were observed in the caudate (p = 0.1) or putamen (p = 0.8) following methylphenidate injection. Our results provide evidence that the AKT1 gene modulates both striatal DRD2 availability and dopamine release in the human brain, which could account for its association with schizophrenia and psychosis. The clinical relevance of the newly characterized AKT1 VNTR merits investigation.SIGNIFICANCE STATEMENT The AKT1 gene has been implicated in schizophrenia and psychosis. This association is likely to reflect modulation of dopamine signaling by Akt1 kinase since striatal dopamine hyperstimulation is associated with psychosis and schizophrenia. Here, using PET with [11C]raclopride, we identified in the AKT1 gene a new variable number tandem repeat (VNTR) marker associated with baseline striatal dopamine D2/D3 receptor availability and with methylphenidate-induced striatal dopamine increases in healthy volunteers. Our results confirm the involvement of the AKT1 gene in modulating striatal dopamine signaling in the human brain. Future studies are needed to assess the association of this new VNTR AKT1 variant in schizophrenia and drug-induced psychoses.
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104
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Walsh Z, Gonzalez R, Crosby K, S. Thiessen M, Carroll C, Bonn-Miller MO. Medical cannabis and mental health: A guided systematic review. Clin Psychol Rev 2017; 51:15-29. [DOI: 10.1016/j.cpr.2016.10.002] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 10/06/2016] [Accepted: 10/10/2016] [Indexed: 12/28/2022]
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105
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van de Giessen E, Weinstein JJ, Cassidy CM, Haney M, Dong Z, Ghazzaoui R, Ojeil N, Kegeles LS, Xu X, Vadhan NP, Volkow ND, Slifstein M, Abi-Dargham A. Deficits in striatal dopamine release in cannabis dependence. Mol Psychiatry 2017; 22:68-75. [PMID: 27001613 PMCID: PMC5033654 DOI: 10.1038/mp.2016.21] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 01/29/2016] [Accepted: 02/02/2016] [Indexed: 12/13/2022]
Abstract
Most drugs of abuse lead to a general blunting of dopamine release in the chronic phase of dependence, which contributes to poor outcome. To test whether cannabis dependence is associated with a similar dopaminergic deficit, we examined striatal and extrastriatal dopamine release in severely cannabis-dependent participants (CD), free of any comorbid conditions, including nicotine use. Eleven CD and 12 healthy controls (HC) completed two positron emission tomography scans with [11C]-(+)-PHNO, before and after oral administration of d-amphetamine. CD stayed inpatient for 5-7 days prior to the scans to standardize abstinence. Magnetic resonance spectroscopy (MRS) measures of glutamate in the striatum and hippocampus were obtained in the same subjects. Percent change in [11C]-(+)-PHNO-binding potential (ΔBPND) was compared between groups and correlations with MRS glutamate, subclinical psychopathological and neurocognitive parameters were examined. CD had significantly lower ΔBPND in the striatum (P=0.002, effect size (ES)=1.48), including the associative striatum (P=0.003, ES=1.39), sensorimotor striatum (P=0.003, ES=1.41) and the pallidus (P=0.012, ES=1.16). Lower dopamine release in the associative striatum correlated with inattention and negative symptoms in CD, and with poorer working memory and probabilistic category learning performance in both CD and HC. No relationships to MRS glutamate and amphetamine-induced subclinical positive symptoms were detected. In conclusion, this study provides evidence that severe cannabis dependence-without the confounds of any comorbidity-is associated with a deficit in striatal dopamine release. This deficit extends to other extrastriatal areas and predicts subclinical psychopathology.
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Affiliation(s)
- Elsmarieke van de Giessen
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York
- New York State Psychiatric Institute, New York
- Department of Nuclear Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | - Jodi J. Weinstein
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York
- New York State Psychiatric Institute, New York
| | - Clifford M. Cassidy
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York
- New York State Psychiatric Institute, New York
| | - Margaret Haney
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York
- New York State Psychiatric Institute, New York
| | - Zhengchao Dong
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York
- New York State Psychiatric Institute, New York
| | - Rassil Ghazzaoui
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York
- New York State Psychiatric Institute, New York
| | - Najate Ojeil
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York
- New York State Psychiatric Institute, New York
| | - Lawrence S. Kegeles
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York
- New York State Psychiatric Institute, New York
| | - Xiaoyan Xu
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York
- New York State Psychiatric Institute, New York
| | - Nehal P. Vadhan
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York
- New York State Psychiatric Institute, New York
- Department of Psychiatry, Stony Brook University School of Medicine, New York
| | - Nora D. Volkow
- National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland
| | - Mark Slifstein
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York
- New York State Psychiatric Institute, New York
| | - Anissa Abi-Dargham
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York
- New York State Psychiatric Institute, New York
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Bloomfield MAP, Mouchlianitis E, Morgan CJA, Freeman TP, Curran HV, Roiser JP, Howes OD. Salience attribution and its relationship to cannabis-induced psychotic symptoms. Psychol Med 2016; 46:3383-3395. [PMID: 27628967 PMCID: PMC5122315 DOI: 10.1017/s0033291716002051] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 07/22/2016] [Accepted: 07/25/2016] [Indexed: 12/16/2022]
Abstract
BACKGROUND Cannabis is a widely used drug associated with increased risk for psychosis. The dopamine hypothesis of psychosis postulates that altered salience processing leads to psychosis. We therefore tested the hypothesis that cannabis users exhibit aberrant salience and explored the relationship between aberrant salience and dopamine synthesis capacity. METHOD We tested 17 cannabis users and 17 age- and sex-matched non-user controls using the Salience Attribution Test, a probabilistic reward-learning task. Within users, cannabis-induced psychotic symptoms were measured with the Psychotomimetic States Inventory. Dopamine synthesis capacity, indexed as the influx rate constant K i cer , was measured in 10 users and six controls with 3,4-dihydroxy-6-[18F]fluoro-l-phenylalanine positron emission tomography. RESULTS There was no significant difference in aberrant salience between the groups [F 1,32 = 1.12, p = 0.30 (implicit); F 1,32 = 1.09, p = 0.30 (explicit)]. Within users there was a significant positive relationship between cannabis-induced psychotic symptom severity and explicit aberrant salience scores (r = 0.61, p = 0.04) and there was a significant association between cannabis dependency/abuse status and high implicit aberrant salience scores (F 1,15 = 5.8, p = 0.03). Within controls, implicit aberrant salience was inversely correlated with whole striatal dopamine synthesis capacity (r = -0.91, p = 0.01), whereas this relationship was non-significant within users (difference between correlations: Z = -2.05, p = 0.04). CONCLUSIONS Aberrant salience is positively associated with cannabis-induced psychotic symptom severity, but is not seen in cannabis users overall. This is consistent with the hypothesis that the link between cannabis use and psychosis involves alterations in salience processing. Longitudinal studies are needed to determine whether these cognitive abnormalities are pre-existing or caused by long-term cannabis use.
