Basic symptoms and P300 abnormalities in young schizophrenic patients

Among the reasons for the relatively limited number of investigations of self-knowledge phenomena should be included, in addition to theoretical motives, the difficulties regarding the use of instruments available for this kind of approach and their content validity. This study investigates the relationship between subjective and objective deficits in schizophrenia, taking into account subjective experiences of cognitive impairment, clinical symptoms, and cognitive evoked potentials (P300 component). A group of 36 young schizophrenic patients (29 on neuroleptic treatment and seven drug-naive) were considered, together with a comparison group of 36 healthy subjects. Auditory event-correlated potentials (ERPs) were obtained using a simple "oddball" paradigm. Clinical symptoms were rated with the Brief Psychiatric Rating Scale (BPRS) and Scales for the Assessment of Positive and Negative Symptoms (SAPS and SANS), and while subjective disturbances were assessed by the Frankfurter Beschwerde Fragebogen (FBF, also called the Complaint Questionnaire). Correlation analysis showed that P300 amplitude was inversely correlated with subjective experiences of cognitive deficit, especially in the area of automatic skills and overstimulation. No relationship emerged between BPRS, SANS, and SAPS scores and P300 alterations. The results suggest that subjective cognitive disturbances, more than objective symptoms, are related to P300 alterations in schizophrenia, and that the FBF questionnaire appropriately covers the domain of schizophrenic cognitive disorders.