Schizophrenia. Conceptual artwork representing schizophrenia. This psychiatric disorder can include disordered thoughts (such as delusions and hallucinations), psychotic episodes (extreme delusions), disturbed moods, an altered sense of self (from withdrawal to a loss of ego boundaries), and a splitting of personality or lack of personality integration. A key defining characteristic of schizophrenia is that it must be a long-term disorder lasting at least 6 months. The cause is unknown, but there is thought to be a genetic predisposition. Treatment includes drugs and psychiatric behaviour therapy.