Despite Progress, Parkinson’s Disease Remains Mysterious

Despite remarkable discoveries and technological advances over the years, medicine still has its mysteries, and Parkinson’s disease is among them.

A neurological disorder of the brain that affects a person’s muscle control and bodily movements, Parkinson’s is named for the English doctor James Parkinson, who first identified and described the condition in 1817 in “An Essay on the Shaking Palsy.”

The symptoms and onset of the disease appear slowly and gradually, usually without the patient’s knowledge, a fact noted by Dr. Parkinson nearly 200 years ago. “So slight and nearly imperceptible are the first inroads of this malady,” he wrote, “and so extremely slow its progress, that it rarely happens that the patient can form any recollection of the precise period of its commencement.”

Nearly 1 million people in the U.S. suffer from the condition, and its incidence is growing; 50,000 to 60,000 new cases are diagnosed each year. It is a disorder affecting an older population, usually beginning in people 60 years of age and up.

Parkinson’s disease causes tremors or shaking of the face, arms, or legs; stiffness in the limbs or trunk; slowness of movement; and poor balance and coordination. It is a chronic condition, persisting over a long time, and it is progressive, with symptoms growing worse over time.

The mystery of Parkinson’s is its cause. While the disease is known to be intrinsic to the brain, where degeneration occurs in certain parts of the brain, the specific causes of the condition are unknown. Several theories about causes do exist, including genetic predisposition, environmental exposure — especially to heavy metals or pesticides — and traumatic head injury.

This lack of a known cause and the absence of testing to pinpoint the disorder — there’s no blood test, X-ray, or other imaging test to diagnose the disease — make it difficult for physicians to get an accurate diagnosis.

Physicians must look beyond the tremors, stiffness, or slow movement and examine how the condition may be affecting aspects of a patient’s daily life. Other indications of the disease may include a decrease in animation of the face (or ‘poker face’), slowness of speech, difficulty with handwriting, problems with sleep, or issues surrounding mood.

One known characteristic of the condition is a dramatic drop in the amount of dopamine in the brain. Dopamine is a neurochemical that sends signals between neurons and helps regulate movement, among other functions. Replacing the dopamine lost over time with medication is part of the treatment for patients with Parkinson’s.

Other medications may be prescribed as well, and in some cases, surgery may be appropriate. This surgery, called deep-brain stimulation, involves implanting electrodes into the brain that are then programmed to reduce tremors and slowness of movement.

Although no cure for Parkinson’s currently exists, research continues, particularly for a medication than can slow the progression of the disease. Current therapies are good at treating the symptoms of Parkinson’s, but nothing is now available to slow its progression.

The good news is that the medications and therapies available now allow patients to live a full life. In diagnosing and treating patients, physicians approach each person individually, tailoring their medications and treatments.

To learn more about Parkinson’s, including early warning signs and living with the disease, visit the American Parkinson Disease Assoc. at www.apdaparkinson.org. And for a video discussion, visit www.physicianfocus.org. v

Drs. Anna Hohler and Samuel Frank are board-certified neurologists at Boston Medical Center who specialize in treating Parkinson’s patients. This article is a service of the Mass. Medical Society.