IS CANNABIS-INDUCED PSYCHOSIS A DISTINCT DIAGNOSTIC ENTITY?
Several criteria can be used to evaluate the validity of psychiatric disorders. In a classic article, Robins and Guze19 proposed that the following interacting phases should be used: clinical description, laboratory studies, delineation from other disorders, follow-up studies, and family studies. The present family study thus provides one approach to validate the diagnosis of cannabis-induced psychosis. In the following paragraphs, we briefly review what other studies have shown regarding the remaining criteria and discuss the findings outlined in the “Results” section in that context. Despite much effort, it has been impossible to establish a symptom profile that consistently differentiates persons with cannabis-induced psychosis from those with other psychotic conditions.3, 5-6,20-21 The same is true for studies comparing persons with schizophrenia who have or have not been using cannabis.4, 8, 10, 22-24 Following the diagnostic criteria, clinicians, therefore, have the difficult tas
