Equivalent mismatch negativity deficits across deviant types in early illness schizophrenia-spectrum patients

Abstract

Neurophysiological abnormalities in auditory deviance processing, as reflected by the mismatch negativity (MMN), have been observed across the course of schizophrenia. Studies in early schizophrenia patients have typically shown varying degrees of MMN amplitude reduction for different deviant types, suggesting that different auditory deviants are uniquely processed and may be differentially affected by duration of illness. To explore this further, we examined the MMN response to 4 auditory deviants (duration, frequency, duration+frequency "double deviant", and intensity) in 24 schizophrenia-spectrum patients early in the illness (ESZ) and 21 healthy controls. ESZ showed significantly reduced MMN relative to healthy controls for all deviant types (p<0.05), with no significant interaction with deviant type. No correlations with clinical symptoms were present (all ps>0.05). These findings support the conclusion that neurophysiological mechanisms underlying processing of auditory deviants are compromised early in illness, and these deficiencies are not specific to the type of deviant presented.

Keywords: Auditory cortex; Event-related potential; MMN; Mismatch negativity; Schizophrenia-spectrum.

Figure 1

Mismatch negativity (MMN) for each group and deviant type. Ear-referenced event-related potential (ERP) difference waveforms averaged at Fz for frequency-deviant, frequency + duration double-deviant, duration-deviant, and intensity-deviant MMN are given for each group (top). Healthy controls (HC) are shown in blue and early illness schizophrenia patients (ESZ) in red. Scalp voltage topography maps of MMN amplitudes are shown for HC (middle) and ESZ (bottom) for each deviant type. MMN topography maps show the group means of MMN amplitudes around the peak latency ±10 ms (indicated by gray bars in ERP difference waveform plots). MMN is reduced in ESZ relative to HC across deviant types.