Can Cannabis Increase the Suicide Risk in Psychosis? A Critical Review

Objectives: This paper aimed to critically review the current literature concerning the possible association between cannabis use and suicidal behavior in patients with psychosis and in non-psychotic samples. Methods: We performed 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 behavior during the period between 1980 and 2011. Results: Most, but not all studies reported an association between suicidal behavior and cannabis use both in psychotic and non-psychotic samples. However, there were also some studies suggesting a weak (not direct) association between these two phenomena. Overall, those who attempt or complete suicide are characterized by additional risk factors such as mood disorders, stressful life events, interpersonal problems, poor social support, lonely lives, and feelings of hopelessness. Limitations: It was not possible to perform a meta-analysis due to the high heterogeneity of individual data. Conclusions: Cannabis use was a relevant risk factor associated with both suicidal attempts and behaviors in psychotic and non-psychotic samples. Preventive programs should be directed on reducing cannabis use, particularly in psychotic subjects. Evidence suggests that targeted suicide prevention programs can be also developed in specific at-risk subgroups such as those at genetic or clinical high risk of psychosis.