Changes in eye tracking during clinical stabilization in schizophrenia.
Eye tracking abnormalities have been proposed as a trait marker for schizophrenia on the basis of their familial prevalence and the consistency of tracking over time in clinically stable patients. However, few studies have examined stability through acute episodes of illness, and most studies have not analyzed changes in different forms of eye movements. Therefore, the authors examined eye tracking, clinical state, and neuroleptic dose during 4 consecutive weeks in nine recently hospitalized schizophrenic patients. For the patients and controls, qualitative ratings of pursuit accuracy remained relatively stable over time. In contrast, saccade frequency increased significantly, with a 57% increase in small saccades and a 77% reduction in larger saccades. In comparison with cross-sectional studies which have found no correlation between neuroleptic dose and tracking performance, a reduction in large saccades was strongly correlated with increase in neuroleptic dose. The findings suggest that pursuit accuracy may be a trait characteristic of schizophrenia, while the frequency and size of saccades are state dependent characteristics.