Parkinson's Disease

Parkinson's disease is a brain disorder that progressively affects a person’s ability to control body movements, caused by a disorder of certain nerve cells in a part of the brain that produces dopamine, a chemical messenger the brain uses to help direct and control body movement. As these nerve cells break down, dopamine levels drop and brain signals that direct movement become abnormal. Symptoms of Parkinson's disease appear when these dopamine-producing nerve cells become damaged or die.

Parkinson's disease typically begins relatively late in life, around age 60 on average, and progresses slowly over time. In 5 to 10 percent of cases, Parkinson's disease may develop in those younger than 50 and, rarely, in those in their 20s or 30s. The term "young-onset Parkinson's disease" is used when symptoms appear before age 50.

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Symptoms

Every Parkinson's patient experiences a combination of three motor symptoms, which typically worsen over time at a pace that varies from person to person. For most people, symptoms begin on one side of the body and later spread to the other side.

Classic symptoms of Parkinson's disease may include:

  • Slowness of movement (bradykinesia)
  • Shaking (tremors)
  • Stiff or rigid muscles
  • Difficulty with balance

Tremor is usually the first symptom people notice, and unlike other tremors, these tremors are typically present when the patient is at rest. Emotional and physical stress tends to make the tremor worse. Sleep, complete relaxation and intentional movement or action usually reduce or stop the tremor. It is important to remember, however, that as many as 30 percent or more of people with Parkinson's disease do not experience tremors.

The muscles of the legs, face, neck or other parts of the body may become unusually stiff or rigid. Another common early sign of the disease is a reduced swing of the arm on one side when the person is walking.

In addition to the four classic motor symptoms, Parkinson's disease can cause a variety of other disabilities as the disease progresses:

  • Lessened dexterity and coordination
  • Changes in handwriting, which becomes progressively smaller
  • Difficulty with daily activities, such as dressing and eating
  • Weakness of face and throat muscles causing talking and swallowing difficulties
  • Choking, coughing or drooling
  • Softer and monotonous speech
  • Stooped posture with bowed head and slumped shoulders
  • "Freezing," a sudden inability to move, which most often affects walking

Finally, people with Parkinson's disease may experience one or more symptoms that typically do not affect their movements. The most typical nonmotor symptoms of Parkinson's disease include:

  • Constipation and urinary problems
  • Loss of smell
  • Sleep problems, including frequent awakenings, acting out dreams (REM-behavior disorder) and sleep apnea
  • Anxiety and depression
  • Blood pressure changes
  • Excessive sweating
  • Loss of memory and difficulty concentrating
  • Sexual problems
  • Weight loss

A person with Parkinson's disease may slowly become more dependent, fearful, indecisive and passive. The person may talk less often, withdraw from people and be inactive unless encouraged to move about. Depression is very common with this disease and can be caused by chemical changes in the brain. Symptoms of depression often improve with proper treatment.


Causes and Risk Factors

The causes for most forms of Parkinson's disease are unknown. Some evidence indicates that inherited (genetic) factors may predispose some people to develop Parkinson's disease; however, the majority of people with Parkinson's don't have a known gene abnormality. Research has indicated that there may be a connection between Parkinson's and environmental toxins that damage dopamine-producing nerves.

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Diagnosis

There is no early-detection screening test for Parkinson's disease at this time. Diagnosis begins when a patient visits their physician with symptoms. The doctor will take a medical history and perform an examination of the nervous system.

Some of the nonmotor symptoms (such as constipation, loss of smell and acting out dreams), can begin before the typical motor symptoms of Parkinson’s disease, and there is hope that these may be used in the future for early diagnosis.

Until recently there has been no laboratory test to confirm the clinical diagnosis of Parkinson’s disease. However, if the symptoms and the doctor’s findings are not entirely typical of the disease, then a DaT scan can be conducted, which involves the injection of a drug into the bloodstream to assess the condition of dopamine-containing neurons.

A magnetic resonance imaging (MRI) scan may be performed to rule out other conditions with similar symptoms. Doctors may also order blood tests to check for abnormal thyroid hormone levels, liver damage or other problems. Another type of imaging, called a positron emission tomography (PET) scan may show low levels of dopamine in the brain – a key sign of Parkinson’s disease.

Once a physician believes that a patient has Parkinson’s disease, a short course of dopamine supplementation, typically using the drug levodopa, may help confirm the diagnosis. About 90 percent of people with Parkinson’s disease respond to levodopa or other dopaminergic medication. If the symptoms improve while the patient takes the medication, Parkinson’s disease is essentially confirmed.

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Treatments

Currently there is no cure for Parkinson’s disease. However, dopaminergic medications can relieve many symptoms. Medication usually is started when symptoms begin to interfere with daily activities. Dosage is based on the stage of the disease and the specific symptoms. Exercise and physical and occupational therapy may be helpful at all stages of Parkinson’s disease to help maintain strength, mobility and independence.

As the individual’s medical condition changes, adjustments in treatment are needed to balance quality-of-life issues and side effects of treatment. When medications alone cannot satisfactorily relieve the symptoms of the disease, surgical treatments like deep brain stimulation (DBS) can be effective.

Emotional support and education about the illness should begin early and continue throughout the course of the disease. Participating in Parkinson’s disease support groups is a good way for patients to learn more and share emotional support.

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