Proof of correlation between psychotic spectrum disorders and suicide are found in literature, as well as between cannabis use disorder (CUD) and suicide and between CUD and schizophrenia. The study population of the selected papers consists of subjects diagnosed with schizophrenia spectrum or cannabis or SCs induced psychosis. Our objective is to assess how suicide risk (defined as suicidal ideation/attempt or death by suicide) in this population may vary with exposure to cannabis or one of its main active compounds. We searched PubMed, Scopus and Psycinfo database from January 2010 to February 2022. Study designs of the included articles are distributed as follows: 6 cross-sectional studies, 3 cohort studies, 1 case-control studies, 1 randomized double-blind study, 1 case report. Selected cohort studies seem to agree in identifying an increased suicide risk in patients with schizophrenia spectrum disorders when exposed to cannabis use. The case-control study and selected cross-sectionals provide contradictory data. However, qualitative analysis seem to point toward a positive correlation between cannabis use and increased suicidal risk in patients with schizophrenia spectrum disorders. In conclusion, emerging data on the correlation between cannabis use and suicide risk in patients with schizophrenia or other schizophrenic spectrum disorders are insufficient to draw firm conclusions. Nonetheless these studies seem to suggest a positive correlation of cannabis use with increased suicide risk, particularly regarding first episode psychosis (FEP) and male gender. Clinicians should be aware of the possibility of a higher risk of suicidal behavior associated specifically with cannabis use for men and patients during FEP.
Keywords: cannabis; first episode psychosis; non-affective psychosis; schizophrenia; suicide; suicide risk.