Effects of cannabidiol on schizophrenia-like symptoms in people who use cannabis

Clinical Psychopharmacology Unit, Sub-Department of Clinical Health Psychology, University College London, London, UK.
The British Journal of Psychiatry (Impact Factor: 7.34). 05/2008; 192(4):306-7. DOI: 10.1192/bjp.bp.107.046649
Source: PubMed

ABSTRACT Cannabis contains various cannabinoids, two of which have almost opposing actions: Delta9-tetrahydrocannabinol (Delta9-THC) is psychotomimetic, whereas cannabidiol (CBD) has antipsychotic effects. Hair samples were analysed to examine levels of Delta9-THC and CBD in 140 individuals. Three clear groups emerged: ;THC only', ;THC+CBD' and those with no cannabinoid in hair. The THC only group showed higher levels of positive schizophrenia-like symptoms compared with the no cannabinoid and THC+CBD groups, and higher levels of delusions compared with the no cannabinoid group. This provides evidence of the divergent properties of cannabinoids and has important implications for research into the link between cannabis use and psychosis.

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    ABSTRACT: Cannabis use is associated with an increased risk of psychosis in vulnerable individuals. Cannabis containing high levels of the partial cannabinoid receptor subtype 1 (CB1) agonist tetrahydrocannabinol (THC) is associated with the induction of psychosis in susceptible subjects and with the development of schizophrenia, whereas the use of cannabis variants with relatively high levels of cannabidiol (CBD) is associated with fewer psychotic experiences. Synthetic cannabinoid receptor agonists (SCRAs) are full agonists and often more potent than THC. Moreover, in contrast to natural cannabis, SCRAs preparations contain no CBD so that these drugs may have a higher psychosis-inducing potential than cannabis. This paper reviews the general toxicity profile and the adverse effects of SCRAs with special emphasis on their psychosis-inducing risk. The review shows that, compared with the use of natural cannabis, the use of SCRAs may cause more frequent and more severe unwanted negative effects, especially in younger, inexperienced users. Psychosis and psychosis-like conditions seem to occur relatively often following the use of SCRAs, presumably due to their high potency and the absence of CBD in the preparations. Studies on the relative risk of SCRAs compared with natural cannabis to induce or evoke psychosis are urgently needed. © The Author(s) 2015.
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