The word 'schizophrenia' is derived from the Greek and means 'split mind'. It was introduced to replace an older name for this illness: 'Dementia praecox' or the 'insanity of youth', as opposed to senile dementia, which is the insanity of old age. As psychiatrists became aware that the illness now called schizophrenia differed from dementia, they realised that there was no impairment of consciousness or memory as is seen with organic mental states, but that there were often disorders of thinking and of feeling, with disorganisation of the patient's personality. So the term schizophrenia became preferred to the misleading 'precocious dementia'. The illness is characterised by a disorder of thinking, feeling and motoractivity, with disorganisation of the personality.