Background: The use of cannabis has been linked to an increased risk for psychosis, irrespective of confounding factors such as age, gender, use of other drugs and reverse causality. Over the last few years a great deal of research has been done to broaden our understanding of the underlying mechanisms of this link.
Aim: To update studies that have examined the link between cannabis use and psychosis and that have investigated the possible mechanisms underlying this link.
Method: This article discusses recent epidemiological and experimental research that sheds light on the nature of the link and the influence of interactions between genes and environment.
Results: The long-term effects of cannabis on the risk factors for psychosis and psychotic disorders are influenced to a large extent by genetic and environmental factors. Furthermore, patients with a psychotic disorder seem to be extremely vulnerable to the acute effects of cannabis.
Conclusion: Studies show that cannabis use is an important risk factor for psychosis and psychotic disorders. So far, however, less research has been done into the effects of cannabis use on patients already suffering from a psychotic disorder.