HoldsUp

DavidPerlmutterMD · 2026-07-07 · David Perlmutter (host), Ray Dorsey

Parkinson's Is a Man-Made Disease: The Chemicals Linked to a 500% Higher Risk | Dr. Ray Dorsey

57 research-tied claims examined: 2 overstated 5 context 37 supported 13 unverified

37 Supported by research
0:06:07Ray Dorseysupportedmoderate

According to the Global Burden of Disease study, approximately 6 million people worldwide had Parkinson's disease as of 2016-2017.

"And 200 years later, the Global Burden of Disease says that 6 million people have the disease." (said at 0:06:07)

The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2016 systematic analysis published in The Lancet Neurology determined that in 2016, approximately 6.1 million individuals worldwide had Parkinson's disease (95% UI 5.0–7.3 million), more than doubling the 2.5 million estimated in 1990.

0:07:08Ray Dorseysupportedhigh

In the United States, 80 to 90 percent of lung cancer cases occur in people who smoke.

"Even today, 80 to 90% of lung cancer in the United States is in people who smoke." (said at 0:07:08)

The speaker's statement accurately reflects established epidemiological data in the United States. Surveillance and registry data from the CDC and national cancer registries consistently show that 80% to 90% of lung cancer cases and deaths in the US are attributable to cigarette smoking.

0:07:44Ray Dorseysupportedmoderate

In the Parkinson's Foundation PD GENEration study of 8,000 individuals with Parkinson's published in Brain, 13% carried a known genetic cause or risk factor, meaning 87% had no known genetic cause or risk factor.

"And last year in a journal called Brain, which you know is one of the top journals in the field, they looked at the genetic testing results of the first 8,000 individuals with Parkinson's disease. Of that 8,000, 13% carry a genetic cause or genetic risk factor for the disease. Said another way, 87% of Americans with Parkinson's, the vast majority of Americans with Parkinson's disease, have no known genetic cause or risk factor for the disease." (said at 0:07:44)

The speaker accurately summarizes the primary findings of the Parkinson's Foundation PD GENEration study (published in Brain), which evaluated genetic testing across a targeted panel of Parkinson's disease (PD)-associated genes (such as GBA1, LRRK2, PRKN, SNCA, and others) in people living with Parkinson's. In the initial cohort of several thousand tested individuals, approximately 13% tested positive for an established causal mutation or clinically relevant risk variant (predominantly in GBA1 and LRRK2), meaning roughly 87% had no identifiable pathogenic or risk-associated variant on the tested panel. Broader multi-ancestry observational cohorts (such as the GP2 initiative partnering with PD GENEration) similarly find that monogenic causal variants occur in ~2.1% of patients and established GBA1/LRRK2 risk variants occur in ~11.8%, corroborating that the vast majority (~86–87%) do not carry known major genetic drivers on standard testing panels.

0:09:15Ray Dorseysupportedmoderate

For 2021, the estimated global prevalence of Parkinson's disease was 11.8 million people.

"For 2021, it's estimated it's 11.8 million." (said at 0:09:15)

According to analyses of the Global Burden of Disease (GBD) Study 2021, the estimated global prevalence of Parkinson's disease in 2021 was approximately 11.76 to 11.77 million individuals (which rounds to 11.8 million), rising from around 3.15 million cases in 1990.

0:10:45Ray Dorseysupportedlow

Exposure to trichloroethylene (TCE) and perchloroethylene (PCE) is associated in a twin study with a 500% increased risk of Parkinson's disease.

"These two chemicals have been associated in a twin study with a 500% increased risk of Parkinson's." (said at 0:10:45)

A 2012 study by Goldman and colleagues evaluated solvent exposures among 99 twin pairs discordant for Parkinson's disease from the NAS/NRC World War II Veteran Twins Cohort. Ever exposure to trichloroethylene (TCE) was associated with a 6.1-fold increased risk of Parkinson's disease (odds ratio 6.1, 95% CI 1.2-33, p = 0.034), which corresponds to an approximate 500% increase in risk. Exposure to perchloroethylene (PERC/PCE) showed an odds ratio of 10.5 (95% CI 0.97-113, p = 0.053). Because this was a retrospective observational study with a relatively small sample size and wide confidence intervals, certainty is rated as low.

0:11:20Ray Dorseysupportedvery low

Pesticides such as paraquat and chlorpyrifos, as well as air pollution and solvents like TCE and PCE, damage the mitochondria in nerve cells.

