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A Common Weed Killer May Also Be Harming Your Brain

By Jennifer Margulis, PhD

man spraying yard chemicals

Glyphosate has been linked to cancer, but scientists say it’s also implicated in cognitive decline

A few weeks ago, I was taking a walk in a new-to-me neighborhood: a tree-lined residential section of Greenville, South Carolina, that has both row houses and larger homes.

I walked by an older man who was up early, spraying his lawn. I noticed warning signs on several front yards: “Recent lawn application,” each sign read, along with a picture of children playing with a slash through it.

The message was clear: Children cannot safely play where herbicides have been applied.

But pesticides and herbicides are not just affecting children.

There’s a growing body of scientific evidence that shows that toxins, most notably the popular and widely used chemical called glyphosate (the main ingredient in Roundup and hundreds of other herbicide formulations) may be contributing to brain challenges and cognitive decline—in adults, children, and even dogs.

Deadly Dementia

Dementia is the umbrella term for cognitive decline, includes challenges with language, memory, problem-solving, and other cognitive abilities serious enough to interfere with your life. According to the World Health Organization and other health agencies, dementia is on the rise.

The Centers for Disease Control and Prevention reported that in 2017 dementia was the primary cause of nearly 262,000 deaths in America. That was up from only 84,000 deaths in 2000, a 188 percent increase in fewer than twenty years.

Chances are very good that dementia was also a factor in many more deaths as well. Dementia is a chronic condition that kills people slowly and makes its victim more vulnerable to acute conditions that may end up being listed as the “primary” cause of death.

Alzheimer’s disease is the most common form of dementia in older adults, according to the National Institute on Aging. The disease is named after Dr. Alois Alzheimer who first identified it in 1906 after examining the brain tissue of one of his patients who died. 

At least five million Americans currently live with Alzheimer’s, which is roughly equivalent of the entire population of South Carolina. 

By 2060 the number of older adults living with this chronic neurodegenerative disease is projected to be nearly fourteen million. 

Concerns About Cognition

If these stats alone aren’t enough to worry you, whether you’re a young person or an older adult, the quality of life for people who live with Alzheimer’s certainly should. 

This disease attacks the part of the brain that controls working knowledge, language, memory, and conscious thoughts, the very part of the brain that houses most of what we identify as “us.”

My daughters and I used to volunteer at a facility for older adults who could no longer care for themselves. 

One of our friends there, Nora, had Alzheimer’s. 

Towards the end of her life even having a bite of food caused her extreme anxiety. 

“What do I do with this?” she would ask, confused, as she held a forkful of food in front of her face.

Over time, as the symptoms worsen, people with Alzheimer’s can experience profound confusion and anxiety, personality changes, mood challenges, and a total loss of independence. 

What’s more, this is a disease that often robs its victims of their minds long before it takes their bodies. 

Some people may live as long as 20 years after their symptoms first appear, according to Johns Hopkins University.

In 2019 a national poll on healthy aging conducted by the University of Michigan found that nearly half of the over one thousand respondents worried that they would develop dementia. 

Forty-four percent of these adults, who were between the ages 50 to 64 years old, responded that they were either “somewhat or very worried” about cognitive decline.

The truth is that the rising rates of Alzheimer’s disease should be a concern to all of us.

If we ourselves are lucky enough to stay mentally sharp until we die, we’re likely to be close to many who are not as lucky.

Weed Killer Doesn’t Just Hurt Unwanted Plants

Scientists having been attempting to tease out just exactly why so many people are affected by dementia these days. 

Some argue that it is just that people are living longer than they used to. Dementia was inevitable, they argue, it’s just that most people died before it could set in. 

While that may be a valid observation, when researchers adjust for age, they still find that rates of dementia have doubled in less than twenty years, according to a 2019 CDC report.


And we also know that many people throughout the world lead long healthy lives, living well past the average life expectancy, without experiencing any cognitive decline.

My colleague, Dr. Stephanie Seneff, is a senior research scientist at MIT with bachelor’s, master’s, engineering, and doctoral degrees all from MIT. She believes a causative factor in the rise of cognitive decline is glyphosate.

As Seneff explained in her 2021 book, “Toxic Legacy: How the Weedkiller Glyphosate Is Destroying Our Health and the Environment,” she combed the scientific literature in order to find the root causes of Alzheimer’s and other neurodegeneration.

