Exploration of the association between cannabis use and the occurrence of early symptoms of psychotic disorders

Abstract

Introduction: The use of addictive substances has been linked with various symptoms such as hallucinations and delusions. Similar symptoms surface in accordance to psychotic disorders. In addition, during recent years, there is an increasing number of studies that link cannabis use with the appearance of schizophrenia. Aim: To investigate whether the use of cannabis is associated with the manifestation of the early symptoms of psychotic disorders. Method: Literature review was performed via EBSCO, Medline and Google Scholar, using as key-words: cannabis, schizophrenia, psychosis, abuse, early onset, risk factor. Eventually, 13 studies fulfilled the inclusion criteria of the review. Results: There were drawn 12 studies that provide evidence for a positive association between cannabis use in early adolescence and the manifestation of early symptoms of psychotic disorders and schizophrenia. However, 8 of them were retrospective in nature, and their design does not allow the confirmation of a causal relationship between these two variables. Conclusions: The latest research evidence does not appear to light out the link between cannabis use and the trigger of psychotic disorders, leading to the conclusion that further research evidence deriving from large prospective studies is essential.