Depressive Symptoms Help Distinguish Cannabis-Induced Psychosis From Primary Psychotic Disorders

Cross-sectional study of 181 patients with psychotic symptoms and cannabis use admitted to psychiatry units at three university hospitals. Diagnoses were made using structured clinical interviews. The Symptom Checklist-90-R and SUMD were used for psychopathological assessment. ROC curve analysis identified the most discriminating variables.

Distinguishing cannabis-induced psychosis from primary psychotic disorders that happen to co-occur with cannabis use has direct treatment implications. Cannabis-induced psychosis may resolve with abstinence, while primary psychotic disorders typically require ongoing antipsychotic treatment. Accurate diagnosis prevents both under- and over-treatment.

The distinction between substance-induced and primary psychotic disorders is one of the most challenging diagnostic questions in psychiatry. This study provided clinically useful markers that could improve diagnostic accuracy in emergency and inpatient settings where cannabis-using patients present with psychotic symptoms.

The cross-sectional design captures a snapshot at hospital admission; some patients initially diagnosed with cannabis-induced psychosis may later develop primary psychotic disorders. The sample came from three university hospitals, which may see more severe cases. The high classification accuracy may not replicate in other settings.