9/14/08

What is Parkinson’s disease?
Parkinson’s disease is a chronic, degenerative neurological disorder that affects one in 100 people over age 60. While the average age at onset is 60, disease onset starts by age 40 in an estimated five to 10 percent of patients, and people as young as 30 can also be affected. There is no objective test, or biomarker, for Parkinson’s, so the rate of misdiagnosis can be relatively high, especially when the diagnosis is made by a non-specialist. Estimates of the number of people living with the disease therefore vary, but recent research indicates that at least one million people in the United States, and six million worldwide, have Parkinson’s.

Parkinson’s disease was first characterized extensively by an English doctor, James Parkinson, in 1817. Today, we understand Parkinson’s to be a disorder of the central nervous system that results from the loss of cells in various parts of the brain, including a region called the substantia nigra. The substantia nigra cells produce dopamine, a chemical messenger responsible for transmitting signals within the brain that allow for coordination of movement. Loss of dopamine causes neurons to fire without normal control, leaving patients less able to direct or control their movement. Parkinson’s is one of several diseases categorized by clinicians as movement disorders.

What range of symptoms are part of Parkinson’s disease?
People are generally most familiar with the motor symptoms of Parkinson’s disease, as they are the most evident signs of the disease from the outside. These symptoms, which are also called the "cardinal" symptoms of PD, are resting tremor, slowness of movement (bradykinesia), postural instability (balance problems) and rigidity. Some other physical symptoms such as gait problems and reduced facial expression are also of note. These are due to the same discoordination of movement that causes the better-known tremor and slowness.

There is also increasing recognition of the importance of other symptoms of PD that are sometimes called "non-motor" or "dopamine-non-responsive" symptoms. While neither of these terms is ideal, these symptoms are common and can have a major impact on people with PD. For example, cognitive impairment, ranging from mild memory difficulties to dementia, and mood disorders, such as depression and anxiety, occur frequently. Also common are sleep difficulties, loss of sense of smell, constipation, speech and swallowing problems, unexplained pains, drooling, constipation, and low blood pressure when standing.

Parkinson’s symptoms manifest differently in different patients. Many patients experience some symptoms and not others, and even the pace at which the disease worsens varies on an individual basis.

How is Parkinson’s disease diagnosed?
The cardinal symptoms of Parkinson’s (resting tremor, slowness of movement (bradykinesia), balance problems (postural instability), and rigidity are the hallmarks of the disease. These symptoms, which often appear gradually yet with increasing severity, are usually what first bring patients to a neurologist for help. Typically, symptoms begin on one side of the body and migrate over time to the other side.

There is no test (such as a blood test, brain scan or EEG) to make a diagnosis of PD. Instead, a doctor takes a careful medical history and performs a thorough neurological examination, looking in particular for two or more of the cardinal signs to be present. Frequently, the doctor will also look for responsiveness to Parkinson’s medications as further evidence that Parkinson’s is the correct diagnosis.

Unfortunately, because there is no definitive test for Parkinson’s disease and because PD’s symptoms are similar to those of other neurological conditions, the misdiagnosis rate is significant. It is worthwhile to consider a second opinion and to reach out to a neurologist with specific expertise in movement disorders.

Y’all take care,

Mandy

Ovarian cancer: It whispers, so listen.