Parkinson's Disease

Parkinson's disease is a disorder of the central nervous system that causes shaking, rigid muscles, slow movements, and poor balance. The disease is progressive, meaning it tends to get worse over time.

Michael J. Fox's Story

American actor Michael J. Fox first noticed the twitch in his left little finger while filming the 1991 movie Doc Hollywood. He remembers looking at the shaking finger and thinking, “Geez, what's that?”

Within six months, Fox's entire left hand started to twitch uncontrollably, and parts of his body started to feel stiff. Fox was concerned, so he visited a doctor.

Fox was only 29 years old and appeared to be in excellent health. His roles often required physical stunts that he performed with ease. He never expected to find out that his shaking hand and rigid muscles meant he had Parkinson's disease, a condition that is more common among people over 50 years of age. Although his doctor told Fox he only had about 10 years left in which he'd be able to work, Fox has continued to act, even starring in his own sitcom, The Michael J. Fox Show, in 2013. Fox also runs a foundation dedicated to Parkinson's research and therapies.

Actor Michael J. Fox was diagnosed with Parkinson's disease at the age of 29.

Actor Michael J. Fox was diagnosed with Parkinson's disease at the age of 29.
Neilson Barnard/MJF2014/Getty Images.

What Is Parkinson's Disease?

* , may also be a factor in Parkinson's disease.

Who Was James Parkinson?

According to the Parkinson's Disease Foundation, Parkinson's disease affects about 1 million people in the United States and more than 4 million people worldwide. About 60,000 people are diagnosed each year in the United States. Symptoms of Parkinson's disease can appear at any age, but the average age of onset is 60. Risk for the disease increases with age; only about 2 percent of those in the United States affected by Parkinson's disease are thought to be below the age of 40, although, since younger people with Parkinson's may be misdiagnosed, this number could be somewhat higher. Parkinson's disease is common in the elderly and affects 1 person in 20 over the age of 80. The disorder occurs in all races, but Parkinson's is somewhat more prevalent among Caucasians. Men develop the disease slightly more often than women. Parkinson's disease is not contagious and cannot pass from one person to another.

The disease is named for a British doctor, James Parkinson, who first described the disease's symptoms in 1817. He called it “Shaking Palsy.” In the 1960s scientists began to understand how the chemical changes in the brain caused the symptoms. Eventually, research led to medications and other treatments to help control the disease.

Did You Know?

Actor Michael J. Fox is not the only famous person with Parkinson's disease who has continued to maintain an active life. Janet Reno, the U.S. attorney general during the Clinton administration, also had Parkinson's. As did boxer Muhammad Ali (1942-2016).

Ali created a dramatic moment at the 1996 Olympics when he carried the torch in Atlanta. In 1998 Ali joined others in promoting more research that involves people of African, Hispanic, and Asian ancestry.

What Are the Symptoms of Parkinson's Disease?

As the disease progresses, the symptoms become more severe. Tremors may appear on both sides of the body. Movement becomes slower and the person may have difficulty with balance and coordination. Reflexes are decreased. At times the person may seem to freeze in the middle of an action.

Eventually the symptoms become so severe the person needs help with simple activities such as walking and eating. Living alone is dangerous for those in the advanced stages of the disease due to their limited mobility and slow reaction time. Most will require a wheelchair or have to stay in bed. Some people with advanced Parkinson's disease experience visual hallucinations * and delusions * .

What Causes Parkinson's Disease?

No one knows exactly what causes the chemical imbalances in the brain that trigger Parkinson's disease. Scientists have noted certain changes that occur in the brains of those affected with Parkinson's, although there is still no answer as to what exactly causes these changes. As of 2016 studies were focusing on a protein called alpha-synuclein. Abnormal deposits of this protein are found in the brains of those with Parkinson's disease and may hold clues for researchers.

Many scientists believe Parkinson's disease is due to genetic factors, environmental factors, or a combination of the two. Although the disease is not often directly inherited, 15 to 25 percent of those with Parkinson's have another relative who is/was also affected. If a person's parent has Parkinson's, he or she has a slightly elevated risk of having it as well. This has led some researchers to look for a gene * that might trigger the disease. They studied a large number of Parkinson's cases among two large European families that appeared to share a defective gene, but the scientists have not been able to find the same abnormal gene in many others with the disease.

Environmental factors that researchers believe may be at play include exposure to certain pesticides, chemicals, or toxins; head injury; drinking well water; and living in rural areas. However, there is no conclusive evidence that any of these factors causes Parkinson's disease, and the vast majority of people exposed to them do not contract the illness. It may be that these factors combine with genetics in some way that triggers Parkinson's in certain people.

