Uncovering the Relationship between Heavy Metal Exposure, Cognitive Function, and Dietary Inflammation Index in Elderly Americans from the National Health and Nutrition Examination Survey 2011-2014

Abstract

Background The consequences of heavy metal exposure on cognitive function in elderly adults have been recognized as primarily attributed to the inflammatory response. It is noteworthy that diet can either exacerbate or reduce the inflammatory response. Despite this, there has been limited study about the effects of diet on the relationship between heavy metal exposure and cognitive function. Methods A cross-sectional study was conducted utilizing data from the 2011–2014 NHANES survey to explore the role of the dietary inflammation index in the association between metal exposure and cognitive function in elderly adults. The study enrolled 1726 participants and generalized linear regression model(GLM), Bayesian kernel machine regression model(BKMR), weighted quantile sum regression(WQS), and quantile g-computation regression analysis(Qg-comp) was conducted to assess the impact of five heavy metals in blood on cognitive function under the anti-inflammatory and pro-inflammatory diet. Results The GLM analysis showed a positive correlation between selenium (Se) and both the instant recall test (IRT) and digit symbol substitution test (DSST), whether taken as continuous or quartile variables.Conversely, cadmium (Cd) was negatively associated with DSST. For IRT, Cd in the highest quartile was negatively associated compared to the lowest quartile. Subgroup analysis revealed the effects of Cd on IRT and DSST and Se on DSST under the pro-inflammatory diet. Furthermore, The BKMR analysis showed an inverted U-shaped curve with the negative effect of metal mixtures and DSST and a linearly negative trend with IRT in the pro-inflammatory diet. Among them, Cd was emphasized as the most potent risk factor, and Se was the most vital protective factor for IRT and DSST in WQS and Qg-comp analysis. Conclusions The study suggests that a high-quality diet could alleviate the adverse effects of Cd on IRT and DSST. Additionally, high Se levels improved IRT and DSST in the inflammatory diet. These findings provide valuable insights into the connection between diet, heavy metal exposure, and cognitive function in elderly adults.