Identification of vulnerability among first-degree relatives of patients with schizophrenia.

OBJECTIVES To evaluate the status of schizotypy, neurological soft signs, and cognitive functions as vulnerability markers for schizophrenia and to investigate the potential value of their combination for early identification of people at high risk for schizophrenia. METHODS A cross-sectional study was conducted. Subjects were drawn from first-degree relatives of inpatients and outpatients with schizophrenia (n = 50). Controls (n = 30) were recruited by word-of-mouth from hospital staff and attendants of hospitalised patients. Subjects who met inclusion criteria on screening were subjected to selected measures for assessment, including Schizotypal Personality Questionnaire-Brief Version, the Cambridge Neurological Inventory, digit span test, paired associate learning test, and visuospatial working memory matrix. Statistical analysis was completed using the independent t test and significance (p value), as well as calculation of effect size (Cohen's d). Discriminant function analysis was used to determine the effect of combining assessment measures. RESULTS First-degree relatives showed higher schizotypy scores (Cohen's d = 0.88) and neurological soft signs (Cohen's d = 1.55). They scored significantly worse on all neurocognitive measures (Cohen's d = -1.27). Discriminant function analysis showed that Schizotypal Personality Questionnaire-Brief Version, neurological soft signs, and total cognitive index (the sum of weighted scores on individual cognitive scales) in combination better discriminated between the first-degree relative and control groups (Wilks' λ = 0.54). CONCLUSION Use of multiple vulnerability markers could enhance the specificity of measures used to determine risk for schizophrenia.