First stages chronic kidney disease have mild effects on cognitive performance. Results of a 15,105 brazilian adult baseline cohort

Abstract Introduction: The aging of the population may lead to an increased prevalence of dementia and chronic kidney disease (CKD) and their overlap. Objective: We investigated the association between CKD and cognitive performance among Brazilian adults (35-74 years). Methods: Baseline data analysis of the Longitudinal Study of Adults (ELSA-Brasil), a multicenter cohort comprising 15,105 civil servants, was performed. Kidney function was defined by the CKD-Epi-estimated GRF and albumin creatinin ratio (ACR). Cognitive performance was measured across tests that included the word memory tests, verbal fluency tests and Trail Making Test B. Multiple logistic and linear regressions were used to investigate the association between CKD and global as well as test-specific lowered cognitive performance. Results: More than 90% of participants did not present CKD even considering reduced GFR or increased ACR simultaneously. Lowered cognitive performance was detected among 15.8% of the participants and mean values of GFR were slightly higher among those with normal than with lowered cognitive performance (86 ± 15 mL/min/1.73 m2 x 85 ± 16 mL/min/1.73 m2, p < 0.01). Age, education, skin-color, smoking, drinking, hypertension, and diabetes were associated with lowered cognition. After adjustment for these variables, there was no association between CKD and lowered cognitive performance. Negligibly small beta values were observed when analyzing CKD and the scores of all tests. Conclusion: These results suggest that cognitive performance remains preserved until renal function reaches significant worsening. Preventive measures to maintain renal function may contribute to the preservation of cognitive function.

【摘要与研究背景】人口老龄化可能导致痴呆症与慢性肾脏病（CKD）的患病率上升，且二者的共病情况也会增加。研究目的：本研究旨在探讨巴西35~74岁成年人群中慢性肾脏病（CKD）与认知功能表现的关联。研究方法：本研究对多中心队列研究「巴西成人纵向研究（ELSA-Brasil）」的基线数据进行分析，该队列共纳入15105名公职人员。肾脏功能以CKD流行病学合作组（CKD-Epi）公式估算的肾小球滤过率（GRF）与尿白蛋白肌酐比值（ACR）进行评估。认知功能表现通过多项测试进行评估，包括词语记忆测试、言语流畅性测试以及连线测验B型（Trail Making Test B）。本研究采用多元logistic回归与线性回归模型，探讨CKD与整体认知功能下降以及各单项测试认知表现降低之间的关联。研究结果：同时合并估算肾小球滤过率降低与尿白蛋白肌酐比值升高的情况下，仍有超过90%的受试者未罹患CKD。15.8%的受试者存在认知功能下降；认知功能正常者的平均肾小球滤过率略高于认知功能下降者（86±15 mL/min/1.73m² vs 85±16 mL/min/1.73m²，p<0.01）。年龄、受教育程度、肤色、吸烟、饮酒、高血压与糖尿病均与认知功能下降存在关联。在对上述变量进行校正后，CKD与认知功能下降之间不再存在显著关联。在分析CKD与各项测试得分的关联时，得到的β值极小，可忽略不计。研究结论：本研究结果提示，在肾脏功能出现显著恶化前，认知功能可维持正常水平。维持肾脏功能的预防措施或有助于认知功能的保护。