The National Institutes of Health (NIH) is working with other organizations, such as the Parkinson's Institute and Clinical Center, the American Parkinson Disease Association, and the Michael J. Fox Foundation for Parkinson's Research, to establish registries for patients who have Parkinson's disease. The intention of these registries is to collect information about potential triggers, risk factors, and causes for Parkinson's disease. These organizations hope that this information will possibly lead to a cure.

How Is Parkinson's Disease Diagnosed?

Parkinson's disease is difficult to diagnose. No single test can determine if a person has it. Diagnosis begins with a neurological history and a physical examination. Additional testing may be necessary to rule out other causes of the symptoms, such as a brain tumor or other brain disorder. As of early 2016, the best option was a brain scanning technique to evaluate dopamine output and the chemical processes in the brain. This test is very expensive, however.

How Is Parkinson's Disease Treated?

Hope is available for people with Parkinson's disease because several prescription drugs can help. For most people, doctors prescribe a combination of drugs that help the brain make dopamine, the chemical needed to help nerve cells communicate in the brain. Other medications act like dopamine in the brain, improving the ability of the brain to control movements. The most commonly used drug to treat Parkinson's disease is levodopa.

The drugs do not cure the disease, but they do treat its symptoms. People are able to perform many of the same activities they did before the disease developed, which is why Michael J. Fox has been able to continue taking acting roles.

In the past, doctors sometimes recommended brain surgery to destroy tiny areas of the brain that were malfunctioning. Fox had this surgery. The elimination of these cells improved the trembling in some people with Parkinson's. While such surgeries are still sometimes performed, as of early 2016 doctors were more commonly turning to deep brain stimulation (DBS). DBS targets the site that researchers believe is the source of Parkinson's disease. In DBS, an implanted electrode is used to inactivate, not destroy, the targeted area. The electrode is connected to the brain by a wire that runs beneath the patient's skin to a stimulator and battery pack in the patient's chest. DBS is a reversible treatment that allows for precise control of symptoms.

Antiparkinson drugs

Antiparkinson drugs
Table by PreMediaGlobal. © 2016 Cengage Learning®.
Parkinsonian Gait

Actor and comedian Billy Connolly was diagnosed with Parkinson's Disease in 2013 by a person who was watching him walk through a hotel lobby in Los Angeles. The person turned out to be a physician from Tasmania who approached the actor and suggested he see his physician because he had a “strange gait.” The Tasmanian physician was correct, and Billy Connolly was diagnosed at the age of 71.

See also Alzheimer's Disease • Dementia • Depressive Disorders: Overview • Fainting (Syncope) • Genetic Diseases: Overview • Lou Gehrig's Disease (Amyotrophic Lateral Sclerosis)


Books and Articles

Ahlskog, J. Eric. The New Parkinson's Disease Treatment Book: Partnering with Your Doctor to Get the Most from Your Medications, 2nd ed. London: Oxford University Press, 2015.

Colen, B. D. “Possible Progress against Parkinson's.” Harvard Gazette. (accessed March 8, 2016).

Hamilton, Jon. “Can a Cancer Drug Reverse Parkinson's Disease and Dementia?” . October 17, 2015. (accessed March 8, 2016).

Palfreman, Jon. Brain Storms: The Race to Unlock the Mysteries of Parkinson's Disease. New York: Scientific American/Farrar, Straus and Giroux, 2015.


Remedy's Communities. “Parkinson's Disease.” (accessed March 8, 2016).


American Parkinson Disease Association. 135 Parkinson Ave., Staten Island, NY 10305. Toll-free: 800-223-2732. Telephone: 718-981-8001. Website: (accessed March 8, 2016).

The Michael J. Fox Foundation for Parkinson's Research. Grand Central Station, PO Box 4777, New York, NY 10163. Toll-free: 800-708-7644. Website: (accessed March 8, 2016).

National Institute of Neurological Disorders and Stroke. PO Box 5801, Bethesda, MD 20824. Telephone: 301-496-5751. Website: (accessed March 6, 2016).

National Parkinson Foundation. 200 SE 1st St., Suite 800, Miami, FL 33131. Toll-free: 800-473-4636. Website: (accessed March 6, 2016).

Parkinson's Disease Foundation. 1359 Broadway, Suite 1509, New York, NY 10018. Telephone: 212-923-4700. Website: (accessed March 6, 2016).

* brain stem is the portion of the brain that connects the brain to the spinal cord. It also controls involuntary muscle movement, regulates essential bodily functions such as breathing and heart rate, and relays messages between the body and the brain.

* hallucination occurs when a person believes he or she is seeing something that is not in reality present or happening.

* delusion a false belief that is firmly held despite evidence to the contrary.

* genes (JEENS) are chemical structures composed of deoxyribonucleic acid (DNA) that help determine a person's body structure and physical characteristics such as hair or eye color. Inherited from a person's parents, genes are contained in the chromosomes found in the body's cells.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)