Auditory mismatch negativity, P300, and disability among first-episode schizophrenia patients without auditory hallucinations

Abstract

Objectives The aim of this study was to determine the functional deficits, including the inter-related domains of attention, memory, and information processing, among first-episode schizophrenia patients without auditory hallucinations. Such deficits could be evaluated objectively utilizing measurements of auditory-evoked potentials. Patients and methods The study sample consisted of two groups: group I included 58 first-episode schizophrenia patients without auditory hallucinations recruited from the psychiatric outpatient's clinics of Zagazig University Hospitals and group II included 53 participants selected randomly from Zagazig University Hospitals' visitors. Patients were subjected to a semistructured psychiatric interview using DSM-IV criteria for diagnosis, and auditory mismatch negativity (MMN) and P300 were assessed in schizophrenia patients before and after treatment. The degree of disability was assessed and its correlation with auditory processing function was determined. Results Our study showed no statistically significant difference as regards MMN measures with any observable effect of atypical antipsychotics; the P300 component showed delayed latency and smaller amplitude before treatment and markedly enhanced after treatment, and there was statistically significant correlation between the degree of disability and MMN, as well as P300 measures, before and after treatment. Conclusion The current study concluded that the attention-dependent processes reflected in P300 measures are already defective during the early stage of schizophrenia and could be improved with the use of an atypical antipsychotic medication.