"So all the pesticides that have been linked, or many of the pesticides linked to Parkinson's disease—paraquat, chlorpyrifos, these chemicals—and air pollution all damage the energy-producing parts of cells. And the cells that are most susceptible to disruption from mitochondrial toxicants are nerve cells, and among nerve cells it's those nerve cells in the part of the brain called the substantia nigra that are lost or damaged, that likely have enormous energy requirements." (said at 0:11:20)

Preclinical in vitro and animal studies support the speaker's claim. Pesticides associated with Parkinson's disease, such as paraquat and chlorpyrifos, cause mitochondrial fragmentation, impair mitochondrial function, and reduce intracellular ATP levels. Experimental models further demonstrate that exposure to these mitochondrial toxicants leads to selective loss and damage of dopaminergic neurons in the substantia nigra. Because this mechanistic evidence derives primarily from cell cultures and animal models, certainty is rated very low.

0:12:25David Perlmutter (host)supportedhigh

More than 70 countries around the world, including China, have banned or curtailed the use of the herbicide paraquat.

"72 countries or maybe more around the world have either banned it outright or significantly curtailed its use, but that's not the case in America." (said at 0:12:25)

Published policy analyses and reviews confirm that approximately 70 countries (and over 67 countries with complete bans alone) have banned or phased out paraquat, including China, the European Union member states, the UK, Switzerland, and Brazil, while the pesticide remains approved and widely used in the United States.

0:13:10Ray Dorseysupportedhigh

Exposing laboratory mammals (including mice, rats, and rabbits) to paraquat induces features of Parkinson's disease, including tremors.

"According to reporting from The Guardian, it appears that a manufacturer of paraquat did those experiments with three different mammals—mice, rats, and rabbits—in the 1960s. So at least evidence from academics for 30 years and possibly from the manufacturer for 60 years knows that when you expose laboratory animals to paraquat, they develop the features, including a tremor." (said at 0:13:10)

The speaker's claim that exposing laboratory mammals (such as mice and rats) to paraquat induces key pathological and motor features of Parkinson's disease, including tremors and neurobehavioral deficits, is well-established and supported by extensive experimental research across decades. Recent reviews on animal models of Parkinson's disease confirm that paraquat exposure is widely used to reproduce key cellular and motor characteristics of Parkinsonism, including loss of dopaminergic neurons in the substantia nigra, oxidative stress, and motor impairments such as tremors, akinesia, and altered neurobehavioral performance.

0:21:09Ray Dorseysupportedmoderate

Research by Dr. Virginia Rauh at Columbia University demonstrated that higher levels of chlorpyrifos in umbilical cord blood correlate with lower IQ scores in children at ages 3, 5, and 7.

"Dr. Virginia Rauh here at Columbia University showed exposure to another pesticide called chlorpyrifos was sprayed inside the homes of people in New York City to kill insects. She finds that pesticide in the umbilical cord blood of children. She then follows these children: the higher their level in umbilical cord blood, the lower the IQ at three, five, and seven." (said at 0:21:09)

Research led by Dr. Virginia Rauh at Columbia University evaluated inner-city New York City children whose mothers were exposed to chlorpyrifos during pregnancy. The investigators measured chlorpyrifos levels in umbilical cord blood plasma and followed the children longitudinally. At age 3, higher prenatal chlorpyrifos exposure was significantly associated with lower scores on the Bayley Mental Development Index and Psychomotor Development Index. By age 7, higher umbilical cord chlorpyrifos levels significantly correlated with deficits in Full-Scale IQ and Working Memory assessed via the Wechsler Intelligence Scale for Children (WISC-IV). While formal IQ testing occurred at age 7 and cognitive development was measured at age 3 (rather than continuous annual testing at ages 3, 5, and 7), the core claim accurately reflects Dr. Rauh's findings regarding umbilical cord chlorpyrifos levels and reduced cognitive/IQ performance.

  • supports: Impact of prenatal chlorpyrifos exposure on neurodevelopment in the first 3 years of life … (Pediatrics 2006) · cited 734x in the literature
    "neurotoxicant effects of prenatal exposure to chlorpyrifos were evaluated in 254 children through the first 3 years of life. This report examined cognitive and motor development at 12, 24, and 36 months (measured with the Bayley Scales of Infant Development II) and child behavior at 36 months (measured with the Child Behavior Checklist) as a function of chlorpyrifos levels in umbilical cord plasma. Highly exposed children (chlorpyrifos levels of >6.17 pg/g plasma) scored, on average, 6.5 points lower on the Bayley Psychomotor Development Index and 3.3 points lower on the Bayley Mental Development Index at 3 years of age compared with those with lower levels of exposure." (abstract, results, passage verified)
    pubmedfull study (doi)
  • supports: Seven-year neurodevelopmental scores and prenatal exposure to chlorpyrifos, a common agric… (Environmental health perspectives 2011) · cited 531x in the literature
    "In a sample of 265 children, participants in a prospective study of air pollution, we measured prenatal CPF exposure using umbilical cord blood plasma (picograms/gram plasma) and 7-year neurodevelopment using the Wechsler Intelligence Scale for Children, 4th edition (WISC-IV)... On average, for each standard deviation increase in CPF exposure (4.61 pg/g), Full-Scale intelligence quotient (IQ) declined by 1.4% and Working Memory declined by 2.8%." (abstract, results, passage verified)
    pubmedfull study (doi)
0:21:30Ray Dorseysupportedmoderate

A study by Dr. Virginia Rauh published in JAMA Neurology showed that higher prenatal chlorpyrifos exposure is associated with structural brain MRI abnormalities and poorer motor function in children aged 6 to 15.

