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Cannabis use and psychotic disorders: an update

Wayne Hall, Louisa Degenhardt, Maree Teesson

Drug and Alcohol Review November 30, 2004 DOI: 10.1080/09595230412331324554 (opens in new tab)

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AI-extracted from the abstract
Characteristics Review Peer reviewed
Topics Cannabis
Citations 105
Key findings Argues that cannabis use is unlikely to cause psychoses that would not have occurred otherwise, because schizophrenia incidence in Australia stayed stable while cannabis use increased over three decades. Contends that cannabis use more likely precipitates schizophrenia in vulnerable individuals, supported by four prospective studies in three countries linking more frequent use to higher risk of schizophrenia diagnosis or psychotic symptoms, and that it may also exacerbate existing psychosis.

Abstract

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 may exacerbate the symptoms of psychosis. There is limited support for the first hypothesis. As a consequence of recent prospective studies, there is now stronger support for the second hypothesis. Four recent prospective studies in three countries have found relationships between the frequency with which cannabis had been used and the risk of receiving a diagnosis of schizophrenia or of reporting psychotic symptoms. These relationships are stronger in people with a history of psychotic symptoms and they have persisted after adjustment for potentially confounding variables. The absence of any change in the incidence of schizophrenia during the three decades in which cannabis use in Australia has increased makes it unlikely that cannabis use can produce psychoses that would not have occurred in its absence. It seems more likely that cannabis use can precipitate schizophrenia in vulnerable individuals. There is also reasonable evidence for the third hypothesis that cannabis use exacerbates psychosis.

Comparable studies

Other narrative reviews on cannabis, most cited first.

Study Year Design Participants
Causal association between cannabis and psychosis: examination of the evidence 2004 Review
Cannabis sativa: A comprehensive ethnopharmacological review of a medicinal plant with a long history. General (historical and pharmacological review) 2018 Review
Psychiatric effects of cannabis 2001 Review
Beyond THC: The New Generation of Cannabinoid Designer Drugs 2011 Review
Cannabidiol, a Cannabis sativa constituent, as an antipsychotic drug 2006 Review

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