Frontiers in Psychiatry
March 27, 2018
Ruth Braidwood, Samantha Mansell, Jon Waldron et al.
7 citations
Research suggests that daily cannabis users have impaired memory for past events, but it is not clear whether they are also impaired in prospective memory (PM) for future events. The present study examined prospective memory in daily cannabis users who were either dependent (n = 18) or non-dependent (n = 18), and compared them with non-using controls (n = 18). The effect of future event...
Psychopharmacology
November 2017
Chandni Hindocha, Will Lawn, Tom P. Freeman et al.
Cannabis and tobacco are often smoked simultaneously in joints, and this practice may increase the risks of developing tobacco and/or cannabis use disorders. Currently, there is no human experimental research on how these drugs interact on addiction-related measures. This study aimed to investigate how cannabis and tobacco, each alone and combined together in joints, affected individuals'...
Scientific Reports
October 13, 2017
Robin Carhart-Harris, Leor Roseman, Mark Bolstridge et al.
590 citations
Psilocybin with psychological support is showing promise as a treatment model in psychiatry but its therapeutic mechanisms are poorly understood. Here, cerebral blood flow (CBF) and blood oxygen-level dependent (BOLD) resting-state functional connectivity (RSFC) were measured with functional magnetic resonance imaging (fMRI) before and after treatment with psilocybin (serotonin agonist) for...
The International Journal of Neuropsychopharmacology
August 30, 2017
Tom P. Freeman, Rebecca Pope, Matthew B. Wall et al.
67 citations
Background: Despite the current shift towards permissive cannabis policies, few studies have investigated the pleasurable effects users seek. Here, we investigate the effects of cannabis on listening to music, a rewarding activity that frequently occurs in the context of recreational cannabis use. We additionally tested how these effects are influenced by cannabidiol, which may offset...
Psychological Medicine
May 30, 2017
Chandni Hindocha, Tom P. Freeman, Joanna Xia et al.
104 citations
BACKGROUND: Cannabis and tobacco have contrasting cognitive effects. Smoking cannabis with tobacco is prevalent in many countries and although this may well influence cognitive and mental health outcomes, the possibility has rarely been investigated in human experimental psychopharmacological research. METHOD: The individual and interactive effects of cannabis and tobacco were evaluated in 24...
Cannabis and Cannabinoid Research
2017
Chandni Hindocha, Tom P. Freeman, Helen Valerie Curran
42 citations
Abstract Introduction: Major gaps exist in the measurement of cannabis exposure. The accuracy of self-reported cannabis and tobacco dose per joint is poorly characterized and has never been investigated following acute cannabis/tobacco exposure. Using an innovative “Roll a Joint” paradigm, this study aims to (1) compare estimated and actual dose of cannabis and tobacco per joint at baseline and...
Translational Psychiatry
November 29, 2016
Claire Mokrysz, Tom P. Freeman, Saana M. Korkki et al.
111 citations
Preclinical research demonstrates that cannabinoids have differing effects in adolescent and adult animals. Whether these findings translate to humans has not yet been investigated. Here we believe we conducted the first study to compare the acute effects of cannabis in human adolescent (n=20; 16-17 years old) and adult (n=20; 24-28 years old) male cannabis users, in a placebo-controlled,...
Psychopharmacology
September 2, 2016
Will Lawn, Tom P. Freeman, Rebecca Pope et al.
177 citations
RATIONALE: Anecdotally, both acute and chronic cannabis use have been associated with apathy, amotivation, and other reward processing deficits. To date, empirical support for these effects is limited, and no previous studies have assessed both acute effects of Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), as well as associations with cannabis dependence. OBJECTIVES: The objectives of...
Proceedings of the National Academy of Sciences
April 11, 2016
Robin Carhart-Harris, Suresh Muthukumaraswamy, Leor Roseman et al.
887 citations
Lysergic acid diethylamide (LSD) is the prototypical psychedelic drug, but its effects on the human brain have never been studied before with modern neuroimaging. Here, three complementary neuroimaging techniques: arterial spin labeling (ASL), blood oxygen level-dependent (BOLD) measures, and magnetoencephalography (MEG), implemented during resting state conditions, revealed marked changes in...
Journal of Psychopharmacology
May 18, 2015
Sunjeev K. Kamboj, Emma J. Kilford, Stephanie Minchin et al.
43 citations
3,4-methylenedioxy- N-methylamphetamine (MDMA) produces diverse pro-social effects. Cognitive training methods rooted in Eastern contemplative practices also produce these effects through the development of a compassionate mindset. Given this similarity, we propose that one potential mechanism of action of MDMA in psychotherapy is through enhancing effects on intrapersonal attitudes (i.e....
European Neuropsychopharmacology
March 2015
Chandni Hindocha, Tom P. Freeman, Gráinne Schäfer et al.
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...
Addiction
October 2014
Tom P. Freeman, Celia J. A. Morgan, Chandni Hindocha et al.
(1) To determine whether measured concentrations of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) in individuals' own cannabis predict their estimates of drug potency and actual titration; and (2) to ascertain if these effects are influenced by frequency of use and cannabis type. Cross-sectional, naturalistic. Participants' own homes. A total of 247 cannabis users in the United...
Journal of Psychopharmacology
August 13, 2014
LH Stewart, Bart Ferguson, CJA Morgan et al.
28 citations
BACKGROUND: Acute recreational use of 3,4-methylenedioxymethamphetamine (MDMA; 'ecstasy') can promote pro-social effects which may alter interpersonal perceptions. AIMS: To explore such effects, this study investigated whether acute recreational use of ecstasy was associated with changes in individual perception of trustworthiness of people's faces and co-operative behaviours. METHOD: An...
