Predictive saccades are impaired in biological nonpsychotic siblings of schizophrenia patients

OBJECTIVE: Although impairments in predictive saccades have been reported in patients with schizophrenia, this has never been explored in their biological relatives. We examined predictive saccades in age-and sex-matched siblings of patients with schizophrenia. METHOD: Thirty siblings of schizophrenia patients, 30 healthy matched control subjects and 30 patients with schizophrenia performed a predictive saccades paradigm. Nonanticipated and anticipated saccades were analyzed separately. RESULTS: Compared with control subjects, primary saccades and final eye position were hypometric (they undershot the target) in siblings, as in patients. The proportion of anticipated saccades and latencies did not differ between the 3 groups. The maximum velocity was decreased only in patients. CONCLUSION: Alterations in predictive saccades observed in biological siblings are similar to those seen in patients, although they tend to be of a lesser degree. This finding supports predictive saccades as a valid endophenotypic marker. Further research is necessary to understand the physiopathological value of these disturbances and their link to a visuospatial representation deficit.