Parkinson’s disease is a progressive brain 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. 

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

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, such as actor Michael J. Fox, who was diagnosed at age 30.

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. People suspected of having Parkinson's disease should consider seeking the care of a neurologist who specializes in Parkinson's Disease, Movement Disorder specialist.

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