5 Risk Factors for Parkinson's Disease

Parkinson's disease is a progressive neurological disorder that can cause uncontrollable movements like shaking or trembling, stiffness, slow or interrupted movements, and problems with coordination and balance. While Parkinson's has no known definitive cause, major risk factors include genetics, environment, lifestyle, and age.

Read on to learn possible Parkinson's disease causes, risk factors theories, and how to potentially reduce your risk.

What Causes Parkinson's Disease?

No known definitive cause of Parkinson's disease exists. It occurs when your nerve cells, or neurons, in the area of your brain that controls movement, begin to weaken or die. They then cannot produce dopamine, which contributes to your ability to feel pleasure and move.

"We don't have one cause," Lynda Nwabuobi, MD, of The Neurology Center in Washington D.C., told Health. "Based on what we have studied and learned, we know Parkinson's disease happens due to an interaction between the aging brain, your genetics, and your environment."

1. Age

Age doesn't directly cause Parkinson's disease, but "being an older person" is the greatest risk factor for the neurological disorder, said Dr. Nwabuobi. As you age:

• Brain cells shrink and become more prone to injury.
• Gene expression—essentially the way a person's genes operate—can morph over time, triggering changes in cellular activity that ultimately lead to Parkinson's.

Usually, people with Parkinson's are diagnosed in their 60s. Early-onset Parkinson's is when the disorder occurs before the age of 50. It's diagnosed in about 5-10% of people with Parkinson's. In those cases, the disease is more likely to be linked to genetics.

2. Genetics

Up to 15% of people with Parkinson's disease have a family history of the condition. About 5-10% of Parkinson's cases are genetic. However, researchers still don't have a full picture of the role genes play. "We know that we're just touching the surface," Dr. Nwabuobi said.

A 2019 study found 90 independent common genetic risk factors for Parkinson's but wider, more diverse research is required.

• SCNA: This gene makes the protein alpha-synuclein.
• GBA1: This gene produces GCase, a protein that essentially clears out unwanted cells.
• LRRK2: This gene produces the protein dardarin. Individuals who are of Ashkenazi Jewish and North African Berber descent are particularly prone to this gene mutation.
• VPS35: This gene produces vacuolar, a protein involved in the cellular recycling process.
• PARK2: This gene produces the protein Parkin, which helps eliminate defective mitochondria. This is the most common cause of recessively inherited early-onset Parkinson's.
• PINK1: This gene is responsible for mitochondrial health. This gene mutation is the second most common cause of recessively inherited early-onset Parkinson's.
• PARK7: This gene is responsible for producing DJ-1 protein.
  

"What we don't know is much more than what we do know," said Dr. Nwabuobi. "I encourage everyone to get genetic testing, especially patients who have a family history. The more people we test, the more we discover."

3. Environmental Triggers

Exposure to environmental toxins can possibly put you at risk for developing Parkinson's disease, but more data is necessary. Toxins can include:

• Heavy metals
• Pesticides
• Psychostimulants, including amphetamine, methamphetamine and cocaine

4. Head Trauma

Traumatic brain injury (TBI) is a possible risk factor for developing Parkinson's disease. The pathologies of brains with TBI and brains with Parkinson's have commonalities including:

• Inflammation
• Metabolism
• Protein aggregation

Working in environments where you might be more prone to head injuries could then theoretically put you at a higher risk of Parkinson's disease. "If you're a football player or a boxer and you've had multiple concussions, that increases your risk," said Dr. Nwabuobi.

5. Medications

Taking certain medications could cause Parkinson's disease symptoms. This is called drug-induced parkinsonism and usually goes away when you stop taking the medication. While it isn't Parkinson's disease itself, it can look and feel a lot like it.

Drugs that can cause Parkinson's disease symptoms include:

• Antipsychotics (like fluphenazine, pimozide, haloperidol, and perphenazine)
• Anti-nausea medications (including chlorpromazine, droperidol, and promethazine)
• Drugs that treat hyperkinetic movement disorders (such as tetrabenazine, deutetrabenazine, and valbenazine)

How To Reduce Your Risk Factors

It may not be possible to prevent Parkinson's disease. Knowing your risk factors is an important step in getting a diagnosis as early as possible. Still, you may be able to reduce risk factors by:

• Exercising regularly and eating a balanced diet
• Limiting alcohol
• Quitting smoking
• Trying to avoid exposure to environmental factors

If you have a family history of Parkinson's, a healthcare provider may recommend genetic testing to determine if you have any gene mutations linked to the disorder.

A Quick Review

Parkinson's disease is a chronic, progressive neurological disorder. It has no known definitive cause, but researchers have identified possible risk factors, including age, genetics, environment, head trauma, and certain medications.

While you may not be able to fully prevent Parkinson's disease from developing, it's possible to reduce risk factors by avoiding environmental factors, exercising regularly, and getting genetic testing if Parkinson's runs in your family. Early diagnosis is key, so talk to a healthcare provider if you suspect you're at risk for Parkinson's.