Relationship between renal function and cognitive impairment in patients with stable schizophrenia: a multicenter cross-sectional study.

Objective: Clinically stable inpatients with schizophrenia have generalized impairment of cognitive function along with abnormalities in renal function, but the link between cognitive function and renal function has been underexplored.

Methods: This study enrolled 216 hospitalized patients with clinically stable schizophrenia. Demographic and renal function parameters were collected from electronic medical records. Cognitive function was assessed using the Chinese Brief Cognitive Test (C-BCT). To analyze the correlations between renal function and processing speed, attention, working memory, and executive function in patients hospitalized with clinically stable schizophrenia. Covariate-adjusted linear and multivariate logistic regression models were constructed to determine the relationship between renal function and cognitive function. ROC analysis was used to further investigate the prediction of renal function indices in assessing stable schizophrenia inpatients.

Results: Significant variations in serum Cystatin C (CysC), β2-microglobulin (β2-MG), and uric acid (UA) levels were observed among hospitalized patients with clinically stable schizophrenia across different cognitive impairment severities. Correlation analysis revealed a significant association between serum CysC levels and C-BCT scores in hospitalized patients with stable schizophrenia (β = 0.174, 95%CI:0.265 ~ 1.720, p = 0.008). Particularly strong correlations were observed with processing speed T-scores (β = -0.200, 95%CI: -33.446 ~ -7.230, p = 0.03) and executive function T-scores (β = -0.171, 95%CI: -17.277 ~ -2.082, p = 0.013). Binary logistic regression analysis further confirmed that CysC may be a risk factor for exacerbation of cognitive impairment in stable schizophrenia (OR = 12.741, 95%CI: 1.424 ~ 114.005, p = 0.023). The combined serum CysC, β2-MG, and UA test for cognitive function in stable schizophrenia inpatients had an AUC area of 0.71, with a sensitivity and specificity of 79.5% and 60.5%, respectively, and a predictive value superior to that of an independent diagnosis.

Conclusion: In hospitalized patients with stable schizophrenia, serum CysC levels are positively correlated with the severity of cognitive impairment, particularly showing significant associations with information processing speed and executive function. CysC may be a risk factor for exacerbating cognitive impairment in these patients. The combined diagnostic value of serum CysC, β2-MG, and UA demonstrated moderate accuracy in identifying stable schizophrenia cognitive impairment. These data support the potential of CysC as a biomarker of cognitive function in stable schizophrenia.