schizophrenia

schizophrenia
A psychosis, more broadly defined in the United States than Britain, typically characterized by delusions or hallucinations, usually developing in late adolescence, and regarded as paradigmatic of madness. The term was introduced in the early 20th century and applied to a condition identified in the mid-19th century as dementia praecox. Evidence indicates genetic predisposition but also the aetiological importance of environment.