Smooth-pursuit eye movement dysfunction in schizophrenia: the role of attention and general psychomotor dysfunctions.

Smooth-pursuit eye-tracking performance was examined in 100 schizophrenic patients and various control groups under both attention-enhancing and attention-distracting conditions. The level of attentional demand was varied by introducing a secondary reaction time task that directed attention either toward or away from the visual-tracking target. Distraction from the target led to a significant deterioration of tracking performance in all subjects, which was most pronounced in the group of schizophrenic patients. Attention-enhancement, on the other hand, did not normalize performance in this group. In schizophrenic patients, mainly in the distraction condition, there was a moderate association between performance in tracking and tests presumably measuring prefrontal functions. Tracking accuracy from both conditions was related to general motor performance as measured by the Neurological Evaluation Scale. It was concluded that in schizophrenic patients attentional factors (distraction) may contribute to eye-tracking impairment, and that the impairment may be viewed as an aspect of general motor dysfunctions.