Neural Correlates of Eye Tracking Deficits in First-degree Relatives of Schizophrenic Patients

Abstract

NEURODEVELOPMENTAL models of schizophrenia have postulated both a genetic and an environmental contribution to the development of the disorder. First-degree relatives of schizophrenic patients are at increased risk of developing schizophrenia, and can transmit the risk without having expressed the clinical syndrome.¹ Several deficits in cognitive and motor tasks found in schizophrenic patients have been identified as well in healthy first-degree relatives of schizophrenic patients. Because they occur at elevated rates in the schizophrenic patients and their relatives but not in the relatives of patients with other psychiatric disorders, they are thought to represent behavioral markers of genetic risk (otherwise conceived of as alternative phenotypic expressions of the disease).^2,3 Abnormalities in smooth pursuit eye tracking are one of the best-documented behavioral markers. Between 50% and 80% of schizophrenic patients have eye tracking deficits (ETD), compared with about 8% of the general population.⁴ Populations at high risk for schizophrenia, including first-degree relatives of schizophrenic patients and individuals with schizophrenia spectrum personality disorders, also have elevated rates of ETD^4-7; first-degree relatives of patients with other psychotic disorders do not.⁴