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 elicited by repeated rare deviants (conventional MMN), we investigated novelty-elicited MMN and P3a in patients with schizophrenia before and after a nonstandardized inpatient treatment. DESIGN Electrophysiological and clinical assessment of patients on admission and discharge from hospital. Assessment of control subjects on 2 sessions. SETTING Inpatient treatment in a psychiatric 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 component MMN amplitudes and latencies, P3a amplitudes and latencies, Positive and Negative Syndrome Scale (PANSS), Global Assessment of Functioning (GAF), Extrapyramidal Symptom Scale (EPS), Abnormal Involuntary Movement Scale (AIMS) and chlorpromazine equivalents. RESULTS In patients with schizophrenia, novelty-elicited MMN was unimpaired on admission, and there was a statistically 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 information processing between conventional and novelty-elicited MMN. Some components of the novelty-elicited MMN might be more state dependent than those of the conventional MMN.