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Psychiatric effects of cannabis

Andrew Johns

The British Journal of Psychiatry February 1, 2001 DOI: 10.1192/bjp.178.2.116 (opens in new tab)

Study at a glance

AI-extracted from the abstract
Characteristics Review Peer reviewed
Topics Cannabis
Citations 474
Key findings Argues that cannabis use carries risks of dependence and adverse effects, including psychotic states after heavy use, and that people with serious mental illnesses like schizophrenia are particularly vulnerable, with cannabis provoking relapse and aggravating symptoms.

Abstract

Background: Cannabis is commonly regarded as an innocuous drug and the prevalence of lifetime and regular use has increased in most developed countries. However, accumulative evidence highlights the risks of dependence and other adverse effects, particularly among people with pre-existing psychiatric disorders.

Aims: To re-evaluate the adverse effects of cannabis in the general population and among vulnerable individuals, including those with serious psychiatric disorders.

Method: A wide-ranging review of the topics related to these issues. Results and conclusions An appreciable proportion of cannabis users report short-lived adverse effects, including psychotic states following heavy consumption, and regular users are at risk of dependence. People with major mental illnesses such as schizophrenia are especially vulnerable in that cannabis generally provokes relapse and aggravates existing symptoms. Health workers need to recognise, and respond to, the adverse effects of cannabis on mental health.