"And then last month in JAMA Neurology, one of the top journals in the field, she does MRIs of these children now 6 to 15: the higher the level, the more structural brain abnormalities on MRI and the worse the motor function." (said at 0:21:30)

A prospective longitudinal cohort study published in JAMA Neurology evaluated 270 children aged 6.0 to 14.7 years with prenatal chlorpyrifos (CPF) exposure measurements. Higher prenatal CPF levels were significantly associated with dose-dependent structural brain alterations on MRI (including thicker frontal, temporal, and posteroinferior cortices and reduced regional white matter volumes) as well as poorer performance on fine motor and motor programming tasks.

  • supports: Brain Abnormalities in Children Exposed Prenatally to the Pesticide Chlorpyrifos. (JAMA neurology 2025) · cited 18x in the literature
    "Participants included 270 youths (123 boys and 147 girls) aged 6.0 to 14.7 years (mean [SD] age, 10.38 [1.12] years) with self-identified Dominican or African American mothers. Progressively higher prenatal CPF exposure levels associated significantly in childhood with progressively thicker frontal, temporal, and posteroinferior cortices; reduced white matter volumes in the same regions; higher fractional anisotropy and lower diffusivity in internal capsule white matter; lower regional blood flow throughout the brain; lower indices of neuronal density in deep white matter tracts; and poorer performance on fine motor (β, -0.30; t261 = -5.0; P < .001) and motor programming (β, -0.27; t261 = -4.36; P < .001) tasks." (abstract, results, passage verified)
    pubmedfull study (doi)
0:23:14Ray Dorseysupportedlow

A study by Kimberly Paul and Beate Ritz from UCLA showed that living or working near areas where paraquat is sprayed is associated with a doubling of Parkinson's disease risk.

"A study done by Dr. Kimberly Paul and Dr. Beate Ritz from UCLA showed that simply living or working near where paraquat is sprayed is associated with doubling of your risk of Parkinson's disease." (said at 0:23:14)

A 2024 population-based case-control study led by Kimberly Paul and Beate Ritz at UCLA evaluated ambient residential and workplace exposure to paraquat in 829 Parkinson's disease (PD) patients and 824 community controls in California's Central Valley. Long-term workplace proximity was associated with a 2.15-fold increase in PD odds (OR 2.15, 95% CI 1.46–3.19), and residential proximity was associated with a 1.91-fold increase in odds (OR 1.91, 95% CI 1.30–2.83), directly supporting the claim of an approximate doubling of risk.

0:27:55Ray Dorseysupportedlow

Studies demonstrate that people diagnosed with Parkinson's disease who continue to be exposed to pesticides experience faster disease progression.

"And indeed, there are studies that have demonstrated that people who already have Parkinson's disease who are exposed to pesticides have a faster rate of progression." (said at 0:27:55)

Observational cohort studies tracking individuals diagnosed with Parkinson's disease (PD) have found that ambient and occupational exposure to specific agricultural pesticides (such as organophosphates, copper sulfate, and MCPA) is associated with faster motor, cognitive, and non-motor symptom progression. Because these findings are derived from longitudinal observational cohorts utilizing geographic information systems and self-reported exposure models, the certainty of evidence is graded as low.

0:28:04Ray Dorseysupportedmoderate

Studies show that individuals with Parkinson's disease exposed to high levels of air pollution have higher rates of hospitalization.

"And there are studies that suggest that individuals who already have Parkinson's disease, who are exposed to high levels of air pollution, are more likely to be hospitalized for their Parkinson's disease." (said at 0:28:04)

Large-scale epidemiological studies evaluating air pollution and Parkinson's disease (PD) have demonstrated that individuals exposed to elevated levels of air pollutants (such as fine particulate matter [PM2.5], nitrogen dioxide [NO2], and carbon monoxide) have higher rates of hospitalization and emergency department visits for PD. For instance, a nationwide longitudinal analysis of over 10 million Medicare beneficiaries found that continuous high exposure to PM2.5 (90th vs. 0.5th percentile) was associated with significantly increased odds of hospitalization with PD (OR 1.634, 95% CI: 1.489–1.792).

0:11:09Ray Dorseysupportedmoderate

Exposure to the herbicide glyphosate is associated with an increased risk of cancer, specifically non-Hodgkin's lymphoma.

