The effects of Δ9-tetrahydrocannabinol on the dopamine system Michael A P Bloomfield, Abhishekh H Ashok, Nora D Volkow, and Oliver D Howes Nature, 2016, 539, 7629, 369–377. doi : 10.1038/nature20153. Preface Δ9-tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis, is a pressing concern to global mental health. Patterns of use are changing drastically due to legalisation, availability of synthetic analogues (‘spice’), cannavaping and aggrandizements in the purported therapeutic effects of cannabis. Many of THC’s reinforcing effects are mediated by the dopamine system. Due to complex cannabinoid-dopamine interactions there is conflicting evidence from human and animal research fields. Acute THC causes increased dopamine release and neuron [...]
Lire la suiteDescriptive Psychopathology of the Acute Effects of Intravenous Delta-9-Tetrahydrocannabinol Administration in Humans Marco Colizzi, NathalieWeltens, Philip McGuire, Lukas Van Oudenhove and Sagnik Bhattacharyya Brain Sciences, 2019, 9, 93 doi : 10.3390/brainsci9040093 Abstract : Background : Cannabis use can increase the risk of psychosis, and the acute administration of its key psychoactive ingredient, delta-9-tetrahydrocannabinol (D9-THC), can induce transient psychotomimetic symptoms. Methods : A double-blind, randomized, placebo-controlled crossover design was used to investigate the symptomatic effects of acute intravenous administration of D9-THC (1.19 mg/2 mL) in 16 healthy participants (seven males) with modest previous cannabis exposure. Results : In the 20 min following acute D9-THC administration, symptomatic effects of [...]
Lire la suiteDoes Cannabis Composition Matter? Differential Effects of Delta-9-tetrahydrocannabinol and Cannabidiol on Human Cognition Marco Colizzi & Sagnik Bhattacharyya Current Addiction Reports, 2017, 4, 62–74 DOI 10.1007/s40429-017-0142-2 Abstract Purpose of Review : The lack of clarity about the effect of cannabis use on cognition may be attributable to the considerable heterogeneity among studies in terms of cannabis composition. This article selectively reviews studies examining the distinctive effects of cannabinoids on human cognition, particularly those of delta-9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD). Recent Findings : Research indicates that Δ9-THC administration acutely impairs cognition, particularly memory and emotional processing. Limited evidence suggests that CBD administration might improve cognition in cannabis [...]
Lire la suiteSchizotypy and psychosis-like experiences from recreational cannabis in a non-clinical sample Emma Barkus, Shon Lewis Psychological Medicine, 2008, 38, 1267-1276. doi:10.1017/S0033291707002619 Research On Line, University of Wollongong, 2008 Copyright Cambridge University Press. Abstract Background : The relationship between cannabis use and psychosis is still a matter for debate. Accounting for the individual differences in subjective experiences to recreational cannabis use in the general population may hold some clues to the aetiological relationship between cannabis and psychotic symptoms. We hypothesized that schizotypy would account for the individual differences in subjective experiences after cannabis use but not in patterns of use. Method : In a sample of 532 young people [...]
Lire la suiteCannabis-induced psychosis-like experiences are associated with high schizotypy BARKUS E.J., STIRLING J., HOPKINS R.S., LEWIS S. Psychopathology, 2006, 39, 4, 175-178 PMID : 16636640 DOI : 10.1159/000092678 Abstract OBJECTIVE: Recent studies have suggested that cannabis use is a risk factor for developing schizophrenia. We tested the hypothesis that cannabis use increases the likelihood of psychosis-like experiences in non-clinical participants who scored highly on a measure of schizotypy. METHOD: The psychological effects of cannabis were assessed in 137 healthy individuals (76% female, mean age 22 years) using a newly developed questionnaire concerned with subjective experiences of the drug: the Cannabis Experiences Questionnaire. The questionnaire has three subscales: Pleasurable [...]
Lire la suiteEffects of delta-9-tetrahydrocannabinol on evaluation of emotional images Michael E Ballard, Gillinder Bedi, and Harriet de Wit Journal of Psychopharmacology, 2012, 26, 10, 1289–1298. doi:10.1177/0269881112446530. Abstract There is growing evidence that drugs of abuse alter processing of emotional information in ways that could be attractive to users. Our recent report that Δ9-tetrahydrocannabinol (THC) diminishes amygdalar activation in response to threat-related faces suggests that THC may modify evaluation of emotionally-salient, particularly negative or threatening, stimuli. In this study, we examined the effects of acute THC on evaluation of emotional images. Healthy volunteers received two doses of THC (7.5 and 15 mg; p.o.) and placebo across separate [...]
Lire la suiteAcute effects of delta-9-tetrahydrocannabinol, cannabidiol and their combination on facial emotion recognition: A randomised, double-blind, placebo-controlled study in cannabis users Chandni Hindocha, Tom P. Freeman, Grainne Schafer, Chelsea Gardener, Ravi K. Das, Celia J.A. Morgan and H. Valerie Curran Eur Neuropsychopharmacology, 2015, 25, 3, 325–334. doi:10.1016/j.euroneuro.2014.11.014 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4398332/?report=printable Abstract Acute administration of the primary psychoactive constituent of cannabis, Δ-9-tetrahydrocannabinol (THC), impairs human facial affect recognition, implicating the endocannabinoid system in emotional processing. Another main constituent of cannabis, cannabidiol (CBD), has seemingly opposite functional effects on the brain. This study aimed to determine the effects of THC and CBD, both alone and in combination on emotional facial affect [...]
Lire la suiteClinical and Preclinical Evidence for Functional Interactions of Cannabidiol and Δ9-Tetrahydrocannabinol Douglas L. Boggs, Jacques D. Nguyen, Daralyn Morgenson, Michael A. Taffe and and Mohini Ranganathan Neuropsychopharmacology, 2018, 43, 142-154 Doi : 10.1038/npp.2017.209; published online 18 October 2017 Abstract The plant Cannabis sativa, commonly called cannabis or marijuana, has been used for its psychotropic and mind-altering side effects for millennia. There has been growing attention in recent years on its potential therapeutic efficacy as municipalities and legislative bodies in the United States, Canada, and other countries grapple with enacting policy to facilitate the use of cannabis or its constituents for medical purposes. There are >550 [...]
Lire la suiteOpposite Effects of Δ-9-Tetrahydrocannabinol and Cannabidiol on Human Brain Function and Psychopathology Sagnik Bhattacharyya, Paul D Morrison,
Lire la suiteWhich biological and self-report measures of cannabis use predict cannabis dependency and acute psychotic-like effects ? H. Valerie Curran, Chandni Hindocha, Celia J. A. Morgan, Natacha Shaban, Ravi K. Das and Tom P. Freeman Psychological Medicine, 2018, 1-7. https://doi.org/10.1017/S003329171800226X Abstract Background : Changes in cannabis regulation globally make it increasingly important to determine what predicts an individual’s risk of experiencing adverse drug effects. Relevant studies have used diverse self-report measures of cannabis use, and few include multiple biological measures. Here we aimed to determine which biological and self-report measures of cannabis use predict cannabis dependency and acute psychotic-like symptoms. Method : In a naturalistic study, 410 [...]
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