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Affiliation(s)
- M. A. P. Bloomfield
- Psychiatric Imaging Group,
MRC Clinical Sciences Centre, Institute of Clinical Sciences, Hammersmith
Hospital, Imperial College London, Du Cane Road,
London W12 0NN, UK
- Department of Psychosis Studies,
Institute of Psychiatry, Psychology & Neuroscience, King's College
London, De Crespigny Park, London SE5
8AF, UK
- Division of Psychiatry,
University College London, 6th Floor Maple
House, 149 Tottenham Court Road, London W1T
7NF, UK
| | - E. Mouchlianitis
- Psychiatric Imaging Group,
MRC Clinical Sciences Centre, Institute of Clinical Sciences, Hammersmith
Hospital, Imperial College London, Du Cane Road,
London W12 0NN, UK
- Department of Psychosis Studies,
Institute of Psychiatry, Psychology & Neuroscience, King's College
London, De Crespigny Park, London SE5
8AF, UK
| | - C. J. A. Morgan
- Clinical Psychopharmacology Unit,
Research Department of Clinical, Educational and Health
Psychology, University College London,
4th Floor, 1–19 Torrington Place,
London WC1E 7HB, UK
- Washington Singer Laboratories,
Department of Psychology, University of
Exeter, Exeter EX4 4QG, UK
| | - T. P. Freeman
- Clinical Psychopharmacology Unit,
Research Department of Clinical, Educational and Health
Psychology, University College London,
4th Floor, 1–19 Torrington Place,
London WC1E 7HB, UK
| | - H. V. Curran
- Clinical Psychopharmacology Unit,
Research Department of Clinical, Educational and Health
Psychology, University College London,
4th Floor, 1–19 Torrington Place,
London WC1E 7HB, UK
| | - J. P. Roiser
- Institute of Cognitive Neuroscience,
University College London, 17 Queen
Square, London WC1N 3AR, UK
| | - O. D. Howes
- Psychiatric Imaging Group,
MRC Clinical Sciences Centre, Institute of Clinical Sciences, Hammersmith
Hospital, Imperial College London, Du Cane Road,
London W12 0NN, UK
- Department of Psychosis Studies,
Institute of Psychiatry, Psychology & Neuroscience, King's College
London, De Crespigny Park, London SE5
8AF, UK
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107
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Thiruchselvam T, Malik S, Le Foll B. A review of positron emission tomography studies exploring the dopaminergic system in substance use with a focus on tobacco as a co-variate. THE AMERICAN JOURNAL OF DRUG AND ALCOHOL ABUSE 2016; 43:197-214. [PMID: 27901585 DOI: 10.1080/00952990.2016.1257633] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
With the evolving sensitivity of positron emission tomography (PET) and the emergence of novel radiotracers, greater insight has been gained into the dopaminergic system as it relates to substance use. In this review, we summarize PET investigations from the last ten years that explore the dopaminergic system in tobacco, alcohol, stimulant, opiates, and cannabis addiction. In light of the prevalence of substance co-use, this review will also explore the effect of tobacco and other substance abuse co-morbidity on the dopaminergic system across study samples in the reviewed literature. In non-dependence, increased DA transmission following acute stimulant administration is a robust and consistent observation but is less detectable following acute alcohol and tobacco, where it likely represents a conditioned effect mediating reward expectation. Chronic drug exposure is generally associated with a hypo-functioning pre-synaptic dopamine system and lower D2/D3 receptor availability relative to healthy controls. Emerging evidence also shows that stimulant use disorders in particular may also be associated with greater D3 receptor availability relative to controls. A defined role for the dopaminergic system in cannabis and opiate use is yet to be elucidated. Future work is also needed to delineate the potential interactive effects of acute and chronic tobacco and substance co-use on the dopaminergic system.
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Affiliation(s)
- Thulasi Thiruchselvam
- b Translational Addiction Research Laboratory, Campbell Family Mental Health Research Institute , Centre for Addiction and Mental Health , Toronto , ON , Canada
| | - Saima Malik
- b Translational Addiction Research Laboratory, Campbell Family Mental Health Research Institute , Centre for Addiction and Mental Health , Toronto , ON , Canada
| | - Bernard Le Foll
- a Addiction Medicine Service, Ambulatory Care and Structured Treatments , Centre for Addiction and Mental Health , Toronto , ON , Canada.,b Translational Addiction Research Laboratory, Campbell Family Mental Health Research Institute , Centre for Addiction and Mental Health , Toronto , ON , Canada.,c Department of Family and Community Medicine , Pharmacology and Toxicology, Psychiatry, Institute of Medical Sciences, University of Toronto , Toronto , ON , Canada.,d Campbell Family Mental Health Research Institute, Center for Addiction and Mental Health , Toronto , ON , Canada
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108
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Phillips JG, Ogeil RP. Cannabis, alcohol use, psychological distress, and decision-making style. J Clin Exp Neuropsychol 2016; 39:670-681. [PMID: 27876440 DOI: 10.1080/13803395.2016.1255311] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
INTRODUCTION There have been suggestions of hypofrontality in cannabis users. To understand cannabis-related differences in decisional processes, Janis and Mann's conflict model of decision making was applied to recreational cannabis smokers who varied in their alcohol use and level of psychological distress. METHOD An online sample of recreational substance users (114 male, 119 female) completed the Melbourne Decision Making Questionnaire, the Alcohol Use Disorders Identification Test (AUDIT), Kessler's Psychological Distress Scale (K10), and the Severity of Dependence Scale (SDS) for cannabis. RESULTS Multivariate analysis of variance examined self-reported decision-making styles as a function of gender, recent cannabis use, risky alcohol consumption, and levels of psychological distress. Psychological distress was associated with lower decisional self-esteem and higher levels of procrastination and buck-passing. There were gender differences associated with cannabis use. Female cannabis users reported higher levels of hypervigilance, while male cannabis users reported lower levels of buck-passing. CONCLUSIONS Although there was little indication of an avoidant decisional style in cannabis users, the results suggest that cannabis affects decisional processes, contributing to panic in females and impulsivity in males.
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Affiliation(s)
- James G Phillips
- a Psychology Department , Auckland University of Technology , Auckland , New Zealand
| | - Rowan P Ogeil
- b Eastern Health Clinical School , Monash University, and Turning Point, Eastern Health , Clayton , Australia
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Bloomfield MAP, Ashok AH, Volkow ND, Howes OD. The effects of Δ 9-tetrahydrocannabinol on the dopamine system. Nature 2016; 539:369-377. [PMID: 27853201 PMCID: PMC5123717 DOI: 10.1038/nature20153] [Citation(s) in RCA: 214] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 10/10/2016] [Indexed: 12/21/2022]
Abstract
The effects of Δ9-tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis, are a pressing concern for global mental health. Patterns of cannabis use are changing drastically owing to legalization, the availability of synthetic analogues (commonly termed spice), cannavaping and an emphasis on the purported therapeutic effects of cannabis. Many of the reinforcing effects of THC are mediated by the dopamine system. Owing to the complexity of the cannabinoid-dopamine interactions that take place, there is conflicting evidence from human and animal studies concerning the effects of THC on the dopamine system. Acute THC administration causes increased dopamine release and neuron activity, whereas long-term use is associated with blunting of the dopamine system. Future research must examine the long-term and developmental dopaminergic effects of THC.
