[Negative schizophrenic symptomatology and the P 300 potential]

We studied the latency and amplitude of the P 300 wave of event-related potentials (P 3) in 19 hospitalised schizophrenic patients. We used an odd ball paradigm procedure in acoustic stimulation. We found a negative correlation between the amplitude of P 3 and negative schizophrenic symptomatology, measured by the negative BPRS score and the SANS score. However, no link would appear to exist in our study between positive symptomatology and P 3 amplitude. The correlation with the negative BPRS score is found in both evaluations, at the beginning and at the end of the period of hospitalisation. P 3 latency would appear to be independent of either positive or negative schizophrenic symptomatology. It would thus appear to us that the negative symptomatology, rather than the positive, could be at the origin of marked changes in P 3, observable fro relatively simple experimental but parameters such as reaction time or error scores remain to be specified, even if they appear to intervene infrequently. The use of event-related potentials would thus appear pertinent in clinical research and could help in the homogenisation of schizophrenic populations studied.