Contributing Factors
What causes Parkinson's disease? Much of it still remains a mystery, but researchers are cracking more and more of the code everyday. In this section we breakdown genetics, environmental factors, and lifestyle choices that may lead to a Parkinson's diagnosis.
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The important thing to remember is that despite any of this - YOU PURPOSEFULLY DID NOTHING - to cause you or your loved one to receive a Parkinson's diagnosis. Just as some people are predispositioned for diabetes, cancer, or heart disease, our genes play a significant role in neurodegenerative conditions as well.
Genetics
The root cause of Parkinson's disease (PD) is unknown, but scientists believe that a combination of genetic and environmental factors are the cause. The extent to which factor is involved varies from person to person. Regardless of how a person gets Parkinson's - through genetics or environment (perhaps even a combination of both,) each person with PD experiences a loss of dopamine in the brain. Symptoms and progression of the disease are unique to each person.
Understanding Genetics
Genetics is the field of science that examines how traits are passed down, or inherited, from parents to children through genes. The study of genetics begins with our DNA. Changes known as mutations in our genes can alter normal function of proteins in our body. While this is mostly harmless, they can affect our risk of getting a disease such as Parkinson's.
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In addition to genetics, environmental factors and lifestyle choices strongly determine if Parkinson's will develop. Understanding the role of genes and PD can help pave the way to understanding the biological causes of disease and develop novel therapies to treat Parkinson's.
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Understanding the connection between Parkinson's and genetics can help us to understand how the disease develops and ultimately how it can be treated or cured.
Parkinson's Genes
Parkinson's is rarely inherited. Genetics cause about 10-15% of all Parkinson's. If a person tests positive for a certain gene mutation associated with Parkinson's - such as a mutation in LRRK2, GBA, and SNCA genes, their risk may increase, but they may never develop Parkinson's. In some families, changes (or mutations) in certain genes are inherited or passed down from generation to generation. Over the years, scientists have studied DNA from people with Parkinson's comparing their genes. They discovered dozens of gene mutations linked to Parkinson's. These genes are now being researched and studied for what role they play in Parkinson's.
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There are ongoing clinical trials testing therapies to treat people who have Parkinson's and carry certain gene mutations, proving that it can be important to know which gene mutation you carry. Consult with your doctor when considering a genetic test to determine if you are eligible to participate in gene-based clinical trials.
PD GENEration: Mapping the Future of Parkinson's Disease
The Parkinson's Foundation, together with the Michael J. Fox Foundation, are partnering on a flagship study aimed to provide free genetic testing and genetic counseling that will empower people with PD and their care teams to improve Parkinson's care and research by accelerating enrollment in clinical trials. Through PD GENEration, the organizations hope to ultimately offer free genetic testing and counseling to 15,000 people with PD in the U.S. They have begun their initial enrollment with 600 participants during a pilot period. PD GENEration is available to people with a confirmed diagnosis of PD, regardless of age, through participating Centers of Excellence and Parkinson Study Group sites. To find out if your center is participating, visit https://www.parkinson.org/advancing-research/our-research/pdgeneration
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To see the latest Clinical Trials being conducted by UAB for Parkinson's, CLICK HERE.
The Role of Stem Cells
Stem cells are unspecialized cells. This means they have the potential to develop into almost any type of cell in the body. They are found in early embryos, fetuses, umbilical cords, and also in some adult tissue.
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Even though researchers don't yet know the cause of PD, they do know that the disease results from the damage and loss of neurons that produce dopamine in the substantia nigra area of the brain. Researchers therefore believe that if they could replace those dopamine cells in the brain, they could reduce the motor issues of the disease, thereby reducing the dependence on medications and giving people with Parkinson's a better quality of life.
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Currently, cell transplantation is the most promising of stem cell therapies. This therapy involves injecting new dopamine-producing neurons into the part of the brain where the dead or dying neurons were once making enough dopamine. There are currently two types of stem cells being developed in cell transplantation for Parkinson's: embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). ESCs are collected from invitro fertilization (IVF) donated tissue, and iPSCs are derived from adult stem cells. Both can become almost any cell in the body, but it can also be a controversial or touchy topic for some people.
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There are several stem cell-based clinical trials of cell transplantation in process around the world. If you or someone you know might want to be involved in a clinical trial for stem cells, a great resource is the Michael J. Fox Foundation's Fox Trial Finder at https://www.michaeljfox.org/trial-finder
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Scientists are hopeful that in the future, stem cell research will help them better understand the underlying causes of Parkinson's. With greater technology and understanding of the disease, they may also be able to screen new drugs and develop new treatments.
Environmental Factors
Epidemiological studies based on large populations suggest that certain toxins increase the risk of developing Parkinson's. For instance, there is an increased risk for people living in rural communities or who drink well water. This may be due to ingestion of or exposure to certain pesticides proven in the laboratory to be toxic to dopamine neurons. Other chemicals, such as solvents used in the industrial dry-cleaning industry have been implicated, suggesting that certain environmental toxins increase the risk of developing Parkinson's.
Lifestyle Factors
The fact that lifestyle factors may increase or decrease a person's risk of developing Parkinson's was researched and published in 2015. Drinking alcohol, well-water ingestion, and exposure to anesthesia, manganese, solvents, and farming chemicals have been found to contribute to Parkinson's. Habits found to potentially protect against developing Parkinson's include drinking coffee or green tea; a diet rich in vitamins, minerals, unsaturated fatty acids, and flavonoids (found in many plant-based foods); and exercise.
Sources:
Parkinson's Foundation, Understanding Parkinson's: Genetics and Parkinson's "Brochure."
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Davis Phinney Foundation for Parkinson's. Every Victory Counts, Your Go-To Resource of Essential Information and Inspiration for Living Well with Parkinson's. Manual. Sixth edition, 2021.
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Marie, Lianna. The Role of Stem Cells. Chapter 39, pages 117-118. The Complete Guide for People with Parkinson's Disease and Their Loved Ones. . Purdue University Press, 2022.