The Role of Cannabinoids in Schizophrenia: Where Have we Been and Where are we Going?

Abstract

Introduction

Several studies have shown that both endocannabinoid system (ECS) and synthetic cannabinoids (SC) might be involved in schizophrenia.

Objectives

To review recent literature on the role of cannabinoids in schizophrenia. The review includes the evidence of cannabis use as a risk factor for the development of schizophrenia, but also the preliminary evidence for the use of cannabinoid-based compounds in the treatment of psychosis.

Methods

The authors made an online search on PubMed for clinical trials and reviews published in the last 12 months, using the keywords: “cannabinoids”, “endocannabinoids”, “phytocannabinoids” and “schizophrenia”.

Results

The use of Cannabis sativa is associated with increased risk of developing psychotic disorders, including schizophrenia, and earlier age at onset of psychosis. Δ9-Tetrahydrocannabinol (THC) has multiple actions in the brain development, including impairment of neuroplasticity, dysregulation of dopamine and glutamate signaling, and, possibly, neurotoxicity. The ECS has been implicated in psychosis both related and unrelated to cannabis exposure. Cannabinoid receptors type 1 (CB1 R) and type 2 (CB2 R), as well as the endogenous ligand N-arachidonoylethanolamine (AEA) and 2-arachidonylglycerol (2-AG) levels, are most likely to be involved in the pathophysiology of this disorder. On the other hand, the antipsychotic effects of some cannabinoids have been investigated in recent studies. Cannabidiol (CBD) and Δ9-tetrahydrocannabivarin (THCV) may have therapeutic potential for the treatment of psychosis.

Conclusions

Emerging evidence suggests an important role of ECB system and SC on schizophrenia. On the other hand, recent studies have shown some phytocannabinoids might represent therapeutic promises in this disorder.

Disclosure of interest

The authors have not supplied their declaration of competing interest.