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Affiliation(s)
- Michael A P Bloomfield
- Psychiatric Imaging Group, Robert Steiner MR Unit, MRC Clinical Sciences Centre, Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital, London W12 0NN, UK
- Psychiatric Imaging Group, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
- Division of Psychiatry, University College London, 6th Floor, Maple House, 149 Tottenham Court Road, London WC1T 7NF, UK
- Department of Psychosis Studies, Institute of Psychiatry, Psychology &Neuroscience, Kings College London, De Crespigny Park, London SE5 8AF, UK
- Clinical Psychopharmacology Unit, Research Department of Clinical, Educational and Health Psychology, University College London, 1-19 Torrington Place, London WC1E 6BT, UK
| | - Abhishekh H Ashok
- Psychiatric Imaging Group, Robert Steiner MR Unit, MRC Clinical Sciences Centre, Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital, London W12 0NN, UK
- Psychiatric Imaging Group, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
- Department of Psychosis Studies, Institute of Psychiatry, Psychology &Neuroscience, Kings College London, De Crespigny Park, London SE5 8AF, UK
| | - Nora D Volkow
- National Institute on Drug Abuse, National Institutes of Health, 6001 Executive Boulevard, Bethesda, Maryland 20892-9561, USA
| | - Oliver D Howes
- Psychiatric Imaging Group, Robert Steiner MR Unit, MRC Clinical Sciences Centre, Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital, London W12 0NN, UK
- Psychiatric Imaging Group, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
- Department of Psychosis Studies, Institute of Psychiatry, Psychology &Neuroscience, Kings College London, De Crespigny Park, London SE5 8AF, UK
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Johnson KA, Lovinger DM. Presynaptic G Protein-Coupled Receptors: Gatekeepers of Addiction? Front Cell Neurosci 2016; 10:264. [PMID: 27891077 PMCID: PMC5104741 DOI: 10.3389/fncel.2016.00264] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 10/31/2016] [Indexed: 12/21/2022] Open
Abstract
Drug abuse and addiction cause widespread social and public health problems, and the neurobiology underlying drug actions and drug use and abuse is an area of intensive research. Drugs of abuse alter synaptic transmission, and these actions contribute to acute intoxication as well as the chronic effects of abused substances. Transmission at most mammalian synapses involves neurotransmitter activation of two receptor subtypes, ligand-gated ion channels that mediate fast synaptic responses and G protein-coupled receptors (GPCRs) that have slower neuromodulatory actions. The GPCRs represent a large proportion of neurotransmitter receptors involved in almost all facets of nervous system function. In addition, these receptors are targets for many pharmacotherapeutic agents. Drugs of abuse directly or indirectly affect neuromodulation mediated by GPCRs, with important consequences for intoxication, drug taking and responses to prolonged drug exposure, withdrawal and addiction. Among the GPCRs are several subtypes involved in presynaptic inhibition, most of which are coupled to the Gi/o class of G protein. There is increasing evidence that these presynaptic Gi/o-coupled GPCRs have important roles in the actions of drugs of abuse, as well as behaviors related to these drugs. This topic will be reviewed, with particular emphasis on receptors for three neurotransmitters, Dopamine (DA; D1- and D2-like receptors), Endocannabinoids (eCBs; CB1 receptors) and glutamate (group II metabotropic glutamate (mGlu) receptors). The focus is on recent evidence from laboratory animal models (and some evidence in humans) implicating these receptors in the acute and chronic effects of numerous abused drugs, as well as in the control of drug seeking and taking. The ability of drugs targeting these receptors to modify drug seeking behavior has raised the possibility of using compounds targeting these receptors for addiction pharmacotherapy. This topic is also discussed, with emphasis on development of mGlu2 positive allosteric modulators (PAMs).
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Affiliation(s)
- Kari A. Johnson
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of HealthBethesda, MD, USA
| | - David M. Lovinger
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of HealthBethesda, MD, USA
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111
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Murray RM, Quigley H, Quattrone D, Englund A, Di Forti M. Traditional marijuana, high-potency cannabis and synthetic cannabinoids: increasing risk for psychosis. World Psychiatry 2016; 15:195-204. [PMID: 27717258 PMCID: PMC5032490 DOI: 10.1002/wps.20341] [Citation(s) in RCA: 146] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Epidemiological evidence demonstrates that cannabis use is associated with an increased risk of psychotic outcomes, and confirms a dose-response relationship between the level of use and the risk of later psychosis. High-potency cannabis and synthetic cannabinoids carry the greatest risk. Experimental administration of tetrahydrocannabinol, the active ingredient of cannabis, induces transient psychosis in normal subjects, but this effect can be ameliorated by co-administration of cannabidiol. This latter is a constituent of traditional hashish, but is largely absent from modern high-potency forms of cannabis. Argument continues over the extent to which genetic predisposition is correlated to, or interacts with, cannabis use, and what proportion of psychosis could be prevented by minimizing heavy use. As yet, there is not convincing evidence that cannabis use increases risk of other psychiatric disorders, but there are no such doubts concerning its detrimental effect on cognitive function. All of the negative aspects are magnified if use starts in early adolescence. Irrespective of whether use of cannabis is decriminalized or legalized, the evidence that it is a component cause of psychosis is now sufficient for public health messages outlining the risk, especially of regular use of high-potency cannabis and synthetic cannabinoids.
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Affiliation(s)
- Robin M. Murray
- Institute of Psychiatry, Psychology and Neuroscience, King's CollegeDe Crespigny ParkLondonSE5 8AFUK
| | - Harriet Quigley
- Institute of Psychiatry, Psychology and Neuroscience, King's CollegeDe Crespigny ParkLondonSE5 8AFUK
| | - Diego Quattrone
- Institute of Psychiatry, Psychology and Neuroscience, King's CollegeDe Crespigny ParkLondonSE5 8AFUK
| | - Amir Englund
- Institute of Psychiatry, Psychology and Neuroscience, King's CollegeDe Crespigny ParkLondonSE5 8AFUK
| | - Marta Di Forti
- Institute of Psychiatry, Psychology and Neuroscience, King's CollegeDe Crespigny ParkLondonSE5 8AFUK
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Tournier BB, Tsartsalis S, Dimiziani A, Millet P, Ginovart N. Time-dependent effects of repeated THC treatment on dopamine D2/3 receptor-mediated signalling in midbrain and striatum. Behav Brain Res 2016; 311:322-329. [DOI: 10.1016/j.bbr.2016.05.045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 05/17/2016] [Accepted: 05/21/2016] [Indexed: 02/07/2023]
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113
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Wiers CE, Shokri-Kojori E, Wong CT, Abi-Dargham A, Demiral ŞB, Tomasi D, Wang GJ, Volkow ND. Cannabis Abusers Show Hypofrontality and Blunted Brain Responses to a Stimulant Challenge in Females but not in Males. Neuropsychopharmacology 2016; 41:2596-605. [PMID: 27156854 PMCID: PMC4987858 DOI: 10.1038/npp.2016.67] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 04/27/2016] [Accepted: 04/30/2016] [Indexed: 12/14/2022]
Abstract
The extent to which cannabis is deleterious to the human brain is not well understood. Here, we test whether cannabis abusers (CA) have impaired frontal function and reactivity to dopaminergic signaling, which are fundamental to relapse in addiction. We measured brain glucose metabolism using PET and [(18)F]FDG both at baseline (placebo) and after challenge with methylphenidate (MP), a dopamine-enhancing drug, in 24 active CA (50% female) and 24 controls (HC; 50% female). Results show that (i) CA had lower baseline glucose metabolism than HC in frontal cortex including anterior cingulate, which was associated with negative emotionality. (ii) MP increased whole-brain glucose metabolism in HC but not in CA; and group by challenge effects were most profound in putamen, caudate, midbrain, thalamus, and cerebellum. In CA, MP-induced metabolic increases in putamen correlated negatively with addiction severity. (iii) There were significant gender effects, such that both the group differences at baseline in frontal metabolism and the attenuated regional brain metabolic responses to MP were observed in female CA but not in male CA. As for other drug addictions, reduced baseline frontal metabolism is likely to contribute to relapse in CA. The attenuated responses to MP in midbrain and striatum are consistent with decreased brain reactivity to dopamine stimulation and might contribute to addictive behaviors in CA. The gender differences suggest that females are more sensitive than males to the adverse effects of cannabis in brain.
