April is National Parkinson's Awareness Month—a timely reminder that neurological disorders, conditions affecting the brain, spinal cord, and nerves, impact one in two Americans and represent one of the greatest threats to global public health. Among these disorders, Parkinson's disease stands out for its scale and trajectory: nearly 90,000 Americans are diagnosed annually, and the number of people living with the disease globally has doubled over the past 25 years.
Yet despite its reach, Parkinson's is frequently misunderstood, misdiagnosed, and mismanaged. That's why Dr. Aasha Trowbridge—medical director of virtual care at Marathon Health—sat down with Dr. Ray Dorsey for this Grand Strides session. Dr. Dorsey is a neurologist, director of the Center for the Brain & Environment at Atria Health and Research Institute, and co-author of the New York Times bestseller The Parkinson's Plan—he shares what we're getting wrong, what prevention really looks like, and how employers can play a meaningful role.
Understanding the causes of Parkinson's disease
Q: Your perspective on the environmental causes of Parkinson's disease is a very different approach than many clinicians were trained on. What are we getting wrong in how we think about brain health today?
Dr. Dorsey: In our medical training, many of us were taught that Parkinson's disease was due to a combination of aging, genetics, bad luck, and a passing mention of pesticides. I think that's largely wrong—I think Parkinson's is largely manmade.
Consider this: Dr. James Parkinson first described this disease in 1817—fast forward 200 years to 2017 and 6 million people had it. How? Today only 13% of people with Parkinson's have a known genetic link, and it's growing faster than aging alone can explain. If you put a mouse in a laboratory and let it age, it will never spontaneously develop Parkinson's—the only way is if you manipulate its genes or expose it to toxic chemicals.
Neurological disorders are not just a natural consequence of aging. They're unnatural ones principally fueled by chemicals we ingest. We can create a world where Parkinson's, Alzheimer's, and ALS are again extraordinarily rare—but only if we start treating them like the environmentally driven diseases they largely are.
Rethinking the prevention of neurological disorders
Q: When we think about prevention of neurological disorders, how should we think about the economics—especially for employers—and the role occupational exposures play in shaping risk and brain health in the workplace?
Dr. Dorsey: In the U.S. healthcare system, you have to follow the financial incentives. Pharmaceutical companies, hospitals, imaging centers—they all benefit financially from more people having disease. When you look at who has a financial incentives to think about the prevention of neurological disorders you're left with the VA, Medicare and Medicaid, and employers, because employees may stay with an organization long enough for prevention to pay off.
I think these diseases are fundamentally preventable and employers must embrace a prevention orientation that goes beyond gym memberships. If you aren't exposed to these toxic chemicals, you're highly unlikely to get Parkinson's. One area of opportunity—forty million Americans get water from wells. Why aren't employers encouraging carbon filters or offering free well water testing for pesticides and industrial chemicals? Why aren't more employers paying attention to air pollution, when the nose is the front door to the brain? Why are we not paying more attention to the food and drinks we serve? We put soda in schools and blame children for getting obese.
If we addressed these upstream environmental factors, we'd see far less prevalence of the chronic diseases that account for 90% of U.S. healthcare spend. It’s time to think about new angles of brain health in the workplace, and outside it.
Q: Early signs of Parkinson's disease often go unnoticed. Where do you see the biggest missed opportunity to change a patient’s trajectory? What early signs should primary care providers be more attuned?
Dr. Dorsey: In 2003, a German pathologist found that the pathology of Parkinson's may not begin in the brain at all. He first found it in the smell center—the olfactory bulb—and in the vagus nerve. His theory was that the pathology of Parkinson's might begin in the gut and spread upward like a row of dominoes, with new symptoms developing as it spreads.
This is consistent with what we know about the anatomy. A lesion in the vagus nerve causes constipation. As it moves up to the pons—where our sleep center is—people start acting out their dreams, a condition called REM sleep behavior disorder. Then it reaches the substantia nigra in the midbrain, and that's when the classic tremor and slowness of movement appear. A "gut-first" form may occur from toxic chemicals being ingested, through contaminated well water for example. The "nose-first" form occurs when chemicals inhaled through the air—weed killers sprayed on nearby farms or golf courses, or outdoor air pollution—enter through the olfactory bulb.
The early signs of Parkinson's disease that primary care providers might see first—constipation, sleep disturbances, loss of smell—may actually be the earliest signals of the disease, years before a tremor ever develops. These are opportunities for primary care providers to detect potential early signals and act accordingly.
Q: What non-pharmaceutical measures have been shown to alleviate Parkinson's symptoms—and how should we think about improving brain health through lifestyle?
Dr. Dorsey: Exercise has by far the most robust evidence and potential to slow the rate of disease progression—there are people with Parkinson's who are in better physical shape today than before their diagnosis. One study showed that exercise among colon cancer patients reduced cancer recurrence by 28%. If that can happen for colon cancer, think about what it can do for neurological diseases, where we know exercise releases neurotrophic factors that protect damaged neurons. Beyond that, it comes down to avoiding ongoing exposure to the environmental chemicals and getting really good care.
