Background. Results of studies on antisaccade (AS) deficit in relatives of patients with schizophrenia are inconclusive. We hypothesized that AS performance in siblings of patients with schizophrenia is worse than in healthy controls and better than in patients with schizophrenia.
Method. We included 55 first-episode patients with schizophrenia, 28 healthy siblings and 36 healthy controls to evaluate AS performance. Eye movements were measured electromagnetically by the double magnetic induction (DMI) method.
Results. Patients with schizophrenia had a significantly higher error rate than siblings (d=0.86, p<0.0001) and controls (d=1.35, p<0.0001). Siblings had a higher mean error rate than healthy controls but this did not reach significance (d=0.56, p=0.29). The intra-class correlation (ICC) was 0.33 for the error rate. Mean AS gain was higher in siblings than in patients (d=0.75, p=0.004) and controls (d=0.6, p=0.05). The ICC was 0.08.
Conclusion. AS parameters in strictly screened healthy young siblings of young first-episode patients with schizophrenia are comparable to results found in studies investigating older relatives. However, the statistical results (i.e. the ICCs) suggest that there is little evidence of shared environmental or genetic factors on error rate variation.
- Biological marker