Influence of duration of untreated psychosis on auditory P300 in drug-naive and first-episode schizophrenia.

P300 amplitude reduction in schizophrenia is, according to previous studies, partially recovered by treatment with neuroleptics. However, whether this medication-induced P300 recovery is associated with duration of untreated psychosis (DUP) remains unreported; the present study is a preliminary examination of this question. Auditory P300 was recorded from 18 drug-naive and first-episode schizophrenia patients, among whom 10 were identified as short DUP, and eight as long DUP. Follow-up event-related potential tests were carried out after treatment with haloperidol or bromperidol for approximately 2 months. Recovery of P300 amplitude was replicated after neuroleptic medication was administered. A significant interaction was found between DUP and the medication effect in P300 amplitude over the left temporo-parietal area; a significant P300 recovery was seen in short DUP but not in long DUP. These results suggest that first-episode schizophrenia patients with long DUP might have severe impairments in the left temporal structures, supporting DUP as a key variable in future neurobiological studies of first-episode schizophrenia.