Smooth pursuit tracking, volumetric MRI, and Wisconsin Card Sorting performance in first-break, adolescent schizophrenia.

The purpose of this study was to examine whether impaired smooth pursuit tracking, which has consistently been found in studies of adult schizophrenics, also characterizes adolescents with this disorder. Volumetric brain imaging (MRI) of specific regions thought to be implicated in disordered tracking (i.e., the frontal eye fields and cerebellar vermis), Wisconsin Card Sorting performance (i.e., WCST; a test considered to index frontal lobe functioning), and a measure of the integrity of visual-vestibular interaction were also assessed to examine the possibility of co-occurrence of deficits across patients in order to provide a better understanding of the correlates of impaired smooth pursuit tracking in this disorder. Subjects included 12 adolescents with schizophrenia (6 males, 6 females; mean age = 17.7 years) who were compared to 12 gender- and age-matched normal controls (mean age = 17.1 years). A surprising absence of group differences was found on standard, computer-quantified measures of smooth pursuit tracking (i.e., root mean-square error, gain, and saccades). However, post-hoc analyses using a visual (non-automated) rating scale revealed that the lack of group differences resulted from both controls and patients displaying high rates of impaired tracking. Although analyses of brain volumetrics revealed no overall group differences, two patient sub-groups were identified based on impairments on the WCST and the visual-vestibular index, providing indirect evidence of frontal and cerebellar involvement in these sub-groups, respectively. These results question the usefulness of smooth pursuit tracking impairment in discriminating individuals with schizophrenia from normals at this young age, and are interpreted as providing indirect support for the neurodevelopmental hypothesis of schizophrenia. The need for further studies of smooth pursuit tracking in this population, using a multiparameter approach, is highlighted