Parkinson's Disease Overview

Parkinson's disease is a motor system disorder, caused by an issue within the body's nervous system, which leads to uncontrollable and unwanted movements.

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Parkinson's disease is a progressive neurological disorder that primarily affects movement, but can also involve non-motor symptoms like depression, memory loss, and constipation. No one knows exactly what causes the condition, but experts believe that most cases are due to an interaction between genes and the environment. Doctors diagnose the disease based on your symptoms and by excluding other possible causes. There's no cure for Parkinson's yet, but there are many treatments and lifestyle measures that can improve quality of life.

What Is It?

Tremors, along with slowness of movement, rigidity and changes in gait and balance are hallmarks of the disease but there can be many other symptoms as well. The early symptoms of Parkinson's, like a tiny tremor in one hand, may go unnoticed. Symptoms are caused by decreasing levels of the neurotransmitter dopamine in your brain. This, in turn, is because the nerve cells that produce dopamine become damaged or die. Parkinson's is most common in older age, with most diagnoses occurring after age 60, but 4 percent of cases are "young onset."

Parkinson's itself is not fatal but complications from Parkinson's, such as falling, are the 14th leading cause of death in the U.S. One million people in the U.S. currently have Parkinson's and about 60,000 people are newly diagnosed each year.


The most common type of Parkinsonism is idiopathic Parkinson's, which means that no one knows what causes it. Some 10 to 15 percent of cases are related to genetics.

There are also conditions called atypical Parkinson's disorders which have many symptoms similar to actual Parkinson's. These include:

  • Multiple System Atrophy (MSA).
  • Progressive Supranuclear Palsy (PSP).
  • Corticobasal Syndrome (CBS).
  • Dementia with Lewy bodies (DLB).
  • Drug-induced Parkinsonism.
  • Vascular Parkinsonism (VP).


Parkinson's symptoms can be divided into two main areas: those related to motor functions and those not related to motor functions. Different people have different constellations of symptoms but in all cases, the symptoms get progressively worse over a period of years.

Motor symptoms are the most recognizable and include:

  • Resting tremor, which is when a hand, foot or other body part trembles when it's not being used.
  • Bradykinesia means slow movements. This may manifest in smaller steps, "freezing" when you actually mean to move, lack of facial expression and smaller handwriting (micrographia).
  • Rigidity or stiffness is due to tensed muscles. An example is not swinging your arms when you walk.
  • Poor balance, which makes it harder to stand up or turn and can cause falls.

Nonmotor symptoms can include:

  • Constipation.
  • Depression and other mood issues.
  • Loss of sense of smell (hyposmia).
  • REM sleep behavior disorder, which is when you seem to act out your dreams.
  • Needing to urinate frequently or feeling an urgent need to urinate.
  • Losing weight or feeling full after eating only small amounts.
  • Fatigue.
  • Lightheadedness.
  • Problems with vision.
  • Dandruff.
  • Speech changes.

The Parkinson's Foundation describes five main stages of the disease:

  • Stage One involves mild symptoms such as a tremor that affects only one side of the body. There can also be changes in facial expressions as well as walking and posture.
  • Stage Two is when tremors and other movement symptoms affect both sides of the body. Problems with walking and posture become more pronounced.
  • Stage Three may involve a loss of balance and slowness of movements. Activities of daily living like dressing and eating become more difficult, although many people can still live independently.
  • Stage Four. Movement may become difficult enough to require a walker, although people may still be able to stand up on their own. They need help at home with activities of daily living.
  • Stage Five. A wheelchair is needed as it is no longer possible to stand or walk. The person needs 24-hour nursing care and may have hallucinations and delusions as well as trouble talking and even swallowing and chewing.


Tremors and other symptoms of Parkinson's disease happen when the nerve cells in your brain which produce dopamine die or are damaged. Dopamine, a neurotransmitter which sends messages between cells, governs movement, but also emotions such as feelings of pleasure and pain. As more and more of these cells die, the symptoms of Parkinson's get progressively worse. Although all people lose dopamine cells as they age, this happens much faster in people with Parkinson's. Symptoms usually appear when half or more of these cells have died.

No one knows exactly what causes the dopamine-producing cells to die. About 10 to 15 percent of Parkinson's cases are genetic and run in families. If you have a parent or sibling with Parkinson's, you have double the risk of developing it as well, compared to someone with no close relatives. In rare cases, a single genetic mutation is responsible.

Certain people are at higher risk of developing the disease including men and people aged 60 or older.

Experts believe most cases are the result of your genes interacting with certain environmental toxins such as herbicides and pesticides. Brain injuries may also contribute, as may working with heavy metals.


Diagnosing Parkinson's disease relies largely on how well a neurologist can assess and interpret your symptoms. It may also take a long time to pinpoint Parkinson's given that many other conditions resemble it. According to the Parkinson's Foundation, you must have at least two of the four main symptoms of Parkinson's disease to receive a diagnosis:

  • Tremor or shaking.
  • Bradykinesia.
  • Stiffness or rigidity in the arms, legs or trunk of your body.
  • Difficulty balancing.

A neurologist will want to know how long you've had your symptoms as well as what medications you are taking, any other medical conditions, whether you've been exposed to any environmental toxins, and your family history. The doctor will ask you to perform certain tasks so he or she can assess your agility, muscle tone, gait, and balance. Blood and imaging tests are sometimes done but usually only to exclude other causes. A doctor may order a dopamine transporter scan (DaTscan) but usually only to confirm a suspected diagnosis. One sign that you have Parkinson's is if you respond to the most common medication for the condition.


There is no cure for Parkinson's disease. Instead, doctors rely largely on medications. Different people respond differently to individual medications, so there is often a period of trial-and-error before finding the right combination. Most people with Parkinson's take more than one drug.

The most common and most effective medication for Parkinson's is levodopa or L-dopa, which helps boost dopamine levels in the brain. It's usually taken in conjunction with carbidopa (Lodosyn). Other drugs either mimic the activity of dopamine in your brain or block an enzyme that would normally break down this neurotransmitter.

Medications typically become less effective over time, in which case doctors can turn to surgical options. Deep brain stimulation (DBS), for instance, involves implanting electrodes which stimulate parts of the brain involved in movement. Pallidotomy and thalamotomy are procedures to reduce symptoms by destroying specific parts of the brain.

Many patients also benefit from physical, speech, and occupational therapy as well as yoga, massage, tai chi, and meditation. Exercise, healthy eating along with rest and adequate sleep are also important.


There is no clear way to prevent Parkinson's disease. Research has linked aerobic activity in earlier adulthood to a lower risk of developing the condition. Preliminary studies suggest that caffeine and green tea may also protect against Parkinson's but it's too early to recommend these beverages as a way to prevent the disease.

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