Are golf course owners putting local people at risk of Parkinson’s disease in their quest for the perfect green? Arizona neurologists claim in a research publication published this June, that liberal use of pesticides by golf clubs could be leading to Parkinson’s disease amongst the neighbours.
The paper, published by JAMA Network, describes how the odds of a person being diagnosed with Parkinson’s disease get bigger: the closer their home address is to a golf course. People who live within a mile of a golf course, the researchers say are 126% more likely to be diagnosed with Parkinson’s disease than people living six miles away. According to the study, people who share water service with a golf course are twice as likely to be diagnosed with Parkinson’s as those who don’t. The authors suggest that a proposed link between pesticides and Parkinson’s Disease could be responsible.
Environmental Impact on Parkinson’s Disease
The research team led by Brittany Krzyzanowski, PhD of Barrow Neurological Institute Phoenix, Arizona, used health records harvested from the Rochester Epidemiology Project (REP) to investigate environmental impacts on Parkinson’s disease diagnoses.
They studied the Parkinson’s prevalence around over 100 golf courses in Minnesota and Wisconsin to see if there existed a link between golf courses and the neurodegenerative disease. They discovered that people with a Parkinson’s diagnosis between 1991 and 2015 were more likely to have been living within three miles of a golf course than six miles or more from one.
Golf Course Clues
Krzyzanowski and her colleagues focused on a specific golf course in Olmstead County, Minnesota, to test their hypothesis that pesticides used to keep the local golf course verdant were slowly poisoning local seniors.
The researchers sought out records of people diagnosed with Parkinson’s in Minnesota and Southern Wisconsin, especially focusing on people who had lived in Olmstead County around the time their symptoms appeared. The team then looked for people in the area who had similar demographic characteristics, age and sex, but no Parkinson’s or Parkinson’s Disease-like symptoms.
They found 450 Parkinson’s cases in Olmstead and matched them with 9000 controls. That means the researchers collected 20 control participants of the same age and sex living in Minnesota or Southern Wisconsin between 1991 and 2015 for every Parkinson’s diagnosis. Once they screened the participants to make sure they could get enough information about where those people had lived, they ended up with 419 Parkinson’s patients and 5,113 control participants.
Most of the people diagnosed with Parkinson’s were seniors, aged between 63 and 80, median 73 years old, with 61% being male. The control participants were matched- their average age was 72 and 59% were male. The median time residents had spent at their last address was 18 years. This is important because if you are checking the impact of something local, you need people to have been living locally long enough for it to have had an effect.
Calculating the odds
The team started by looking to see whether people who had been diagnosed with Parkinson’s were more likely to live near a golf course than people without a diagnosis.
Through a simple comparison, they found that the addresses of people with Parkinson’s disease three years or more before they reported symptoms were clustered around golf courses, mostly between 1.7 and 2.7 miles away. The control participants, however, were more spread out, on average living between 1.2 and 4.3 miles away from the course. This is a pretty small difference at first glance, so the investigators pulled a mulligan and brought in some more complicated statistical methods to tease out the relationship. This time they compared the prevalence of Parkinson’s at set distances from the golf course. Would they find a more defined pattern?
When the researchers calculated how many people with Parkinson’s lived within a specific radius of the golf course compared to the local population, they found that the odds of a person having Parkinson’s disease decreased by 9% for every mile further from the golf course they lived.
The relationship between Parkinson’s and proximity to a golf course was non-linear, with more people diagnosed living within three miles of a links. The evidence seems to show that in 2015, you were more likely to find people with Parkinson’s disease living near a golf course. This does not, however, show a cause and effect relationship.
Water Table Trouble
An argument supported by circumstantial evidence is built piece by piece, so the neurology/epidemiology researchers moved on to the next layer of evidence. Since they hypothesized that the trouble was caused by pesticides rather than the golf course itself, the team switched their attention to the water supply.
The team speculated that if people were being affected by pesticides or herbicides from the golf course, the most likely cause was chemical nasties leaching into the water. The researchers identified golf courses with vulnerable groundwater; they assumed that in these places water washing off the golf courses was soaking into the ground and then leaching into the water supply.
