The difference in Mismatch negativity between the acute and post-acute phase of schizophrenia.

In order to investigate the trait and state aspects of Mismatch negativity (MMN) amplitude reduction in schizophrenia, auditory MMNs were measured from 13 schizophrenic patients on two occasions, initially when they showed acute exacerbation and later when their symptoms improved. Patients exhibited reduced mean amplitude of the MMN recorded at Fz. There were no significant changes in the amplitude of MMN at Fz between the acute patients and the post-acute patients, despite significant improvement in symptomatology. However, the acute patients showed a significant attenuation of MMN recorded at both mastoids as compared with the post-acute patients. Although the findings of the MMN at Fz support the overall longitudinal stability of MMN deficits in schizophrenia, the acute phase patients showed a modestly altered MMN activity compared with the post-acute phase patients, suggesting that there is some state-dependent modulation of these deficits.