Schizophrenia is a severe mental disorder which is characterized by a wide range of unusual behaviors: hearing voices (hallucinations) and distorted or false perception, often bizarre beliefs. They are unable to distinguish between reality and imaginative events. These unusual experiences seem real to the person whereas others assume that the person is lost in their own world. Schizophrenia - an easy to understand guide covering causes, diagnosis, symptoms, treatment and prevention plus additional in depth medical information. 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 mental health condition that affects how you think, feel and behave. Symptoms include delusions, hallucinations and psychosis.