"So glyphosate is associated with cancer and non-Hodgkin's lymphoma." (said at 0:11:09)

The claim is supported by epidemiological meta-analyses and authoritative agency evaluations. In 2015, the International Agency for Research on Cancer (IARC) classified glyphosate as probably carcinogenic to humans (Group 2A), identifying non-Hodgkin lymphoma (NHL) as the primary cancer associated with exposure. A 2019 meta-analysis by Zhang et al. evaluating human epidemiological studies found that high cumulative exposure to glyphosate-based herbicides was associated with a statistically significant 41% increased risk of NHL (meta-RR = 1.41, 95% CI: 1.13–1.75). While some individual cohort studies (such as the Agricultural Health Study) and subsequent analyses have shown mixed or subtype-specific risks (e.g., diffuse large B-cell lymphoma), the epidemiological association between glyphosate exposure and NHL is well-documented.

0:05:40Ray Dorseysupportedhigh

In his 1817 medical description of the shaking palsy, Dr. James Parkinson described six individuals with the condition.

"Parkinson's disease, according to Dr. James Parkinson when he wrote the major description of the disease in 1817, he said this is a disease that's not been classified in the medical literature. He writes what he in all likelihood thinks is a new disease. He describes six people with the disease in 1817 amongst the industrial revolution in London" (said at 0:05:40)

The claim is fully supported. In his seminal 1817 monograph 'An Essay on the Shaking Palsy', Dr. James Parkinson described the condition as a distinct medical entity not yet properly classified in nosology and detailed the clinical histories of six individuals (cases I through VI) exhibiting the characteristic resting tremor, weakness, and festinant gait.

  • supports: An essay on the shaking palsy (Brain 2017) · cited 31x in the literature
    "Two hundred years ago at the age of 62, James Parkinson wrote a 66 page treatise entitled An Essay on the Shaking Palsy. He believed that he had identified a new ‘medical species’ that had ‘not yet obtained a place in the classification of nosologists’ (Parkinson, 1817)... Chapter 1 of The Essay concludes with six clinical vignettes." (abstract, passage verified)
    openalexfull study (doi)
0:31:27Ray Dorseysupportedmoderate

PM2.5 particles can directly penetrate the olfactory nerve, carrying toxic metals such as lead from gasoline, iron from brakes, and platinum from catalytic converters into the brain.

"But some are so small, they're 2.5 microns, 1/1000th of a millimeter. They're a 30th the width of my hair. And some directly penetrate the nerve responsible for smell. And they're like a Trojan horse. They're not carrying in troops, but they're carrying in toxic metals into the brain: lead from gasoline, iron from brakes, platinum from catalytic converters." (said at 0:31:27)

Evidence supports the direct nose-to-brain transport of airborne metal-bearing particulate matter via the olfactory nerve and olfactory bulb pathway. Specifically, ultrafine nanoparticles (which form the sub-fraction of PM2.5, generally <200 nm) generated from vehicle combustion, brake wear, and catalytic converter emissions have been shown in toxicological and human autopsy studies to bypass the blood-brain barrier by translocating along olfactory sensory nerve axons directly into the brain, carrying transition metals like iron and other toxic co-pollutants.

0:31:50Ray Dorseysupportedlow

Toxic metals carried into the brain by air pollution are associated with the misfolding of alpha-synuclein in Parkinson's disease and beta-amyloid in Alzheimer's disease.

"And many of these toxic metals have been associated with misfolding of proteins, a protein called alpha-synuclein in Parkinson's disease, a protein called beta-amyloid in Alzheimer's disease." (said at 0:31:50)

Toxic metals (including airborne metal nanoparticles and heavy metals such as cadmium, mercury, iron, and aluminum) have been extensively demonstrated in observational neuropathology and mechanistic studies to be associated with and induce the misfolding and aggregation of alpha-synuclein in Parkinson's disease and beta-amyloid in Alzheimer's disease.

0:32:18Ray Dorseysupportedmoderate

Loss of smell is one of the earliest features of Parkinson's and Alzheimer's disease, preceding memory loss and tremor by years or decades.

"And we know one of the earliest features of both these diseases is loss of smell, and which precedes the memory loss and tremor by years, if not decades." (said at 0:32:18)

The speaker's claim is supported by robust clinical and cohort evidence. Olfactory dysfunction (hyposmia or anosmia) is well-established as one of the earliest prodromal features of both Parkinson's disease (PD) and Alzheimer's disease (AD). In PD, loss of smell is a classic non-motor symptom that can precede motor symptoms like tremor by years or even decades. In AD, longitudinal cohort studies demonstrate that olfactory decline is detectable up to 10 years before the clinical onset of cognitive impairment or dementia diagnosis.

0:33:04Ray Dorseysupportedmoderate

The economic burden of Parkinson's disease in the United States is $50 billion, and the economic burden of Alzheimer's disease is $300 billion.

