Background: Patients with atrial fibrillation (AF) is linked to increased risk of cognitive dysfunction, and serum uric acid levels plays an important factor in cognitive dysfunction. However, optimal serum uric acid levels in patients with AF remains unclear. Therefore, we aimed to explore the relationship of serum uric acid and cognitive dysfunction in patients with AF. Methods: 583 patients were conducted in the Affiliated Hospital of Jining Medical University, Shandong Province, China from February 2020 to November 2022. Cognitive dysfunction was assessed by Montreal Cognitive Assessment (MoCA). The relationship between serum uric acid levels and the risk of cognitive dysfunction in patients with AF was analyzed using smoothing spline fitting model and threshold analysis. Results: The average serum uric acid levels of 583 patients was (383.26±110.11)μmol/l, and the incidence of cognitive dysfunction was 79.76%. There was a non-linear relationship between serum uric acid levels and the risk of cognitive dysfunction in patients with AF, and the inflection point was 352μmol/l. At the left of the inflection point, the relationship was significant (OR=1.02, 95%CI=1.00-1.04). At the right of the inflection point, there was no statistical difference (P=0.101). Conclusion: When the serum uric acid levels is less than 352 μmol/L, the risk of cognitive dysfunction increases by 2% for each unit increases in serum uric acid levels in patients with AF. The study provides evidence for the treatment of serum uric acid levels in patients with AF.

Background. Evidence regarding the relationship between body mass index (BMI) and cognitive function was limited. Therefore, the objective of this research is to investigate whether BMI is independently related to cognitive function in Chinese patients with atrial fibrillation after adjusting for other covariates. Methods. The present study is a cross-sectional study. A total of 281 patients with atrial fibrillation who were hospitalized at the Affiliated Hospital of Jining Medical University in Shandong Province from January 2021 to November 2021 were included in the study. The target independent variable and the dependent variable were BMI and cognitive function in patients with atrial fibrillation, respectively. The patients’ general information, BMI, past history, medication history, and other disease-related data were collected. The Montreal cognitive assessment scale (MoCA) was used to evaluate cognitive function. Results. A total of 244 patients with atrial fibrillation were collected in this study, with an average age of (67.28 ± 10.33) years, of whom 55.3% were male. The average BMI was (25.33 ± 4.27) kg/m2, and the average cognitive function score was (19.25 ± 6.88) points. The results of the smooth curve fitting and threshold effect tests showed that there was a curve correlation between BMI and cognitive function score, and its inflection point was 24.56 kg/m2. To the left of the inflection point, the relationship was significant; the effect size and the confidence interval were 0.43 and 0.01–0.85, respectively. To the right of the inflection point, there was no significant correlation between BMI and cognitive function ( P = 0.152 ). Conclusion. When BMI is lower than 24.56 kg/m2, the cognitive function score increases by 0.43 points for each unit increase in BMI in patients with atrial fibrillation. An increase in BMI at this time is a protective factor for cognitive function. Within the normal range of BMI, the higher the BMI in atrial fibrillation patients, the higher the cognitive function score. We encourage atrial fibrillation patients with normal BMI to maintain their current weight.