Schizophrenia can be predicted years before development
Jan 7, 2005 - 4:41:38 AM

It is possible to predict with some accuracy which people in a high-risk group who will (and will not) develop schizophrenia, some years before the development of the psychosis. The latest publication from the Edinburgh High-Risk Study, which appears in the January 2005 issue of the British Journal of Psychiatry, has shown that among people at increased genetic risk of schizophrenia, a state of vulnerability will occur in many more individuals than will actually develop the disorder.

Simple behavioural measures of e.g. social withdrawal or odd behaviour, and 'schizotypal' thinking ('sometimes I get a weird feeling that I am not really here') provide the best evidence for distinguishing high-risk individuals who will develop schizophrenia from those who will not.

The purpose of the Edinburgh High-Risk Study, which began in 1994, is to determine what distinguishes high-risk individuals who go on to develop schizophrenia from those who do not, and to compare relevant factors in affected and unaffected high-risk people with matched controls.

A high-risk sample was recruited of 163 young adults aged 16-24 with two relatives with schizophrenia. The control groups were made up of young people who were well, and individuals in the first episode of schizophrenia who did not have a family risk of the disorder.

In this study the high-risk group and 36 controls were examined. Baseline measures were compared between those who did develop schizophrenia, a well control group, a well high-risk group and high-risk participants with partial or isolated psychotic symptoms.

Of those at high risk, 20 developed schizophrenia within 2.5 years. Just over half of those who fell ill were in the 'psychotic or possibly psychotic symptoms' group on entry to the study. However, many of the high-risk group who did not fall ill were just as symptomatic on entry as any of those who did.

The filmed records of interviews from this study show that such symptoms often appear to have been associated with little distress or functional impairment. They may be short-lived and followed by years in which they do not occur at all.

Those who developed schizophrenia differed from those who did not on social anxiety, withdrawal and other 'schizotypal' features, all of which were best assessed by simple behavioural and cognitive measures. Other measures, particularly in terms of neuropsychology, were also predictive, especially assessments of episodic memory (which are suggestive of temporal lobe dysfunction).

The authors of the study comment that the findings are consistent with the view that schizophrenia is primarily a disorder of temporal lobe structure and function that develops slowly over several years. The exact nature of the change that pushes an individual into psychosis is not yet clear, but continuing studies, particularly of functional brain imaging, may reveal this.

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