If they could compare Parkinson’s rates near golf courses with more vulnerable groundwater to golf courses with less likelihood of contaminated water supplies, they reasoned, they should see a difference. The team matched each address to its tap water supply. Did they get their water from a private well on their property, was their water supply taken from an area near a golf course with vulnerable groundwater, or was the nearby golf course on a site invulnerable to contamination?
When the researchers mapped Parkinson’s diagnoses onto areas with vulnerable or less vulnerable groundwater, they saw an 82% increase in the chances that a person would have the condition, if the golf course was likely leaching water into the water supply. This increased to a 92% increase in the chance that a person would have a Parkinson’s diagnosis compared to someone who did not live near a golf course.
Interestingly, people who got their water from a municipal well located on the golf course showed no increase in their liklihood of being diagnosed with Parkinson’s versus people who did not live near a golf course.
Under par or over powered?
While this sounds like a neat little story, there are some important caveats to consider before you toss your golf clubs or put your home on the market.
Firstly, these are small changes. A 92% increase in the odds just means that the probability is nearly twice as high in one group than the other. This doesn’t tell you much about your absolute probability of being diagnosed with Parkinson’s Disease. A 126% increase in a small number is still a small number.
The team did not look at the address history more than three years prior to diagnosis. If somebody moved to Olmstead County in 1989 with early symptoms and reported them in 1991, would that skew the results? How long would somebody need to live near the golf course for it to have affected their neurological health? If only two to three years of exposure to whatever was causing the symptoms were necessary, should we not see gardeners and other people working at the golf course showing up with Parkinson’s Disease in similar or greater numbers in the area?
On the other hand, the median time living in the area was 18 years, so at least half of the Parkinson’s patients had been exposed to the golf course over a very long time. There is evidence that some people have a genetic predisposition that makes them more vulnerable to neurodegenerative diseases triggered by pesticides. A subset of agricultural workers exposed to pesticides over a long period have reported Parkinson’s-like symptoms, but many other workers seem unaffected. Researchers are still grappling with find ways to unravel this knotty problem. Are pesticides and Parkinson’s Disease linked?
Confounding Variables
The researchers did not take groundwater samples, or collect data on the pesticides and herbicides used by the golf course. We don’t know which, if any, herbicides or pesticides were in use at the time. Given that the data is between ten and 34 years old, it also doesn’t tell us about the current risks of living near a golf course- how have regulations changed?
It’s also important to consider why someone at an elevated risk of Parkinson’s disease might choose to live near a golf course. Golf has been posited as having rehabilitative potential for Parkinson’s disease, and is very popular with seniors as a way to exercise and socialize. Could older people starting to develop mobility issues be living closer to the golf course so that they can access the course more easily? Not only this, but the Parkinson’s disease diagnosed participants had a significantly higher household income than the average local person and were more likely to live in an urban area than people with no diagnosis. We are not told whether any care homes or Parkinson’s support services are located in Olmstead County or how far they are from the golf course.
Staying the Course: Pesticides and Parkinson’s Disease
This research project is an intriguing start to a bigger study into how management of private property can have far-reaching effects on local people, and how environmental protections can mitigate serious injury. It may also give us some clues about the triggers for Parkinson’s disease. Is there a subet of patients who are more vulnerable to developing the condition when pesticides come into the mix?
Krzyzanowski B, Mullan AF, Dorsey ER, et al. Proximity to Golf Courses and Risk of Parkinson Disease. JAMA Network Open. 2025;8(5):e259198. doi:10.1001/jamanetworkopen.2025.9198
de Graaf L, Boulanger M, Bureau M, et al. Occupational pesticide exposure, cancer and chronic neurological disorders: A systematic review of epidemiological studies in greenspace workers. Environ Res. 2022;203:111822. doi:10.1016/j.envres.2021.111822
Cash MF, Ulanowski E, Danzl M. Development of a community-based golf and exercise program for people with Parkinson’s disease. Complement Ther Clin Pract. 2018;33:149-155. doi:10.1016/j.ctcp.2018.09.006
Bliss RR, Church FC. Golf as a Physical Activity to Potentially Reduce the Risk of Falls in Older Adults with Parkinson’s Disease. Sports (Basel). 2021;9(6):72. doi:10.3390/sports9060072
Are golf course owners putting local people at risk of Parkinson’s disease in their quest for the perfect green? Arizona neurologists claim in a research publication published this June, that liberal use of pesticides by golf clubs could be leading to Parkinson’s disease amongst the neighbours.
