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Parkinson’s disease is a progressive disorder that is caused by degeneration of nerve cells in the part of the brain called the substantia nigra, which controls movement. These nerve cells die or become impaired, losing the ability to produce an important chemical called dopamine. Studies have shown that symptoms of Parkinson’s develop in patients with an 80 percent or greater loss of dopamine-producing cells in the substantia nigra.

Normally, dopamine operates in a delicate balance with other neurotransmitters to help coordinate the millions of nerve and muscle cells involved in movement. Without enough dopamine, this balance is disrupted, resulting in tremor (trembling in the hands, arms, legs and jaw); rigidity (stiffness of the limbs); slowness of movement; and impaired balance and coordination – the hallmark symptoms of Parkinson’s.

The cause of Parkinson’s essentially remains unknown. However, theories involving oxidative damage, environmental toxins, genetic factors and accelerated aging have been discussed as potential causes for the disease. In 2005, researchers discovered a single mutation in a Parkinson’s disease gene (first identified in 1997), which is believed responsible for five percent of inherited cases.

Prevalence And Incidence

It is estimated that 60,000 new cases of Parkinson’s disease are diagnosed each year, adding to the estimated one to 1.5 million Americans who currently have the disease. There were nearly 18,000 Parkinson’s disease-related deaths in the United States in 2003. While the condition usually develops after the age of 55, the disease may affect people in their 30s and 40s.

Common Symptoms

  • Tremor or the involuntary and rhythmic movements of the hands, arms, legs and jaw
  • Gradual loss of spontaneous movement
  • Gradual loss of automatic movement
  • A stooped, flexed posture with bending at the elbows, knees and hips
  • Depression or dementia
  • Muscle rigidity or stiffness of the limbs – most common in the arms, shoulders or neck
  • Decreased mental skill or reaction time, voice changes, decreased facial expression, etc.
  • Decreased blinking, decreased frequency of swallowing and drooling
  • Unsteady walk or balance

Diagnosis

Presently, the diagnosis of Parkinson’s is primarily based on the common symptoms outlined above. There is no X-ray or blood test that can confirm the disease. However, noninvasive diagnostic imaging, such as positron emission tomography (PET) can support a doctor’s diagnosis. Conventional methods for diagnosis include:

  • The presence of two of the three primary symptoms
  • The absence of other neurological signs upon examination
  • No history of other possible causes of parkinsonism, such as the use of tranquilizer medications, head trauma or stroke
  • Responsiveness to Parkinson’s medications, such as levodopa

Medical Treatment

The majority of Parkinson’s patients are treated with medications to relieve the symptoms of the disease. These medications work by stimulating the remaining cells in the substantia nigra to produce more dopamine (levodopa medications) or by inhibiting some of the acetylcholine that is produced (anticholinergic medications), therefore restoring the balance between the chemicals in the brain. It is very important to work closely with the doctor to devise an individualized treatment plan. Side effects vary greatly by class of medication and patient.