Meducated

Sarah Palis, Walton High School (Marietta, GA)

Parkinson’s disease is a neuron-damaging disorder which primarily affects dopaminergic neurons in the substantia nigra of the brain. Dopaminergic neurons produce dopamine, a common neurotransmitter which allows the body to feel pleasure, satisfaction, and motivation. The substantia nigra is found in the middle of the brain and plays a critical role on the body’s motor movement.  When Parkinson’s disease is prevalent, the side-effects range from impacting voluntary movement to cognition and learning.

Genetic factors of Parkinson’s disease come into play mainly by inheritance passed down in the family. However, Parkinson’s is considered random rather than inherited since it is caused by mutations in DNA [A mutation is a permanent change in a DNA sequence]. Direct inheritance of Parkinson’s disease is because of mutations specifically in the genes of LRRK2, PARK7, PINK1, PRKN, or SNCA.  Mutations of the GBA and UCHL1 gene increase the percentage of risk to develop Parkinson’s disease, although they do not directly cause Parkinson’s. What do these mutations do, exactly? These mutations inhibit microglia, a cell that gets rid of unwanted proteins of dopaminergic neurons, therefore causing buildup of these unwanted proteins.  This buildup leads to loss of function or death of cells, ultimately resulting in Parkinson’s disease.

Environmental factors that contribute to Parkinson’s disease mainly include the patient’s living conditions. TBI (traumatic brain injury) has always been known to increase the risk of developing Parkinson’s. This is because damaged neural tissue (caused by TBI) can lead to cells attacking each other, causing alpha-synuclein (a misfolded protein that causes Parkinson’s when it builds up) dysfunction. 

Since TBI and Parkinson’s disease are closely associated with each other, many causes of TBI are also the causes of Parkinson’s. This includes the occupation of the patient; however, different occupations contribute to both disorders. Extractive workers (miners, and well drillers), have a higher risk of TBI because of an increased exposure to heavy-forced head trauma; while agricultural occupations can contribute to higher risk of Parkinson’s because of the overexposure to solvents and pesticides. Overexposure of Trichloroethylene (a colorless liquid used in many household applications, as well as found as a contaminant in groundwater) causes the dysfunction of LRRK2, and when this gene is mutated, it is a direct cause of Parkinson’s. While there are many environmental factors that are widely known to cause Parkinson’s disease, more research must be conducted to further understand the full broad range of environmental causes.

The progression of Parkinson’s disease is very slow because the symptoms of this disease only become evident after more than half the dopaminergic neurons have misfunctioned or died. Parkinson’s disease is irreversible, so there is no cure — only options for treatment. Many causes of Parkinson’s disease still remain widely unknown. However, with the genetic and environmental causes that are known, scientists can research and understand even more variables that contribute to this disease in order to find cures for those who are affected and find preventions for those who are at risk.

References:

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8. Mclean, Pamela. “Neurobiology of Parkinson’s Disease Laboratory – Traumatic Brain Injury and Parkinsonism.” Mayo Clinic, 20 Mar. 2019, http://www.mayo.edu/research/labs/neurobiology-parkinsons-disease/projects/traumatic-brain-injury-parkinsonism#:~:text=We%20hypothesize%20that%20a%20traumatic,promote%20intracellular%20alpha%2Dsynuclein%20aggregation. 
9. Caroline M. Tanner, MD. “Occupation and Risk of Parkinsonism: A Multicenter Case-Control Study.” Archives of Neurology, JAMA Network, 1 Sept. 2009, jamanetwork.com/journals/jamaneurology/fullarticle/797977#:~:text=Specific%20occupations%20(agriculture%2C%20education%2C,or%20information%20from%20prior%20publications. 
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11. “Environmental Factors.” Parkinson’s Foundation, http://www.parkinson.org/understanding-parkinsons/causes/environmental-factors. Accessed 3 Mar. 2024.