[Correlations between delayed auditory evoked potentials and clinical evaluation of schizophrenic symptoms]

Late auditory evoked potentials (AEPs) were recorded by the "odd-ball" method in 20 schizophrenic patients according to DSM III R diagnosis criteria compared with 30 control subjects matched for sex and age. Patients were on antipsychotic medications; mean duration of illness was 3, 55 years. We have also proceeded to a clinical quantitative assessment of negative and positive symptoms of schizophrenia with Andreasen's rating scales. In the group of patients, we have observed a significant lengthening of the latency of N 1, N 2, P 3, N 3 and a decreased amplitude of N 1 and P 3. These results are in favour of an impairment of cerebral information processing probably localized in the subcortical level. Statistically significant correlations have been noticed between the anomalies of the last stages of information processing (P 3, N 3) and negative symptoms, more particularly affective flattening and attentional impairment. The disturbances of the first stages of information processing (P 2) and of automatic information processing (N 2) were related to positive symptoms, hallucinations and delusions especially. The anomalies of N 2 were also related to the sum of the global scores: an attentional impairment could be a main factor in the determinism of schizophrenia.