What are the policy implications of the evidence on cannabis and psychosis?

Hall, Wayne. and Degenhardt, L. (2006) What are the policy implications of the evidence on cannabis and psychosis?. Canadian Journal of Psychiatry-Revue Canadienne De Psychiatrie, 51 9: 566-574.

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Author Hall, Wayne.
Degenhardt, L.
Title What are the policy implications of the evidence on cannabis and psychosis?
Journal name Canadian Journal of Psychiatry-Revue Canadienne De Psychiatrie   Check publisher's open access policy
ISSN 0706-7437
Publication date 2006-08-01
Year available 2015
Sub-type Critical review of research, literature review, critical commentary
Open Access Status File (Publisher version)
Volume 51
Issue 9
Start page 566
End page 574
Total pages 9
Editor Joel Paris
Place of publication Ottawa, Canada
Publisher Canadian Psychiatric Assoc
Language eng
Subject C1
321202 Epidemiology
730205 Substance abuse
111706 Epidemiology
1117 Public Health and Health Services
Abstract 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 between observational evidence and action on cannabis. We examined arguments on the grounds of public health prudence for discouraging cannabis use by young individuals. With the assumption that the relation may be causal, we considered recommendations for policy in mental health services, health education, and public policy toward cannabis. Results: The observational evidence and biological plausibility of the hypothesis that cannabis is a contributory cause of psychosis is at least as strong as evidence for causal relations between heavy alcohol and amphetamine use and psychosis. On public health grounds, there is a good case for discouraging cannabis use among adolescents and young adults. It remains uncertain how best to discourage use and at whom campaigns to reduce cannabis use should be targeted. Conclusions: We should discourage young adults seeking treatment in mental health services from using cannabis and inform them of the probable mental health risks of cannabis use, especially of early and frequent use. We must exercise caution in liberalizing cannabis laws in ways that may increase young individuals' access to cannabis, decrease their age of first use, or increase their frequency of cannabis use. We should consider the feasibility of reducing the availability of high-potency cannabis products.
Keyword Cannabis use
Mental health services
Health education
Severe mental-illness
Marijuana use
Amphetamine psychosis
Australian adults
Q-Index Code C1
Institutional Status UQ

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
Collections: Excellence in Research Australia (ERA) - Collection
2007 Higher Education Research Data Collection
School of Public Health Publications
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Citation counts: TR Web of Science Citation Count  Cited 30 times in Thomson Reuters Web of Science Article | Citations
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Created: Wed, 15 Aug 2007, 19:29:05 EST