1. Introduction
Extensive use of illicit drugs is common in patients with non-affective psychosis, typically about40–50% of patients with psychosis report life time substance use disorder. The range of reported substance use disorder is large in psychosis, however, from10%to70%, depending on methodological differences and population characteristics. Rates of cannabis use have been found to be especially high; are view reported that median rate for current cannabis use
disorder was28.6%in first-episode and 22.0% for more longlasting non-affective psychosis. Substance use in psychosis has been associated with more hospitalizations,