Delayed visual NA potential in remitted schizophrenia: a new vulnerability marker for psychotic relapse under low-dose medication

Background: Lasting cognitive dysfunction throughout remission has been regarded as a biological vulnerability in schizophrenia, which may produce psychotic relapses with characteristic symptoms. Our hypothesis was that an abnormality in event-related potentials (ERPs) may be a neurophysiological marker of vulnerability to psychotic relapse in remitted schizophrenia. We conducted a 2-year follow-up study after evaluating ERP abnormalities to find a new ERP marker for schizophrenic relapse. Methods: Visual ERPs were recorded from outpatients with remitted schizophrenia under maintenance pharmacotherapy (n = 44) and normal controls (n = 20) during a letter discrimination task. Based on the prospective study, the patients were divided into a relapse group (n = 20) and a nonrelapse group (n = 24). ERP findings that related to psychotic relapse within 2 years were analyzed. Results: Compared with controls, the relapsers showed ERP abnormalities in the NA, N2, and P3 components, and the nonrelapsers in the P3 component. The peak latency of the NA potential was delayed significantly in the relapse group relative to the nonrelapse group, and predicted a psychotic relapse with about 90% probability. Conclusions: The delayed NA, which reflects early perceptual disorganization, may be a promising neurophysiological predictor of psychotic relapse in remitted schizophrenia under maintenance pharmacotherapy.