University of Waterloo: Mariam Malik and Her Insights #3

Hi everyone! I’m Mariam Malik and I am a recent graduate from the University of Waterloo, with Bachelor’s in Honours Health Sciences and Diploma in Gerontology. I am hoping to become a researcher either in health statistics or aging research. In my free time, I love reading and listening to audiobooks and I am always looking for recommendations!

Reviewed Article: A Novel Risk Factor for Dementia: Chronic Microplastic Exposure by Gecegelen et al.

Main Argument & Findings:

Numerous authors and research articles have consistently concluded that dementia is a multifactorial condition. Risk factors for dementia span the physical, mental and social domains. However, more recent research is focusing on the relationship between dementia and the environment. Epidemiological studies have highlighted that air pollution, specifically atmospheric particulate matter exposure (mixture of particles of dust, dirt and liquids that are suspended in the air), increases the risk of dementia, Alzheimer's disease and mild cognitive impairment. Microplastics, a pervasive contaminant increasingly studied in relation to various diseases, are now being proposed as a novel risk factor for dementia. Microplastics are plastic particles smaller than 5mm that can enter the human body through multiple exposure routes (ingestion, inhalation, and dermal/skin contact). These are commonly used in various commercial and industrial applications, such as microbeads in facial washes and plastic production pellets.

Microplastics are also released into the environment as plastics degrade, originating from sources such as bottles, bags, and other plastic products. A surprisingly common source of microplastics is washing and drying synthetic polymer textiles. Studies found that during a normal wash cycle, between 1900 and 700,000 plastic microfibers enter wastewater systems.

Researchers are investigating the role that microplastics may play in the development and progression of various diseases, with neurodegeneration emerging as a key area of concern. Microplastic-induced neurodegeneration occurs through 4 mechanisms: oxidative stress, the neuroinflammatory cascade, accelerated amyloid-beta pathology, and its role as a chemical carrier.

The first, and most researched mechanism of microplastic-induced neurodegeneration, is the oxidative stress pathway. Oxidative stress happens when the body has a high abundance of harmful molecules and not enough antioxidant enzymes to neutralize them. These molecules, also known as free radicals, include reactive oxygen species (ROS) and reactive nitrogen species (RNS). At low levels, free radicals play an integral role in cell signalling and homeostasis. High levels can damage DNA, proteins, and fats, disrupting normal cellular functioning. The nervous system is particularly vulnerable to oxidative stress due to high oxygen consumption and limited antioxidant enzyme activity. Microplastics contribute to neurodegeneration in two ways: they promote ROS production and deplete antioxidant enzymes needed to neutralize them, leading to neural inflammation, damage, and dysfunction. Experiments in mice have shown that microplastics increase neural inflammation and damage specific brain regions. The damage was reversed when antioxidant enzymes were introduced, indicating that the brain was experiencing oxidative stress.

In addition to oxidative stress, microplastics trigger a neuroinflammatory cascade in the brain (a chain reaction of immune responses that are triggered in the brain, leading to inflammation and neuron damage). The neuroinflammatory cascade is activated by microglia, the primary immune cells of the nervous system. Studies have found that microplastics directly activate microglia and increase the number of inflammatory molecules in the brain. Ultimately, this disrupts synaptic transmission, disrupts plasticity and increases the permeability of the blood-brain barrier (which increases the likelihood of other toxic chemicals entering the brain and causing harm). One of the most notable features of microplastic-induced neurodegeneration is the acceleration of amyloid beta plaque formation in the brain.

One of the hallmarks of Alzheimer’s disease is the presence of amyloid beta plaque (clumps of protein that disrupt normal brain function). Microplastics can significantly influence how quickly amyloid-beta plaques form and which types form, with smaller peptides being more toxic to neurons.

Microplastics not only have harmful properties but can also serve as vectors for various other neurotoxic environmental contaminants, such as persistent organic pollutants (POPs) and heavy metals. These compounds have been shown to disrupt normal neurodevelopmental processes, promote neurodegeneration, and induce neural inflammation.

Now, various studies have seen that individuals with dementia and Alzheimer’s disease have high concentrations of microplastics in their brains compared to those individuals without dementia. However, more studies are needed to solidify this relationship before environmental organizations and regulatory bodies implement regulations against microplastics.

Importance for Youth:

For youth, this topic highlights the deep interconnection between environmental and neurological health. We often view dementia as a distant concern, but emerging research on air pollution and microplastics shows that neurodegenerative processes may begin long before symptoms occur. Understanding these links matters because it reframes dementia from being solely an age-related condition to one shaped by lifelong environmental exposures. This awareness encourages young people to think about sustainability in terms of our long-term cognitive and general well-being.

What I Learned: 

Rather than addressing diseases like dementia and Alzheimer’s, it cannot just be left to neurologists or geriatric specialists; it requires a multitude of systems to work together. The evidence linking microplastic exposure to oxidative stress, neuroinflammation and amyloid-beta aggregation suggests that dementia is not solely a biological disorder but also is mediated by the environment. In addition, dementia prevention needs to go beyond biomarkers and medical treatment; it must include policies that reduce exposure to environmental toxicants, regulate microplastic emissions, and raise awareness of long-term exposure risks. This underscores the importance of involving environmental organizations and other sectors in health policy discussions.

Citations: Gecegelen, E., Ucdal, M., & Dogu, B. B. (2025). A novel risk factor for dementia: Chronic microplastic exposure. Frontiers in Neurology, 16, 1581109. https://doi.org/10.3389/fneur.2025.1581109

LinkedIn: https://www.linkedin.com/in/mariammmalik/