Since the increasing use of glyphosate so strongly correlated with the rise in Alzheimer’s and other brain disorders, Seneff decided to investigate biologically plausible mechanisms of harm.

What she discovered was no less than “stunning,” as she puts it. 

According to Seneff, glyphosate damages more than just unwanted plants. It also affects physiological pathways in the human body, causing biochemical disruptions that may well damage our brains. 

Protein Problems

Glyphosate has the chemical formula C3H8NO5P. 

It is an organic molecule that resembles the amino acid glycine.


Seneff argued that glyphosate’s biological resemblance to glycine is the primary source of glyphosate toxicity. 

Zach Bush, a medical doctor specializing in internal medicine, endocrinology, and hospice care, has made the same argument

Proteins carry out most of the important functions in our bodies. Each function requires very specific proteins that are “coded” into our DNA. 

Though this isn’t something most of us usually think about, protein synthesis itself (that is, the production of more proteins) is actually extremely important to our health and well-being. 

Enter glycine. 

Glycine is one of only 20 coding amino acids, which means that it is used in the production of more proteins. It is also the smallest. 

Glycine is a flexible, multi-purpose amino acid, used in a variety of ways by the body. It is found in ion channels in cell membranes that need to open and close, for example.

Seneff’s theory is this: Glyphosate is biologically so similar to glycine that the body can be fooled into using it while making proteins, incorporating it into places where glycine is supposed to go.

This is a problem. Glyphosate is negatively charged and much bulkier than glycine and glyphosate substitution for glycine can then change the shape of the proteins, causing them to be misfolded.

Misfolded proteins don’t work, which means that the body has to make many more copies of the same protein to make up for the defective ones, using up precious energy and amino acids.

Glyphosate and Alzheimer’s

The defective proteins believed to indicate Alzheimer’s are called amyloid beta proteins. 

But in several fascinating studies, scientists have found that some older adults with excellent cognitive recall also have these proteins in their brains. 

So the issue is likely not the presence of the proteins themselves, but when the proteins become soluble sheets. These “sheets” accumulate to become the amyloid plaques found in the brains of people suffering from Alzheimer’s.

Seneff argued that glyphosate also makes it easier for aluminum to cross the blood-brain barrier. 

Alzheimer’s has been consistently linked to high levels of aluminum in the brain. 

A study published in the Journal of Alzheimer’s Disease Reports in April of 2021 found aluminum tangled within neurons in the brains of people with Alzheimer’s.

You Are What You Eat (and Drink)

At the end of July of 2021, Bayer—the company that now makes Roundup—announced that they would replace glyphosate-based formulations with herbicides that do not contain glyphosate in some of their lawn care residential products. 

However, the company also said they will do this to stop the lawsuits against them—since glyphosate has been linked repeatedly to cancer, in particular non-Hodgkin’s lymphoma—not because of any safety concerns.

But Dr. Zach Bush has argued that we must get the glyphosate out of our food and our water supply, which means we must practice regenerative farming practices and only eat food grown without this chemical weed killer. 

Yet it is getting harder and harder to find conventionally grown food that doesn’t contain glyphosate or other toxins.

If you want to live a long healthy life and stave off Alzheimer’s and other cognitive problems, it’s imperative to eat only organic food. 

Crops cannot be designated as “organic” if they have been sprayed with glyphosate or any other herbicides.

I’m too shy to talk to strangers who are spraying their lawns. And I wouldn’t want to offend them. I have considered leaving a copy of Toxic Legacy on the front porches of the houses where people are still spraying their lawns. But that seems gauche too.

Maybe I’ll get lucky and they’ll read this article. Or maybe you will print out a copy and bring it to a friend’s house and spend some time talking together about glyphosate over a cup of organic green tea.


After all, even if you’d rather have a head cold than talk about this chemical, according to researchers in Taiwan, the more social interactions you have, the more you lower your risk of developing Alzheimer’s.

Jennifer Margulis
Jennifer Margulis

Jennifer Margulis, Ph.D., is an award-winning health and science writer. The author/editor of eight books, she writes a popular Substack called Vibrant Life. A different version of this article was first published in The Epoch Times. Learn more about her at her website:


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