Parkinson's Disease Causes

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The causes of Parkinson's disease come down to genetic and environmental factors that, in turn, produce changes in the brain's chemical makeup, such as

Reduced dopamine levels. Parkinson’s disease can kill nerve cells in the brain that produce dopamine. Dopamine is a neurotransmitter (brain chemical) that carries messages to the part of the brain that controls muscle movement. Low dopamine levels are responsible for the motor symptoms of Parkinson's.

Reduced norepinephrine levels. Another neurotransmitter, norepinephrine, is crucial to the function of the sympathetic nervous system. Low norepinephrine levels foster the nonmotor symptoms of this condition.

Accumulation of Lewy bodies. Many people with Parkinson’s disease develop Lewy bodies, abnormal deposits of alpha-synuclein, a protein, in the brain. This is a major area of focus among researchers.

What Is Parkinson's Disease?

Parkinson's disease, a health condition that affects the brain and nervous system, It's classified as a neurological movement disorder because it affects the brain’s ability to control movement. Signs and symptoms include tremors, muscle rigidity, and difficulties with movement, balance, and coordination.

Parkinson’s disease is progressive, meaning it gets worse over time. There's no cure, but a person with Parkinsons typically can manage it with medication and surgery, often for a significant time. The average life expectancy of a person with Parkinson’s disease is similar to that of a person who does not.

Symptoms

The symptoms of Parkinson’s disease fall into two groups: motor symptoms and nonmotor symptoms. 

Motor Symptoms

Motor symptoms are movement-related problems that occur because the brain cannot send signals to the muscles the way it is supposed to.

These are some of the motor symptoms of Parkinson’s disease:

  • Tremors in the hands, feet, or jaw
  • Slow movements
  • Rigid muscles 
  • Limited range of motion
  • Unsteady walk 
  • Stooped posture
  • Difficulty with balance and coordination
  • Muscle cramps and spasms
  • Reduced facial expressions
  • Slurred or softer speech
  • Smaller handwriting

The movement-related symptoms of Parkinson’s disease can make daily activities such as bathing, getting dressed, walking, talking, writing, and driving difficult. They can also increase your risk of falling and injuring yourself.

Nonmotor Symptoms

Parkinson's affects the sympathetic nervous system, which is responsible for autonomic body functions such as digestion and circulation. Some of the nonmotor symptoms of Parkinson’s disease are:

Nonmotor symptoms such as loss of smell, constipation, restless legs, and difficulty sleeping often appear before motor symptoms such as tremors and muscle stiffness become noticeable.

Diagnosis

Diagnosing Parkinson’s disease can be tricky because there is no straightforward blood test or screening that can determine whether you have it. Instead, Parkinson’s disease is diagnosed clinically, which means a healthcare provider performs a physical and neurological exam.

Your healthcare provider will also review your medical history, family history of neurological diseases, and potential exposure to toxins and pesticides to determine your risk factors for Parkinson's disease.

Labwork such as blood and urine tests and imaging scans such as MRI, CAT, and DaT scans can help rule out other possibilities.

The current standard for diagnosing Parkinson’s disease is a checklist developed by the International Parkinson and Movement Disorder Society.

Since diagnosing Parkinson’s disease relies heavily on clinical judgment, your primary care physician may refer you to a neurologist who specializes in movement disorders for an accurate diagnosis. 

Risk Factors Associated With Parkinson's Disease

  • Age: This is the most significant risk factor for the condition since most people develop it after the age of 60.
  • Family history: Having a family history of this condition can raise your chances of getting it.
  • Sex: 50% more men than women develop Parkinson’s disease.
  • Exposure to pesticides and toxins: Air pollution, pesticides, and certain industrial pollutants are linked to an increased risk of Parkinson’s disease.
  • Head injury: Having a head injury can lead to lower dopamine levels, particularly in people who have also been exposed to pesticides.