From awareness to action: Driving change to improve brain health
Q: Healthcare often moves slowly, even when evidence is strong. What do you see as the biggest barrier to acting on what we already know about brain health—and how do we overcome it?
Dr. Dorsey: I don't think the change is going to come from within medicine—it has to come from without, and will likely come from the people most directly affected by these diseases.
We live in a world largely free of polio not because neurologists sounded the alarm, but because a president who had polio led the March of Dimes, and 17 years later, Dr. Jonas Salk held up a vaccine. In 1987, activists facing the AIDS epidemic said "Silence equals death," made their voices heard, and changed the course of HIV—today preventable and at its lowest incidence since 1990.
The same kind of pressure needs to happen for brain health. We're starting to see it—parents concerned about nerve toxins being sprayed at kids' schools, studies linking soccer playing to ALS, people starting to pay attention to their food, water, and air. Doctors can help guide these conversations and bring credible science to patients, employers, and insurers. The goal should be a world where we're not spending one in every five dollars of society's money on sick care, but actually preventing people from getting these diseases in the first place.
Q: What’s one small thing primary care providers could do differently at the clinic level that would make a meaningful difference?
Dr. Dorsey: Start measuring these chemicals. I'm a neurologist and until two months ago, I had never measured a pesticide level in my entire career. When someone is diagnosed with cancer, we don't measure the carcinogens they may have been exposed to. We don't measure trichloroethylene, PFAS, organochlorine pesticides, benzene—the list is long, and it's a fundamental gap. There are affordable, available tests we should all become familiar with. What gets measured gets managed, so we need to ensure we're measuring the important things—including the upstream root causes of these diseases.
Q: As individuals, what’s one thing we can do to improve our own brain health?
Dr. Dorsey: One chemical in particular concerns me greatly: trichloroethylene. It's a six-atom molecule that's been used in the U.S. for 100 years, a known carcinogen linked to multiple cancers, and it's associated with a 500% increased risk of Parkinson's disease. It's widely used in degreasing and dry cleaning, so it’s best to find an organic or green dry cleaner. More than half of Superfund sites in the country are contaminated with it, and many of us live near these sites without knowing it. If you use a conventional dry cleaners or live near a Superfund site, it's worth finding out if this chemical is in your environment.
Q: What kinds of preventative or therapeutic innovations in the field of Parkinson's disease are you most excited about?
Dr. Dorsey: The most exciting shift is a growing realization that diseases have causes—and that our job as doctors is to find them. Because once you figure out the cause of a disease, it's much easier to prevent or even cure it. For stroke, if you find AFib, you give an anticoagulant and reduce future risk—today the incidence of stroke is 30% lower than it was in 1990. Studies show that up to 45% of Alzheimer's disease may be potentially preventable. If almost half of Alzheimer's is preventable, what portion of Parkinson's or ALS is preventable?
A renewed focus on root causes is what I'm most excited about. We already do this well in other parts of neurology—for seizures, strokes, neuropathies. If we applied that same rigor to neurodegenerative diseases, we would find their causes and create a world where people aren't suffering from them.
What this means for you
When it comes to brain health, there's meaningful action that employers, patients, and providers can all take—and prevention is a powerful place to start.
- Examine environmental exposures—toxic chemicals in air, water, and food—in your workplace, neighborhoods, and homes. These are increasingly recognized as primary culprits, and employer-sponsored health and safety can address upstream risks that most of the healthcare system isn't motivated to act on.
- Invest in primary care to promote healthy lifestyles and early detection of brain disease. Constipation, sleep disturbances, and loss of smell can signal Parkinson's years before tremor develops—care teams with the time and continuity to screen for these early signs of Parkinson’s can meaningfully change a patient's trajectory.
- Prevention shouldn't stop at the clinic door. From encouraging well water testing to prioritizing air quality, employers can extend brain health beyond the appointment—and care teams can help connect patients to the right resources and referrals before disease takes hold.
Neurological disease is not an inevitable consequence of aging, and those who invest in care—built around prevention, early detection, and the whole-person—are best positioned to improve outcomes and reduce long-term healthcare spend.
This interview has been condensed and edited for clarity and brevity.
About Grand Strides
Marathon Health’s Grand Strides series brings our clinical community together for candid conversations with trailblazers in healthcare. These sessions are designed to spark new thinking, share actionable insights, and inspire our teams as we navigate the evolving landscape of care.
Looking for more healthcare optimism? Read the recap from Grand Strides with substance use disorder expert, Dr. Jacob "Gus" Crothers.
About Grand Strides
Marathon Health’s Grand Strides series brings our clinical community together for candid conversations with trailblazers in healthcare. These sessions are designed to spark new thinking, share actionable insights, and inspire our teams as we navigate the evolving landscape of care. Looking for more healthcare optimism? Read the recap from Grand Strides with Dr. Amy Abernethy.