Objective:To explore the correlation between the expression level of the serum CircRNA_ 0005853 and cognitive impairment in elderly patients with acute cerebral infarction (ACI).Methods:A total of 120 elderly patients with ACI admitted to Haikou Third People′s Hospital from January 2019 to March 2022 were retrospectively selected. According to the Montreal Cognitive Assessment (MoCA) score of the patients 4 weeks after treatment, they were divided into a cognitive impairment free group (MoCA score≥26, 55 cases) and a cognitive impairment group (MoCA score<26, 65 cases). The cognitive impairment group was redivided into mild group (MoCA score 21-25, 16 cases), moderate group (MoCA score 15-20, 38 cases), and severe group (MoCA score<15, 11 cases) based on the severity of cognitive impairment. The serum CircRNA_0005853 expression level of each group was compared. multivariate logistic regression analysis was applied to identify the risk factors for cognitive impairment after ACI. A receiver operating characteristic (ROC) curve was drown to analyze the value of CircRNA_0005835 expression level in predicting cognitive impairment. Using Pearson correlation analysis, the correlation between the expression level serum CircRNA_0005835 and MoCA score in patients with cognitive impairment was analyzed.Results:There were statistically significant differences in age, infarct size, and triglycerides between the cognitive impairment group and the non cognitive impairment group (all P<0.05). The MoCA score of the cognitive impairment group was lower than that of the non cognitive impairment group [(19.62±2.73)points vs (28.10±1.05)points, P<0.001]. The expression level of Serum CircRNA_0005835 in the cognitive impairment group was higher than that of the non cognitive impairment group (2.48±1.02 vs 1.25±0.46, P<0.001), and in the severe group, the expression level of the serum CircRNA_0005835 (2.90±1.26) was higher than that of the moderate group (1.87±0.84) and the mild group (0.92±0.35) ( P<0.001). Multivariate logistic regression analysis shew that age ( OR=1.662, 95% CI: 1.140-2.873), infarct size>3.0 cm 2 ( OR=1.853, 95% CI: 1.317-4.112), and CircRNA_0005835 ( OR=2.217, 95% CI: 1.635-5.540) were risk factors for cognitive impairment after ACI. The area under the curve (AUC) of CircRNA_0005835 expression level predicting cognitive impairment was 0.837(95% CI: 0.779-0.894), with a sensitivity of 80.2% and a specificity of 83.7%. The AUC of CircRNA_0005835 expression level predicting cognitive impairment was 0.837(95% CI: 0.779-0.894), with a sensitivity of 80.2% and a specificity of 83.7%. The correlation analysis shew that the expression level of serum CircRNA_0005835 in elderly ACI patients was negatively correlated with MoCA score ( r=-0.773, P<0.001). Conclusions:The increased expression level of serum CircRNA_0005853 is related to the occurrence and development of cognitive dysfunction after elderly ACI, and has certain value in predicting cognitive dysfunction.