The International Journal of Neuropsychopharmacology
September 9, 2026
Marta Di Forti, Isabelle Austin-Zimmerman, Edoardo Spinazzola et al.
Abstract Background Epidemiological data have consistently shown an association between heavy cannabis use and increased risk of psychotic disorders. Nevertheless, not all cannabis users develop the illness. Evidence from other substance of abuse such as Alcohol suggest how genetic differences in enzymes involved in its metabolism influence individual response to the drug. No studies to data...
Frontiers in Psychiatry
July 21, 2026
Kenneth P. Finn, Robin Murray, Elizabeth Stuyt et al.
Cannabis is one of the most widely used psychoactive substances, with higher use rates in countries that have implemented policies to legalize medical or recreational use. Following the development of cannabis products with concentrations well above 10% THC (high potency, delta-9 tetrahydrocannabinol), the number of psychosis cases has also increased. Cannabis-attributable psychosis cases...
Biological Psychiatry Global Open Science
May 13, 2026
Isabelle Austin-Zimmerman, Qiang Li, E. Johnson et al.
Background Cannabis use is associated with increased risk of psychotic disorders, but the underlying biological mechanisms remain unclear. We used genetic data to investigate the molecular pathways contributing to the association between cannabis use disorder (CUD) and psychosis. Methods We conducted a cross-disorder meta-analysis of genome-wide association studies (GWASs) on schizophrenia and...
Neuropsychiatrie
August 20, 2025
Robin Murray, Alessandra Paparelli, Marta Di Forti et al.
4 citations
Recreational use of psychotogenic drugs has become more common in the last 30 years with consequent increase in drug-induced psychosis; 25-50% of such psychoses progress to schizophrenia within 5 years. Most cases result from abuse of methamphetamine or cannabis. The spread of methamphetamine psychosis has occurred without any liberalisation of laws; it is highly addictive and easy to make in...
Psychological Medicine
August 8, 2025
Giulia Trotta, Edoardo Spinazzola, Hannah Degen et al.
4 citations
Childhood trauma is a well-established risk factor for psychosis, paranoia, and substance use, with cannabis being a modifiable environmental factor that exacerbates these vulnerabilities. This study examines the interplay between childhood trauma, cannabis use, and paranoia using standard tetrahydrocannabinol (THC) units as a comprehensive measure of cannabis exposure. Data were derived from...
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...
Cambridge University Press eBooks
May 12, 2023
Edoardo Spinazzola, Marta Di Forti, Robin Murray
The fact that not all cannabis users will develop psychosis suggests that cannabis may exert its causal role only in pre-disposed individuals. However, since the number of people who use cannabis worldwide is so high, those who will eventually develop psychosis, whilst still a minority, represent a large number. The evidence indicates that different patterns of cannabis use have a different...
Psychological Medicine
May 4, 2023
Giulia Trotta, Victoria Rodriguez, Diego Quattrone et al.
Abstract Background Childhood adversity and cannabis use are considered independent risk factors for psychosis, but whether different patterns of cannabis use may be acting as mediator between adversity and psychotic disorders has not yet been explored. The aim of this study is to examine whether cannabis use mediates the relationship between childhood adversity and psychosis. Methods Data were...
Psychological Medicine
May 2, 2023
Edoardo Spinazzola, Diego Quattrone, Victoria Rodriguez et al.
Abstract Background While cannabis use is a well-established risk factor for psychosis, little is known about any association between reasons for first using cannabis (RFUC) and later patterns of use and risk of psychosis. Methods We used data from 11 sites of the multicentre European Gene-Environment Interaction (EU-GEI) case–control study. 558 first-episode psychosis patients (FEPp) and 567...
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 Canadian Journal of Psychiatry
August 1, 2022
Russell C. Callaghan, Marcos Sanches, Robin Murray et al.
Objective Cannabis legalization in many jurisdictions worldwide has raised concerns that such legislation might increase the burden of transient and persistent psychotic illnesses in society. Our study aimed to address this issue. Methods Drawing upon emergency department (ED) presentations aggregated across Alberta and Ontario, Canada records (April 1, 2015–December 31, 2019), we employed...
The World Journal of Biological Psychiatry
March 22, 2022
Deepak C. D’Souza, Marta DiForti, Suhas Ganesh et al.
Abstract Objectives The liberalisation of cannabis laws, the increasing availability and potency of cannabis has renewed concern about the risk of psychosis with cannabis. Methods The objective of the WFSBP task force was to review the literature about this relationship. Results Converging lines of evidence suggest that exposure to cannabis increases the risk for psychoses ranging from...
Translational Psychiatry
August 10, 2021
Diego Quattrone, Ulrich Reininghaus, Anne Richards et al.
