125. Deficits in Complex Deviance Detection in First-Episode Schizophrenia

Abstract

Background: Complex pattern deviance may be more suitable for elucidating subtle deficits in auditory perception at first-episode compared to single-tones deviance detection and may be a useful biomarker for presence the of schizophrenia.

Methods: We measured MMN to an extra tone among standard groups of 3 tones (1 kHz, 50 ms duration, 5 ms rise/fall, 80 dB, 330 ms SOA, 800 ms ITI) in 24 individuals at their first episode of schizophrenia (within 6 months of first-episode; FE), 23 healthy controls matched to the FE group (HCFE), 24 individuals with long-term schizophrenia (minimum 5 years of diagnosis; SZ), and 23 healthy controls matched to the SZ group (HCSZ).

Results: For the complex extra tone MMN, all groups produced an early MMN (more sensory-driven; ~140 ms after deviant onset), but the late MMN (more cognitively driven, ~400 ms after deviant onset) was significantly blunted in SZ (P = .043) and in FE (P = .003) compared to their matched controls.

Conclusion: Together, this suggests deficits in top-down deviance detection in FE, and relatively intact sensory-driven deviance detection, by contrast with SZ, where sensory and cognitive MMN are impaired. Complex late MMN may be a more powerful biomarker for indicating disease presence. To verify this, the next step will be to measure complex MMN in prodromal individuals.