The paper, published by JAMA Network, describes how the odds of a person being diagnosed with Parkinson’s disease get bigger: the closer their home address is to a golf course. People who live within a mile of a golf course, the researchers say are 126% more likely to be diagnosed with Parkinson’s disease than people living six miles away. According to the study, people who share water service with a golf course are twice as likely to be diagnosed with Parkinson’s as those who don’t. The authors suggest that a proposed link between pesticides and Parkinson’s Disease could be responsible.
Environmental Impact on Parkinson’s Disease
The research team led by Brittany Krzyzanowski, PhD of Barrow Neurological Institute Phoenix, Arizona, used health records harvested from the Rochester Epidemiology Project (REP) to investigate environmental impacts on Parkinson’s disease diagnoses.
They studied the Parkinson’s prevalence around over 100 golf courses in Minnesota and Wisconsin to see if there existed a link between golf courses and the neurodegenerative disease. They discovered that people with a Parkinson’s diagnosis between 1991 and 2015 were more likely to have been living within three miles of a golf course than six miles or more from one.
Golf Course Clues
Krzyzanowski and her colleagues focused on a specific golf course in Olmstead County, Minnesota, to test their hypothesis that pesticides used to keep the local golf course verdant were slowly poisoning local seniors.
The researchers sought out records of people diagnosed with Parkinson’s in Minnesota and Southern Wisconsin, especially focusing on people who had lived in Olmstead County around the time their symptoms appeared. The team then looked for people in the area who had similar demographic characteristics, age and sex, but no Parkinson’s or Parkinson’s Disease-like symptoms.
They found 450 Parkinson’s cases in Olmstead and matched them with 9000 controls. That means the researchers collected 20 control participants of the same age and sex living in Minnesota or Southern Wisconsin between 1991 and 2015 for every Parkinson’s diagnosis. Once they screened the participants to make sure they could get enough information about where those people had lived, they ended up with 419 Parkinson’s patients and 5,113 control participants.
Most of the people diagnosed with Parkinson’s were seniors, aged between 63 and 80, median 73 years old, with 61% being male. The control participants were matched- their average age was 72 and 59% were male. The median time residents had spent at their last address was 18 years. This is important because if you are checking the impact of something local, you need people to have been living locally long enough for it to have had an effect.
Calculating the odds
The team started by looking to see whether people who had been diagnosed with Parkinson’s were more likely to live near a golf course than people without a diagnosis.
Through a simple comparison, they found that the addresses of people with Parkinson’s disease three years or more before they reported symptoms were clustered around golf courses, mostly between 1.7 and 2.7 miles away. The control participants, however, were more spread out, on average living between 1.2 and 4.3 miles away from the course. This is a pretty small difference at first glance, so the investigators pulled a mulligan and brought in some more complicated statistical methods to tease out the relationship. This time they compared the prevalence of Parkinson’s at set distances from the golf course. Would they find a more defined pattern?
When the researchers calculated how many people with Parkinson’s lived within a specific radius of the golf course compared to the local population, they found that the odds of a person having Parkinson’s disease decreased by 9% for every mile further from the golf course they lived.
The relationship between Parkinson’s and proximity to a golf course was non-linear, with more people diagnosed living within three miles of a links. The evidence seems to show that in 2015, you were more likely to find people with Parkinson’s disease living near a golf course. This does not, however, show a cause and effect relationship.
Water Table Trouble
An argument supported by circumstantial evidence is built piece by piece, so the neurology/epidemiology researchers moved on to the next layer of evidence. Since they hypothesized that the trouble was caused by pesticides rather than the golf course itself, the team switched their attention to the water supply.
The team speculated that if people were being affected by pesticides or herbicides from the golf course, the most likely cause was chemical nasties leaching into the water. The researchers identified golf courses with vulnerable groundwater; they assumed that in these places water washing off the golf courses was soaking into the ground and then leaching into the water supply.