"The economic burden of Parkinson's disease in the United States is $50 billion. I think the economic burden of Alzheimer's disease is $300 billion." (said at 0:33:04)

The speaker's estimates closely reflect widely cited national economic analyses in the United States. A comprehensive 2020 analysis published in npj Parkinson's Disease calculated the total economic burden of Parkinson's disease in the US to be $51.9 billion in 2017 (comprising $25.4 billion in direct medical costs and $26.5 billion in indirect/non-medical costs). For Alzheimer's disease and related dementias, the Alzheimer's Association 2020 Facts and Figures report estimated total healthcare, long-term care, and hospice payments at $305 billion for 2020.

0:33:30David Perlmutter (host)supportedhigh

In 1982 to 1983, Dr. William Langston discovered that MPTP, a contaminant in synthetic heroin, induced immediate Parkinsonism in exposed individuals.

"Back in 1982 into '83, Dr. Langston, a neurologist at Stanford, was confronted by individuals in the emergency room who had suddenly developed Parkinson's seemingly out of the blue. Detective work he he engaged revealed that they had all gotten a a drug that was uh synthetic heroin... Anyway, so it turns out that they discovered that a contaminant, if you will, of the synthetic heroin, MPTP, induced Parkinsonism immediately in these people" (said at 0:33:30)

In 1982–1983, Dr. J. William Langston and colleagues identified that 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a chemical byproduct/contaminant in a synthetic heroin analog (MPPP), caused rapid and severe parkinsonism in young drug users in Northern California. Their landmark case report was published in Science in 1983 and led to widespread understanding of MPTP neurotoxicity and animal models of Parkinson's disease.

  • supports: The MPTP Story (Journal of Parkinson s Disease 2017) · cited 423x in the literature
    "The identification of MPTP, a relatively simple compound which causes selective degeneration of the substantia nigra after systemic administration, has had an a significant impact on the understanding and treatment of Parkinson’s disease (PD) over the last 30 years. This article is prefaced by the intriguing “medical detective story” that lead to the discovery of the biological effects of MPTP in humans." (abstract, passage verified)
    openalexfull study (doi)
  • supports: MPTP Parkinsonism and Implications for Understanding Parkinson's Disease (Movement Disorders Clinical Practice 2021) · cited 23x in the literature
    "In 1983, Langston et al first reported chronic parkinsonism in individuals following self-injection of intravenous heroin contaminated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP).1 This astute clinical observation and subsequent work led to the discovery of MPTP as a dopaminergic neurotoxin... The original 4 cases were individuals from northern California who had recently injected a new synthetic form of heroin." (abstract, passage verified)
    openalexfull study (doi)
0:34:28David Perlmutter (host)supportedvery low

Examination of the brain of an MPTP-exposed patient 13 years later revealed an ongoing chronic immune response by activated microglial cells in the substantia nigra.

"And but what was interesting is 13 years later, one of the patients passed away and he examined the brain of this patient. What he found was an ongoing immune response by cells in the brain called the microglia cells digesting away the part of the brain that's the center of Parkinson's, the substantia nigra." (said at 0:34:28)

A landmark postmortem case series by Langston et al. (1999) examined the brains of three patients who had developed severe parkinsonism after accidental MPTP exposure, with survival times ranging from 3 to 16 years post-exposure (including a patient surviving ~12–16 years). Neuropathological examination demonstrated severe loss of pigmented dopaminergic neurons in the substantia nigra accompanied by marked gliosis, extraneuronal melanin, and activated microglia clustering around degenerating nerve cells, indicating an ongoing, self-perpetuating neuroinflammatory/neurodegenerative process years after the initial toxic insult. As this evidence comes from a small postmortem case series (n=3), the GRADE certainty is very low.

  • supports: Evidence of active nerve cell degeneration in the substantia nigra of humans years after 1… (Annals of neurology 1999) · cited 969x in the literature
    "Survival times ranged from 3 to 16 years. Neuropathological examination revealed moderate to severe depletion of pigmented nerve cells in the substantia nigra in each case. Lewy bodies were not present. In Patients 1 and 2, there was gliosis and clustering of microglia around nerve cells. Patient 3 had a similar picture and also showed large amounts of extraneuronal melanin. These findings are indicative of active, ongoing nerve cell loss, suggesting that a time-limited insult to the nigrostriatal system can set in motion a self-perpetuating process of neurodegeneration." (abstract, results, passage verified)
    pubmedfull study (doi)
0:37:24Ray Dorseysupportedhigh

A study in the New England Journal of Medicine showed that exercise decreases the risk of colon cancer recurrence.

"Uh it turns out that exercise can help uh decreases your risk of recurrence of colon cancer in a study in the New England Journal of Medicine." (said at 0:37:24)

A landmark phase 3 multicenter randomized controlled trial published in the New England Journal of Medicine (the CHALLENGE trial) evaluated a 3-year structured exercise program versus health-education materials in 889 patients with resected colon cancer after adjuvant chemotherapy. At a median follow-up of 7.9 years, the exercise group showed a statistically significant 28% reduction in the risk of disease recurrence, new primary cancer, or death (hazard ratio 0.72; 95% CI, 0.55 to 0.94; P = 0.02), with 5-year disease-free survival rates of 80.3% versus 73.9%.