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Affiliation(s)
- Corinde E Wiers
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA,National Institute on Alcohol Abuse and Alcoholism, Laboratory of Neuroimaging, National Institutes of Health, 10 Center Drive, Room B2L124, Bethesda, MD 20892, USA, Tel: +1 301 451 3021 or +1 301 402 0868, Fax: +1 301 496 5568, E-mail: or
| | - Ehsan Shokri-Kojori
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Christopher T Wong
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Anissa Abi-Dargham
- Division of Translational Imaging, Department of Psychiatry, Columbia University and New York State Psychiatric Institute, New York, NY, USA
| | - Şükrü B Demiral
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Dardo Tomasi
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Gene-Jack Wang
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Nora D Volkow
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA,National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD, USA,National Institute on Alcohol Abuse and Alcoholism, Laboratory of Neuroimaging, National Institutes of Health, 10 Center Drive, Room B2L124, Bethesda, MD 20892, USA, Tel: +1 301 451 3021 or +1 301 402 0868, Fax: +1 301 496 5568, E-mail: or
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114
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Martz ME, Trucco EM, Cope LM, Hardee JE, Jester JM, Zucker RA, Heitzeg MM. Association of Marijuana Use With Blunted Nucleus Accumbens Response to Reward Anticipation. JAMA Psychiatry 2016; 73:838-44. [PMID: 27384542 PMCID: PMC4972653 DOI: 10.1001/jamapsychiatry.2016.1161] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
IMPORTANCE Marijuana use may alter ventral striatal response to reward, which might heighten susceptibility to substance use disorder. Longitudinal research is needed to determine the effects of marijuana use on neural function involved in reward response. OBJECTIVE To determine whether marijuana use among young adults prospectively affects nucleus accumbens (NAcc) activation during reward anticipation. DESIGN, SETTING, AND PARTICIPANTS One hundred eight young adults were recruited from the Michigan Longitudinal Study, an ongoing study of youth at high risk for substance use disorder and a contrast sample of control families. Participants underwent 3 consecutive functional magnetic resonance imaging scans at approximate ages of 20 (time 1), 22 (time 2), and 24 (time 3) years. Self-report data on marijuana and other drug use occasions were collected annually since age 11 years. MAIN OUTCOMES AND MEASURES Cross-lagged models were used to test the association of marijuana use with neural response in the NAcc to reward anticipation during a monetary incentive delay task controlling for sex, age, other substance use, and family history of substance use disorder. RESULTS Of 108 participants, 39 (36.1%) were female and mean (SD) age at baseline was 20.1 (1.4) years. Greater marijuana use was associated with later blunted activation in the NAcc during reward anticipation (time 1 to time 2: β = -0.26, P = .04; time 2 to time 3: β = -0.25, P = .01). When the cross-lagged model was tested with the inclusion of previous and concurrent cigarette use, the effect of marijuana use from time 2 to time 3 remained significant (β = -0.29; P = .005) and the effect of cigarette use was nonsignificant. CONCLUSIONS AND RELEVANCE The findings of this study indicate that marijuana use is associated with decreased neural response in the NAcc during the anticipation of nondrug rewards. Over time, marijuana use may alter anticipatory reward processing in the NAcc, which may increase the risk for continued drug use and later addiction.
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Affiliation(s)
- Meghan E. Martz
- Department of Psychiatry and Addiction Research Center, University of Michigan 4250 Plymouth Rd., Ann Arbor, MI 48109, USA,Department of Psychology, University of Michigan, 530 Church St., Ann Arbor, MI 48108, USA
| | - Elisa M. Trucco
- Department of Psychiatry and Addiction Research Center, University of Michigan 4250 Plymouth Rd., Ann Arbor, MI 48109, USA,Department of Psychology, Center for Children and Families, Florida International University, 11200 SW 8th Street, Miami, FL 33199, USA
| | - Lora M. Cope
- Department of Psychiatry and Addiction Research Center, University of Michigan 4250 Plymouth Rd., Ann Arbor, MI 48109, USA
| | - Jillian E. Hardee
- Department of Psychiatry and Addiction Research Center, University of Michigan 4250 Plymouth Rd., Ann Arbor, MI 48109, USA
| | - Jennifer M. Jester
- Department of Psychiatry and Addiction Research Center, University of Michigan 4250 Plymouth Rd., Ann Arbor, MI 48109, USA
| | - Robert A. Zucker
- Department of Psychiatry and Addiction Research Center, University of Michigan 4250 Plymouth Rd., Ann Arbor, MI 48109, USA,Department of Psychology, University of Michigan, 530 Church St., Ann Arbor, MI 48108, USA
| | - Mary M. Heitzeg
- Department of Psychiatry and Addiction Research Center, University of Michigan 4250 Plymouth Rd., Ann Arbor, MI 48109, USA
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115
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Borg J, Cervenka S, Kuja-Halkola R, Matheson GJ, Jönsson EG, Lichtenstein P, Henningsson S, Ichimiya T, Larsson H, Stenkrona P, Halldin C, Farde L. Contribution of non-genetic factors to dopamine and serotonin receptor availability in the adult human brain. Mol Psychiatry 2016; 21:1077-84. [PMID: 26821979 DOI: 10.1038/mp.2015.147] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 07/10/2015] [Accepted: 08/05/2015] [Indexed: 12/12/2022]
Abstract
The dopamine (DA) and serotonin (5-HT) neurotransmission systems are of fundamental importance for normal brain function and serve as targets for treatment of major neuropsychiatric disorders. Despite central interest for these neurotransmission systems in psychiatry research, little is known about the regulation of receptor and transporter density levels. This lack of knowledge obscures interpretation of differences in protein availability reported in psychiatric patients. In this study, we used positron emission tomography (PET) in a twin design to estimate the relative contribution of genetic and environmental factors, respectively, on dopaminergic and serotonergic markers in the living human brain. Eleven monozygotic and 10 dizygotic healthy male twin pairs were examined with PET and [(11)C]raclopride binding to the D2- and D3-dopamine receptor and [(11)C]WAY100635 binding to the serotonin 5-HT1A receptor. Heritability, shared environmental effects and individual-specific non-shared effects were estimated for regional D2/3 and 5-HT1A receptor availability in projection areas. We found a major contribution of genetic factors (0.67) on individual variability in striatal D2/3 receptor binding and a major contribution of environmental factors (pairwise shared and unique individual; 0.70-0.75) on neocortical 5-HT1A receptor binding. Our findings indicate that individual variation in neuroreceptor availability in the adult brain is the end point of a nature-nurture interplay, and call for increased efforts to identify not only the genetic but also the environmental factors that influence neurotransmission in health and disease.
