Patients Ask: What Are the Causes of Parkinson's Disease?

January 12, 2023Neelem Sheikh

Parkinson’s disease is a neurodegenerative disease in which parts of the brain become progressively more damaged over time. It primarily impacts nerve cells (neurons) that produce dopamine in a specific area of the brain that is essential for movement and motor control (the substantia nigra). Dopamine is a chemical messenger that allows nerve cells to send messages to one another. When these nerve cells become damaged or die, it causes motor-related symptoms like tremors, slowed movement (bradykinesia), muscle rigidity, and postural instability. 

Although it is not entirely clear what causes the nerve cells to die, scientists believe it may be due to a combination of several factors, including genetics and the environment. In this article, we will discuss the potential causes of Parkinson’s disease.

Causes of Parkinson’s Disease

Age and biological sex are not direct causes of Parkinson’s disease but rather increase the risk of developing it. It is well-known that the risk of developing Parkinson’s disease increases with age. The average age of onset is 60, however, it can also develop in people under 50 which is known as young-onset Parkinson’s disease. Additionally, Parkinson’s disease is more common in men than in women as men are twice as likely to develop Parkinson’s disease. 

As far as direct causes, experts suggest that genetic and environmental factors are the primary causes of Parkinson’s disease. Some cases of Parkinson’s disease may be primarily caused by genetics while others may be primarily caused by environmental factors.

Genetic Causes of Parkinson’s Disease

According to the Parkinson’s Foundation, genetics cause between 10 and 15% of all cases of Parkinson’s disease. Over the past several decades, researchers have discovered many variants in genes that may contribute to the development of Parkinson’s disease. Several mutations have been reported to be linked to Parkinson’s disease.

Gene

Encodes For

Mutation

Inheritance Pattern

Alpha-synuclein (SNCA)

alpha-synuclein protein

Missense or multiplication

Dominant 

Parkin (PRKN)

parkin

Missense or loss of function

Recessive

Parkinson’s protein 7 (PARK7)

DJ-1

Missense

Recessive

Leucine-rich repeat kinase 2 (LRRK2)

dardarin

Missense

Dominant 

Glucocerebrosidase beta (GBA)

beta-glucocerebrosidase

Missense or loss of function

Dominant (incomplete penetrance)

Other mutations that have been reported to cause Parkinson’s disease include:

  • UCHL1
  • POLG
  • HTRA2
  • ATP13A2
  • FBX07
  • GIGYF2
  • PLA2G6
  • EIF4G1
  • VPS35
  • DNAJC6
  • TMEM230
  • VPS13C
  • LRP10

Carrying mutations on specific genes, such as those listed above, may increase your risk of developing Parkinson’s disease. Having a genetic mutation that has been associated with Parkinson’s disease development does not mean you will definitely go on to develop Parkinson’s, however, some mutations are linked to a greater risk.

Environmental Causes of Parkinson’s Disease

Environmental factors, such as exposure to chemicals and toxins and exposure to certain heavy metals, and head trauma, are also believed to be possible causes of Parkinson’s disease. The level of exposure to environmental factors depends on things like your occupation, geographical location, and area of residence, among others.

Exposure to chemicals and toxins: Chemicals and toxins that have been linked to Parkinson’s disease include:

  • Pesticides and herbicides (e.g., paraquat)
  • MPTP (a neurotoxin)
  • Agent Orange (a mixture of herbicides used by the U.S. military)
  • Solvents (e.g., trichloroethylene)
  • Polychlorinated biphenyls (a group of man-made chemicals previously used in industrial applications)

Exposure to certain metals: Many studies have found a link between exposure to certain metals and Parkinson’s disease. For example, high-dose manganese exposure, which may occur in occupations like welding, has been shown to cause manganese-induced Parkinsonism (manganism). Other metals that have been associated with Parkinson’s disease include mercury, lead, copper, iron, zinc, aluminum, bismuth, and thallium.

Head trauma: Traumatic brain injury, or TBI, is an acquired brain injury that happens when a sudden trauma causes damage to the brain. A history of TBI has been linked to an increased risk of developing Parkinson’s disease later in life. TBI is commonly caused by falls, motor vehicle crashes, and firearm-related injuries. 

Currently, there is no proven way to prevent Parkinson’s disease—but there are still things you can do to reduce your risk. Limit your exposure to harmful substances, such as chemicals, toxins, and certain metals whenever possible and take appropriate steps to protect your brain from injury. Finally, stay in touch with your brain health. Whether you’re 30 or 70, getting cognitive tests done should be as normal as going to the dentist.

Altoida’s mission is to accelerate and improve drug development, neurological disease research, and patient care. To learn more about our precision-neurology platform and app-based medical device, contact us.

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