Schizophrenia is a mental illness that interferes with normal thought processes, causing delusions, hallucinations, mental disorganization, and physical symptoms. Schizophrenia is perhaps the most severe common mental disorder. It affects men and women equally, and it is believed to afflict about 1% of the population of the United States. Its symptoms usually appear in late adolescence or young adulthood, though some young children are also afflicted. Though in rare cases a person may be diagnosed with schizophrenia and then recover with few after-effects, it is most usually a long-term illness with no definite cure. However, the symptoms can be treated successfully with drugs.

Schizophrenia was first described in 1896 by the German psychiatrist Emil Kraepelin. He called it dementia praecox, and divided it into three subtypes: paranoid, hebephrenic, and catatonic. In 1911 a Swiss psychiatrist, Eugen Bleuler, renamed the disease schizophrenia. Kraepelin's three categories are still retained in modern clinical practice...