Types

Parkinson’s disease falls into two broad categories, based on the age when the symptoms first appear:

Early-Onset Parkinson’s
  • People with this type of Parkinson’s disease first see symptoms before the age of 50.

  • This form of Parkinson’s may be inherited.

Late-Onset Parkinson’s
  • People with this type of Parkinson’s disease first see symptoms after the age of 60.

  • Certain genetic mutations may also play a role in some cases of late-onset Parkinson’s.

Treatment

Treatment for Parkinson’s disease can help slow its progression and reduce its symptoms; however, it cannot cure the disease. Your healthcare provider can evaluate you and suggest a course of treatment, which may include medication and surgery.

Medication

Healthcare providers generally prescribe from this list to treat Parkinson’s disease:

  • Levodopa. The brain's nerve cells use levodopa to make dopamine. Another drug, carbidopa, makes levodopa more effective and reduces its side effects. Brand names include Rytary, Sinemet, and Inbrija.
  • Dopamine agonists. This group of drugs mimics the effects of dopamine and includes Neupro (rotigotine), Requip (ropinirole), Mirapex (pramipexole), and Apokyn (apomorphine).
  • COMT and MAO B inhibitors, These block the function of COMT and MAO B enzymes, which break down dopamine in the brain. COMT inhibitors include Ongentys (opicapone), Comtan (entacapone), and Tasmar (tolcapone). MAO-B inhibitors include Xadago (safinamide), Azilect (rasagiline), Eldepryl (selegiline), and Zelapar (selegiline).
  • Anticholinergics. These drugs help with symptoms such as tremors and muscle rigidity. Anticholinergics include Artane (trihexyphenidyl) and Cogentin (benztropine).
  • Amantadine: This antiviral medication can help with the symptoms of Parkinson’s disease and the side effects of levodopa. It is sold under the brand names Gocovri, Symmetrel, and Osmolex ER. 

Medication can make a significant difference in the symptoms of Parkinson’s disease, especially in its early stages. Over time, however, it can become less effective, and the symptoms may start to reappear. 

Surgery

Surgery may be an option for some people if medication is no longer helpful. 

Deep brain stimulation is an FDA-approved procedure involving surgically implanted electrodes in the brain and an electrical device in the chest. The device emits painless electrical signals that stimulate the brain and block the irregular brain activity that causes the motor symptoms of Parkinson’s.

Pallidotomy and thalamotomy selectively destroy small parts of the brain responsible for symptoms such as tremors, muscle rigidity, and involuntary movements. 

Approximately 90,000 people are diagnosed with Parkinson’s disease in the United States every year, a significant increase over previous estimates.

Coping

These are some strategies that can help you cope with Parkinson’s disease:

  • Learn about the condition: Educating yourself about the condition can help you take an active role in your care and prepare yourself for the stages ahead. 
  • Expect changes: The symptoms of Parkinson’s disease can make routine activities difficult. Being patient with yourself and accepting your limitations can help prevent anger and frustration.
  • Accept support from loved ones: Sharing your feelings with loved ones, asking for what you need, and accepting their support and assistance can help you cope with the condition.
  • Stay mentally and physically active: Staying active and engaged can help reduce the rate of physical and cognitive decline.
  • Seek support and resources: It can be helpful for you and your loved ones to identify support groups and resources nearby for advice, information, and medical care.
  • Prevent falls: You can optimize your living situation to prevent falls, a health hazard associated with Parkinson’s disease.

Summary

Parkinson’s disease is marked by a gradual decline in physical and cognitive abilities; however, medication and surgery can help you enjoy a better quality of life for longer. Being informed and prepared can help you and your loved ones cope with this condition and the changes it brings.

1 Source
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Willis, A.W., Roberts, E., Beck, J.C. et al. Incidence of Parkinson disease in North America. npj Parkinsons Dis. 8, 170 (2022). doi:10.1038/s41531-022-00410-y

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By Sanjana Gupta
Sanjana is a health writer and editor. Her work spans various health-related topics, including mental health, fitness, nutrition, and wellness.