SMOOTH-PURSUIT EYE-MOVEMENT DIFFERENCES BETWEEN FAMILIAL AND NONFAMILIAL SCHIZOPHRENIA

Disrupted smooth pursuit eye tracking characterizes a greater proporti on of individuals with schizophrenia than in the normal population. Th e finding of a similar increased incidence of eye tracking abnormality in first degree relatives of schizophrenics implicates this disorder as a potential biological marker for schizophrenia. To test the assump tion that the eye tracking dysfunction of schizophrenics is geneticall y related, left and right smooth pursuit gain and phase shift were com pared between 20 schizophrenics with a family history of schizophrenia or schizophrenia-related disorders, 18 schizophrenics without a famil y history, as well as for 18 normal controls. Subjects tracked pendula r targets on an LED light bar moving at frequencies of 0.2 and 0.7 Hz. Horizontal eye movements were recorded using DC-electro-oculography. Results indicate that schizophrenics with a positive family history ha d significantly reduced right pursuit gain compared with controls, whi le right gain for negative family history schizophrenics did not diffe r from either group. Schizophrenic subjects also were administered neu ropsychological tests. Linear regression by groups analyses reveal tha t neuropsychological measures significantly predicted right gain to sl ower targets (0.2 Hz) for the positive family history schizophrenics, but not for negative family history schizophrenics.