International Journal of Drug Policy
August 1, 2026
Myfanwy Graham, Yimin Ge, Rosalie Liccardo Pacula et al.
1 citation
We know little about the extent psychedelic substances are consumed therapeutically and/or discussed with medical professionals despite renewed global interest in these substances. We examined self-reported responses from the 2023 International Cannabis Policy Study (ICPS) in repeated cross-sectional surveys in Canada, the United States, Australia, and New Zealand. The survey included questions...
Addiction
March 2026
Jack Chung, Daniel Stjepanović, Brandon Cheng et al.
Cannabis use is associated with psychiatric comorbidities, and the use of elta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) produces different neurophysiological and pharmacological effects. This study estimated the strength of associations between vaping of THC and CBD with depressive and anxiety symptoms in adolescents. Observational data were drawn from three years of the nationally...
Annual Review of Psychology
August 2, 2024
Keith Humphreys, Daniel Stjepanović, Wayne Hall et al.
18 citations
Therapeutic claims about many psychedelic drugs have not been evaluated in any studies of even modest rigor. The science of psychedelic drugs is strengthening, however, making it easier to differentiate some promising findings amid the hype that suffuses this research area. Ketamine has risks of adverse side effects (e.g., addiction and cystitis), but multiple studies suggest it can benefit...
Addiction
June 6, 2024
Wayne Hall, Keith Humphreys, John Marsden et al.
18 citations
Abstract The turn of the century brought a resurgence of interest in psychedelics as a treatment for addiction and other psychiatric conditions, accompanied by extensive positive media attention and private equity investment. Government regulatory bodies in Australia, Israel, Canada and the United States now permit use of psychedelics for medical purposes. In the United States, citizen action...
Addiction
May 21, 2024
Shane Darke, Johan Duflou, Amy Peacock et al.
14 citations
Abstract Background and aims Lysergic acid diethylamide (LSD) and psilocybin are used as recreational drugs, and there is renewed interest in their clinical use. The current study aimed to (1) determine the circumstances of death and case characteristics of LSD‐ and psilocybin‐related death in Australia, 2000–23; and (2) determine the toxicological profile and major autopsy findings of these...
Frontiers in Psychiatry
January 9, 2023
Wayne Hall
Appraisals of the evidence on the relationship between cannabis use and psychosis are often biased by appraisers' pre-existing views on whether adult cannabis use should or should not be legal. This viewpoint gives examples of such policy-biased appraisals and suggests strategies for avoiding them.
Psychological Medicine
October 1, 2022
Wayne Hall, Keith Humphreys
18 citations
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Psychological Medicine
March 24, 2022
Tessa Robinson, Muhammad Usman Ali, Bethany Easterbrook et al.
61 citations
BACKGROUND: Epidemiological studies show a dose-response association between cannabis use and the risk of psychosis. This review aimed to determine whether there are identifiable risk-thresholds between the frequency of cannabis use and psychosis development. METHODS: Systematic search of Embase, MEDLINE, PsycINFO, CINAHL, and Web of Science for relevant studies (1 January 2010-26 April 2021)....
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...
Psychological Medicine
2022
Wayne Hall
Advocates of the therapeutic use of psychedelic drugs have argued that a promising approach to treatment was prematurely abandoned in the 1960s primarily because of Richard Nixon's 'War on Drugs'.This paper (1) briefly describes research in the 1950s and 1960s in North America on the use of LSD to treat alcohol dependence, anxiety in terminal illness, and anxiety and depression; and (2)...
Addictive Behaviors
December 1, 2021
G. Chan, Tianze Sun, Carmen C. W. Lim et al.
AIM To test the age, cohort, and period effect on past-year use trends in psychedelic drugs and ecstasy. METHOD Data were from a repeated cross-sectional nationally representative household survey in Australia conducted every three years between 2001 and 2019. An age-period-cohort model was used to test the effect of age, birth cohort, and period on past year psychedelic and ecstasy use....
Addiction
October 11, 2021
Wayne Hall, Michael Farrell
Aldous Huxley's personal account of his experience taking mescaline in The Doors of Perception (1954) has influenced popular understandings of the effects of psychedelic drugs and encouraged many personal experiences with these drugs. Huxley encouraged the psychiatrist Humphry Osmond to coin the term 'psychedelic'. He knew many of the leading figures in early psychedelic research and advocated...
