Mismatch negativity at acute and post-acute phases of first-episode schizophrenia.

The objective of this study was to evaluate the mismatch negativity (MMN) in patients with first-episode schizophrenia at acute and post-acute phases in order to determine the contribution of trait and/or state features to MMN disturbances in schizophrenia. Subject groups comprised 30 patients with first-episode schizophrenia at the acute phase and 34 healthy controls. Ten patients were neuroleptic-naive during testing at the acute phase. Twenty-one patients were retested at the post-acute phase when their symptoms improved. All patients were taking antipsychotic medication at the post-acute retest session. MMN amplitude of the patients at acute phase did not differ from controls. However, MMN amplitude at post-acute phase was reduced compared to both controls and acute phase. Similar results were obtained when the analyses were confined to neuroleptic-naive patients. The sensory memory functions indexed by MMN seem to be unaffected at the onset of schizophrenia but deteriorated during the post-acute illness phase. MMN reduction at the post-acute phase might be emerged from antipsychotic medication.