Smooth pursuit performance in families with multiple occurrence of schizophrenia and nonpsychotic families

Background: Eye tracking dysfunction (ETD) has been put forward as a trait marker for biological susceptibility to schizophrenia with the hope of iden tifying a link to specific cerebral lesions. Methods: Eye movements were recorded using infrared oculography in 8 famili es (67 members) showing multiple occurrence of schizophrenia and in 9 nonps ychotic families (80 members). Triangle wave stimuli at 15 degrees/s and 30 degrees/s were used and gains (eye velocity/target velocity), rates and am plitudes of different saccade categories (catch-up, back-up, anticipatory s accades, and square-wave-jerks) were determined. Results: In the relatives, the same deficit in maintenance of smooth pursui t performance was found as was seen in the schizophrenic patients. This def icit, which was not observed in the nonpsychotic families, consisted of low er gains for leftward as compared to rightward pursuit. This was emphasized most clearly at 30 degrees/s and was associated with an excess of catch-up saccades in the schizophrenic patients, whereas in the relatives a tendenc y to exhibit more and larger anticipatory saccades was observed Conclusions: The results confirm the hypothesis that eye-tracking dysfuncti on is a phenotypic marker for genetic liability to schizophrenia. Neurophys iologically, a cerebral dysfunction which includes one or more of the oculo motor centers can be assumed in subjects who carry a genetic susceptibility to schizophrenia. (C) 1999 Society of Biological Psychiatry.