The main active ingredient in cannabis, delta-9-tetrahydrocannabinol (THC), can acutely induce psychotic symptoms and impair episodic and working memory. Another major constituent, cannabidiol (CBD), may attenuate these effects. This study aimed to determine the effects of THC and CBD, both alone and in combination on psychotic symptoms and memory function. A randomised, double-blind crossover...
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...
Abstract Ayahuasca is a natural psychedelic brew, which contains dimethyltryptamine (DMT). Its potential as a psychiatric medicine has recently been demonstrated and its non-medical use around the world appears to be growing. We aimed to investigate well-being and problematic alcohol use in ayahuasca users, and ayahuasca’s subjective effects. An online, self-selecting, global survey examining...
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...
We present a review and analysis of the ethical considerations in off-label ketamine use for severe, treatment-resistant depression. The analysis of ethical considerations is contextualised in an overview of the evidence for ketamine use in depression, and a review of the drug's safety profile. We find that, based on current evidence, ketamine use for severe, treatment-resistant depression does...
BACKGROUND: Worldwide, alcohol abuse is a burgeoning problem. Abstinence is key to allow recovery of physical and mental health as well as quality of life, but treatment for alcohol dependence is associated with high relapse rates. Preliminary data have suggested that a combined repeated ketamine and psychological therapy programme may be effective in reducing relapse in severe alcohol use...
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...
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...
(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...
The MTLs appear to be specifically implicated in the mechanism of action of MDMA, but further work is required to elucidate how the drug's characteristic subjective effects arise from its modulation of spontaneous brain activity.
3,4-methylenedioxymethamphetamine (MDMA) is a potent monoamine-releaser that is widely used as a recreational drug. Preliminary work has supported the potential of MDMA in psychotherapy for post-traumatic stress disorder (PTSD). The neurobiological mechanisms underlying its putative efficacy are, however, poorly understood. Psychotherapy for PTSD usually requires that patients revisit traumatic...
Cannabis acutely increases schizotypy and chronic use is associated with elevated rates of psychosis. Creative individuals have higher levels of schizotypy, however links between cannabis use, schizotypy and creativity have not been investigated. We investigated the effects of cannabis smoked naturalistically on schizotypy and divergent thinking, a measure of creativity. One hundred and sixty...
Studies of the chronic effects of MDMA, or 'ecstasy', in humans have been largely inconsistent. We explored whether study-level characteristics are associated with the effect size estimate reported. We based our analyses on the recent systematic review by Rogers and colleagues, focusing on those meta-analyses within this report where there was a relatively large number of studies contributing...
Semantic deficits constitute a core cognitive abnormality in schizophrenia. In the current study, the N-methyl-d-aspartate receptor antagonist ketamine was administered to healthy individuals acutely while they performed semantic processing tasks that included word pairs of differing degrees of semantic relatedness. Two dimensions of semantic processing were investigated: (1) explicit versus...
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...
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...
'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...
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...
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...