Schizophrenia is the most common form of severe mental illness and affects one in 100 people at some point in their lives. There are about 250,000 diagnosed cases in Britain. The disease tends to begin in men in their late teens and in women a few years later.

Schizophrenia is not 'split personality'. It is the result of a breakdown in communication between different parts of the brain.

Common symptoms include 'positive symptoms':

hallucinations (hearing, seeing, tasting, smelling or feeling things that are not there)

delusions (believing you are someone famous or that people are out to get you)

and 'negative symptoms': apathy, depression, confused thinking, poor concentration and speech.

The causes of schizophrenia are unknown, but the condition may run in families, and various anatomical abnormalities in the brain have been described.

It can take various courses. About a quarter of people have one episode and make a good recovery; half get symptoms at infrequent intervals; and the remainder have a chronic illness which, if left untreated, results in frequent symptoms. About one in 10 people with schizophrenia dies an unnatural death, usually suicide.