0:39:08Ray Dorseysupportedhigh

Clinical trial results for co-enzyme Q10 in Parkinson's disease showed no therapeutic benefit.

"And the the last trial showed no benefit. Now that was at that dose in those individuals." (said at 0:39:08)

The largest and definitive phase III randomized controlled trial of coenzyme Q10 in early Parkinson's disease (the QE3 trial, n=600) evaluated high doses (1200 mg/d and 2400 mg/d) and found no evidence of clinical benefit, terminating early for futility. Subsequent systematic reviews and meta-analyses of randomized trials have confirmed that CoQ10 does not improve motor or non-motor outcomes compared with placebo in Parkinson's disease.

0:41:00David Perlmutter (host)supportedmoderate

Type 2 diabetics have approximately a 40% increased risk of developing Parkinson's disease.

"type 2 diabetics have about perhaps a 40% increased risk of of Parkinson's?" (said at 0:41:00)

The speaker's statement that individuals with diabetes have approximately a 40% increased risk of developing Parkinson's disease is well supported by systematic reviews and meta-analyses of population-based cohort studies. Earlier landmark meta-analyses reported a 37% to 38% increased relative risk (e.g., RR = 1.38, 95% CI: 1.18–1.62 in Yue et al., 2016; RR = 1.37, 95% CI: 1.21–1.55 in Cereda et al., 2011). More recent comprehensive meta-analyses including tens of millions of participants estimate this elevated relative risk between 22% and 29% (e.g., RR = 1.27, 95% CI: 1.20–1.35 in a 2023 meta-analysis of 15 cohort studies by European Journal of Epidemiology).

0:43:00Ray Dorseysupportedmoderate

There are approximately 1.2 million people with Parkinson's disease in the United States.

"And we want everyone to know about this because if you have Parkinson's disease, among the 1.2 million people with Parkinson's, why not slow that progression? And that's just in the US." (said at 0:43:00)

A landmark 2018 multi-cohort epidemiological study evaluating Parkinson's disease (PD) prevalence across North America calculated that approximately 680,000 individuals aged 45 and older had PD in the United States in 2010, and projected that this number would reach approximately 930,000 by 2020 and 1,238,000 (approx. 1.2 million) by 2030 due to population aging.

  • supports: Prevalence of Parkinson's disease across North America. (NPJ Parkinson's disease 2018) · cited 1027x in the literature
    "Using our age- and sex-specific meta-estimates from California, Minnesota, and Ontario and the US population structure from 2010, we estimate the overall prevalence of PD among those aged ≥45 years to be 572 per 100,000 (95% confidence interval 537-614) that there were 680,000 individuals in the US aged ≥45 years with PD in 2010 and that that number will rise to approximately 930,000 in 2020 and 1,238,000 in 2030 based on the US Census Bureau population projections." (abstract, results)
    pubmedfull study (doi)
0:43:48Ray Dorseysupportedlow

A study by Dr. Brittany Krzyzanowski and Dr. Rodolfo Savica in Rochester, Minnesota, found that living within one mile of a golf course was associated with a 126% increased risk of developing Parkinson's compared to living six miles or more away.

"And my colleagues Dr. Brittany Krzyzanowski at Barrow Neurological Institute in Phoenix and Dr. Rodolfo Savica at the Mayo Clinic, a neurologist like David and and me, um they looked at the incidence, number of new cases of Parkinson's in Rochester, Minnesota, where the Mayo Clinic is located, where they have really good data on number of new cases, and they found using sophisticated mapping of golf courses that individuals who lived within one mile of a golf course had a 126% increased risk of developing Parkinson's compared to people who lived six miles or more away." (said at 0:43:48)

A 2025 population-based case-control study by Krzyzanowski, Savica, and colleagues using Rochester Epidemiology Project data analyzed 419 incident Parkinson's disease cases and 5,113 matched controls in Olmsted County/Rochester, Minnesota. After multivariable adjustment for demographic and neighborhood factors, living within 1 mile of a golf course was associated with a 126% increase in the odds of developing Parkinson's disease compared to living more than 6 miles away (adjusted OR 2.26, 95% CI 1.09–4.70). Evidence certainty is rated low due to the observational case-control design.

0:44:28Ray Dorseysupportedvery low

A case report in Annals of Neurology found 18 people living around a golf course who had Parkinson's disease, 15 of whom lived downwind.

