Chronic mental disorder with periods of psychosis, disturbed behavior and thought, and decline of functioning lasting ≥6 months (including prodrome and residual symptoms). - Associated with ↑ dopaminergic activity, ↓ dendritic branching.- Associated with frequent cannabis use.- Lifetime prevalence – 1.5% (males>females, African Americans=Caucaisans). - Presents earlier in men (late teens to early 20s vs late 20s to early 30s in women).- Patients at ↑ risk for suicide.

Diagnosis requires ≥2 of the following symptoms for ≥1 month, and at least 1 of these should include #1-3:1. Delusions2. Hallucinations – often auditory3. Disorganized speech4. Disorganized or catatonic behavior5. Negative symptoms (affective flattening, avolition, anhedonia, asociality, alogia - lack of speech)

- Ventriculomegaly on brain imaging

Treatment: atypical antipsychotics (eg, risperidone) are first line.- Negative symptoms often persist after treatment, despite resolution of positive symptoms.

Brief psychotic disorder – ≥1 positive symptom(s) lasting <1 month, usually stress related.Schizophreniform disorder – ≥2 symptoms, lasting 1-6 months.Schizoaffective disorder – Meets criteria for schizophrenia in addition to major mood disorder (major depressive or bipolar). To differentiate from major mood disorder with psychotic features, patients must have >2 weeks of psychotic symptoms without major mood episode.