Artist's abstract depiction of schizophrenia. Schizophrenia, or split personality, is a general term for a group of psychotic illnesses characterized by disturbed thinking, emotional reaction, and behaviour. Here, the split personality is shown in light and dark in which the sufferer's thoughts and feelings become illo- gical. Thought is deluded so that many sufferers perceive that other people's thoughts are being planted into their heads (thought insertion). Jealousy, depression, even catatonia, may result. Schizophrenia is the most common psychotic ill- ness, with inheritance known to play a role. Long- term rehabilitation and control is necessary.