Addiction
August 12, 2021
Wayne Hall, Michael Farrell
8 citations
The history of research on the use of psychedelic drugs to treat alcohol dependence in the 1950s and 1960s suggests the need for caution in their proposed clinical use. Since 2006 there has been a revival of interest in using psychedelics to treat depression and post-traumatic stress disorders [1] and the addictions [2]. What lessons may we glean from research in the 1950s and 1960s on the use...
World Psychiatry
May 18, 2021
Wayne Hall
17 citations
A psychedelic drug is one that “produces thought, mood and perceptual changes otherwise rarely experienced except in dreams, contemplative and religious exaltation, flashes of vivid involuntary memory, and acute psychosis”1. It does so “without causing physical addiction, craving, major physiological disturbances, delirium, disorientation or amnesia”1. The “classic psychedelics” include...
PLoS Medicine
September 28, 2009
Louisa Degenhardt, Wayne Hall, Michael T. Lynskey et al.
48 citations
N Comparative risk assessments estimate the proportion of a disease that can be attributed to a particular risk exposure and are important guides for health planning.N In observational studies, there has been consistent evidence that cannabis use is associated with an increased risk of schizophrenia and more generally, psychosis.N There is debate about whether such observational evidence is...
World Psychiatry
2008
Wayne Hall, Louisa Degenhardt
WE BRIEFLY REVIEW THE EVIDENCE THAT CANNABIS USE IN ADOLESCENCE AND YOUNG ADULTHOOD IS A CONTRIBUTORY CAUSE OF SCHIZOPHRENIFORM PSYCHOSES, BY SUMMARISING LONGITUDINAL STUDIES THAT: a) have examined relationships between cannabis use and the risk of psychosis or psychotic symptoms; and b) have controlled for potential confounders, such as other forms of drug use and personal characteristics that...
Psychological Medicine
July 1, 2007
Louisa Degenhardt, Chris Tennant, Stuart Gilmour et al.
The aim was to examine the temporal relationships over 10 months between cannabis use and symptoms of psychosis and depression in people with schizophrenia and related disorders. The design was a prospective study of 101 patients with schizophrenia and related disorders who were assessed monthly over 10 months on medication compliance, cannabis and other drug use, symptoms of depression and...
The Canadian Journal of Psychiatry
August 1, 2006
Wayne Hall, Louisa Degenhardt
Objective: To explore the implications for mental health services, for health education about the risks of cannabis use, and for public policy toward cannabis use of observational evidence that cannabis use is a contributory cause of psychosis. Method: Using comparative analyses of similar evidence for the harmful effects of alcohol, tobacco, and amphetamine use, we considered the relation...
The Canadian Journal of Psychiatry
August 1, 2006
Louisa Degenhardt, Wayne Hall
Objective: To assess whether cannabis use in adolescence and young adulthood is a contributory cause of schizophreniform psychosis in that it may precipitate psychosis in vulnerable individuals. Method: We reviewed longitudinal studies of adolescents and young adults that examined the relations between self-reported cannabis use and the risk of diagnosis with a psychosis or of reporting...
Drug and Alcohol Review
November 30, 2004
Wayne Hall, Louisa Degenhardt, Maree Teesson
105 citations
This paper evaluates three hypotheses about the relationship between cannabis use and psychosis in the light of recent evidence from prospective epidemiological studies. These are that: (1) cannabis use causes a psychotic disorder that would not have occurred in the absence of cannabis use; (2) that cannabis use may precipitate schizophrenia or exacerbate its symptoms; and (3) that cannabis use...
Cambridge University Press eBooks
May 27, 2004
Wayne Hall, Louisa Degenhardt
27 citations
There are good reasons to be concerned about the possibility that cannabis use may be a cause of psychotic disorders. Psychoses are serious and disabling disorders (Bromet et al. , 1995). Cannabis is widely used during late adolescence in many developed societies (Hall et al. , 1999), and high doses of tetrahydrocannabinol (THC) – the psychoactive substance in cannabis – have been reported to...
British Journal of Addiction
August 1, 1992
Nadia Solowij, Wayne Hall, Nicole Lee
417 citations
Abstract ‘Ecstasy’ (3,4‐methylenedioxymethampketamine or MDMA) is a recreational drug that is gaining popularity world wide. There is a paucity of research regarding the ways in which Ecstasy is used and the nature of its effects. A ‘snowball’ peer network technique was used to recruit 100 users who completed anonymous questionnaires. The research revealed that Ecstasy is primarily used by...