Schizophrenia Spectrum and Other Psychotic Disorders
Symptom domains
Positive (delusions, hallucinations, disorganised speech/behaviour), negative (avolition, blunted affect, alogia, anhedonia, asociality) and cognitive (attention, working memory, executive function). First-rank (Schneiderian) symptoms are historical but useful descriptively.
Diagnoses
Schizophrenia requires ≥6 months of disturbance with ≥1 month of active symptoms and functional decline. Schizophreniform disorder (1-6 months), brief psychotic disorder (<1 month with full return), delusional disorder (≥1 month, function preserved, non-bizarre delusions), schizoaffective disorder (mood episodes with ≥2 weeks of psychosis without mood symptoms), substance/medication-induced and catatonia specifier.
Traps
Confusing schizoaffective disorder with bipolar disorder with psychotic features; missing medical mimics (encephalitis, temporal lobe epilepsy, autoimmune, delirium); attributing negative symptoms to depression; overlooking catatonia, which is treatable with benzodiazepines and ECT.
Management
Antipsychotics (first- or second-generation), clozapine for treatment resistance (two failed trials), monitoring for metabolic effects and agranulocytosis, psychosocial interventions (family psychoeducation, supported employment, CBTp).
Worked rule of thumb
If psychotic symptoms occur exclusively during mood episodes, do not diagnose schizophrenia. Require at least two weeks of psychosis in the absence of prominent mood symptoms for schizoaffective disorder.