Examining the associations between toxic heavy metal exposure and Alzheimer’s Disease

My name is Ryan Turlip, and I am a rising Senior at the University of Pennsylvania. I am originally from Scranton, Pennsylvania, and I study Neuroscience with minors in Chemistry and Health Services Management. At Penn, I have always been interested in how environmental and social factors affect health. This Summer, I had the opportunity to expand upon these interests by working with Dr. Jianghong Liu in the STEER program. 

What is your summer research project?

Combining my background in Neuroscience and neurodegenerative diseases with Dr. Liu’s specialty in environmental health, I conducted a systematic review measuring the associations between toxic heavy metal exposure and Alzheimer’s Disease (AD). Non-essential heavy metals, such as Aluminum, Cadmium, Mercury, and Lead, have long been implicated in leading to AD pathology. However, the results are largely contradictory and inconclusive. The goal of this systematic review was to analyze the current evidence in the scientific literature to provide a consensus for each metal’s role in AD.

In this project, I retrieved articles from several online databases and sorted the studies based on agreed-upon inclusion criteria. After excluding irrelevant articles, I was left with a cohort of 41 studies with similar methodologies from which I could directly compare. Our included articles either measured heavy metal levels through in vivo circulatory samples of biological fluids (e.g. blood, plasma, cerebrospinal fluid, etc) or post-mortem autopsy samples of brain tissue. We stratified our results based on these differing sample methods and organized them by metal. Further information from each article was then gathered and analyzed both quantitatively and qualitatively.

What are the implications of your research?

The prevalence of AD is extensive, as over five million adults above the age of 65 have an AD diagnosis in the United States, and it is the 5th leading cause of death among this group. Further, we are exposed to toxic heavy metals through many facets of our everyday lives. Whether it be the foods we eat, the water we drink, or the air we breathe, non-essential metals are entering the human body constantly, especially if the geographical area is polluted.

Since prior research has shown correlations between non-essential heavy metals and AD neuropathology, it is crucial to elucidate this connection. By understanding how toxic heavy metal imbalances affect AD development, it could lead to new therapeutic targets to slow the disease progression. Further, it has the potential to guide future environmental health policies to limit the levels of toxic metals that individuals are exposed to.

What new skills have you gained through your research?

This project allowed me to strengthen my prior foundation in literature reviews. I gained the ability to analyze current literature to find gaps in what was being studied to contribute meaningfully to the field. From this, I learned how to synthesize a project from its conception and see it through to its completion. Additionally, this project taught me how to scrutinize the quality and methodologies of previously published studies that may have impacted their results. By synthesizing these evaluations, I was able to draw extensive conclusions in my project. Most importantly, I learned how to craft a narrative during manuscript writing to present the results of our study in a meaningful and impactful manner.