Parkinson’s Disease and the Modern World: Uncovering the Chemical Causes

Parkinson’s Disease is becoming more prevalent.

The incidence of Parkinson’s disease is increasing globally. PD is more prevalent in males than females and some racial groups are at higher risks than others. For example, studies in the United States have found that the prevalence of Parkinson’s disease is higher among ‘White’ populations than among African American, Hispanic/Latino, and Asian populations. Nevertheless, it is present in all groups.

Several factors may be contributing to the observed increase, including an aging population, changes in lifestyle and environmental exposures. As the population ages, the number of individuals at risk for Parkinson’s disease increases. Furthermore, improvements in medical diagnosis, awareness of Parkinson’s disease and better reporting is increasing the numbers. Nevertheless, it is most likely that changes in one or more lifestyle factors is making a major impact on the observable increasing incidence of the disease.

It is important to note that while the incidence of Parkinson’s disease is increasing, the number of individuals living with the disease at a given time (the prevalence) is also increasing. This is likely due to improvements in medical treatment and management of the disease, which allow individuals with Parkinson’s disease to live longer and better-quality lives.

What is Parkinson’s disease

Parkinson’s disease is a neurodegenerative disorder that affects the central nervous system. Parkinson’s has four main symptoms:

• Tremor in the hands, arms, legs, jaw, or head
• Muscle stiffness including extended contraction
• Slowness of movement
• Impaired balance and coordination. This can sometimes lead to a fall

Other symptoms may include:

• Depression and other emotional changes
• Difficulty swallowing, chewing, and speaking
• Urinary problems and/or constipation
• Skin problems

The symptoms of Parkinson’s and the rate of progression differ among individuals. Early symptoms can be very subtle. The symptoms may commence on one side of the body and even though they progress to both sides, one side might be more affected.

The medical description is that there is a gradual loss of dopamine-producing brain cells in a specific area of the brain called the substantia nigra. The decrease in dopamine production leads to a range of symptoms, including tremors, stiffness, slowed movement, and difficulty with balance and coordination.

Parkinson’s disease is progressive, meaning that the symptoms worsen over time, and there is currently no known cure. However, there are treatments available that can help manage symptoms and improve quality of life for people with Parkinson’s disease.

Which chemical exposures are associated with Parkinson’s disease?

There is compelling evidence to suggest that exposures to certain chemicals are associated with an increased risk of Parkinson’s disease. Workers in some professions are at higher risk. These include:

1. Agricultural work: Farmers and agricultural workers who are exposed to pesticides and herbicides, such as paraquat and rotenone, have an increased risk of Parkinson’s disease.
2. Welding and metal work: Welders and other metal workers who are exposed to metals such as manganese have an increased risk of Parkinson’s disease.
3. Industrial chemical manufacturing: Workers in industries that manufacture chemicals such as solvents, including trichloroethylene (TCE) and perchloroethylene (PERC), are at increased risk for Parkinson’s disease.
4. Healthcare: Healthcare workers, particularly those who work with anaesthetics, and certain cleaning agents, are at increased risk for Parkinson’s disease.
5. Teaching: Studies have found that teachers may have an increased risk of Parkinson’s disease, possibly due to exposure to certain chemicals in the classroom environment.

Which chemicals should the general Community be aware of?

1. Pesticides: Studies have shown that exposure to certain pesticides, including paraquat and rotenone, increases the risk of Parkinson’s disease. You might be exposed to paraquat, which is a commonly used herbicide. You could be exposed through your skin or through contaminated foods and beverages. In many countries there are regulations controlling the use of paraquat, but it is still widely used in agriculture and unless you only consume organically grown food, you could be exposed.
2. Herbicides: Exposure to the herbicide Agent Orange, which was used during the Vietnam War, has been linked to an increased risk of Parkinson’s disease. It isn’t quite clear that Agent Orange is the cause as Vietnam Veterans were exposed to several other herbicides as well as AO.
3. Solvents: Exposure to certain solvents, including trichloroethylene (TCE) and perchloroethylene (PERC), are associated with an increased risk of Parkinson’s disease. TCE is commonly used as a degreaser and as a stain remover (especially in dry cleaning). In the USA, studies have shown that up to 10% of people may have detectable levels of TCE in their blood. PERC is widely used in industrial and dry-cleaning operations. PERC gets into both indoor and outdoor air by evaporation and is very common where chemical wastes are stored or disposed of.
4. Metals: Exposure to certain metals, including manganese and lead, has been linked to an increased risk of Parkinson’s disease. In recent decades, exposure to lead has decreased markedly as the lead content of paint, petrol and other consumer goods has been reduced. Manganese exposures most commonly occurs after exposure to welding fumes.
5. Carbon monoxide: Exposure to carbon monoxide, which is produced by the incomplete combustion of fossil fuels, is also associated with an increased risk of Parkinson’s disease.
6. Phosphates in drinks (see next section).

It’s important to note that while these chemicals have been associated with an increased risk of Parkinson’s disease, not everyone who is exposed to them will develop the disease. Other factors, especially genetics, also play a role in the development of Parkinson’s disease.

Which genes are associated with a risk for Parkinson’s disease?

Several genes have been identified that are associated with an increased risk of Parkinson’s disease. The most well-known of these genes is called SNCA, which codes for alpha-synuclein, a protein that is abundant in the brain and is a major component of Lewy bodies, which are characteristic of Parkinson’s disease. Mutations in the SNCA gene can cause the protein to clump together and form Lewy bodies, leading to the death of dopamine-producing cells in the brain.

There are several other genes that are associated with an increased risk of Parkinson’s disease. It’s important to note that while mutations in these genes can increase the risk of Parkinson’s disease, not everyone with a mutation will develop the disease. Parkinson’s disease is likely caused by a complex interplay of genetic and environmental factors.

There is growing evidence that Type 2 Diabetes (T2DM) and Parkinson’s Disease share a ‘pathogenic pathway’. Both of these diseases seem to be increased by the consumption of certain ‘soft drinks’. For T2DM, this is sugar-sweetened beverages, but soft drinks have also been shown to increase the risk of Parkinson’s.  Researchers propose that the risk for Parkinson’s is increased by phosphates or phosphoric acid. Phosphoric acid is found in many soft drinks, especially colas, but it can also be found in dairy products, cereal bars, flavoured waters, and processed meats.

Are there any nutrients that reduce the risk of Parkinson’s disease?

There is some evidence to suggest that certain nutrients may be associated with a reduced risk of Parkinson’s disease. These nutrients include:

1. Vitamin D: Several studies have found an association between low levels of vitamin D and an increased risk of Parkinson’s disease. However, more research is needed to determine whether vitamin D supplementation can reduce the risk of the disease.
2. Caffeine: Studies have suggested that caffeine intake may be associated with a reduced risk of Parkinson’s disease, possibly due to its effects on dopamine production in the brain.

3. Antioxidants: Some studies have suggested that diets high in antioxidants, such as vitamin C and vitamin E, may be associated with a reduced risk of Parkinson’s disease.
4. Omega-3 fatty acids: Some studies have suggested that diets high in omega-3 fatty acids, found in fatty fish such as salmon and mackerel, may be associated with a reduced risk of Parkinson’s disease.
5. Coenzyme Q10: Some studies have suggested that the dietary supplement coenzyme Q10 may be associated with a reduced risk of Parkinson’s disease. However, more research is needed to confirm these findings.

It’s important to note that while these nutrients may be associated with a reduced risk of Parkinson’s disease, more research is needed to confirm these findings and determine the optimal levels of intake.