Cannabis use and psychosis.
W Hall
Drug and Alcohol Review December 1, 1998 DOI: 10.1080/09595239800187271 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Review Peer reviewed |
|---|---|
| Topics | Cannabis |
| Key findings | There is more support for the hypothesis that cannabis use may precipitate schizophrenia, with a large prospective study showing a linear relationship between frequency of cannabis use by age 18 and subsequent schizophrenia risk over 15 years, though causality remains uncertain. |
Abstract
This paper reviews evidence on two hypotheses about the relationship between cannabis use and psychosis. The first hypothesis is that heavy cannabis use may cause a "cannabis psychosis"-a psychosis that would not occur in the absence of cannabis use, the symptoms of which are preceded by heavy cannabis use and remit after abstinence. The second hypothesis is that cannabis use may precipitate schizophrenia, or exacerbate its symptoms. Evaluation of these hypotheses requires evidence of an association between cannabis use and psychosis, that is unlikely to be due to chance, in which cannabis use precedes psychosis, and in which we can exclude the hypothesis that the relationship is due to other factors, such as other drug use, or a personal vulnerability to psychosis. There is some clinical support for the first hypothesis. If these disorders exist they seem to be rare, because they require very high doses of THC, the prolonged use of highly potent forms of cannabis, or a pre-existing (but as yet unspecified) vulnerability. There is more support for the second hypothesis, in that a large prospective study has shown a linear relationship between the frequency with which cannabis has been used by age 18 and the risks over the subsequent 15 years of a diagnosis of schizophrenia. It is still unclear whether this means that cannabis use precipitates schizophrenia, whether it is a form of "self-medication", or whether the association is due to the use of other drugs, such as amphetamines, which heavy cannabis users are more likely to use. There is stronger evidence that cannabis use can exacerbate the symptoms of schizophrenia. Mental health services should identify patients with schizophrenia who use alcohol, cannabis and other drugs and advise them to abstain or to greatly reduce their drug use.
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 |
Citations in the library
Cited by 21
- Cannabis use and psychotic disorders: an update Drug and Alcohol Review November 30, 2004
- Should Burden of Disease Estimates Include Cannabis Use as a Risk Factor for Psychosis? PLoS Medicine September 28, 2009
- The link between cannabis use and psychosis: furthering the debate Psychological Medicine December 23, 2002
- Atypical course in severe catatonic schizophrenia in a cannabis-dependent male adolescent: a case report Journal of Medical Case Reports September 11, 2015
- Neurological soft signs in Tunisian patients with first-episode psychosis and relation with cannabis use Annals of General Psychiatry July 12, 2017
and 16 more in the library
Cites 18
- Acute Effects of Drug Abuse in Schizophrenic Patients: Clinical Observations and Patients' Self-reports Schizophrenia Bulletin 1990
- Psychotic Reactions Following Cannabis Use in East Indians Archives of General Psychiatry 1974
- Drug Induced Psychosis The British Journal of Psychiatry February 1, 1996
- Marihuanann Psychosis JAMA October 13, 1969
- Forty-Six Cases of Psychosis in Cannabis Abusers Gunila Bernhardson International Journal of the Addictions 1972
and 13 more in the library