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Affiliation(s)
- J Borg
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet, Stockholm, Sweden.,Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - S Cervenka
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet, Stockholm, Sweden
| | - R Kuja-Halkola
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - G J Matheson
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet, Stockholm, Sweden
| | - E G Jönsson
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet, Stockholm, Sweden.,NORMENT, KG Jebsen Centre for Psychosis Research, Institute of Clinical Medicine, Psychiatry Section, University of Oslo, Oslo, Norway
| | - P Lichtenstein
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - S Henningsson
- Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital, Hvidovre, Denmark
| | - T Ichimiya
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet, Stockholm, Sweden.,Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan
| | - H Larsson
- Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
| | - P Stenkrona
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet, Stockholm, Sweden
| | - C Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet, Stockholm, Sweden
| | - L Farde
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet, Stockholm, Sweden.,AstraZeneca Translational Science Center at Karolinska Institutet, Stockholm, Sweden
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116
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Abstract
Advances in neuroscience identified addiction as a chronic brain disease with strong genetic, neurodevelopmental, and sociocultural components. We here discuss the circuit- and cell-level mechanisms of this condition and its co-option of pathways regulating reward, self-control, and affect. Drugs of abuse exert their initial reinforcing effects by triggering supraphysiologic surges of dopamine in the nucleus accumbens that activate the direct striatal pathway via D1 receptors and inhibit the indirect striato-cortical pathway via D2 receptors. Repeated drug administration triggers neuroplastic changes in glutamatergic inputs to the striatum and midbrain dopamine neurons, enhancing the brain's reactivity to drug cues, reducing the sensitivity to non-drug rewards, weakening self-regulation, and increasing the sensitivity to stressful stimuli and dysphoria. Drug-induced impairments are long lasting; thus, interventions designed to mitigate or even reverse them would be beneficial for the treatment of addiction.
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Affiliation(s)
- Nora D Volkow
- National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Marisela Morales
- National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD 20892, USA
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117
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Núñez C, Ochoa S, Huerta-Ramos E, Baños I, Barajas A, Dolz M, Sánchez B, Del Cacho N, Usall J. Cannabis use and cognitive function in first episode psychosis: differential effect of heavy use. Psychopharmacology (Berl) 2016; 233:809-21. [PMID: 26621349 DOI: 10.1007/s00213-015-4160-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 11/15/2015] [Indexed: 11/26/2022]
Abstract
RATIONALE First episode patients and patients with schizophrenia exhibit increased rates of cannabis use compared to the general population. Contrary to what has been reported in studies with healthy people, most of the published studies so far have reported no impairments or even beneficial effects on neurocognition associated with cannabis consumption in psychotic patients. However, these studies did not address the effects of very high cannabis consumption. OBJECTIVES Our aim in this study was to assess the effects on neurocognition of medium and heavy cannabis consumption in first psychotic episode patients. METHODS A total of 74 patients were included in the study and assigned to three different groups according to their mean cannabis consumption during the last year (non-users, medium users, and heavy users). Participants were administered verbal memory and other neurocognitive tasks. RESULTS Heavy cannabis users were significantly impaired in all the verbal memory measures with respect to non-users, including immediate (p = .026), short-term (p = .005), and long-term (p = .002) memory. There were no significant differences between medium and non-users. Moreover, non-users performed better than all cannabis users in the arithmetic task (p = .020). Heavy cannabis consumption was associated with more commission errors in the continuous performance task (CPT) (p = .008) and more time to complete trail making test A (TMT-A) (p = .008), compared to the group of medium users. CONCLUSIONS Heavy cannabis consumption seems to impair verbal memory in first psychotic episode patients. Heavy users also perform worse than medium users in other neurocognitive tasks. Based on the results and the available evidence, a dose-related effect of cannabis consumption is suggested.
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Affiliation(s)
- Christian Núñez
- Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain.
- Universitat de Barcelona, Barcelona, Spain.
| | - Susana Ochoa
- Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain
- Instituto de Salud Carlos III, Centro de Investigación en Red de Salud Mental (CIBERSAM), Madrid, Spain
| | - Elena Huerta-Ramos
- Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain
- Instituto de Salud Carlos III, Centro de Investigación en Red de Salud Mental (CIBERSAM), Madrid, Spain
| | - Iris Baños
- Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain
- Instituto de Salud Carlos III, Centro de Investigación en Red de Salud Mental (CIBERSAM), Madrid, Spain
| | - Ana Barajas
- Research Unit, Centre d'Higiene Mental Les Corts, Barcelona, Spain
| | - Montserrat Dolz
- Instituto de Salud Carlos III, Centro de Investigación en Red de Salud Mental (CIBERSAM), Madrid, Spain
- Psychiatry Department, Hospital Sant Joan de Déu, Esplugues de Llobregat, Spain
| | - Bernardo Sánchez
- Psychiatry Department, Hospital Sant Joan de Déu, Esplugues de Llobregat, Spain
| | - Núria Del Cacho
- Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain
| | - Judith Usall
- Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain
- Instituto de Salud Carlos III, Centro de Investigación en Red de Salud Mental (CIBERSAM), Madrid, Spain
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118
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MacDonald K, Pappas K. WHY NOT POT?: A Review of the Brain-based Risks of Cannabis. INNOVATIONS IN CLINICAL NEUROSCIENCE 2016; 13:13-22. [PMID: 27354924 PMCID: PMC4911936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this review, we provide a historical perspective on marijuana, and survey contemporary research investigating its potential negative effects on the brain. We discuss the evidence regarding cannabis dependence, driving under the influence of cannabis, underachievement, inducing (or worsening) certain psychiatric conditions, and the potential for progression to use of more dangerous drugs-summarized by the acronym DDUMB, a cognitive tool that may help healthcare providers in their risk/benefit discussions with patients who use cannabis. We also review and discuss the impact of marijuana use on target populations, including adolescents (who are at increased risk of harm); heavy users; and people suffering from-or at high risk of- mental illness. While cannabis presents certain subjective, healthrelated, and pecuniary benefits to users, growers, and other entities, it is also associated with several brainbased risks. Understanding these risks aids clinicians and their patients in making informed and balanced decisions regarding the initiation or continuance of marijuana use.
