This article is based on my conversation with Dr. Dominic Ng , author of the Brain Health, Decoded Substack, this is day 4 of the first-ever Brain Health Substack Summit hosted by The Habit Healers.

Click here to join tomorrow for Brain Health Substack Summit Day 5 with Chris Miller MD, where will discuss the brain and inflammation.

*Our final conversation will be on Saturday with Chef Martin Oswald and we will dive into all the delicious recipes he created for each of our Brain Health Substack Summit panelists.

If you missed Day 1 of our Brain Health Summit with Julie Fratantoni, PhD you can watch it here. We discussed how to exercise your brain day to day.

If you missed Day 2 of our Brain Health Summit with Annie Fenn, MD you can watch it here. We discussed foods to decrease dementia risks.

If you missed Day 3 of our Brain Health Summit with Jud Brewer MD PhD you can watch it here. We discussed how to unwind your anxiety.

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In December 2024, a neuropathologist named Elaine Bearer was looking through her microscope at brain tissue from two deceased dementia patients at the University of New Mexico when she spotted something she couldn’t explain. Strange brown lumpy things, she called them. They weren’t cells. They weren’t proteins. They weren’t any of the usual suspects you find when you go looking for what killed someone’s brain.

They were plastic.

This was the opening act of a study that would be published in Nature Medicine in early 2025 by Dr. Matthew Campen, a toxicologist at the University of New Mexico. His team did something no one had done at this scale before. They took brain tissue samples from people who had died in 2024 and compared them to brain tissue from people who had died in 2016. They dissolved the tissue into a slurry, spun it in a centrifuge, and pulled out a small pellet of undissolved material. Then they heated that pellet to 600 degrees Celsius.

What they found was about 4,800 micrograms of plastic per gram of brain tissue. If you gathered it all together, it would weigh roughly seven grams. That is the weight of a standard plastic spoon.

When I sat down with Dr. Dominic Ng for Day Four of the Brain Health Substack Summit, he held up that exact prop. A plastic spoon. “Don’t say I don’t come prepared,” he said from his home in Scotland.

Dr. Ng is a physician neuroscientist. He grew up in Hong Kong, moved to the UK for medical school, and took one of his earliest jobs working for the CJD surveillance unit, traveling around the country diagnosing prion disease (a rare and fatal brain condition caused by misfolded proteins). That work led him deeper into neurology, and eventually into Alzheimer’s disease and motor neuron disease, which Americans know as ALS or Lou Gehrig’s disease. He is now completing his PhD at the University of Edinburgh under some of the leading researchers in neurodegeneration and aging, and he writes the popular Substack newsletter Brain Health, Decoded.

He came on the summit to talk about microplastics. And the first thing he wanted people to understand is that this problem, while real, is more complicated than the headlines make it sound.

The Spoon in Your Head

The Campen study found that the amount of plastic in human brains had roughly doubled between 2016 and 2024. That tracks with what we’d expect as global plastic production continues to climb. More than half of all plastic ever manufactured has been produced since 2002, and production is on pace to double again by 2040.

But the study also turned up a finding that nobody predicted. Age didn’t matter. The brain of a 24-year-old and the brain of an 84-year-old contained approximately the same amount of plastic.

Think about that for a second. If microplastics were simply accumulating over a lifetime the way plaque builds up in arteries, you’d expect people in their eighties to have far more than people in their twenties. They’ve been alive longer. They’ve eaten more food, breathed more air, drunk more water from plastic bottles. The older brain should be packed tighter.

It wasn’t. And that one observation tells us something important. The brain appears to be clearing microplastics at roughly the same rate it takes them in. There is some kind of equilibrium going on, a biological trade where the brain absorbs a certain load and then dumps it. The amounts are the same across age groups because the intake and the outflow have reached a balance.

This is the first piece of genuinely good news in the microplastics conversation. Your brain isn’t just passively filling up like a landfill. It’s fighting back.

The Hitchhiker Problem

To understand why microplastics are concerning even if the brain can partially manage them, you need to know what plastic actually is.

Dr. Ng broke it down this way. Plastics are polymers, which means they are long chains of small molecules derived from fossil fuels. The word “polystyrene” means multiple styrenes linked together. “Polyester” means multiple esters. These long molecular chains are what give plastic its structure.

But the chains alone don’t give plastic all the properties we rely on, things like flexibility, durability, and heat resistance. To achieve those, manufacturers add chemicals. Phthalates go into PVC and cling film to make them bendable. Bisphenols go into thermal receipt paper and food containers. PFAS, sometimes called forever chemicals, coat nonstick pans.

And this is where the real trouble starts. Microplastics, Dr. Ng explained, probably aren’t doing most of their damage on their own. They’re doing damage because they carry things with them.

He used an analogy anyone who’s stored leftover tomato sauce in a plastic container will recognize. You know how the red stain never fully comes out? That happens because plastic absorbs what it touches. The same thing happens in the environment. As plastic breaks down into tiny fragments, about the size of a virus at around 200 nanometers, those fragments pick up environmental toxins, heavy metals, and industrial chemicals.

