Continuous-processing related ERPS in adult schizophrenia: continuity with childhood onset schizophrenia

Background: Previous work with schizophrenic children disclosed deficits on two continuous performance tests (CPTs) and ERP indices of reduced attentional resource allocation. Methods: The two CPTs were administered to adult schizophrenics and matched control subjects. The simple CPT required only that the subject respond whenever the target digit was displayed. The complex version required a response whenever any digit was displayed on two successive trials. Event-related potentials (ERPs) were recorded during task performance. Results: Schizophrenics had fewer hits on both CPT versions, showed a greater drop in performance from the simple to the complex CPT, and took longer to respond than controls. The processing negativity (Np) showed a greater amplitude increase from nontarget to target in normals than in schizophrenics, and the overlapping P2 component was more negative in normals. P3 latency was longer in schizophrenics, but P3 amplitude did not differ. Conclusions: Group performance and processing negativity effects replicated those from an earlier study of schizophrenic and normal children administered the same versions of the CPT, suggesting similar abnormalities in the allocation and modulation of information processing resources.