Simple clinical measures predict schizophrenia development

Not all people who have a genetic risk for the development of schizophrenia go on to develop the condition, note researchers who believe they have found a simple way of predicting the development of schizophrenia in at-risk individuals before its onset.

"Among individuals at enhanced genetic risk of schizophrenia, a state of vulnerability, including transient and partial symptoms, will occur in many more individuals than will develop florid schizophrenia," explain Eve Johnstone and colleagues from the University of Edinburgh in the UK.

They found that simple measures of schizotypal behavior and thinking, including social anxiety and withdrawal, provided the best means of distinguishing high-risk individuals who go on to develop schizophrenia from those who do not.

The findings are the latest from the Edinburgh High-Risk study, which began in 1994. A total of 163 young adults, aged between 16 and 24 years, who had two relatives with schizophrenia were enrolled as a high-risk group.

These individuals were examined together with 36 mentally healthy controls, and baseline measures were compared for those who went on to develop schizophrenia during the next 8 years, controls, those at high-risk who did not develop schizophrenia, and high-risk participants with partial or isolated psychotic symptoms.

Among the high-risk individuals, 20 developed schizophrenia within 2.5 years. These patients could be distinguished from those who did not go on to develop the condition based on scores on the Structural Interview for Schizotypy (SIS) and the Rust Inventory of Schizotypal Cognitions (RISC).

In contrast, neuropsychological and neurodevelopmental measures were more successful in distinguishing high-risk individuals from controls.

"The SIS and the RISC are simple measures that could be widely employed, and it is possible that this could be helpful for clinicians, parents, and individuals," Johnstone et al. comment in the British Journal of Psychiatry.

"This study shows that... worthwhile new insights into a common and crippling disorder can be obtained using simple clinical methods."

Br J Psychiatry 2005; 186: 18-25