Effects of Cannabidiol on Psychiatric Symptoms, Cognition, and Cannabis Consumption in Cannabis Users With Recent-Onset Psychosis

This is a double-blind, randomized, placebo-controlled trial, evaluating the effects of a 12-week treatment course with CBD on psychiatric symptoms, cognition, and cannabis consumption in regular cannabis users with recent-onset psychosis. The study will be conducted at the Maryland Psychiatric Research Center (University of Maryland School of Medicine) and associated Early Intervention Programs in Baltimore, at the Sheppard Pratt Health System in Baltimore, and at the Psychosis Clinic of the University of California Los Angeles. The daily dose of CBD is 600 mg (p.o.), administered as adjunct medication. Any non-exclusionary antipsychotic, antidepressant, anxiolytic, or other medication prescribed prior to the trial will be continued. Participants may, but do not have to be taking conventional antipsychotic medication. The study will include 84 regular cannabis users with a schizophrenia-spectrum disorder who experienced their first psychotic episode within the last 5 years (90). Participants will be randomized 1:1 to either the CBD or the placebo group. Outcome measures include psychiatric symptoms, cognition, global functioning, and drug use, and will be assessed at baseline, and every 3 or 6 weeks thereafter (depending on the measure), until the end of treatment at 12 weeks. Outcome will be assessed again at a 3-month follow-up.