Parkinson’s Cases Are Going Up. Are Golf Courses To Blame?

New study: lawn pesticides may silently shape neurologic health

Photo by Splash Pic on Unsplash

Hello, brain health ambassadors. I am happy to report I am back home in my favorite chair on the screened-in porch, my dogs Livvie and Orzo draped over my feet. They are both aloof yet clingy in that way dogs can be after a long trip. Now I have a week to catch up before the next brain health retreat in Tecate, Mexico. This will be my 10th year teaching at Rancho La Puerta and I’ll be overseeing their very first Brain Health Week. I’ll be sure to update you from the road.

Did you see the headlines last month about Parkinson’s? A new study suggests living near a golf course increases Parksinon’s risk by 126%. Researchers imply pesticides in the air and drinking water may be to blame.

While this study made a big splash in the news, the link between pesticides and Parkinson’s disease (PD) is nothing new. There’s a large body of research going back decades that points to environmental toxins as a major risk factor for PD, a movement disorder that can lead to dementia. I’ll get into the details, below, along with a list of action items you can take to protect your brain from these toxins.

If you follow a brain-healthy diet, you’ll be happy to learn that eating this way can also protect you from toxin exposure and reduce the risk of Parkinson’s. More on that, below.

This post kicks off a new mini-series about the impact of environmental toxins on brain health.

It’s a huge topic, one that’s rife with both solid data and misinformation. In subsequent posts, I’ll give you practical guides to limit your everyday exposure to these known brain health toxins:

• Heavy metals: how to choose low-toxin chocolate, fish and seafood, and other foods

• Micro- and nanoplastics in the kitchen: a practical guide to minimizing exposure

• Advanced glycation end products (AGEs): cooking techniques to minimize this toxin implicated with poor cognitive aging

• Plus, Is “nontoxic” cookware worth the price? We’ll look at the data.

I’d love to hear your thoughts: what else are you curious to learn about environmental toxins and brain health?

First, let’s talk about Parkinson’s, which is currently the fastest growing neurodegenerative disease.

5 things to know about Parkinson’s

1. Parkinson’s disease (PD) occurs when brain cells that make dopamine no longer function or die, leading to symptoms of tremor, slowness, stiffness, and walking and balance problems.

2. Seventy percent of people living with PD will eventually develop dementia.

3. Where you live determines your PD risk. There’s a “Parkinson’s Belt” in the U.S.—a cluster of states including Florida, Texas, and Central Valley, California— with the most cases.

4. Parkinson's disease is believed to be caused by a combination of genetics and environmental factors, with men 1.25 times more likely to develop the disease.

5. Alzheimer’s is the most common type of dementia, accounting for 70%, with numbers that keep going up. But Parkinson’s cases are rising even more steeply.

   Parkinson’s was almost unheard of prior to 1950. Now it’s the fastest growing neurodegenerative disease. The number of cases more than doubled from 1990 to 2015 and could double again by 2040, far more than expected based on our aging population.

The first newsletter of the month is always free. Please share.

Sign up as a paying subscriber for full access to all articles, recipes, and guides I share. As a Founding Member, you’ll also get 4 live on zoom cooking classes a year. (For the next class on June 29, 2025, we’ll be cooking a few veg-forward recipes I brought back from Italy.)

The Proximity to Golf Courses Study

In this paper published in JAMA Network Open, researchers posed the question: Does living within proximity to a golf course affect the risk of Parkinson disease (PD)? To find out, they created a Parkinson’s “map” of the 450 participants who developed the disease between 1991 and 2015. They focused on golf courses across 27 counties in Wisconsin and Minnesota known to have more people living with PD.

Researchers found a linear correlation between PD and golf course proximity. Those living within one mile had the highest risk—an increase of 126%—compared to those who live more than six miles away. Researchers hypothesize that pesticides used on golf courses are contributing to an increased risk of Parkinson's in these areas.

In a nutshell, the closer one lived to a golf course, the greater the chance of getting Parkinson’s.

Is drinking water to blame?

Photo by Daniel Hooper 🌊 on Unsplash

The study shows that areas that shared drinking water supplies with water used near golf courses were the most greatly impacted. In fact, those who got their water from the same source as the nearby golf course had double the risk of PD compared to those who sourced water elsewhere. It is well documented that pesticides applied to golf courses can leach into the ground and contaminate drinking water supplies. Common culprits include paraquat and rotenone, both of which have been linked to neurodegeneration.

Pitfalls of the study

This study is a case-controlled observational study, meaning it doesn’t have the power to prove cause and effect. Instead, it gives us information about PD cases in a geographic area.

Researchers adjusted participants for age, sex, race and ethnicity, index year (date of PD symptom onset for cases), household income, and urban or rural category. One of the pitfalls of the study, however, is that they didn’t adjust for other known PD risk factors, such as history of head trauma and occupational exposure. And they didn’t look at part-time vs. permanent golf course residents. Still, this study is a striking demonstration on the potential impact of geography on PD risk.

The JAMA Parkinson’s risk in proximity to golf courses study isn’t just about people who golf. It’s about the impact of environmental toxins on the neurological health of communities who live near high use areas.

The risk of living in a Parkinson’s Belt

Previous studies have already shown geography determines PD risk. This “Parkinson’s Belt” mirrors the Rust Belt in the U.S.—states with the highest concentration of industry and agriculture.

Parkinson’s prevalence by state. Source: Michael J. Fox Foundation from the Parkinson’s Prevalence Project, 2018.

