Abnormal pitch mismatch negativity in individuals with schizotypal personality disorder

Abstract

Background: The goal of the study was to examine mismatch negativity (MMN) in schizotypal personality disorder (SPD) individuals. Abnormal MMN has been a consistent finding in chronic schizophrenia and there are also have been reports of reduced duration MMN in first episode schizophrenia patients (Umbricht & Krljes, 2005), with some studies finding no pitch MMN amplitude differences (Salisbury et al., 2002) while others reporting a modest reduction (Umbricht et al., 2006) in recent onset schizophrenia patients. To our knowledge no reports exist of MMN in SPD individuals. Methods: Twenty six normal (14 females) control and 23 SPD (12 females) individuals were tested using the pitch MMN paradigm. Normal control (NC) and SPD individuals were recruited from the general population and assessed using DSM-IV. SPD individuals were included if they met 5 or more criteria for SPD disorder. The subjects listened to 2000 frequent 1 kHz pure tones and 100 rare 1.2 kHz pure tones while reading a magazine article. MMN was measured from a difference waveform within the latency window of 175–276 msec. Results: Reduced MMN amplitude was found in SPD relative to NC subjects (p< 0.045). Conclusions: These results point to potential differences between SPD and schizophrenia, where no reduction in MMN was found in most studies of first episode patients.