Relationship between cannabis use and schizophrenia

Abstract

Introduction

Numerous studies have shown evidence that cannabis use increases the appearance of psychotic symptoms and disorders, and worsens the course of the disease in those with schizophrenia. However, a causal relationship between cannabis and schizophrenia has not been well established yet.

Objectives

In this presentation we try to review the relationship between cannabis use and prevalence of schizophrenia.

Methods

We performed a search of Medline looking for systematic reviews and methodologically robust studies in the field published in English in the last 5 years.

Results

A number of studies, both cross-sectional and prospective, find a prevalence of schizophrenia several times higher among cannabis users than in non-users. This association becomes stronger the lower the age of cannabis use onset, the higher the amount consumed and the higher the THC concentration are. Half of the patients with a cannabis-induced psychotic disorder turn into a diagnosis of schizophrenia within a few years. So far, it has not been possible to demonstrate a global increased prevalence of schizophrenia in relation to the increase of cannabis use in the population in recent decades.

Conclusions

Cannabis and schizophrenia have a complex relationship model; we still cannot clearly establish whether it is causal or the first works as a trigger for pathology in vulnerable subjects.

Disclosure

No significant relationships.