Cannabis consumption and psychosis or schizophrenia development

Objective: Cannabis consumption produces psychopathology, in some cases psychotic episodes, which are of our interest in this work. However, the relationship between cannabis use and psychosis has not been fully elucidated. The objectives of this work are to (1) review the current state of knowledge on the association of cannabis use with the risk of the development of psychosis or psychotic symptoms in people without schizophrenia and (2) assess the consistency of the hypothesis that cannabis use is associated with increased risk of psychosis in people without schizophrenia. Method: This work included research done in humans until May 2018 with the keywords ‘cannabis’ and ‘psychosis’, published in English and Spanish, in the PubMed database. Results: In all, 66 papers were analyzed, of which 23 were cohort trials and 43 were reviews. Conclusion: Cannabis use doubles the risk of developing psychosis in vulnerable people. There even exists a relationship regarding the dose used and the age of first use. Gene–environment interactions that modulate the association between cannabis use and the presence of psychosis have also been described.