P300 subcomponents reflect different aspects of psychopathology in schizophrenia

Background: The aim of the study was to investigate abnormalities of P300 subcomponents in schizophrenic patients as well as relationships between these subcomponents and positive versus negative schizophrenic symptoms. Methods: Nineteen schizophrenic patients and 19 healthy controls were tested with an auditory event-related potential oddball paradigm designed to elicit the P300. The P300 data were analyzed by separating P300 subcomponents with a recently developed dipole source model. Results: Compared to healthy controls, schizophrenic patients showed reduced P300 amplitudes of the temporo-basal dipoles, corresponding mainly to P3b. Positive symptoms of the Positive and Negative Syndrome Scale correlated positively with the temporo-basal but not with temporo-superior dipole P300 activities, whereas negative symptoms correlated positively with the temporo-superior but not with temporo-basal dipole activities. Conclusions: The P300 subcomponents separated with the dipole model are affected in a different manner by positive versus negative symptoms. Furthermore, the positive correlation between the severity of psychopathology and the P300 amplitudes of the different dipole activities appears to be a state-dependent effect, which has to be separated from the P300 amplitude reduction as a trait marker in schizophrenic patients.