Authors:

Grace Ann Kowis

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This study investigates the role of cumulative metal exposure- specifically lead (Pb)-in relation to neurodegeneration in an elderly population, with a focus on Alzheimer's disease (AD). Lead is a well- established neurotoxin associated with various adverse health effects, including cognitive decline. While animal studies have demonstrated promising associations between heavy metal exposure and the development of AD- or Parkinsons disease (PD)-associated neuropathology, they cannot confirm the presence of these neurodegenerative disorders. Human-based research remains limited and often inconclusive. To address this gap, we utilized both a portable X-ray fluorescence (pXRF) device and a benchtop XRF system to non- invasively measure lead concentrations in skull bones from 191 elderly human donors, including individuals diagnosed with AD. Bones were scanned for 12 minutes using the pXRF and for 7 minutes using the benchtop XRF. Data were processed and analyzed using MATLAB to quantify Pb concentrations, while statistical analysis was conducted in R using parametric and non-parametric tests such as ANOVA, Kruskal- Wallis, Wilcoxon rank-sum, and Spearman correlation. The averaged Pb concentrations were compared across biological sex and APOE genotype. Associations between bone Pb levels and cognitive diagnosis, as well as neuropathological markers, were also examined. Preliminary results show that males had higher average bone Pb levels than females (pXRF p-value = 0.00162, benchtop p-value 0.00205).This can be attributed to higher rates of bone resorption during female menopause, which can release Pb from bone into the bloodstream. Additionally, while a trend was observed between elevated bone Pb levels and certain cognitive and neuropathological markers, the association with APOE genotype was weaker than expected (ANOVA p-value = 0.851). This provides limited support for the hypothesis that APOE genotype influences Pb accumulation. However, as this study only examined one genetic factor and one environmental exposure, further research is needed before broader conclusions about gene-environment † Presenting Undergrad Author; ‡ Contributing Undergrad Author; * Undergrad Acknowledgment interactions in AD can be made. These findings are still under analysis, and continued statistical investigation is necessary to draw definitive conclusions. Keywords: Lead (Pb); Alzheimer's Disease (AD); X-Ray Fluorescence (XRF); Apoe Genotype; Neurodegeneration

Source:

Purdue University / 2025

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Co-authors:

Grace Ann Kowis