Oculomotor and neuropsychological effects of antipsychotic treatment for schizophrenia

Cognitive enhancement has become an important target for drug therapies in schizophrenia. Treatment development in this area requires assessment approaches that are sensitive to procognitive effects of antipsychotic and adjunctive treatments. Ideally, new treatments will have translational characteristics for parallel human and animal research. Previous studies of antipsychotic effects on cognition have relied primarily on paper-and-pencil neuropsychological testing. No study has directly compared neurophysiological biomarkers and neuropsychological testing as strategies for assessing cognitive effects of antipsychotic treatment early in the course of schizophrenia. Antipsychotic-naive patients with schizophrenia were tested before treatment with risperidone and again 6 weeks later. Matched healthy participants were tested over a similar time period. Test-retest reliability, effect sizes of within-subject change, and multivariate/univariate analysis of variance were used to compare 3 neurophysiological tests (visually guided saccade, memory-guided saccade, and antisaccade) with neuropsychological tests covering 4 cognitive domains (executive function, attention, memory, and manual motor function). While both measurement approaches showed robust neurocognitive impairments in patients prior to risperidone treatment, oculomotor biomarkers were more sensitive to treatment-related effects on neurocognitive function than traditional neuropsychological measures. Further, unlike the pattern of modest generalized cognitive improvement suggested by neuropsychological measures, the oculomotor findings revealed a mixed pattern of beneficial and adverse treatment-related effects. These findings warrant further investigation regarding the utility of neurophysiological biomarkers for assessing cognitive outcomes of antipsychotic treatment in clinical trials and in early-phase drug development.