I’m about to show you a graph—but before I do, I need to warn you: when I first saw it, it felt like a jump scare.
I actually tipped back on my stool, nearly fell over, and had to check the numbers again and again just to be sure I was reading the axes correctly.
Unfortunately, I was.
I’ll reveal it to you in parts… so as not to scare you too much at once.
What you’re looking at below is a graph of microplastics in the human brain, published in Nature Medicine 2025.
There’s a lot going on visually, so let me break it down.
On the x-axis is year of brain sample collection.
On the y-axis is the concentration of microplastics in brain tissue.
Each color represents samples taken from different locations and research centers—but all were analyzed using the same methodology.
What emerges is a striking and unmistakable pattern: brain microplastic levels increase sharply over time.
And this point is critical—this is not an association with age.
In other words, this isn’t simply a matter of someone having more years to accumulate plastics. It’s a matter of when they lived, not how long they lived.
As the authors put it:
“While we suspected that microplastics and nanoplastics might accumulate in the body over a lifespan, the lack of correlation between total plastics and decedent age (P = 0.87 for brain data) does not support this.
However, total mass concentration of plastics in the brain analyzed in this study increased by approximately 50% in the last eight years.”
Simply put: While we might expect that micro- and nanoplastics would slowly build up in the body as people age, what mattered really was when they (we) live.
The researchers go on to suggest that the exponentially increasing concentrations of microplastics and nanoplastics in the environment may be driving a parallel increase in maximal tissue concentrations in the human brain.
Placing these two graphs side-by-side tells a sobering story.
Brain Microplastics are Linked with Dementia
Now, if that’s unsettling, what comes next is outright terrifying…
When the graph is completed, purple dots appear—these represent cases of dementia.
And the difference is impossible to miss. Brain microplastic levels in individuals with dementia are dramatically higher than in those without dementia. So much higher, in fact, that the y-axis has to be compressed just to fit all the data onto the page.
Of course, it’s fair to say that correlation does not equal causation. But two points matter here.
First, you cannot establish causation in humans with a randomized controlled trial in this context—it’s neither ethical nor feasible.
Second, when an association is this large, this consistent, and this clearly separates two groups—dementia versus no dementia—it more strongly suggests a real, biologically meaningful relationship.
Reverse causality is also unlikely.
It strains credulity to believe that developing dementia somehow causes massive accumulation of microplastics and nanoplastics in the brain.
The far more plausible interpretation is that microplastics and nanoplastics are contributing to the development of dementia, including Alzheimer’s disease and vascular dementia.
So, let’s pause here and summarize…
Quick Summary, So Far
Microplastics and nanoplastics are accumulating in the human brain.
Brain plastic burden has increased by roughly 50% in just the past eight years, tracking the explosive rise of plastics in the environment.
This is not an age effect. Higher brain plastic levels reflect when someone lived, not how long they lived.
Dementia is strongly linked to higher brain plastic levels.
Now, take a moment to breathe—because this is where the line is drawn.
Everything up to this point has been about understanding the problem. What follows is about what to do next.
And I promise solutions.
In the remainder of this letter, available exclusively to StayCurious Premium subscribers, I’ll go deeper into the data, mechanisms, and solutions.
We will discuss:
Mechanisms by which brain microplastics could cause dementia
The largest sources of exposure to the plastics found in the brain
Practical tips to reduce your exposure and protect your brain
*One important disclosure before we continue: I’ll also be discussing a company with which I’m personally involved—one that is being developed specifically to help address the microplastic problem as it relates to human health. I want to be upfront so you can weigh everything that follows with full transparency.
If you’re ready to move from awareness to action, the rest of this letter is for you.