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Affiliation(s)
- Kai MacDonald
- Dr. MacDonald and Ms. Pappas are with UC San Diego Psychiatry, San Diego, CA, USA
| | - Katherine Pappas
- Dr. MacDonald and Ms. Pappas are with UC San Diego Psychiatry, San Diego, CA, USA
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119
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Reduced sleep duration mediates decreases in striatal D2/D3 receptor availability in cocaine abusers. Transl Psychiatry 2016; 6:e752. [PMID: 26954979 PMCID: PMC4872440 DOI: 10.1038/tp.2016.14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 11/21/2015] [Accepted: 01/19/2016] [Indexed: 12/12/2022] Open
Abstract
Neuroimaging studies have documented reduced striatal dopamine D2/D3 receptor (D2/D3R) availability in cocaine abusers, which has been associated with impaired prefrontal activity and vulnerability for relapse. However, the mechanism(s) underlying the decreases in D2/D3R remain poorly understood. Recent studies have shown that sleep deprivation is associated with a downregulation of striatal D2/D3R in healthy volunteers. As cocaine abusers have disrupted sleep patterns, here we investigated whether reduced sleep duration mediates the relationship between cocaine abuse and low striatal D2/D3R availability. We used positron emission tomography with [(11)C]raclopride to measure striatal D2/D3R availability in 24 active cocaine abusers and 21 matched healthy controls, and interviewed them about their daily sleep patterns. Compared with controls, cocaine abusers had shorter sleep duration, went to bed later and reported longer periods of sleep disturbances. In addition, cocaine abusers had reduced striatal D2/D3R availability. Sleep duration predicted striatal D2/D3R availability and statistically mediated the relationship between cocaine abuse and striatal D2/D3R availability. These findings suggest that impaired sleep patterns contribute to the low striatal D2/D3R availability in cocaine abusers. As sleep impairments are similarly observed in other types of substance abusers (for example, alcohol and methamphetamine), this mechanism may also underlie reductions in D2/D3R availability in these groups. The current findings have clinical implications suggesting that interventions to improve sleep patterns in cocaine abusers undergoing detoxification might be beneficial in improving their clinical outcomes.
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120
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Wiers CE, Cabrera E, Skarda E, Volkow ND, Wang GJ. PET imaging for addiction medicine: From neural mechanisms to clinical considerations. PROGRESS IN BRAIN RESEARCH 2015; 224:175-201. [PMID: 26822359 DOI: 10.1016/bs.pbr.2015.07.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Positron emission tomography (PET) has been shown to be an effective imaging technique to study neurometabolic and neurochemical processes involved in addiction. That is, PET has been used to research neurobiological differences in substance abusers versus healthy controls and the pharmacokinetics and pharmacodynamics of abused drugs. Over the past years, the research scope has shifted to investigating neurobiological effects of abstinence and treatment, and their predictive power for relapse and other clinical outcomes. This chapter provides an overview of PET methodology, recent human PET studies on drug addiction and their implications for clinical treatment.
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Affiliation(s)
- Corinde E Wiers
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA.
| | - Elizabeth Cabrera
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Emily Skarda
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Nora D Volkow
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA; National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD, USA
| | - Gene-Jack Wang
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
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121
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Abstract
After more than a century of work concentrating on the motor functions of the basal ganglia, new ideas have emerged, suggesting that the basal ganglia also have major functions in relation to learning habits and acquiring motor skills. We review the evidence supporting the role of the striatum in optimizing behavior by refining action selection and in shaping habits and skills as a modulator of motor repertoires. These findings challenge the notion that striatal learning processes are limited to the motor domain. The learning mechanisms supported by striatal circuitry generalize to other domains, including cognitive skills and emotion-related patterns of action.
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Affiliation(s)
- Ann M Graybiel
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 20139 Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 20139
| | - Scott T Grafton
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California 93106-9660 Department of Psychological and Brain Sciences, University of California, Santa Barbara, California 93106-9660
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122
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Abstract
Adolescence is characterized by heightened risk-taking, including substance misuse. These behavioral patterns are influenced by ontogenic changes in neurotransmitter systems, particularly the dopamine system, which is fundamentally involved in the neural coding of reward and motivated approach behavior. During adolescence, this system evidences a peak in activity. At the same time, the dopamine (DA) system is neuroplastically altered by substance abuse, impacting subsequent function. Here, we describe properties of the dopamine system that change with typical adolescent development and that are altered with substance abuse. Much of this work has been gleaned from animal models due to limitations in measuring dopamine in pediatric samples. Structural and functional neuroimaging techniques have been used to examine structures that are heavily DA-innervated; they measure morphological and functional changes with age and with drug exposure. Presenting marijuana abuse as an exemplar, we consider recent findings that support an adolescent peak in DA-driven reward-seeking behavior and related deviations in motivational systems that are associated with marijuana abuse/dependence. Clinicians are advised that (1) chronic adolescent marijuana use may lead to deficiencies in incentive motivation, (2) that this state is due to marijuana's interactions with the developing DA system, and (3) that treatment strategies should be directed to remediating resultant deficiencies in goal-directed activity.
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123
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Bossong MG, Mehta MA, van Berckel BN, Howes OD, Kahn RS, Stokes PR. Further human evidence for striatal dopamine release induced by administration of ∆9-tetrahydrocannabinol (THC): selectivity to limbic striatum. Psychopharmacology (Berl) 2015; 232:2723-9. [PMID: 25801289 PMCID: PMC4816196 DOI: 10.1007/s00213-015-3915-0] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 02/23/2015] [Indexed: 02/07/2023]
Abstract
RATIONALE Elevated dopamine function is thought to play a key role in both the rewarding effects of addictive drugs and the pathophysiology of schizophrenia. Accumulating epidemiological evidence indicates that cannabis use is a risk factor for the development of schizophrenia. However, human neurochemical imaging studies that examined the impact of ∆9-tetrahydrocannabinol (THC), the main psychoactive component in cannabis, on striatal dopamine release have provided inconsistent results. OBJECTIVES The objective of this study is to assess the effect of a THC challenge on human striatal dopamine release in a large sample of healthy participants. METHODS We combined human neurochemical imaging data from two previous studies that used [(11)C]raclopride positron emission tomography (PET) (n = 7 and n = 13, respectively) to examine the effect of THC on striatal dopamine neurotransmission in humans. PET images were re-analysed to overcome differences in PET data analysis. RESULTS THC administration induced a significant reduction in [(11)C]raclopride binding in the limbic striatum (-3.65 %, from 2.39 ± 0.26 to 2.30 ± 0.23, p = 0.023). This is consistent with increased dopamine levels in this region. No significant differences between THC and placebo were found in other striatal subdivisions. CONCLUSIONS In the largest data set of healthy participants so far, we provide evidence for a modest increase in human striatal dopamine transmission after administration of THC compared to other drugs of abuse. This finding suggests limited involvement of the endocannabinoid system in regulating human striatal dopamine release and thereby challenges the hypothesis that an increase in striatal dopamine levels after cannabis use is the primary biological mechanism underlying the associated higher risk of schizophrenia.
