Schizophrenia is a serious mental illness characterised by disturbances in a person's thoughts, perceptions, emotions and behaviour. It affects approximately one in every hundred people and first onset commonly occurs in adolescence or early adulthood.

There are a number of signs and symptoms that are characteristic of schizophrenia. However, the symptoms vary greatly from one individual to another. Symptoms are divided into two groups, 'positive' symptoms (also referred to as psychotic) that reflect new or unusual forms of thought and behaviour, and 'negative' symptoms, which reflect a loss of previous feelings and abilities. No one single cause has yet been found; several factors may play a role including hereditary and environmental factors.

Treatment of the illness involves suppressing psychotic symptoms, reducing the patient's level of anxiety, restoring a clear mental understanding of reality and helping to rebuild the person's life in such a way that is satisfying but not too stressful. The result of treatment can be variable; 25% will experience a full recovery, 40% will experience recurrent episodes and 35% will experience long-term schizophrenia, with a high rate of both hospital admission and social disability.