This is a proof-of-concept of a new Virtual Reality (VR) Avatar Intervention for Cannabis Use Disorders (CUD) in patients with psychotic disorders and/or mood disorders. The primary outcomes are reductions in cannabis use, cannabis use disorder severity, and increased quality of life.

Cannabis use disorder (CUD) is a complex issue, even more so when it is comorbid with a psychotic disorder or a mood disorder. Indeed, this population seems more vulnerable to this substance since the incidence of developing CUD is five to six times higher compared to the general population. In these populations, cannabis use is one of the key factors leading to psychiatric re-hospitalization. It is associated with depressive symptoms, medication non-compliance, hostility, as well as reduced quality of life. Unfortunately, there is no evidence-based intervention available for the treatment of CUD in this population. Novel interventions for CUD are thus critically needed. Virtual reality-based therapies are a promising avenue that allow patients to try novel strategies in real time instead of having to learn abstract concepts. In response to this clinical need, our team has created a distinctive intervention for CUD in patients with psychotic disorders and/or mood disorders. The Avatar Intervention displays strong experiential and relational components that are crucially missing in conventional interventions. This proposal thus aims to conduct a proof-of-concept to assess the efficacity of Avatar Intervention for CUD in patients with psychotic disorders and/or mood disorders. The primary objective of this open trial will be to determine whether cannabis-related outcomes (i.e. frequency and quantity of use) diminish after treatment as well as 3- 6- and 12-months follow-up. As for secondary objectives, the investigator will seek to determine the effect of the intervention on motivation to change, severity of cannabis dependence, psychiatric symptoms (mood and psychotic) and whether quality of life improves after treatment, at 3- 6- and 12-months follow-up. As there is no evidence-based therapeutic options for CUD in patients with psychotic disorders and/or mood disorders, the current trial will contribute to the validation of a novel approach and create new therapeutic possibilities.

Inclusion Criteria:

• Males or females over 18 years of age who meet the DSM-5 criteria for CUD (≥4 criteria) ;
• Patients will meet the DSM-5 criteria for schizophrenia, schizoaffective disorder, bipolar disorder and major depression. Diagnoses will be established with the Structured Interview for DSM-5 (SCID-5).

Exclusion Criteria:

• Ongoing pharmacological or psychological treatment for CUD ;
• Ongoing detoxification for cannabis withdrawal ;
• Presence of neurological disorders ;
• Presence of a severe and unstable physical illness ;
• Inability to provide consent.