"There was an a report small report case report, Annals of uh Neurology, maybe a decade ago found two neurologists found about 18 people who lived around a golf course had Parkinson's disease and 15 of them lived uh downwind." (said at 0:44:28)

A correspondence/case report published in Annals of Neurology in 2012 is titled 'Is living downwind of a golf course a risk factor for parkinsonism?'. As an observational cluster report / letter to the editor, the certainty of evidence for causality is very low, but the speaker accurately described the published report's existence, journal, timeframe, and topic.

0:51:22Ray Dorseysupportedmoderate

Farmers who work directly with Paraquat have a 150% increased risk of Parkinson's disease, and people living or working near where Paraquat is sprayed have a 100% increased risk.

"we know the farmer who works with Paraquat has 150% increased risk. And now we know that people who live or work near where that farmer sprays Paraquat have 100% increased risk." (said at 0:51:22)

The speaker's figures closely reflect key observational studies evaluating occupational and ambient paraquat exposure and Parkinson's disease (PD). In the landmark Agricultural Health Study (Tanner et al., 2011), farmers with occupational exposure to paraquat had an odds ratio (OR) of 2.5 (95% CI: 1.4–4.7), which represents a 150% increase in risk. For residential and workplace proximity to agricultural spraying, large population-based studies from California's Central Valley (e.g., Furlong et al., 2024) found that living or working near commercial paraquat applications is associated with odds ratios around 1.91 to 2.15 (a 91% to 115% increased risk, effectively a doubling or ~100% increase).

0:51:33Ray Dorseysupportedlow

Three studies have shown that green space workers like golf course landscapers have an increased risk of Parkinson's disease.

"We know from three studies have found that green space workers like landscapers on golf courses have increased risk of Parkinson's disease" (said at 0:51:33)

A systematic review on occupational pesticide exposure and health risks in greenspace workers (including gardeners, landscapers, golf course maintenance workers, and nursery employees) identified multiple epidemiological studies evaluating chronic neurological disorders and found elevated risks of Parkinson's disease in this occupational group. Because the underlying evidence base consists of observational cohort and registry studies with variable exposure assessment, the overall certainty is low, but the claim accurately reflects the published literature.

0:54:04Ray Dorseysupportedhigh

Jean-Martin Charcot first described amyotrophic lateral sclerosis (ALS) in 1869.

"And not until 1869 did Jean-Martin Charcot, the father of modern neurology, describe ALS." (said at 0:54:04)

Jean-Martin Charcot, often referred to as the father of modern neurology, first characterized and described amyotrophic lateral sclerosis (ALS) in 1869 (with foundational publications and lectures at the Salpêtrière identifying the distinct pathology involving anterior horn cells and lateral corticospinal tracts), establishing it as a distinct clinical-pathological entity.

0:57:10Ray Dorseysupportedlow

Paraquat exposure and traumatic brain injury with loss of consciousness interact synergistically to amplify the risk of developing Parkinson's disease.

"So it turns out that exposure to Paraquat increases your risk of Parkinson's disease. Head trauma, loss of consciousness increases your risk of Parkinson's. Together they amplify the risk." (said at 0:57:10)

Epidemiological and preclinical research directly supports the claim. A population-based case-control study (Lee et al., 2012, PMID 23150532) examining 357 incident Parkinson's disease (PD) cases and 754 controls found that traumatic brain injury (TBI) with loss of consciousness for more than 5 minutes was associated with a 2-fold increased risk of PD (AOR 2.00, 95% CI 1.28–3.14), ambient paraquat exposure alone was associated with a modest increase (AOR 1.36, 95% CI 1.02–1.81), and combined exposure to both factors resulted in an approximately 3-fold higher risk (AOR 3.01, 95% CI 1.51–6.01), demonstrating a more-than-additive (synergistic) interaction. Preclinical rodent models also show that TBI primes nigrostriatal dopaminergic neurons to be more vulnerable to subsequent paraquat exposure (PMID 21644813).

  • supports: Traumatic brain injury in adult rats causes progressive nigrostriatal dopaminergic cell lo… (Journal of neurotrauma 2011) · cited 131x in the literature
    "TBI alone increased microglial activation in the substantia nigra, and caused a 15% loss of dopaminergic neurons ipsilaterally. Paraquat increased the TBI effect, causing a 30% bilateral loss of dopaminergic neurons, reduced striatal tyrosine hydroxylase (TH) immunoreactivity more than TBI alone, and induced alpha-synuclein accumulation in the substantia nigra pars compacta." (abstract, results, passage verified)
    pubmedfull study (doi)
  • supports: Traumatic brain injury, paraquat exposure, and their relationship to Parkinson disease. (Neurology 2012) · cited 135x in the literature
    "In logistic regression analyses, we observed a 2-fold increase in risk of PD for subjects who reported a TBI (adjusted odds ratio [AOR] 2.00, 95% confidence interval [CI] 1.28-3.14) and a weaker association for paraquat exposures (AOR 1.36, 95% CI 1.02-1.81). However, the risk of developing PD was 3-fold higher (AOR 3.01, 95% CI 1.51-6.01) in study participants with a TBI and exposure to paraquat than those exposed to neither risk factor. While TBI and paraquat exposure each increase the risk of PD moderately, exposure to both factors almost tripled PD risk. These environmental factors seem to act together to increase PD risk in a more than additive manner." (abstract, results and conclusions, passage verified)
    pubmedfull study (doi)
0:36:04Ray Dorseysupportedmoderate

In 2003, Dr. Heiko Braak proposed that misfolded protein pathology in Parkinson's disease propagates progressively from nerve cell to nerve cell.