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Affiliation(s)
- Matthijs G. Bossong
- Brain Center Rudolf Magnus, Department of Psychiatry, University Medical Center Utrecht, the Netherlands
,Department of Psychosis Studies, Institute of Psychiatry, King’s College London, United Kingdom
| | - Mitul A. Mehta
- Centre for Neuroimaging Sciences, Institute of Psychiatry, King’s College London, United Kingdom
| | - Bart N.M. van Berckel
- Brain Center Rudolf Magnus, Department of Psychiatry, University Medical Center Utrecht, the Netherlands
,Department of Nuclear Medicine & PET Research, VU University Medical Center, Amsterdam, the Netherlands
| | - Oliver D. Howes
- Department of Psychosis Studies, Institute of Psychiatry, King’s College London, United Kingdom
,Psychiatry Group, MRC Clinical Sciences Centre, Imperial College London, United Kingdom
| | - René S. Kahn
- Brain Center Rudolf Magnus, Department of Psychiatry, University Medical Center Utrecht, the Netherlands
| | - Paul R.A. Stokes
- Psychiatry Group, MRC Clinical Sciences Centre, Imperial College London, United Kingdom
,Centre for Affective Disorders, Department of Psychological Medicine, Institute of Psychiatry, King's College London, United Kingdom
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124
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Tomasi D, Wang GJ, Volkow ND. Balanced modulation of striatal activation from D2 /D3 receptors in caudate and ventral striatum: Disruption in cannabis abusers. Hum Brain Mapp 2015; 36:3154-66. [PMID: 26058801 DOI: 10.1002/hbm.22834] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 04/27/2015] [Accepted: 04/28/2015] [Indexed: 02/05/2023] Open
Abstract
Proper communication between dorsal caudate (CD) and ventral striatum (VS) is likely to be crucial for on-time responses and its disruption might result in impulsivity. Here, we used functional magnetic resonance imaging (fMRI) with a sensorimotor reaction time task and positron emission tomography (PET) with [(11)C]raclopride in 14 healthy controls and 18 cannabis abusers to contrast the modulation of striatal fMRI responses by dopamine receptors (D2 /D3 R) in CD and VS. In controls, we show that the fMRI signals in VS that occurs concomitantly with on-time responses showed opposite modulation from D2 /D3 R in CD (inhibitory) and D2 /D3 R in VS (stimulatory). In contrast, this modulation was not significant in cannabis abusers. Findings suggest that action speed requires balanced VS-inhibition from D2 /D3 R in CD and VS-facilitation from D2 /D3 R in VS.
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Affiliation(s)
- Dardo Tomasi
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland, 20892
| | - Gene-Jack Wang
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland, 20892
| | - Nora D Volkow
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland, 20892.,National Institute on Drug Abuse, National Institutes of Health, Bethesda, Maryland, 20892
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125
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Panlilio LV, Goldberg SR, Justinova Z. Cannabinoid abuse and addiction: Clinical and preclinical findings. Clin Pharmacol Ther 2015; 97:616-27. [PMID: 25788435 DOI: 10.1002/cpt.118] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 03/13/2015] [Indexed: 01/11/2023]
Abstract
Cannabinoid abuse disorders represent a widespread public health issue, but there are no approved medications for their treatment. This review describes efforts to understand the mechanisms of cannabinoid abuse and its adverse effects, to identify molecular targets for pharmacotherapy, and to evaluate potential treatments in human volunteers and animal models of cannabinoid reward, withdrawal, and relapse.
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Affiliation(s)
- L V Panlilio
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, NIH, DHHS, Baltimore, Maryland, USA
| | - S R Goldberg
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, NIH, DHHS, Baltimore, Maryland, USA
| | - Z Justinova
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, NIH, DHHS, Baltimore, Maryland, USA
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126
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Nutt DJ, Lingford-Hughes A, Erritzoe D, Stokes PRA. The dopamine theory of addiction: 40 years of highs and lows. Nat Rev Neurosci 2015; 16:305-12. [PMID: 25873042 DOI: 10.1038/nrn3939] [Citation(s) in RCA: 349] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
For several decades, addiction has come to be viewed as a disorder of the dopamine neurotransmitter system; however, this view has not led to new treatments. In this Opinion article, we review the origins of the dopamine theory of addiction and discuss the ability of addictive drugs to elicit the release of dopamine in the human striatum. There is robust evidence that stimulants increase striatal dopamine levels and some evidence that alcohol may have such an effect, but little evidence, if any, that cannabis and opiates increase dopamine levels. Moreover, there is good evidence that striatal dopamine receptor availability and dopamine release are diminished in individuals with stimulant or alcohol dependence but not in individuals with opiate, nicotine or cannabis dependence. These observations have implications for understanding reward and treatment responses in various addictions.
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Affiliation(s)
- David J Nutt
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Burlington Danes Building, Imperial College London, London W12 0NN, UK
| | - Anne Lingford-Hughes
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Burlington Danes Building, Imperial College London, London W12 0NN, UK
| | - David Erritzoe
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Burlington Danes Building, Imperial College London, London W12 0NN, UK
| | - Paul R A Stokes
- 1] Centre for Neuropsychopharmacology, Division of Brain Sciences, Burlington Danes Building, Imperial College London, London W12 0NN, UK. [2] Centre for Affective Disorders, Department of Psychological Medicine, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London, London SE5 8AF, UK
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127
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Dopaminergic system dysfunction in recreational dexamphetamine users. Neuropsychopharmacology 2015; 40:1172-80. [PMID: 25394786 PMCID: PMC4367461 DOI: 10.1038/npp.2014.301] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 10/30/2014] [Accepted: 10/31/2014] [Indexed: 11/08/2022]
Abstract
Dexamphetamine (dAMPH) is a stimulant drug that is widely used recreationally as well as for the treatment of attention-deficit hyperactivity disorder (ADHD). Although animal studies have shown neurotoxic effects of dAMPH on the dopaminergic system, little is known about such effects on the human brain. Here, we studied the dopaminergic system at multiple physiological levels in recreational dAMPH users and age, gender, and IQ-matched dAMPH-naïve healthy controls. We assessed baseline D2/3 receptor availability, in addition to changes in dopamine (DA) release using single-photon emission computed tomography and DA functionality using pharmacological magnetic resonance imaging, following a dAMPH challenge. Also, the subjective responses to the challenge were determined. dAMPH users displayed significantly lower striatal DA D2/3 receptor binding compared with healthy controls. In dAMPH users, we further observed a blunted DA release and DA functionality to an acute dAMPH challenge, as well as a blunted subjective response. Finally, the lower D2/3 availability, the more pleasant the dAMPH administration was experienced by control subjects, but not by dAMPH users. Thus, in agreement with preclinical studies, we show that the recreational use of dAMPH in human subjects is associated with dopaminergic system dysfunction. These findings warrant further (longitudinal) investigations and call for caution when using this drug recreationally and for ADHD.
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128
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Kluger B, Triolo P, Jones W, Jankovic J. The therapeutic potential of cannabinoids for movement disorders. Mov Disord 2015; 30:313-27. [PMID: 25649017 DOI: 10.1002/mds.26142] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 11/10/2014] [Accepted: 12/01/2014] [Indexed: 01/12/2023] Open
Abstract
There is growing interest in the therapeutic potential of marijuana (cannabis) and cannabinoid-based chemicals within the medical community and, particularly, for neurological conditions. This interest is driven both by changes in the legal status of cannabis in many areas and increasing research into the roles of endocannabinoids within the central nervous system and their potential as symptomatic and/or neuroprotective therapies. We review basic science as well as preclinical and clinical studies on the therapeutic potential of cannabinoids specifically as it relates to movement disorders. The pharmacology of cannabis is complex, with over 60 neuroactive chemicals identified to date. The endocannabinoid system modulates neurotransmission involved in motor function, particularly within the basal ganglia. Preclinical research in animal models of several movement disorders have shown variable evidence for symptomatic benefits, but more consistently suggest potential neuroprotective effects in several animal models of Parkinson's (PD) and Huntington's disease (HD). Clinical observations and clinical trials of cannabinoid-based therapies suggests a possible benefit of cannabinoids for tics and probably no benefit for tremor in multiple sclerosis or dyskinesias or motor symptoms in PD. Data are insufficient to draw conclusions regarding HD, dystonia, or ataxia and nonexistent for myoclonus or RLS. Despite the widespread publicity about the medical benefits of cannabinoids, further preclinical and clinical research is needed to better characterize the pharmacological, physiological, and therapeutic effects of this class of drugs in movement disorders.