Diagnostic categories do not completely reflect the heterogeneous expression of psychosis. Using data from the EU-GEI study, we evaluated the impact of schizophrenia polygenic risk score (SZ-PRS) and patterns of cannabis use on the transdiagnostic expression of psychosis. We analysed first-episode psychosis patients (FEP) and controls, generating transdiagnostic dimensions of psychotic symptoms...
Dialogues in Clinical Neuroscience
September 2020
Paul D. Morrison, Robin Murray
Cannabis can elicit an acute psychotic reaction, and its long-term use is a risk factor for schizophrenia. The main active psychoactive ingredient ∆9-tetrahydrocannabinol (Δ9-THC) activates cannabinoid 1 (CB1) receptors, which are localized to the terminals of glutamate and GABA neurons in the brain. The endogenous cannabinoids are involved in information processing and plasticity at synapses...
Psychological Medicine
March 18, 2020
Diego Quattrone, Laura Ferraro, Giada Tripoli et al.
89 citations
Abstract Background Daily use of high-potency cannabis has been reported to carry a high risk for developing a psychotic disorder. However, the evidence is mixed on whether any pattern of cannabis use is associated with a particular symptomatology in first-episode psychosis (FEP) patients. Method We analysed data from 901 FEP patients and 1235 controls recruited across six countries, as part of...
Schizophrenia Bulletin
July 2, 2019
Laura Ferraro, Caterina la Cascia, Diego Quattrone et al.
25 citations
Psychotic patients with a lifetime history of cannabis use generally show better cognitive functioning than other psychotic patients. Some authors suggest that cannabis-using patients may have been less cognitively impaired and less socially withdrawn in their premorbid life. Using a dataset comprising 948 patients with first-episode psychosis (FEP) and 1313 population controls across 6...
The Lancet Psychiatry
May 1, 2019
Marta Di Forti, Diego Quattrone, Tom P. Freeman et al.
Summary Background Cannabis use is associated with increased risk of later psychotic disorder but whether it affects incidence of the disorder remains unclear. We aimed to identify patterns of cannabis use with the strongest effect on odds of psychotic disorder across Europe and explore whether differences in such patterns contribute to variations in the incidence rates of psychotic disorder....
bioRxiv (Cold Spring Harbor Laboratory)
March 16, 2019
Diego Quattrone, Laura Ferraro, Giada Tripoli et al.
3 citations
preprint
Abstract Objective The evidence is mixed on whether cannabis use is associated with a particular symptomatology in first episode psychosis (FEP) patients. The authors set out to investigate a) patterns of association between cannabis use and transdiagnostic symptom dimensions; b) whether the extent of use of cannabis contributes to the variation in clinical and subclinical symptom profiles....
Schizophrenia Bulletin
August 6, 2018
Ulrich Reininghaus, Margaret Oorschot, Steffen Moritz et al.
33 citations
Cognitive models of psychosis posit that reasoning biases are an important mechanism contributing to the formation of psychotic symptoms, in part through transforming anomalous experiences of aberrant salience into frank psychotic symptoms. This study aimed to investigate the interplay of liberal acceptance (LA) bias, which is a specific type of reasoning bias, and momentary aberrant salience...
The British Journal of Psychiatry
April 1, 2018
Marco Colizzi, Robin Murray
Summary: It is now incontrovertible that heavy use of cannabis increases the risk of psychosis. There is a dose–response relationship and high potency preparations and synthetic cannabinoids carry the greatest risk. It would be wise to await the outcome of the different models of legalisation that are being introduced in North America, before deciding whether or not to follow suit. Declaration...
Schizophrenia Bulletin
April 1, 2018
Caterina la Cascia, L. Ferraro, Fabio Seminerio et al.
Abstract Background Patients presenting to psychiatric services with their first episode of psychosis (FEP) report higher rates of previous cannabis use than the general population (Donoghue et al., 2011; Myles, Myles and Large, 2016). Evidence suggested that patients suffering from psychosis with a history of cannabis use have an earlier age of onset of psychosis (AOP) than those who never...
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...
The Lancet Psychiatry
July 10, 2017
Tabea Schoeler, Natalia Petros, Marta Di Forti et al.
142 citations
Background Cannabis use following the onset of first-episode psychosis has been linked to both increased risk of relapse and non-adherence with antipsychotic medication. Whether poor outcome associated with cannabis use is mediated through an adverse effect of cannabis on medication adherence is unclear. Methods In a prospective analysis of data acquired from four different adult inpatient and...
Schizophrenia Bulletin
March 1, 2017
Robin Murray
Overall Abstract: Dr Marta Di Forti Cannabis use across Europe and its interaction with the polygenic risk score for schizophrenia. Dr Di Forti examined the pattern of cannabis use across 16 European sites as part of the EU-GEI study. She will show striking differences in incidence of psychosis (high in North and low in South), and how differences in pattern of cannabis use result in...