Familial and sporadic schizophrenics: a study of pursuit eye movements.

15 familial schizophrenics, 15 sporadic schizophrenics, 15 normal sibs of familial schizophrenic probands, 15 normal sibs of sporadic schizophrenic probands and 15 normal subjects were examined by electro-oculogram (EOG) for the quality of their smooth pursuit eye movements. Results confirm the previous findings of SPEM dysfunction among schizophrenics as a group, but the trait-marker status of SPEM impairment of schizophrenia has been questioned and discussed. It has been suggested that the increased prevalence of impaired pursuit eye movement among sporadic schizophrenics may be due to the environmental factors of specific or non-specific nature. SPEM dysfunction could also be of pathoplastic significance in the manifestation of psychosis.