Unique contributions of sensory discrimination and gamma synchronization deficits to cognitive, clinical, and psychosocial functional impairments in schizophrenia

Abstract Background Schizophrenia patients show widespread deficits in neurocognitive, clinical and psychosocial functioning. Mismatch negativity (MMN) and gamma-band auditory steady-state response (ASSR) are robust biomarkers for domains of neuropsychiatric disorders that are impaired in schizophrenia patients and are separately associated with cognitive dysfunction, negative symptom severity and psychosocial disability. Although these measures of early auditory information processing are conceptually linked, it is unclear, whether these measures are redundant or account for unique variance in important outcome measures. In this study, we aimed to determine whether MMN and gamma-band ASSR are associated with cognitive, clinical, and functional variables and, if so, whether they account for shared vs. non-shared variance in those important domains. Methods Multiple regression analyses with MMN, gamma-band ASSR and clinical measures were performed in large cohorts of schizophrenia outpatients (N=428) and healthy comparison subjects (N=283). Results Reduced MMN ( d = 0.67), gamma-band ASSR ( d = –0.40), and lower cognitive function were confirmed in schizophrenia patients compared to healthy comparison subjects. Regression analyses revealed that both MMN and gamma-band ASSR have significant unique associations with tasks measuring of working memory, and daily functioning in schizophrenia patients. Conclusion These findings suggest that MMN and ASSR measures are non-redundant and complementary measures. Studies are needed to clarify the neural substrates of MMN and gamma-band ASSR in order to improve our understanding of pathophysiology of schizophrenia and accelerate their use in the development of novel therapeutic interventions.