Cannabis use and psychosis: a review of clinical and epidemiological evidence.
W Hall, L Degenhardt
Australian & New Zealand Journal of Psychiatry February 1, 2000 DOI: 10.1046/j.1440-1614.2000.00685.x (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Review Peer reviewed |
|---|---|
| Topics | Cannabis |
| Key findings | There is limited evidence for a distinct 'cannabis psychosis', but stronger evidence that cannabis use may precipitate or exacerbate schizophrenia, though causality remains unclear. |
Abstract
This paper evaluates evidence for two hypotheses about the relationship between cannabis use and psychosis: (i) that heavy cannabis use causes a 'cannabis psychosis', i.e. a psychotic disorder that would not have occurred in the absence of cannabis use and which can be recognised by its pattern of symptoms and their relationship to cannabis use; and (ii) that cannabis use may precipitate schizophrenia, or exacerbate its symptoms. Literature relevant to drug use and schizophrenia is reviewed. There is limited clinical evidence for the first hypothesis. If 'cannabis psychoses' exist, they seem to be rare, because they require very high doses of tetrahydrocannabinol, the prolonged use of highly potent forms of cannabis, or a preexisting (but as yet unspecified) vulnerability, or both. 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 had been used by age 18 and the risk over the subsequent 15 years of receiving a diagnosis of schizophrenia. It is still unclear whether this means that cannabis use precipitates schizophrenia, whether cannabis use 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 better clinical and epidemiological evidence that cannabis use can exacerbate the symptoms of schizophrenia.
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 32
- Causal association between cannabis and psychosis: examination of the evidence The British Journal of Psychiatry January 30, 2004
- Effects of cannabis use on outcomes of psychotic disorders: systematic review The British Journal of Psychiatry October 31, 2008
- Long-term consequences of adolescent cannabinoid exposure in adult psychopathology Frontiers in Neuroscience November 10, 2014
- Cannabis use and cognitive dysfunction Indian Journal of Psychiatry 2011
- Pathways from Cannabis to Psychosis: A Review of the Evidence Frontiers in Psychiatry 2013
and 27 more in the library
Cites 12
- 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
- Forty-Six Cases of Psychosis in Cannabis Abusers Gunila Bernhardson International Journal of the Addictions 1972
- Cannabis Psychotic Disorder American Journal on Addictions 1994
and 7 more in the library