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Affiliation(s)
- Benzi Kluger
- Movement Disorders Center, Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA
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129
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Fischer B, Murphy Y, Kurdyak P, Goldner E, Rehm J. Medical marijuana programs - Why might they matter for public health and why should we better understand their impacts? Prev Med Rep 2015; 2:53-6. [PMID: 26844050 PMCID: PMC4721313 DOI: 10.1016/j.pmedr.2014.12.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Objective Although cannabis is an illegal drug, ‘medical marijuana programs’ (MMPs) have proliferated (e.g., in Canada and several US states), allowing for legal cannabis use for therapeutic purposes. While both health risks and potential therapeutic benefits for cannabis use have been documented, potential public health impacts of MMPs — also vis-à-vis other psychoactive substance use — remain under-explored. Methods We briefly reviewed the emerging evidence on MMP participants' health status, and specifically other psychoactive substance use behaviors and outcomes. Results While data are limited in amount and quality, MMP participants report improvements in overall health status, and specifically reductions in levels of risky alcohol, prescription drug and — to some extent — tobacco or other illicit drug use; at the same time, increases in cannabis use and risk/problem patterns may occur. Conclusion MMP participation may positively impact — for example, by way of possible ‘substitution effects’ from cannabis use — other psychoactive substance use and risk patterns at a scale relevant for public health, also influenced by the increasing population coverage of MMPs. Yet, net overall MMP-related population health effects need to be more rigorously and comprehensively assessed, including potential increases in cannabis use related risks and harms.
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Affiliation(s)
- Benedikt Fischer
- Centre for Applied Research in Mental Health and Addictions (CARMHA), Faculty of Health Sciences, Simon Fraser University, Vancouver, British Columbia V6B 5K3, Canada; Social & Epidemiological Research, Centre for Addiction & Mental Health (CAMH), Toronto, Ontario M5S 1S1, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario M5T 1R8, Canada
| | - Yoko Murphy
- Centre for Applied Research in Mental Health and Addictions (CARMHA), Faculty of Health Sciences, Simon Fraser University, Vancouver, British Columbia V6B 5K3, Canada; Social & Epidemiological Research, Centre for Addiction & Mental Health (CAMH), Toronto, Ontario M5S 1S1, Canada
| | - Paul Kurdyak
- Department of Psychiatry, University of Toronto, Toronto, Ontario M5T 1R8, Canada; Mental Health & Addiction Research Program, Institute of Clinical Evaluative Sciences, Toronto, Ontario M4N 3M5, Canada
| | - Elliot Goldner
- Centre for Applied Research in Mental Health and Addictions (CARMHA), Faculty of Health Sciences, Simon Fraser University, Vancouver, British Columbia V6B 5K3, Canada
| | - Jürgen Rehm
- Social & Epidemiological Research, Centre for Addiction & Mental Health (CAMH), Toronto, Ontario M5S 1S1, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario M5T 1R8, Canada; Dalla Lana School of Public Health, University of Toronto, Ontario M5T 3M7, Canada
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130
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Collo G, Cavalleri L, Spano P. Structural plasticity in mesencephalic dopaminergic neurons produced by drugs of abuse: critical role of BDNF and dopamine. Front Pharmacol 2014; 5:259. [PMID: 25505416 PMCID: PMC4243500 DOI: 10.3389/fphar.2014.00259] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Accepted: 11/06/2014] [Indexed: 01/10/2023] Open
Abstract
Mesencephalic dopaminergic neurons were suggested to be a critical physiopathology substrate for addiction disorders. Among neuroadaptive processes to addictive drugs, structural plasticity has attracted attention. While structural plasticity occurs at both pre- and post-synaptic levels in the mesolimbic dopaminergic system, the present review focuses only on dopaminergic neurons. Exposures to addictive drugs determine two opposite structural responses, hypothrophic plasticity produced by opioids and cannabinoids (in particular during the early withdrawal phase) and hypertrophic plasticity, mostly driven by psychostimulants and nicotine. In vitro and in vivo studies identified BDNF and extracellular dopamine as two critical factors in determining structural plasticity, the two molecules sharing similar intracellular pathways involved in cell soma and dendrite growth, the MEK-ERK1/2 and the PI3K-Akt-mTOR, via preferential activation of TrkB and dopamine D3 receptors, respectively. At present information regarding specific structural changes associated to the various stages of the addiction cycle is incomplete. Encouraging neuroimaging data in humans indirectly support the preclinical evidence of hypotrophic and hypertrophic effects, suggesting a possible differential engagement of dopamine neurons in parallel and partially converging circuits controlling motivation, stress, and emotions.
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Affiliation(s)
- Ginetta Collo
- Department of Molecular and Translational Medicine, University of Brescia Brescia, Italy
| | - Laura Cavalleri
- Department of Molecular and Translational Medicine, University of Brescia Brescia, Italy
| | - PierFranco Spano
- Department of Molecular and Translational Medicine, University of Brescia Brescia, Italy
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131
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Covey DP, Wenzel JM, Cheer JF. Cannabinoid modulation of drug reward and the implications of marijuana legalization. Brain Res 2014; 1628:233-43. [PMID: 25463025 DOI: 10.1016/j.brainres.2014.11.034] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 11/11/2014] [Accepted: 11/15/2014] [Indexed: 10/24/2022]
Abstract
Marijuana is the most popular illegal drug worldwide. Recent trends indicate that this may soon change; not due to decreased marijuana use, but to an amendment in marijuana's illegal status. The cannabinoid type 1 (CB1) receptor mediates marijuana's psychoactive and reinforcing properties. CB1 receptors are also part of the brain endocannabinoid (eCB) system and support numerous forms of learning and memory, including the conditioned reinforcing properties of cues predicting reward or punishment. This is accomplished via eCB-dependent alterations in mesolimbic dopamine function, which plays an obligatory role in reward learning and motivation. Presynaptic CB1 receptors control midbrain dopamine neuron activity and thereby shape phasic dopamine release in target regions, particularly the nucleus accumbens (NAc). By also regulating synaptic input to the NAc, CB1 receptors modulate NAc output onto downstream neurons of the basal ganglia motor circuit, and thereby support goal-directed behaviors. Abused drugs promote short- and long-term adaptations in eCB-regulation of mesolimbic dopamine function, and thereby hijack neural systems related to the pursuit of rewards to promote drug abuse. By pharmacologically targeting the CB1 receptors, marijuana has preferential access to this neuronal system and can potently alter eCB-dependent processing of reward-related stimuli. As marijuana legalization progresses, greater access to this drug should increase the utility of marijuana as a research tool to better understand the eCB system, which has the potential to advance cannabinoid-based treatments for drug addiction.
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Affiliation(s)
- Dan P Covey
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jennifer M Wenzel
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joseph F Cheer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA.
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132
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Dopamine challenge reveals neuroadaptive changes in marijuana abusers. Proc Natl Acad Sci U S A 2014; 111:11915-6. [PMID: 25114244 DOI: 10.1073/pnas.1412314111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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