Association Between Blood Heavy Metal Levels and Cognitive Impairment in Elderly Patients with CKD: NHANES, 2011-2014

Background: This study aimed to investigate the association between blood heavy metal levels and cognitive impairment (CI) in elderly patients with chronic kidney disease (CKD). Methods: Patient data was extracted from the 2011-2014 National Health and Nutrition Examination Survey (NHANES). Four cognitive tests were administered: the consortium to establish a registry for Alzheimer’s disease (CERAD) delayed recall and word learning tests, the animal fluency test (AFT), and the digit symbol substitution test (DSST). Spearman correlation, logistic regression analyses and restricted cubic spline (RCS) models were employed to evaluated the relationship between variables. Additionally, Stratified analyses explored associations between blood lead (Pb) levels and CI across subgroups. Results: This analysis included 628 CKD patients aged ≥60 years. We found that mercury (Hg), selenium (Se), and manganese (Mn) were positively correlated with DSST score. However, no significant monotonic relationship was observed between blood Pb levels and DSST score. Adjusted logistic regression showed no significant associations between cadmium (Cd), Hg, Mn, Se, and CERAD, AFT, or DSST scores. Notebally, blood Pb levels were significantly associated with the DSST scores, with RCS analysis suggesting a "J-shaped" relationship. In subgroup analyses, elevated blood Pb levels were associated with CI by DSST scores in male participants, drinkers, smokers, hypertensive individuals, nondiabetics, those with UACR < 30 mg/g, and patients with 30 ≤ eGFR < 90 mL/min/1.73 m2. Conclusion: Our study suggested that blood Pb levels may be linked to an increased risk of cognitive decline in elderly CKD patients. Reducing Pb exposure could potentially benefit cognitive function in this population. Funding: Government Support – Non-U.S.Restricted cubic spline (RCS) plot of the association between blood Pb levels and CI in elderly CKD patients.