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Associations of blood heavy metals with cognitive function in older US adults: single and mutually adjusted effects.

  • 2026-05-27
  • Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology 47(6)
    • Na Wang
    • Liang Guo
    • Menglian Shi
    • Long Wang
    • Ying Zhou
    • Huanbing Liu
    • Xinqun Xu

Study Design

Type
Observational
Sample size
n = 1,460
Population
1460 participants aged ≥ 60 years
Methods
Observational study utilizing data from NHANES between 2011 and 2014; blood heavy metals measured by ICP-MS; cognitive function assessed by IRT, DRT, AFT, DSST; linear regression, RCS, subgroup analyses
Funding
Unclear

Background

Heavy metal exposure has been associated with various diseases. The purpose of this study was to determine the single and mutually adjusted associations between blood heavy metals and cognitive function in older adults.

Methods

This observational study utilizes data from the National Health and Nutrition Examination Survey (NHANES) between 2011 and 2014 and involved 1460 participants aged ≥ 60 years. The concentrations of blood lead (Pb), cadmium (Cd), mercury (Hg), selenium (Se), and manganese (Mn) were measured using inductively coupled plasma mass spectrometry (ICP-MS). Cognitive function was assessed using the Immediate Recall Test (IRT), delayed recall test (DRT), animal fluency test (AFT), and digit symbol substitution test (DSST). Mutually adjusted linear regression models, restricted cubic spline (RCS) analyses, and subgroup analyses were performed to evaluate individual and mutually adjusted associations between blood metal concentrations and cognitive function.

Results

Multiple linear regression analysis revealed an inverse association between Cd concentrations and cognitive scores (β=-2.698, 95% CI: -4.842, -0.554). Blood Se levels were positive associations with cognitive scores (β = 0.049, 95% CI: 0.022, 0.076) and all four cognitive domains. The RCS showed that the dose-response association between Cd and cognitive scores appeared to be linear (P-nonlinear = 0.566), while Se exhibited a left-skewed inverted U-shaped curve with cognitive scores (P-nonlinear = 0.013).

Conclusions

A high concentration of Cd is strongly associated with cognitive decline. However, the protective effect of Se on cognitive function plateaus after reaching a certain concentration. These findings may have significance for the development of interventions aimed at alleviating cognitive impairment.

Research Insights

  • Manganese→Reduced Cognitive Function

    The abstract does not report a separate significant association for manganese in the mutually adjusted model; null finding implied.

    Effect
    Neutral
    Effect size
    Small
  • Selenium→Improved Cognitive Function

    Blood Se levels were positive associations with cognitive scores (β=0.049, 95% CI: 0.022, 0.076) and all four cognitive domains.

    Effect
    Beneficial
    Effect size
    Small
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