Psychotic Disorders
Core concepts
Schizophrenia requires ≥2 core symptoms (delusions, hallucinations, disorganized speech, grossly disorganized/catatonic behaviour, negative symptoms) with at least one from the first three, plus functional decline and duration ≥6 months (DSM-5). Know positive vs negative vs cognitive symptom domains and their treatment implications. Schizoaffective disorder requires a major mood episode concurrent with psychotic symptoms, with ≥2 weeks of delusions/hallucinations without mood symptoms. Delusional disorder: non-bizarre delusions, function relatively preserved, mood episodes brief. Brief psychotic disorder (<1 month) and schizophreniform (1-6 months). Understand first-episode psychosis, the critical period, and the rationale for early intervention. Antipsychotic choice: high vs low potency, metabolic vs EPS risk, clozapine for treatment resistance (≥2 failed trials) with mandatory monitoring. Know the dopamine hypothesis and its refinements.
Traps
Do not diagnose schizophrenia if mood episodes dominate the course - consider schizoaffective or mood disorder with psychotic features. Distinguish delusional disorder (non-bizarre, preserved function) from schizophrenia. Remember clozapine monitoring: agranulocytosis, myocarditis, seizures, and the need for regular FBC.
Rule of thumb
Duration ladder: <1 month = brief psychotic disorder; 1-6 months = schizophreniform; ≥6 months = schizophrenia.