To critically review the current literature concerning the possible association between cannabis use and suicide behaviour in clinical (particularly in psychosis) and non clinical samples.

A detailed Pubmed/Medline, Scopus, PsycLit, and PsycInfo search to identify all papers and book chapters focusing on the association between cannabis use, and suicidal behaviour in psychosis during the period between 1980 and 2011 was performed.

Most of studies reported a relevant association between suicidal behaviour and cannabis both in clinical and non clinical samples. However, there were also some studies suggesting a weak (not direct) association between cannabis and suicide. Those who attempt or complete suicide, either in clinical and non-clinical samples, are characterized by having other risk factors such as mood disorders, stressful life events, interpersonal problems, poor social support, lonely lives, and feelings of hopelessness. The association between cannabis use and suicidal behaviour in psychosis resulted still poor investigated. Limitations: It was not possible to perform a meta-analysis due to the excess in the heterogeneity of data. Also, although the effort to summarize the research in this field, the inclusion and exclusion of papers cited in this paper may reflect the authors’ choice.

Cannabis use was a relevant risk factor associated with both suicidal attempts and behaviours in clinical and non clinical samples. Therefore, preventive programs should be directed on reducing cannabis use in both clinical samples and general population. Evidence suggests that targeted suicide prevention programs can be also developed in specific at-risk subgroups.