Do microplastics cross the blood-brain barrier?

Do Microplastics Cross The Blood-Brain Barrier

⚕️ MEDICAL DISCLAIMER: This article is for informational and educational purposes only and is not intended as medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider before making any changes to your health regimen, diet, or supplement use, especially if you have existing medical conditions or take medications. The information presented here should not be used to diagnose, treat, cure, or prevent any disease.

Imagine saying this in 2005, “there are microplastics in your brain”. As unimaginable as that would be back then, the statement is now mainstream. Scientific studies, from engineered blood-brain barrier (BBB) models to dissected brain samples, show strong evidence that nanoplastics and even small microplastics can breach the brain’s protective barrier. This article explores how microplastics enter the brain, what happens once they’re there, and what the long-term health impacts of microplastics in your brain. 

Microplastics in your brain – how do they get there? 

Both microplastics and nanoplastics can cross the blood-brain barrier (BBB) [1–3]. This highly selective barrier, formed by endothelial cells with tight junctions, normally filters out most foreign substances from entering brain tissue [2, 18–19]. This is essential for our health. Otherwise, we could easily be harmed or killed by foreign objects entering our brain through our blood. However, research has now shown that microplastic particles, but more so nanoplastic particles, can bypass this protection via multiple routes [1–3].

The Role of Particle Size and Surface Chemistry In Influencing How Microplastics Enter The Brain

Smaller microplastics are more likely to breach the BBB than larger microplastics. Studies using in vitro models show that 0.2 μm polystyrene particles, or those about twice the size of most viruses, can cross with far greater efficiency than 1.0 μm particles, those that are the size of a bacteria. In doing so, these smaller particles produce 15.6-fold and 2-fold increases in permeability after 24 hours, respectively [19]. After 72 hours, the disparity widens further: a 27.3-fold increase for 0.2 μm particles compared to just 4.5-fold for 1.0 μm [19]. The process is even more aggressive under inflammatory conditions, which can weaken tight junction integrity and accelerate translocation [19]. Therefore, under simple assumptions, the more inflammation or stress that your brain experiences, the more likely it is for microplastics and nanoplastics to enter. 

In addition to size, surface properties also matter. Charged or chemically modified plastics exhibit different transport dynamics across the BBB, and association with cholesterol has been shown to enhance their uptake and speed [9, 27].

Biological Transport Mechanisms for Microplastics To Enter The Brain

Microplastics appear to use a variety of entry methods, ranging from passive diffusion and pore penetration to active transport via vesicles and carrier proteins [18]. Some particles may exploit existing endothelial cell channels or mimic ligands to gain entry [27]. Once inside, they can travel further into brain tissue and accumulate in specific regions such as the hippocampus and cortex [17, 19].

Microplastic Inhalation and the Olfactory Pathway

Intranasal exposure opens another route of microplastics to enter the brain. Mouse studies show that microplastics can enter via olfactory neurons in the nasal cavity, bypassing the BBB altogether and reaching the olfactory bulb through direct neuronal transmission [2, 13, 15, 26]. Microplastics have been identified in the human olfactory bulb, confirming the plausibility of this route in real-world exposures [15].

Real Evidence from Animals and Humans – Microplastics In Your Brain

Animal models provide compelling proof that microplastics can enter the brain. Polystyrene nanoplastics smaller than 50 nm, half the size of common viruses, have been shown to cross the BBB in mice, accumulating in regions associated with cognitive and emotional processing [20]. In Crucian carp, a type of fish, nanoplastic exposure altered foraging behavior and disrupted neurochemical balance, correlating with confirmed BBB penetration [5]. Human studies have detected polypropylene in brain tissues sampled during autopsy, suggesting that chronic exposure can lead to long-term bioaccumulation [15, 27–28].

The Biomolecular Corona Effect

Once inside the body, microplastics quickly adsorb proteins, lipids, and other biomolecules, forming a “biomolecular” or “protein corona” that governs their fate [3, 12, 27]. This corona can alter how particles interact with cell membranes, influence uptake rates, and even trigger immune recognition. It’s increasingly recognized as a major determinant of how and where nanoplastics accumulate, including their ability to reach and affect the brain.

What Happens After Microplastics Enter The Brain? 

Neurotoxicity and Inflammation Caused By Microplastics

Once plastics enter the brain, they activate microglia, the brain’s immune cells, triggering inflammatory cascades that lead to oxidative stress, mitochondrial dysfunction, and neuronal damage [1, 2, 10, 14, 15, 17, 19]. These processes are observed across rodent models and cell culture systems, particularly in regions critical for memory and emotional regulation [1, 5, 6, 10, 14, 19, 29–30].

Behavioral and Cognitive Changes Caused By Microplastics

The downstream effects of microplastics in your brain don’t stay at the molecular-level. In some studies, mice and fish exposed to microplastics and nanoplastics display deficits in learning, increased anxiety, and disrupted motor activity [1, 3, 5–7, 10, 15, 17, 19, 31]. In fish, these changes correlate with reduced AChE activity, disrupted gene expression, and heightened oxidative stress [7]. In mammals, structural brain alterations often accompany these behavioral changes, furthering demonstrating the impact of microplastics on the brain. 

Links to Neurodegenerative Disease

Microplastics may be contributing to conditions like Alzheimer’s and Parkinson’s disease. Polystyrene nanoplastics can impair energy metabolism and induce α-synuclein aggregation. Both of these effects are key hallmarks in these neurological disorders [1, 3, 10, 14, 15, 32]. Chronic inflammation and oxidative damage, coupled with disrupted autophagy, may serve as the mechanistic bridge between exposure and neurodegeneration. 

Gut-Brain Axis Disruption

Lastly, microplastics don’t need to be in the brain to affect it. Several studies link gut dysbiosis caused by microplastic ingestion to neuroinflammation via the gut-brain axis [1, 10, 13, 17]. Inflammatory signals, microbial metabolites, and altered neurotransmitter synthesis in the gut can all impact brain function, highlighting a multi-system pathway by which plastics can exert neurological effects.

How To Avoid Microplastics 

There is now clear evidence that both microplastics and nanoplastics can cross the blood-brain barrier through multiple mechanisms. There’s strong evidence to show that there are microplastics in your brain. Once in the brain, they can induce inflammation, disrupt cellular metabolism, and potentially contribute to neurodegenerative diseases. Therefore, for individuals concerned about their health, developing a strategy to reduce microplastics intake is critical to promote proper brain function. While it’s extremely difficult, if not impossible, to avoid microplastics, there are many small, simple actions that you can take each day to lower the amount of microplastics you consume. This is why we developed the Deplasto platform. 

Our platform, consisting of a wellness-enhancing supplement, a microplastic intake tracking app, and lifestyle recommendations is intended to help you avoid microplastics. Our scientifically-supported supplement is formulated to support your body’s natural detoxification defenses, including oxidative stress management, cellular repair, and antioxidant support. Our microplastic intake app is designed to show you an estimate of your daily exposure, with every datapoint backed by scientific studies, to help you understand how you can best avoid microplastics. Lastly, given that it’s nearly impossible to completely avoid microplastic exposure, we have a plethora of lifestyle recommendations designed to help you make small changes for big impacts. 

Overall, we believe that the best way to eliminate microplastics begins with you and the changes you make to your daily life. Over time, collectively, we can make a significant difference in your health and the environment.

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