RCT Comparing Avatar Intervention to Supportive Intervention to Reduce Cannabis Use in Patients With Psychotic Disorders

Psychotic disorders (PD) are characterized by a loss of contact with reality. Cannabis use is one of the key factors leading to psychiatric re-hospitalization in PD. In these populations, cannabis use is also 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 cannabis use disorder (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 rules. To fill a clinical need, the investigators have created a distinctive intervention for CUD in patients with PD. The Avatar Intervention displays strong experiential and relational components that are crucially missing in conventional interventions.

Hence, the primary outcomes are reductions in cannabis use, cannabis use disorder severity, and increased quality of life. The investigators will also explore whether the greater improvements attributable to the Avatar Intervention persist in time, and perform analyses on sex/gender, motivation to change cannabis habits, psychotic relapses, and THC metabolite levels.

Noteworthily, cannabis-related hospitalizations have been identified as one of the core indicators to measure the success of cannabis legalization. As a result, there is a pressing need to design innovative interventions that could have a significant impact on this costly and prime outcome. As there is no evidence-based therapeutic options for CUD in patients with PD, 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, or bipolar disorder with psychotic symptoms. Diagnoses will be established with the Structured Interview for DSM-5 (SCID-5).

Exclusion criteria

• Current SUD for a substance other than cannabis ;
• 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.