Parkinson's disease is believed to be caused by a combination of genetics and environmental factors. One of the strongest risk factors has to do with occupation. Farmers, groundskeepers, and people working in the dry cleaning industry have all been found to have a significantly increased risk.

Exposure alone does not increase PD risk. But if a person carries one of a dozen genetic variants and they are exposed to certain toxins, risk goes way up. These gene variants impair a cell’s ability to get rid of waste products, a process called autophagy, giving them an Achilles heel to the neurotoxic effects of pesticides.

Those at greatest risk of PD have all factors at play:

• Occupational exposure to pesticides and other toxins

• Living near areas of high toxin use

• A gene variant that impairs the cell’s ability to take out toxin “trash”

Environmental toxins linked to Parkinson’s and other neurodegenerative diseases

There is mountain of data going back decades that links certain toxins to increased PD risk. Many are also linked to increased risk of Alzheimer’s, multiple sclerosis, and ADHD.

Some toxins, such as MPTP, have actually been shown to cause parkinsonism, a syndrome like Parkinson’s disease. Neurologists discovered this link when a group of intravenous drug users in California in the 1980s injected a synthetic heroin that had been contaminated with MPTP and developed immediate symptoms of parkinsonism.

Others are mostly seen in narrow sectors of industry, such as manganese exposure in welding. A form of parkinsonism called manganism has been observed in welders.

Here are the most commonly used chemicals in high prevalence areas like the Parkinson’s Belt.

Pesticides/herbicides: This includes the insecticides rotenone and permethrin (which may be found in clothing or nets treated to kill mosquitoes, for example); organochlorines, such as beta-hexachlorocyclohexane; and the herbicides glyphosate, paraquat, and 2,4- dichlorophenoxyacetic acid (2,4-D). Learn more about how difficult it has been to regulate pesticides in this opinion piece by Parkinson’s experts: The inadequacy of current pesticide regulations for protecting brain health: the case of glyphosate and Parkinson's disease

Action item: Purchase organic food whenever possible; wash conventional produce well.

Action item: Test drinking water for pesticide residue; use a high-quality water filter.

Action item: Advocate for organic golf courses.

Solvents: Trichloroethylene (TCE) is a chemical used in many industrial settings, such as metal degreasing and dry cleaning, and in paint thinners and detergents. Some studies have shown a link between long-term exposure to solvents and development of Parkinson’s.

Action item: Seek out “clean” dry cleaners who don’t use TCE.

If you’ve been eating a brain-healthy diet to reduce dementia risk, this may protect you from Parkinson’s, too.

While there’s no guaranteed way to prevent Parkinson’s, there are several lifestyle factors known to either increase or decrease risk. Of note, not all are environmental toxins. Just like with fending off Alzheimer’s, a brain-healthy diet and exercise are at the top of the list. This diagram illustrates other known factors, such as traumatic brain injury, smoking, and medications.

Source: Linking environmental risk factors with epigenetic mechanisms in Parkinson’s disease, Nature, 2023.

Everyone can take action to protect themselves from Parkinson’s. Genetics are central, so those with a family history of Parkinson’s would be wise to check off all of these boxes.

Action items:

Follow the MIND diet, a brain-protective dietary pattern. In this study from Rush University, following the MIND diet closely delayed Parkinson’s up to 7.4 years in men and 17.4 years in women.

Enjoy high-quality coffee (caffeinated and made with a paper filter). Caffeine in coffee seems to interrupt the depletion of dopamine in people with PD. For maximum benefit, drink at least 1 and up to 3 cups of caffeinated coffee per day.

Limit dairy products. This Harvard study showed that consuming three or more servings per day of low-fat dairy products was associated with an increased risk of Parkinson’s. This may be because dairy products reduce the levels of urate, a bioactive substance that may slow progression of Parkinson’s. This could explain why the MIND diet fared better at Parkinson’s risk reduction than the Mediterranean diet—it limits dairy products to a greater degree.

Smoking. No one is advocating smoking to reduce risk, but it is interesting to note that smoking tobacco has been shown to be mildly protective of PD in men but not women.

Learn more here about what to eat to prevent Parkinson’s.

Preventing Parkinson’s Through Food

That’s all for today

I’ll be back next time with a practical guide to limiting exposure to micro- and nanoplastics in your kitchen and your life. This is a beast of a topic, but I aim to give you some clarity about risk along with doable action items. Let me know what questions you have.

If you found this post helpful, please tap on the heart button, restack, or share with someone you love.

As always, thank you for reading, sharing, and taking the best care of your brain.

Love,

Annie

Brain Health Retreats Update

Want to join me on a Brain Health Retreat this year? Your brain will thank you! For detailed information about each trip, click on the links below or tap on RETREATS on the homepage.

BHK Retreat at Rancho La Puerta, Mexico June 7 to 14, 2025. Join me at the Ranch during Brain Health Week for a special retreat within a retreat. To register or submit questions, contact Donna Sher at 858.449.3672 or email her at dsher52@hotmail.com. This retreat is sold out. I’ll host another retreat at Rancho La Puerta November 15 to 22, 2025. Contact Donna for more info.

Sardinia’s Secrets For a Long and Healthy Life, October 12 to 19, 2025. This fall I am headed back to Italy to explore Sardinia’s blue zones. Find all the details here; call 877-298-9677 for more information and to reserve your spot. This Brain Health Retreat was featured in National Geographic Traveller UK.

Costa Rica in February 5 to 10, 2026: Fitness + brain health in the jungle by the beach! This retreat is 100% plant-based and alcohol-free. Learn more and reserve your spot here. 3 cabañas left!