Novelty-elicited mismatch negativity in patients with schizophrenia on admission and discharge

Objective: Given recent reports of differences between mismatch negativity (MMN) elicited by always novel sounds (novelty-elicited MMN) and that elici ted by repeated rare deviants (conventional MMN), we investigated novelty-e licited MMN and P3a in patients with schizophrenia before and after a nonst andardized inpatient treatment. Design: Electrophysiological and clinical a ssessment of patients on admission and discharge from hospital. Assessment of control subjects on 2 sessions. Setting: Inpatient treatment in a psychi atric university hospital. Subjects: 20 patients with schizophrenia and 21 healthy control subjects of similar age and sex. Selection of patients with first- to third-episode schizophrenia. Outcome measures: Early and late co mponent MMN amplitudes and latencies, P3a amplitudes and latencies, Positiv e and Negative Syndrome Scale (PANSS), Global Assessment of Functioning (GA F), Extrapyramidal Symptom Scale (EPS), Abnormal Involuntary Movement Scale (AIMS) and chlorpromazine equivalents. Results: In patients with schizophr enia, novelty-elicited MMN was unimpaired on admission, and there was a sta tistically significant reduction of the late MMN component with treatment. Improvements in symptom expression were associated with increased latencies of the early MMN component. Conclusion: Results indicate differences in in formation processing between conventional and novelty-elicited MMN. Some co mponents of the novelty-elicited MMN might be more state dependent than tho se of the conventional MMN.