So when microplastics enter your body through the food you eat, the water you drink, or the air you breathe, they don’t travel alone. They bring hitchhikers. And those hitchhikers, the bisphenols and phthalates and PFAS, are what scientists call endocrine disruptors. Your endocrine system is essentially the body’s internal messaging network. It controls your hormones, which in turn regulate your body temperature, blood sugar absorption, metabolism, thyroid function, and reproductive health. When you throw foreign chemicals into that system, the effects ripple everywhere. Research has linked these disruptors to increased risk of type 2 diabetes, heart attacks, and kidney disease.

Why Your Brain Is the Perfect Trap

A single liter of bottled water contains roughly 250,000 plastic particles. Your indoor air carries about 500 particles per cubic meter, shed from your clothing, furniture, and carpet fibers. It enters through your gut, crosses into your blood, and from there, goes everywhere. But the brain accumulates far more than other organs. In the Campen study, brain tissue contained concentrations seven to thirty times higher than the liver or kidneys.

Dr. Ng explained why with another kitchen analogy. “Have you ever tried to clean bacon grease out of a plastic container?” he asked. Fat clings to plastic because both are lipophilic, meaning they are chemically attracted to each other.

Your brain, by dry weight, is approximately 60 percent fat. Your liver and kidneys contain much lower percentages. On top of that, the brain receives about 25 percent of your heart’s total blood output, despite accounting for only about 2 percent of your body weight. So you have a high-fat organ with a massive blood supply. If microplastics are floating through your bloodstream, the brain is essentially a magnet for them.

The technical term for the layer of fat that insulates brain cells is the myelin sheath. It wraps around neurons and helps regulate the speed of electrical signals. Campen’s team found that microplastics tend to concentrate in exactly these fatty myelin cells. The plastic lodges itself in the insulation of your wiring.

The Brain’s Drainage System

The reason younger and older brains contain similar amounts of plastic brings us to one of the more remarkable discoveries in modern neuroscience, and it happened only about a decade ago.

In 2012, researchers identified the glymphatic system, a waste-clearance network in the brain. Think of it as the brain’s internal plumbing. While you sleep, cerebrospinal fluid (the clear liquid that cushions your brain and spinal cord) flushes through channels between brain cells, washing away metabolic waste products. This is the same system responsible for clearing out the protein fragments associated with Alzheimer’s disease.

Dr. Ng believes this is almost certainly how the brain manages its microplastic load. There is no published research yet directly connecting glymphatic clearance to microplastic removal, and he was careful to say that. “We’re still in pretty early days when it comes to this research,” he told me. But the logic is sound. The glymphatic system is the only known route the brain has for clearing foreign material, and it is most active during deep sleep. Exercise also appears to enhance its function.

Which means the same habits that protect you from Alzheimer’s disease may also be protecting you from microplastic accumulation. Sleep, exercise, and keeping your brain’s waste-clearance system running well.

The Dementia Question

One finding from the Campen study raised eyebrows. Brains from patients who had died with dementia contained three to five times more microplastics than brains from patients without dementia.

That sounds alarming. But Dr. Ng pointed out what the researchers themselves noted: the cause likely runs in the opposite direction. Dementia makes the brain more porous. The blood-brain barrier, which is the tightly controlled gateway that normally filters what gets into brain tissue, degrades as dementia progresses. A more porous brain means more plastic gets through. The dementia came first. The extra plastic followed.

That said, animal studies have shown that microplastic exposure can trigger chronic inflammation in the brain. Your immune system recognizes the particles as foreign material and mounts a defense, releasing chemical signals that put surrounding cells on high alert. In the short term, this is useful. It’s the same mechanism that fights off bacteria. But when the alarm never shuts off, that sustained inflammation damages healthy tissue. And we know that chronic inflammation is one of the central drivers of neurodegenerative disease.

Dr. Ng was also frank about one frustrating reality. The immune system can’t actually break down the plastic. “Part of the reason we choose plastics is because they’re so durable,” he said. “Those chemical bonds are really strong.” Even at the nanoscale, the particles resist degradation. The body can move them out, but it can’t destroy them.

What You Can Actually Do

When I asked Dr. Ng whether we should all be panicking, he referenced the Leonardo DiCaprio movie Don’t Look Up, where an asteroid threatens Earth and everyone either ignores it or spirals into hysteria. “That’s not where we’re at,” he said. “But I also don’t think we’re at the point where everything is fine.”

He put it this way: it is perfectly rational to want to reduce your exposure, even without definitive proof of a specific threshold for harm. You don’t need to wait for ironclad evidence to make reasonable changes.

His practical advice for reducing exposure came down to a few key habits.

Swap your containers. Replace plastic cups, bottles, and food storage with glass or stainless steel. Heat accelerates plastic breakdown, so never microwave food in a plastic container or drink hot beverages from plastic-lined takeaway cups. This is one of the single largest sources of microplastic ingestion.

Filter your water. A reverse osmosis filter removes about 99 percent of microplastics from tap water. Standard pitcher filters, many of which are housed in plastic, are less effective and may even add microplastics back in. Canada has already begun implementing advanced filtration at the municipal level, with pilot programs in Ottawa removing about 90 percent of particles from public water supplies.

