Cannabis use is linked to an earlier onset of psychosis and more severe manic symptoms and conceptual disorganization, but not to delusions, hallucinations, negative symptoms, or daily functioning. In a naturalistic cohort of 502 patients with first-episode psychosis assessed at entry to services and after one year, those who reduced or stopped cannabis use showed the greatest improvement in symptoms, while continued users remained more symptomatic than non-users. Effective interventions to reduce cannabis use could yield significant health benefits for this population.
Childhood adversity and cannabis use are both known risk factors for psychosis. This study examined whether cannabis use might explain the link between childhood adversity and psychotic disorders. Data from 881 first-episode psychosis patients and 1231 controls from the EU-GEI study showed that household discord was associated with psychosis partly through cannabis use. Lifetime cannabis use mediated 17% of the association, cannabis potency mediated 14%, and frequency of use mediated 29%. Similar results appeared for early exposure to household discord. The findings suggest that harmful cannabis use patterns partially explain how household discord leads to psychosis, and children exposed to challenging home environments could benefit from interventions to prevent cannabis misuse.