Schizophrenia is a mental disorder that causes psychosis and affects 1 in 300 people worldwide. It is associated with disability, stigma, and human rights violations. Learn about its symptoms, causes, services, and WHO's response. Schizophrenia is a chronic brain disorder that affects about one percent of the population. When schizophrenia is active, symptoms can include delusions, hallucinations, disorganized speech, trouble with thinking and lack of motivation. Learn about NIMH research on schizophrenia. Find resources on the signs and symptoms of schizophrenia, risk factors, and potential treatments and therapies. Schizophrenia - an easy to understand guide covering causes, diagnosis, symptoms, treatment and prevention plus additional in depth medical information.