Saccadic eye movements in families multiply affected with schizophrenia: The Maudsley family study

Objective: Family studies have shown that abnormalities of smooth pursuit e ye movement are increased in the adult relatives of schizophrenic probands as well as in the probands themselves. More recently, an inability of schiz ophrenic subjects to inhibit reflexive saccades reliably has been shown. Th is study aimed to test the hypothesis that the latter dysfunction is part o f the extended schizophrenia phenotype. Method: With the use of infrared oc ulography, measurements of reflexive saccades and antisaccades were underta ken in 29 probands with schizophrenia, 50 of their nonpsychotic first-degre e relatives, and 38 unrelated healthy volunteers. Results: Probands, relati ves, and healthy subjects showed no overall differences in the generation o f reflexive saccades. However, in the antisaccade task, probands showed mor e saccadic distractibility when they were required to inhibit reflexive sac cades. Analysis of corrective saccades showed that this was not due to fail ed comprehension or motivation. Relatives of the probands with high saccadi c distractibility showed a higher distractibility rate than relatives of th e probands with normal distractibility. Across all subjects, females showed a higher rate of distractibility errors than males. Conclusions: The abili ty to suppress reflexive saccades is an objective neurocognitive measure th at is impaired in schizophrenic patients and in a proportion of their biolo gical relatives. This antisaccade abnormality may be a vulnerability marker in a subset of schizophrenic patients and their families.