Writing in the current edition of the British Journal of Psychiatry, the research team, led by Professor Eve Johnstone from the University of Edinburgh, explains that among people with an increased genetic risk of schizophrenia, a "state of vulnerability" will occur in many more individuals than will actually develop the disorder.

Professor Johnstone and her team therefore conducted a study to see which early behavioural and mental factors can help distinguish high-risk individuals who go on to develop schizophrenia from those who do not.

The investigators recruited 163 young adults, aged 16 to 24 years, who were considered to be at high risk of schizophrenia because they each had two relatives who had been diagnosed with the disorder.

Over the next 2.5 years, 20 of the participants developed schizophrenia.

The researchers found that those who developed schizophrenia tended to have been more anxious and withdrawn and to have exhibited more "schizoptypal features" at the beginning of the study than those who did not develop the disorder.

Furthermore, tests showed that people who developed schizophrenia tended to have more lapses in their memory than participants who did not go on to develop the condition. This, say the researchers, suggests a dysfunction in an area of the brain called the temporal lobe.

They conclude: "It is possible, using simple behavioural assessments of schizotypal and anxiety cognitions, to predict with some accuracy those of a high-risk group who will (and with considerable accuracy those who will not) develop schizophrenia, some years before the development of the psychosis."

The investigators add that their findings are consistent with the view that schizophrenia is primarily a disorder of the temporal lobe that develops slowly over several years.