Schizophrenia is chronic psychotic disorder that affects 20 million people worldwide. Onset is typically during late adolescence or early adulthood, and is caused by many factors including genetic, environmental, or chemical. As the disorder progresses, symptoms may include delusions, hallucinations, disorganized speech, and disorganized behavior. Someone with schizophrenia might also suffer from a lack of normal behaviors such as emotional expression and interest/enthusiasm.