BJPsych Open
August 25, 2026
Edward Chesney, Millie Lloyd, Sébastien Brodeur et al.
BACKGROUND: Cannabis use is common in people with psychosis and is associated with poor outcomes. AIMS: To assess insight into cannabis use disorder, perceptions about how cannabis use influences mental health and the desire to change cannabis use among people with psychotic disorders. METHOD: Adults with a psychotic disorder and comorbid cannabis use disorder were asked about the impact of...
Neuroscience & Biobehavioral Reviews
June 3, 2026
Isabella Goodwin, Dominic Oliver, Edward Chesney et al.
Global shifts towards the liberalisation of cannabis policies have increased the potency of cannabis products, alongside their accessibility, diversity, and the number of inexperienced cannabis consumers. There is a lack of systematic evidence on the subjective effects of cannabis' main psychoactive compound, Δ9-tetrahydrocannabinol (THC). We systematically reviewed and meta-analysed data from...
Psychological Medicine
May 4, 2026
Kristine Rømer Thomsen, B. Thylstrup, Morten Hesse et al.
Abstract Background In recent decades, the potency of cannabis resin increased globally, raising concerns, as higher potency has been associated with increased risk of psychiatric harms at the individual level. The aim here was to examine whether changes over time in the potency of seized cannabis resin samples were associated with psychiatric harms at the population level. Methods Data on...
Neuropsychopharmacology
November 2025
Edward Chesney, Dominic Oliver, Ananya Sarma et al.
In patients with schizophrenia, cannabis use exacerbates symptoms and can lead to a relapse of psychosis. Some experimental studies in healthy volunteers suggest that pre-treatment with cannabidiol (CBD) may reduce these effects, but others do not. Here, we investigated whether pre-treatment with CBD ameliorates the acute adverse effects of cannabis in patients with schizophrenia. Participants...
Addiction
February 2024
Dominic Oliver, Amir Englund, Edward Chesney et al.
To test how attentional bias and explicit liking are influenced by delta-9-tetrahydrocannabinol (THC) and whether these effects are moderated by cannabidiol (CBD). Double-blind, randomised, within-subjects cross-over study. NIHR Wellcome Trust Clinical Research Facility at King's College Hospital, London, United Kingdom. Forty-six infrequent cannabis users (cannabis use <1 per week). Across...
Frontiers in Psychiatry
2024
Xinyi Liang, Maria-Mihaela Avram, Toni Gibbs-Dean et al.
Cannabis users present an important group for investigating putative mechanisms underlying psychosis, as cannabis-use is associated with an increased risk of psychosis. Recent work suggests that alterations in belief-updating under uncertainty underlie psychosis. We therefore compared belief updating under uncertainty between cannabis and non-cannabis users. 49 regular cannabis users and 52...
Addiction
February 8, 2023
Will Lawn, Katie Trinci, Claire Mokrysz et al.
36 citations
Abstract Background and Aims Long‐term harms of cannabis may be exacerbated in adolescence, but little is known about the acute effects of cannabis in adolescents. We aimed to (i) compare the acute effects of cannabis in adolescent and adult cannabis users and (ii) determine if cannabidiol (CBD) acutely modulates the effects of delta‐9‐tetrahydocannabinol (THC). Design Randomised, double‐blind,...
Cannabis and Cannabinoid Research
December 9, 2022
Lucy Chester, Amir Englund, Edward Chesney et al.
20 citations
Background: The effects of cannabis are thought to be mediated by interactions between its constituents and the endocannabinoid system. Delta-9-tetrahydrocannabinol (THC) binds to central cannabinoid receptors, while cannabidiol (CBD) may influence endocannabinoid function without directly acting on cannabinoid receptors. We examined the effects of THC coadministered with different doses of CBD...
Neuropsychopharmacology
November 16, 2022
Amir Englund, D. Oliver, Edward Chesney et al.
As countries adopt more permissive cannabis policies, it is increasingly important to identify strategies that can reduce the harmful effects of cannabis use. This study aimed to determine if increasing the CBD content of cannabis can reduce its harmful effects. Forty-six healthy, infrequent cannabis users participated in a double-blind, within-subject, randomised trial of cannabis preparations...
The Lancet Psychiatry
August 2017
Amir Englund, Tom P. Freeman, Robin Murray et al.
Cannabis use and related problems are on the rise globally alongside an increase in the potency of cannabis sold on both black and legal markets. Additionally, there has been a shift towards abandoning prohibition for a less punitive and more permissive legal stance on cannabis, such as decriminalisation and legalisation. It is therefore crucial that we explore new and innovative ways to reduce...
World Psychiatry
September 22, 2016
Robin Murray, Harriet Quigley, Diego Quattrone et al.
319 citations
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...
Journal of Psychopharmacology
October 5, 2012
Amir Englund, Paul D. Morrison, Judith Nottage et al.
463 citations
Community-based studies suggest that cannabis products that are high in Δ⁹-tetrahydrocannabinol (THC) but low in cannabidiol (CBD) are particularly hazardous for mental health. Laboratory-based studies are ideal for clarifying this issue because THC and CBD can be administered in pure form, under controlled conditions. In a between-subjects design, we tested the hypothesis that pre-treatment...