"Dr. Heiko Braak in 2003 said that misfolded protein—he didn't say this, but he said misfolded protein spreads from nerve cell to nerve cell, which we now know. He says it's like a fall of a row of dominoes and that process has been triggered and it's ongoing." (said at 0:36:04)

In 2003, Dr. Heiko Braak and colleagues published a landmark neuropathological staging system for Parkinson's disease based on the progressive, stereotypic anatomical spread of alpha-synuclein (Lewy body/neurite) pathology. The model proposed that pathology initiates at specific induction sites (the enteric/vagal system and olfactory bulb) and spreads sequentially across axonally connected vulnerable neuronal populations into the brainstem and cortex.

0:38:08David Perlmutter (host)supportedvery low

MPP+, the active metabolite of MPTP, causes mitochondrial toxicity by damaging complex I of the electron transport chain.

"I think primarily what happened was there was a mitochondrial injury, a mitochondriopathy was induced, complex I of electron transport was was damaged by this assault, by this MPP+ actually, that the metabolite of MPTP." (said at 0:38:08)

The host's statement is fully supported by scientific literature. MPP+ (1-methyl-4-phenylpyridinium) is the active toxic metabolite of MPTP. Once inside dopaminergic neurons, MPP+ concentrates within the mitochondria where it binds to and inhibits complex I (NADH:ubiquinone oxidoreductase) of the electron transport chain. This inhibition impairs mitochondrial respiration, depletes ATP, and generates reactive oxygen species, leading to mitochondrial dysfunction (mitochondriopathy) and cell death. Although this mechanism is highly established in neurotoxicology, the certainty is graded as very low because the evidence is derived from in vitro and animal models of Parkinson's disease.

1:02:12Ray Dorseysupportedhigh

Brain diseases have become the world's leading source of disability.

"brain diseases have become the world's leading source of disability." (said at 1:02:12)

According to the Global Burden of Disease (GBD) 2021 systematic analysis published in The Lancet Neurology, conditions affecting the nervous system (including neurological conditions, neurodevelopmental disorders, and secondary nervous system damage from infectious or neonatal conditions) collectively became the leading cause of global disease burden and disability-adjusted life-years (DALYs) in 2021, accounting for 443 million DALYs and affecting approximately 3.4 billion individuals (43.1% of the global population).

1:02:32Ray Dorseysupportedmoderate

Parkinson's disease is one of the world's fastest growing brain diseases.

"There are reasons why Parkinson's is one of the world's fastest growing." (said at 1:02:32)

Global epidemiological analyses, notably from the Global Burden of Disease (GBD) studies and recognized by the World Health Organization (WHO), identify Parkinson's disease as the fastest-growing neurological disorder worldwide in terms of prevalence, disability-adjusted life years (DALYs), and deaths, primarily driven by population aging and increased longevity.

1:02:42Ray Dorseysupportedhigh

Dementia with Lewy bodies was not described in the medical literature until 1976.

"There are reasons why dementia with Lewy bodies was not described until 1976." (said at 1:02:42)

Dementia with Lewy bodies (initially termed diffuse Lewy body disease) was first described in the medical literature in 1976 by Kenji Kosaka and colleagues, who reported an autopsy case presenting with progressive dementia and widespread Lewy bodies.

1:03:53David Perlmutter (host)supportedmoderate

Only about 6% of American adults are metabolically healthy, meaning roughly 94% have at least one marker of metabolic syndrome.

"about 6% of American adults is metabolically intact, meaning about 94% of American adults has at least one issue related to metabolic syndrome" (said at 1:03:53)

A nationally representative study of 55,081 U.S. adults from the National Health and Nutrition Examination Survey (NHANES 1999–2018), published in the Journal of the American College of Cardiology (O'Hearn et al., 2022), evaluated cardiometabolic health across five components: adiposity, blood glucose, blood lipids, blood pressure, and clinical cardiovascular disease. In 2017–2018, only 6.8% (95% CI: 5.4%–8.1%) of U.S. adults had optimal levels across all cardiometabolic components, meaning approximately 93.2% (roughly 94%) had at least one intermediate or poor cardiometabolic risk marker.

Unverified means no publication matching the claim was located; it does not prove the claim false. Spotted an error? See the corrections policy - disputes from the people quoted are prioritized.