[Correlation of the peripheral serum complement protein levels and cognitive function in first-episode drug-naive...

Objective: To explore the role of peripheral serum complement protein in the pathogenesis of cognitive impairment by analyzing the correlation between peripheral serum levels of complement protein and cognitive function in first-episode drug-naive patients with schizophrenia. Methods: A total of 66 first-episode drug-naive schizophrenics (schizophrenia group) from the Third Affiliated Hospital of Sun Yat-sen University and 88 healthy volunteers (control group) were enrolled. Peripheral serum levels of complements (C3, C4 and CH50) were separately examined by liposome immunoassay and turbidimetric inhibition immunoassay. The MATRICS Consensus Cognitive Battery (MCCB) was used to assess the cognitive function. Results: Peripheral serum levels of C4, but not C3 and CH50, were significantly lower in patients with schizophrenia [0.20(0.16, 0.25) g/L] than those in the control group [0.23 (0.19, 0.27) g/L] (P<0.05). Moreover the peripheral serum levels of C3, C4 and CH50 were positively correlated with MCCB verbal fluency (r=0.258, r=0.283 and r=0.330, all P<0.05), and the peripheral serum levels of CH50 were negatively correlated with attention and alertness (r=-0.257, P<0.05). Conclusion: The decrease of peripheral serum complement C4 protein levels may be involved in the mechamism of cognitive impairment in schizophrenia.