Primary psychosis. Variable reported cannabis use (25% prevalence of positive cannabis urine toxicology in schizophrenia). A diagnosis of primary psychosis (eg, schizophrenia) is warranted in the absence of heavy cannabis use or withdrawal (for at least 4 weeks), or if symptoms preceded onset of heavy use.

CIP. Heavy cannabis use within the past month.

Discussion. A diagnosis of primary psychosis (eg, schizophrenia) is warranted in the absence of heavy cannabis use or withdrawal (for at least 4 weeks), or if symptoms preceded onset of heavy use. The age at which psychotic symptoms emerge has not proved to be a helpful indicator; different studies show a conflicting median age of onset.