Abstract: Background: Cognitive deficits in learning, memory, attention, executive functioning, spatial working memory and cognitive processing speed are core features of schizophrenia, which may be associated with clinical variables. However, the pathological mechanisms of cognitive deficits in schizophrenia are still unclear. We have investigated the demographic and clinical characteristics that may be related to cognitive deficits and their possible underlying mechanism in schizophrenia. Methods: We examined the cognitive functions in both chronic medicated and first-episode drug-naïve schizophrenia patients versus healthy controls by using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) or the MATRICS Consensus Cognitive Battery (MCCB). We assessed patient psychopathology using the Positive and Negative Syndrome Scale. At the same time, some biomarkers in serum and the related gene polymorphisms were measured in both groups. Results: We found significantly lower cognitive scores on the RBANS or MCCB total score and mostly of their subscales in both chronic and first-episode patients than healthy controls.  Compared to first-episode patients, chronic patients displayed worse cognitive performance in some domains. Some clinical variables, such as clinical symptoms, tardive dyskinesia, smoking, and comorbid diabetes were associated with cognitive impairments in schizophrenia patients.  Meanwhile, some biomarkers such as BDNF, cytokine, and free radical parameters were found to be associated with cognitive deficits in patients. Also, some gene polymorphisms, such as BDNF and MnSOD were also involved in cognitive deficits in patients. Conclusions: The extensive compromised cognition is present in the early stage of schizophrenia, some of which could be more severe in the chronic stage of illness. Some demographic and clinical variables are risk factors for cognitive deficits in schizophrenia. Some biomarkers may play important roles for the cognitive impairments in schizophrenia.

Key words: Schizophrenia, cognition, clinical correlate, biomarker, gene polymorphism