What Is Parkinson's Disease?

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Quick summary

Parkinson's disease is a complex and progressive neurological disorder. Symptoms differ greatly from person to person, so much so that there's no predicting for sure which ones a patient will experience or how quickly. No cure exists yet. However, as neurological disorders go, this one is among the most treatable. Responses to treatment vary, but medications can give a patient substantial symptom relief and a good quality of life for many years, sometimes a decade or more. When drugs aren't enough, brain surgery may be an option. Here's a primer on the disease.


Parkinson's disease gradually impairs the ability to move, walk, talk, and swallow. It typically develops when patients are in their 50s or 60s, but in roughly 8 percent of cases it strikes before age 40.

For some people, the condition can be severely debilitating in the long term; others are able to function relatively well even after 25 years of living with Parkinson's disease.

The disease stems from gradual destruction of certain nerve cells -- in a part of the brain called the substantia nigra -- that make a key chemical known as dopamine. Dopamine helps relay messages within the brain centers that orchestrate muscles of the body to produce smooth, coordinated motions. Without that signal, muscles can't respond properly.

Parkinson's isn't a death sentence

With current treatments, average life expectancy with Parkinson's disease is nearly normal, and the disease process isn't itself fatal. But severely disabled patients can die from complications of the illness. For instance, problems with swallowing can cause patients to choke or aspirate food into their lungs, leading to infection and deadly pneumonia. Or a bad fall might cause a broken hip and contribute to a general decline from which the patient never recovers.

Diagnosis can be tricky in early stages

About 5 to 10 percent of Parkinson's disease patients are wrongly told at first that they have some other condition. And up to 20 percent of people given a Parkinson's diagnosis don't actually have the illness. To obtain an accurate assessment, it would be best for a patient to see a movement disorder specialist, a neurologist with one to two years of extra training in treating Parkinson's disease and similar illnesses.

Because there's no lab test to pinpoint Parkinson's disease, the doctor identifies it by examining and questioning the patient, looking for a certain constellation of clinical signs. Parkinson's disease belongs to a category of neurologic disorders that all cause similar symptoms, known as parkinsonism. So the physician must rule those out and other potential diagnoses such as small strokes, arthritis, head injury, and essential tremor.

What Parkinson's disease looks like

Motor symptoms


The first hints of the illness are usually mild, intermittent, and show up on just one side of the body. Three cardinal signs are:

  • Shakiness, from a tremor in a hand, arm, or leg or the jaw or face when the patient isn't actively moving.
  • Stiffness, or rigidity of the arms, legs, and torso.
  • Slowness of movements, also known as bradykinesia.

Other common signs and symptoms include:

  • Small, cramped handwriting.
  • A stooped posture.
  • Less arm-swinging than before while walking.
  • A blank, "masklike" facial expression.

As the disorder progresses, additional problems may grow more significant, including:

  • Problems with balance and falling.
  • Walking with small, shuffling steps.
  • Moments of "freezing" when the patient's feet suddenly can't move forward.
  • Difficulty swallowing.
  • A weak and muffled voice.
Nonmotor symptoms

A patient may not develop these difficulties, but over time, up to 60 percent of patients suffer from more than one nonmotor symptom. Many are treatable with standard therapies.

Cognitive and behavioral problems:

  • Depression
  • Apathy
  • Fatigue
  • Dementia
  • Anxiety
  • Sle ep disorders
  • Difficulty with impulse control
  • Sensory difficulties
  • Loss of sense of smell
  • Pain in a limb affected by muscle stiffness

Problems with bodily functions

  • Drooling
  • Fainting or dizziness after standing up, due to abnormalities in blood pressure regulation
  • Sexual dysfunction
  • Constipation
  • Frequent urination or incontinence
  • Skin problems, such as eczema or excessive sweating


Treatments That Ease Parkinson's Disease

No currently available treatments can stop or slow down Parkinson's disease. However, doctors now have more than a dozen drugs to control symptoms. The name of the game is to make up for the loss of dopamine in the brain, in a variety of ways. Again, it's crucial for patients to consult an expert. Most of Parkinson's disease treatment is a matter of juggling and tweaking medications, and a movement disorder specialist will have a lot more experience doing that than a general neurologist, says Martha Gardner, a Parkinson's patient and former nurse who is coordinator of the American Parkinson Disease Association (APDA) Information and Referral Center at Stanford University.

  • Drugs

The gold standard medicine is levodopa, sold as Sinemet, which is converted in the brain into dopamine. Other classes of drugs -- such as dopamine agonists, COMT inhibitors, and MAO-B inhibitors -- either mimic the actions of dopamine or counteract its breakdown in the brain.

If a patient has run-of-the-mill Parkinson's disease, Sinemet or dopamine agonists are likely to work well for several years after diagnosis. Over time, though, symptoms start to re-emerge. And side effects from the drugs themselves begin to become problematic. Most troublesome are the random wiggly, writhing movements called dyskinesias.

  • Surgery

If adjustments in a patient's medication regimen fail to adequately solve these challenges, surgical treatments may improve the situation. In particular, in some patients a method called deep brain stimulation can reduce the need for drugs: Electrodes are permanently placed in the brain and connected to a battery-operated pacemaker (implanted in the chest). The pacemaker sends electrical signals to the brain that block the abnormal nerve impulses causing motor symptoms.

  • Other strategies for improving and maintaining a patient's functioning

Regular stretching, strengthening, and aerobic exercises can help a person stay flexible, improve posture, and move more easily. As the disease advances, physical therapy and occupational therapy can offer advice and strategies for navigating difficulties with the daily activities of living. And speech therapy can train a patie nt to talk at a louder volume to be understood clearly.

Forecasting Parkinson's prognosis is difficult

In some Parkinson's disease patients, symptoms slowly worsen over 20 years or more, but in others the pace is faster. Which course any individual's illness will take is hard to say. However, according to the American Academy of Neurology, some evidence suggests that patients who are diagnosed at an older age, and whose initial symptoms do not include tremor, will see their Parkinson's disease advance more rapidly.

On the other hand, someone who comes in chiefly complaining of a tremor on one side of the upper body may feel miserable about it, but the shakiness can be a positive sign, says Susan Imke, a gerontological nurse practitioner in Fort Worth, Texas. "That's a good prediction of typical Parkinson's disease that responds well to medicine for many years," she says.

Another potential clue to a patient's long-term outlook is how the illness unfolds in the first few years, because in any given individual, the disease tends to progress at the same rate over time. "Parkinson's that creeps along in the early stages doesn't tend to just start to gallop at some point," says Imke.

Ingfei Chen

Ingfei Chen has witnessed the hope and hype and miracles and failings of medical care and scientific research during more than 15 years of covering both areas as a journalist. See full bio