Mismatch negativity deficits in schizophrenia and bipolar disorder

Objectives: Numerous studies have demonstrated mismatch negativity (MMN) deficits in schizophrenia (SCZ), and growing evidence suggests similar deficits in bipolar disorder (BPD). However, no large-scale MMN study has been conducted on Chinese patients with SCZ and BPD. This study aims to validate the presence of MMN deficits in SCZ patients and assess whether BPD patients exhibit similar deficits, using a large-scale Chinese cohort. Methods: MMN data, Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) scores, and other clinical interview and assessment data were collected from participants (SCZ: n = 208; BPD: n = 144; healthy controls (HC): n = 324). Analysis of covariance (ANCOVA) was used to examine group differences in MMN amplitudes/areas, with age and gender as covariates. Additionally, correlation analyses were performed to explore the relationships between MMN amplitudes/areas and clinical assessments. To further investigate neural processing, event-related spectral perturbation (ERSP) and inter-trial phase coherence (ITC) analyses within the theta and alpha frequency bands were conducted for both standard and deviant stimuli in the duration MMN (dMMN) and frequency MMN (fMMN) paradigms. Results: ANCOVA results for dMMN and fMMN amplitudes/areas, adjusted for age and gender, revealed significantly smaller MMN amplitudes in both SCZ and BPD groups compared to HC. Strong and significant correlations were observed between MMN mean amplitude and peak amplitude/area for both dMMN and fMMN. ERSP and ITC analyses showed that SCZ patients exhibited significantly reduced theta and alpha ITC and ERSP compared to HC. BPD patients also demonstrated reductions in these measures, though to a lesser extent. Negative correlations between MMN mean amplitude and both ERSP and ITC were found across all groups. In SCZ patients, the mean amplitude of dMMN was negatively correlated with RBANS scores. Conclusions: Our results demonstrate MMN deficits in both SCZ and BPD patients within a large Chinese cohort. The ERSP and ITC analyses highlight the importance of theta and alpha oscillations in auditory processing and reveal distinct neural processing differences between clinical groups and HC.