Clean your air. Indoor environments carry roughly 500 microplastic particles per cubic meter, released from synthetic clothing, upholstery, and carpeting. Vacuuming more frequently and using a damp mop picks up settled particles before they become airborne again. An air purifier with a HEPA filter adds another layer of protection.

Be smarter about laundry. Synthetic fabrics shed microfibers every time they go through the wash. Reducing load frequency and washing fuller loads cuts down on fiber release. You’re not generating less dirty laundry, you’re just being more strategic about how you process it.

And then there are the habits that support your brain’s own clearance system.

Sleep. The glymphatic system does its heaviest work during deep sleep. Chronic sleep deprivation means your brain’s plumbing runs at reduced capacity, whether the waste is protein fragments or plastic particles.

Exercise. Physical activity enhances glymphatic function and increases blood flow to the brain. It doesn’t have to be punishing. Dr. Ng emphasized that it should be something you enjoy, ideally with other people.

Social connection. This one surprised me, but Dr. Ng was emphatic. Connection with family and friends, initiating gatherings, staying socially engaged: these are among the most protective factors against cognitive decline. He admitted it sounds soft coming from a neuroscientist, but the data is consistent.

The Future of Alzheimer’s, and Why It Matters Here

Toward the end of our conversation, Dr. Ng shared something from his Alzheimer’s research that reframes how we should think about brain health in general.

He described a gap between how researchers talk about Alzheimer’s and how patients talk about it. Patients think of it as something that happens to you in old age, a diagnosis you receive when memory starts failing. Researchers increasingly see it as a process that begins 20 years before any symptoms show up. And the tools to detect it that early already exist.

Blood tests can now measure levels of amyloid beta and phosphorylated tau, two proteins whose accumulation is a hallmark of Alzheimer’s pathology. The vision Dr. Ng described is one where a routine blood draw in your forties or fifties could flag elevated levels, and a doctor would sit you down and say: here is what we need to change. More exercise. Better diet. Better sleep. More social connection. Not a drug. A prescription for living differently.

This is the same prescription that protects against microplastic accumulation. The same habits that keep your brain’s clearance system functioning. The same behaviors that lower chronic inflammation.

It all points in one direction. The basics work. And they work across multiple threats simultaneously.

As Dr. Ng put it, people spend too much energy chasing the 5 percent optimizations while ignoring the 80 percent. Supplements, biohacks, and boutique protocols are fine in their place. But the foundation is diet, movement, sleep, and human connection. Get those right and you’ve pulled the biggest levers available.

Takeaways

Everyone already has microplastics in their brain. The 2025 Campen study found approximately seven grams, the weight of a plastic spoon, in human brain tissue. This amount has roughly doubled since 2016.

The brain accumulates more plastic than other organs because it is 60 percent fat and receives 25 percent of the body’s blood supply. Microplastics are lipophilic (attracted to fat), so the brain acts as a concentration point.

Age doesn’t predict how much plastic you carry. Young adults and elderly adults had similar amounts, which suggests the brain has an active clearance mechanism, likely the glymphatic system.

Microplastics are Trojan horses. The particles themselves may be less harmful than the chemicals they carry: phthalates, bisphenols, PFAS, and environmental toxins that act as endocrine disruptors and trigger chronic inflammation.

You can meaningfully reduce your exposure. Switch to glass containers, use a reverse osmosis water filter, avoid heating plastic, clean indoor air with a HEPA filter, vacuum and damp mop regularly, and wash laundry in fuller loads.

The same habits that fight Alzheimer’s fight microplastic damage. Sleep fuels the glymphatic system, exercise enhances brain clearance, diet reduces inflammation, and social connection protects against cognitive decline.

This is not an asteroid-level crisis, but it is not nothing. Dr. Ng says we are somewhere in the middle. Concern is rational. Panic is not. The most protective steps are also the simplest ones.

Dr. Dominic Ng writes Brain Health, Decoded on Substack, where he translates cutting-edge neuroscience into practical tools for cognitive performance and mental wellbeing.

Inspired by Dr. Ng’s brain health food recommendations, Chef Martin Oswald created the Pumpkin Seed-Crusted Salmon with Sauce Gribiche, Roasted Beets & Leeks, packing seven brain-boosting ingredients into a single dish for the Brain Health Summit.

This interview is part of The Habit Healers Brain Health Substack Summit. For more expert conversations on protecting and improving your brain health, subscribe to The Habit Healers.

PS. Want to train your brain with games backed by science? Check out my free weekly Substack, Train the Brain Games, where I share cognitive challenges focused on processing speed and other skills the research actually supports.

References

* Nihart AJ, Garcia MA, El Hayek E, et al (Campen MJ). Bioaccumulation of microplastics in decedent human brains. Nat Med. 2025;31(4):1114-1119. doi:10.1038/s41591-024-03453-1

* Iliff JJ, Wang M, Liao Y, et al. A paravascular pathway facilitates CSF flow through the brain parenchyma and the clearance of interstitial solutes, including amyloid β. Sci Transl Med. 2012;4(147):147ra111. doi:10.1126/scitranslmed.3003748

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