Psychosis caused by cannabis: Intoxication or induced?

Telling the difference between primary psychosis, cannabis intoxication and cannabis‐induced psychosis is challenging but important, especially now that it's known that almost 50% of cannabis‐induced psychosis precedes primary psychosis. A fictional case study reported in Paediatrics & Child Health makes these challenges come to life. But the purpose of the case study is only as an introduction to the meat of the article, which is how to differentiate between the three. The authors are psychiatrists from Canada.