[Correlation of serum level of homocysteine and insulin resistance with cognitive dysfunction in first-episode schizophrenics]

Abstract

Objective: To explore the relationship of serum level of homocysteine (Hcy) and insulin resistance with cognitive function in first-episode drug-free schizophrenics. Methods: A total of 80 first-episode drug-free schizophrenics (schizophrenia group) from the First Affiliated Hospital of Zhengzhou University and 70 healthy individuals (control group) were enrolled.The serum concentration of Hcy was measured by the enzymatic cycling assay, the concentration of serum fast blood-glucose(FPG) by glucose oxidase method and fast insulin (FINS) by electrical chemiluminescence immunoassay.Then insulin resistance index was calculated in the form of HOMA-IR.Positive and Negative Syndrome Scale (PANSS) was used to evaluate the mental symptoms and Matrics Consensus Cognitive Battery (MCCB) was used to evaluate the cognitive function. Results: (1) The serum level of Hcy in schizophrenia group [(24±6) μmoL/L]was significantly higher than that in control group[(16±4) μmoL/L] (P<0.001). And the serum level of FINS in schizophrenia group [(8.0±2.1) mU/L] was significantly higher than that in control group[(6.0±1.3) mU/L] (P<0.001). The HOMA-IR of schizophrenia group (1.6±0.5) was higher than that of control group (1.3±0.4) (P<0.001). The serum level of Hcy in schizophrenia group had positive correlations with serum FINS level, HOMA-IR and negative symptoms (r=0.365, 0.354 and 0.233, all P<0.05). In comparison with the control group , scores were significantly lower in the seven domains of cognitive function in the schizophrenia group (all P<0.05). (2) In schizophrenia group, the serum level of Hcy had a negative correlation with Information processing rate P points, Attentional facilitating P points , and Verbal learning P points (r=-0.231, -0.339, -0.255, all P<0.05); the serum level of FINS was negatively related to Attentional facilitating P points, Working memory P pointsand Visual memory P points (r=-0.317, -0.309, -0.318, all P<0.05); HOMA-IR had a negative correlation with Attentional facilitating P points, Working memory P points, and Visual memory P points (r=-0.286, -0.224, -0.266, all P<0.05). After the influencing factors were adjusted by multiple regression, the associations of serum Hcy level with Information processing rate P points, Attentional facilitating P points and Verbal learning P points were still evident, and HOMA-IR was still related with Attentional facilitating P points and Visual memory P points (all P<0.05). Conclusion: The increase of serum Hcy and insulin resistance in first-episode schizophrenics, both have some relevance with cognitive dysfunction.

Keywords: Cognitive function; Homocysteine; Insulin resistance; Schizophrenia.