Schizophrenia is characterized by a constellation of distinctive and predictable symptoms. The symptoms that are most commonly associated with the disease are called positive symptoms, that denote the presence of grossly abnormal behavior. These include thought disorder, delusions, and hallucinations. Thought disorder is the diminished ability to think clearly and logically. Often it is manifested by disconnected and nonsensical language that renders the person with schizophrenia incapable of participating in conversation, contributing to his alienation from his family, friends, and society.
Delusions are common among individuals with schizophrenia.
Such voices may describe the person's actions, warn him of danger or tell him what to do. At times the individual may hear several voices carrying on a conversation. While schizophrenia can affect anyone at any point in life, it is somewhat more common in those persons who are genetically predisposed to the disease. The first psychotic episode generally occurs in late adolescence or early adulthood. Three-quarters of persons with schizophrenia develop the disease between 16 and 25 years of age.