Daily use of high-potency cannabis is associated with more positive symptoms and fewer negative symptoms in first-episode psychosis patients. Among 901 patients and 1,235 controls across six European countries, those who used high-potency cannabis daily had the highest scores on positive symptoms, while negative symptoms were more common in patients who never used cannabis. Psychotic experiences in controls were linked to current cannabis use but not to lifetime use. Depressive symptoms showed no differences related to cannabis use in either group.
Cannabis-associated psychosis is argued to be a distinct diagnostic category separate from schizophrenia and other psychotic disorders. The paper first establishes an epistemological basis for recognizing this specific condition. It then reviews the clinical features that characterize psychoses linked to cannabis use. Finally, it examines the biological and genetic factors that may underlie cannabis-associated psychosis.
This article summarizes the main substrates of cannabis-associated psychoses. It first introduces an epistemological framework to support the existence of a specific "cannabis-associated psychosis" as a distinct nosological entity separate from idiopathic schizophrenia and other psychotic disorders. It then examines the main clinical features of cannabis-associated psychoses and presents their biological and genetic correlates.