Abstract
OBJECTIVE: The authors evaluated concordance rates among three electrophysiological measures in patients with schizophrenia, nonschizophrenic first-degree relatives of schizophrenia patients, and healthy comparison subjects. The purpose of the study was to provide data for defining a common endophenotype for genetic studies of schizophrenia and for improving the criteria for diagnosis. METHOD: P50 event-related potential inhibition, antisaccade, and smooth pursuit eye tracking paradigms were measured. Data for all three paradigms were available for 81 patients with schizophrenia, 25 parents of patients with schizophrenia, and 60 healthy comparison subjects. RESULTS: The schizophrenia patients and the patients’ parents showed a high rate of inhibitory deficits measured by the P50 inhibition and antisaccade paradigms. Both groups had a high prevalence of eye tracking dysfunction. Smooth pursuit gain and the error rate in the antisaccade paradigm were significantly correlated in the schizophrenia patients and the parents, whereas P50 inhibition showed no correlation with smooth pursuit gain or antisaccade paradigm measurements. CONCLUSIONS: Despite superficial similarities, two paradigms designed to measure central inhibition processes (antisaccade and P50 inhibition) do not appear to reflect the same neurobiological substrates. In contrast, the convergence in performance data for the antisaccade and eye tracking paradigms suggests that the neural circuitry underlying these tasks may overlap. P50 inhibition and antisaccade errors were the optimal paradigms for discrimination between comparison subjects, patients with schizophrenia, and the parents of patients with schizophrenia.