Addiction
July 21, 2011
Celia J. A. Morgan, Helen Valerie Curran
645 citations
AIMS: Ketamine remains an important medicine in both specialist anaesthesia and aspects of pain management. At the same time, its use as a recreational drug has spread in many parts of the world during the past few years. There are now increasing concerns about the harmful physical and psychological consequences of repeated misuse of this drug. The aim of this review was to survey and integrate...
Neuropsychopharmacology
March 2011
Yen F Tai, Rosa Hoshi, Catherine M Brignell et al.
Ecstasy (±3,4-methylenedioxymethamphetamine, MDMA) is a popular recreational drug with known serotonergic neurotoxicity. Its long-term effects on dopaminergic function are less certain. Studying the long-term effects of ecstasy is often confounded by concomitant polydrug use and the short duration of abstinence. We used (18)F-dopa positron emission tomography (PET) to investigate the long-term...
The British Journal of Psychiatry
October 2010
Celia J. A. Morgan, Gráinne Schäfer, Tom P. Freeman et al.
The two main constituents of cannabis, cannabidiol and Δ(9)-tetrahydrocannabinol (THC), have opposing effects both pharmacologically and behaviourally when administered in the laboratory. Street cannabis is known to contain varying levels of each cannabinoid. To study how the varying levels of cannabidiol and THC have an impact on the acute effects of the drug in naturalistic settings. Cannabis...
Neuropsychopharmacology
August 2010
Celia J A Morgan, Tom P. Freeman, Gráinne Schäfer et al.
Worldwide cannabis dependence is increasing, as is the concentration of Delta(9)-tetrahydrocannabinol (THC) in street cannabis. At the same time, the concentration of the second most abundant cannabinoid in street cannabis, cannabidiol (CBD), is decreasing. These two cannabinoids have opposing effects both pharmacologically and behaviorally when administered in the laboratory. No research has...
Addiction
January 2010
Celia J. A. Morgan, Leslie Muetzelfeldt, Helen Valerie Curran
'Recreational' use of ketamine is spreading rapidly among young people. In healthy individuals an acute dose of the N-methyl D-aspartate (NMDA) receptor antagonist ketamine induces marked psychosis-like effects and cognitive impairments, but little is known about the long-term effects of the drug. To evaluate the long-term neuropsychiatric or cognitive consequences. A total of 150 individuals...
Journal of Psychopharmacology
November 25, 2009
Celia J. A. Morgan, Leslie Muetzelfeldt, Mark Muetzelfeldt et al.
80 citations
Nutt and colleagues' 'rational' scale to assess the harms of commonly used drugs was based on ratings by a panel of experts. This survey aimed to assess drug users' views of the harms of drugs using the same scale. As users' drug choices are not solely based on harms, we additionally assessed perceived benefits. The survey was hosted at http://www.nationaldrugsurvey.org. UK residents reported...
Psychopharmacology
March 1, 2009
Mark Blagrove, Celia J. A. Morgan, Helen Valerie Curran et al.
Ketamine is an N-methyl-D: -aspartate (NMDA) receptor antagonist with psychotogenic effects and for which there are diverse reports of whether pleasant or unpleasant dreams result during anaesthesia, post-operatively or after sub-anaesthetic use. To assess in healthy volunteers the incidence of unpleasant dreams over the three nights after receiving a sub-anaesthetic dose of ketamine, in...
Schizophrenia Research
August 2008
Oliver J Mason, Celia J M Morgan, Ana Stefanovic et al.
This study reports a new measure of psychotomimetic states in the context of cannabis and ketamine use. The Psychotomimetic States Inventory (PSI) has sub-scales of Delusory Thinking, Perceptual Distortions, Cognitive Disorganization, Anhedonia, Mania and Paranoia. The PSI was administered in two independent group, repeated measures designs: an experimental study of ketamine and a naturalistic...
Psychopharmacology
October 2007
Rosa Hoshi, Kate Mullins, Catherine Boundy et al.
Despite years of research and much controversy surrounding the effects of ecstasy use, findings are equivocal. Attempting to reduce methodological problems, such as concurrent use of other recreational drugs, could lead to a clearer picture of the effects of ecstasy use on cognitive function. The aim of this study is to investigate the effects of both prolonged abstention from ecstasy use and...
Experimental and Clinical Psychopharmacology
August 2007
Rosa Hoshi, Lisa Cohen, Lucy Lemanski et al.
+/-3, 4-methylenedioxymethamphetamine (MDMA or ecstasy) remains a widely used recreational drug, which, in animals, can produce long-lasting changes to the brain's serotonergic system. As serotonin has been implicated in human aggression, it is possible that ecstasy users are at risk of increased aggression even after prolonged abstention from the drug. The objective of this study was to...
Journal of Psychopharmacology
March 2006
Rosa Hoshi, Hannah Pratt, Sachin Mehta et al.
The lowering of serotonin for a period following MDMA use could account for the increases in both self-rated and objective measures of aggression previously found in ecstasy users several days after taking the drug. There is some evidence of gender differences in the acute, sub-acute and long-term effects of MDMA use, and given that gender differences have been found in aggression, it is...
Human Psychopharmacology: Clinical and Experimental
October 1, 2003
Suzanne L. Verheyden, John A. Henry, Helen Valerie Curran
171 citations
Abstract This study examined the reported psychological effects of different patterns of MDMA use in men and women, and how they are modified by use of other psychoactive substances. A semi‐structured interview was conducted with 466 regular MDMA users, exploring the perceived acute, sub‐acute and long‐term subjective effects of this drug. Factor analysis established three main categories of...