The Five Environmental Causes of Parkinson’s Disease

environmental causes of Parkinson's

Parkinson’s disease is a brain disorder that develops and becomes worse over time. The typical symptoms of the disease include tremor, stiffness, slowness of movement, and balance problems.  These symptoms develop when the brain lost its ability to produce a sufficient amount of dopamine, a neurotransmitter responsible for controlled body movement.

Researchers have identified a variety of environmental factors that are linked to Parkinson’s disease. Some of these factors may directly cause the disease symptoms, others may increase the risk of developing it.

Here are the 5 main environmental factors that are linked to Parkinson’s disease development.

1. Environmental Toxins

Many environmental toxins have been identified that are known to cause Parkinson’s disease. Among them, MPTP, 6-hydroxydopamine, and pesticides are widely studied in research. Animal research has confirmed that exposure to these compounds causes Parkinson’s-like changes in the brain.

MPTP  (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)

This compound was accidentally discovered as the causative agent of Parkinson’s when it caused a severe form of Parkinson’s in young drug addicts in California in 1982. It was used in the illegal preparation of heroin substitutes.

The compound is very specific in destroying the dopamine cells in the substantia nigra part of the brain. And because of that, it’s widely used in animal models for testing possible therapies in humans.


This is a dopamine-like chemical that causes damage to dopamine cells. Besides dopamine cells, it can affect the cells that produce other neurotransmitters such as epinephrine and norepinephrine.

The compound causes damage to the brain by encouraging the production of oxidative stress, which is strongly linked to Parkinson’s. It may also severely affect the functions of mitochondria, which are parts of the cell that supply energy to the brain cells.

Like MPTP, this compound is also used in animal research to find possible therapies for Parkinson’s disease.


Pesticides are among the leading environmental factors that contribute to the development of Parkinson’s disease. These chemicals enter the body via inhalation, eating, drinking, or skin contact.

Since farmers are more exposed to pesticides, they have a high chance of developing Parkinson’s-like symptoms compared to others.

The two well-known pesticides that are strongly linked to Parkinson’s disease include rotenone and paraquat. Rotenone acts by damaging the mitochondria and deprives the brain cells of energy. Whereas, paraquat produces free radicals that cause damage to cell vital components like DNA, protein, and lipids.

A study published in the Journal of Environmental Health Perspectives has reported that the chances of developing Parkinson’s increases 2.5 times more in those who use either of these pesticides compared to those who don’t

2. Diet-related Factors

Diet has become an increasingly important part of Parkinson’s disease development. Numerous research studies have been started to explore the role of specific foods in the progression of Parkinson’s disease. Researchers have found that consuming food that is deficient of coenzyme Q10 and vitamin D might increase the chances of developing the disease symptoms.

Coenzyme Q10 

This organic compound is distributed throughout the body. Its highest amount can be found in the heart, brain, liver, and kidney.

Parkinson’s patients are reported to have a reduced level of coenzyme Q10 (CoQ-10). A study published in the Journal of Annals of Neurology found a 35% lower level of CoQ-10 in the blood from Parkinson’s patients than in the blood from control subjects. Similar kinds of results were also observed in other studies.

This suggests that people with (CoQ-10) deficiency are more susceptible to develop Parkinson’s symptoms than those who don’t.

Vitamin D

Vitamin D is another dietary component that might have a role in the development of Parkinson’s disease.

A study, published in the peer-reviewed medical journal Archives of Neurology in 2010, reported that people with the lowest levels of vitamin D had a three-fold higher risk of developing Parkinson’s disease than those with the highest.

Other studies have also suggested a link between vitamin D deficiency and the risk of Parkinson’s disease. Researchers are now trying to explore the possible mechanism through which its deficiency leads to Parkinson’s disease.

3. Traumatic Brain Injury

Accumulating evidence suggests that there is a link between traumatic brain injury (TBI) and the risk of Parkinson’s disease and that TBI could be one of the potential risk factors for the disease.

A study published in the Journal of Neurology reported that mild TBI increases the risk of Parkinson’s up to 56% and moderate to severe TBI increases the risk of Parkinson’s up to 83%.

While the exact cause of this is unknown, it is observed that people with TBI have abnormally lower levels of dopamine in the brain regions involved in Parkinson’s disease.

4. Lack of Exercise/Physical Activities

The idea that exercise might have a role in Parkinson’s disease is not new. Researchers have been trying to find a connection between Parkinson’s and exercise for many years. They think that those who do regular exercise are less likely affected by the disease than those who don’t.

A study published in the Journal of Neurology suggests that higher levels of physical activity may reduce the risk of developing Parkinson’s disease. In this study, 125,828 (including both men and women) provided information on physical activity in early adulthood. During the follow-up, a total of 387 Parkinson’s cases were identified. The study found that the people (the men) who didn’t develop the disease were mostly involved in some sort of higher levels of physical activity.

Similarly, one meta-analysis that included data from 8 prospective studies has concluded that moderate to vigorous physical activity may have an inverse relationship with a risk of Parkinson’s.

Although it is not known how exercise could protect someone from developing Parkinson’s, researchers think that it may inhibit abnormal changes in dopamine neurons and contribute to the healthy functioning of brain parts involved in body movement.

5. Stress

People who have gone through stressful life events may have a high chance of developing Parkinson’s symptoms than those who have not.

One case study, published in the Journal of Neuropsychiatric Disease and Treatment, found that extreme emotional stress is directly involved in the development of Parkinson’s disease. In this study, a 38-years old woman experienced a sudden strong tremor in her left arm 1 week after knowing that her husband had an affair with another woman. Prior to this incident, the woman was in a healthy condition and had no history of brain diseases. Her symptoms were relieved when she was treated with Parkinson’s disease medications. After clinical examination, the woman was diagnosed with early-onset Parkinson’s disease.

However, this is a single case study that was reported in 2013, and since then there has not been any other report published that shows the direct involvement of stress in Parkinson’s disease.

So, stress could be one of the risk factors but not necessarily the cause of Parkinson’s disease.

Disclaimer: The information shared here should not be taken as medical advice. The opinions presented here are not intended to treat any health conditions. For your specific medical problem, consult with your health care provider.


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