If they could compare Parkinson’s rates near golf courses with more vulnerable groundwater to golf courses with less likelihood of contaminated water supplies, they reasoned, they should see a difference. The team matched each address to its tap water supply. Did they get their water from a private well on their property, was their water supply taken from an area near a golf course with vulnerable groundwater, or was the nearby golf course on a site invulnerable to contamination?
When the researchers mapped Parkinson’s diagnoses onto areas with vulnerable or less vulnerable groundwater, they saw an 82% increase in the chances that a person would have the condition, if the golf course was likely leaching water into the water supply. This increased to a 92% increase in the chance that a person would have a Parkinson’s diagnosis compared to someone who did not live near a golf course.
Interestingly, people who got their water from a municipal well located on the golf course showed no increase in their liklihood of being diagnosed with Parkinson’s versus people who did not live near a golf course.
Under par or over powered?
While this sounds like a neat little story, there are some important caveats to consider before you toss your golf clubs or put your home on the market.
Firstly, these are small changes. A 92% increase in the odds just means that the probability is nearly twice as high in one group than the other. This doesn’t tell you much about your absolute probability of being diagnosed with Parkinson’s Disease. A 126% increase in a small number is still a small number.
The team did not look at the address history more than three years prior to diagnosis. If somebody moved to Olmstead County in 1989 with early symptoms and reported them in 1991, would that skew the results? How long would somebody need to live near the golf course for it to have affected their neurological health? If only two to three years of exposure to whatever was causing the symptoms were necessary, should we not see gardeners and other people working at the golf course showing up with Parkinson’s Disease in similar or greater numbers in the area?
On the other hand, the median time living in the area was 18 years, so at least half of the Parkinson’s patients had been exposed to the golf course over a very long time. There is evidence that some people have a genetic predisposition that makes them more vulnerable to neurodegenerative diseases triggered by pesticides. A subset of agricultural workers exposed to pesticides over a long period have reported Parkinson’s-like symptoms, but many other workers seem unaffected. Researchers are still grappling with find ways to unravel this knotty problem. Are pesticides and Parkinson’s Disease linked?
Confounding Variables
The researchers did not take groundwater samples, or collect data on the pesticides and herbicides used by the golf course. We don’t know which, if any, herbicides or pesticides were in use at the time. Given that the data is between ten and 34 years old, it also doesn’t tell us about the current risks of living near a golf course- how have regulations changed?
It’s also important to consider why someone at an elevated risk of Parkinson’s disease might choose to live near a golf course. Golf has been posited as having rehabilitative potential for Parkinson’s disease, and is very popular with seniors as a way to exercise and socialize. Could older people starting to develop mobility issues be living closer to the golf course so that they can access the course more easily? Not only this, but the Parkinson’s disease diagnosed participants had a significantly higher household income than the average local person and were more likely to live in an urban area than people with no diagnosis. We are not told whether any care homes or Parkinson’s support services are located in Olmstead County or how far they are from the golf course.
Staying the Course: Pesticides and Parkinson’s Disease
This research project is an intriguing start to a bigger study into how management of private property can have far-reaching effects on local people, and how environmental protections can mitigate serious injury. It may also give us some clues about the triggers for Parkinson’s disease. Is there a subet of patients who are more vulnerable to developing the condition when pesticides come into the mix?
Krzyzanowski B, Mullan AF, Dorsey ER, et al. Proximity to Golf Courses and Risk of Parkinson Disease. JAMA Network Open. 2025;8(5):e259198. doi:10.1001/jamanetworkopen.2025.9198
de Graaf L, Boulanger M, Bureau M, et al. Occupational pesticide exposure, cancer and chronic neurological disorders: A systematic review of epidemiological studies in greenspace workers. Environ Res. 2022;203:111822. doi:10.1016/j.envres.2021.111822
Cash MF, Ulanowski E, Danzl M. Development of a community-based golf and exercise program for people with Parkinson’s disease. Complement Ther Clin Pract. 2018;33:149-155. doi:10.1016/j.ctcp.2018.09.006
Bliss RR, Church FC. Golf as a Physical Activity to Potentially Reduce the Risk of Falls in Older Adults with Parkinson’s Disease. Sports (Basel). 2021;9(6):72. doi:10.3390/sports9060072
