Consensus paper of the WFSBP task force on cannabis, cannabinoids and psychosis

Abstract

Objectives

The liberalisation of cannabis laws, the increasing availability and potency of cannabis has renewed concern about the risk of psychosis with cannabis.

Methods

The objective of the WFSBP task force was to review the literature about this relationship.

Results

Converging lines of evidence suggest that exposure to cannabis increases the risk for psychoses ranging from transient psychotic states to chronic recurrent psychosis. The greater the dose, and the earlier the age of exposure, the greater the risk. For some psychosis outcomes, the evidence supports some of the criteria of causality. However, alternate explanations including reverse causality and confounders cannot be conclusively excluded. Furthermore, cannabis is neither necessary nor sufficient to cause psychosis. More likely it is one of the multiple causal components. In those with established psychosis, cannabis has a negative impact on the course and expression of the illness. Emerging evidence also suggests alterations in the endocannabinoid system in psychotic disorders.

Conclusions

Given that exposure to cannabis and cannabinoids is modifiable, delaying or eliminating exposure to cannabis or cannabinoids, could potentially impact the rates of psychosis related to cannabis, especially in those who are at high risk for developing the disorder.

Keywords:

• Cannabis
• cannabinoids
• psychosis
• schizophrenia
• cognition

Acknowledgements

None.

Statement of interest

Deepak Cyril D’Souza has received funding from the US National Institutes of Health, VA R&D, the Heffter Institute, the Wallace Foundation, Takeda, Biogen, Boehringer Ingelheim, Ceruvia and Jazz Pharmaceuticals and served as a consultant for Abide Therapeutics and Jazz Pharmaceuticals. Tony George has received grant support from NIDA, CIHR and the CAMH Foundation, and is a consultant to Frutarom, Marshall University, Sanford Burnham Prebys and the Canadian Centre for Substance Use and Addiction (CCSA). Robin Murray has received payments for non-promotional lectures from Janssen, Sunovion, Otsuka, Lundbeck, and attending an advisory board for Merck. Oliver Howes is a part-time employee of H Lundbeck A/s. He has received investigator-initiated research funding from and/or participated in advisory/ speaker meetings organised by Angellini, Autifony, Biogen, Boehringer-Ingelheim, Eli Lilly, Heptares, Global Medical Education, Invicro, Jansenn, Lundbeck, Neurocrine, Otsuka, Sunovion, Recordati, Roche and Viatris/ Mylan. Neither Oliver Howes or his family have holdings/ a financial stake in any pharmaceutical company.