Pathophysiology and epidemiology Dopamine theory: Overactive dopamine system, especially in the mesolimbic area, causes the positive symptoms of schizophrenia. Associated brain changes: Larger lateral ventricles. Reduced volume of the frontal lobe, parahippocampal gyrus, hippocampus, temporal lobe, and/or amygdala. None of these changes are especially sensitive or specific. Epidemiology: 0.5% lifetime risk. Presentation Signs and symptoms Positive symptoms: Hallucinations: commonly auditory. Usually in the 3rd person but can be 2nd person. May include thought echo, running commentary, or overheard conversations. Delusions: persecutory, reference, interference, passivity. Thought disorder: derailment, poverty, circumstantiality, perseveration, blocking. Negative symptoms: Apathy Self-neglect Paucity of speech. Social withdrawal. Emotional blunting. Anhedonia First-rank symptoms: A group of symptoms which are common and easy to identify. Individually not very sensitive, but all fair...