Pursuit eye movement dysfunctions in schizophrenia. Family evidence for specificity

In a number of previous investigations, eye tracking dysfunctions had been reliably found in from 50% to 85% of schizophrenic patients, about 40% of manic-depressive patients, and about 8% of the normal population. We report similar smooth pursuit eye movement dysfunctions in 34% of the parents (or 55% of parental pairs) of schizophrenic patients compared with 10% of the parents (or 7% of parental pairs) of manic-depressive patients. Parental eye movement dysfunctions are significantly related to the diagnosis of the patient and not to the patient's eye tracking performance. These data suggest that, in the absence of other CNS disease, these eye tracking dysfunctions represent familial markers of vulnerability to schizophrenia.