Parkinson's disease (PD) is a disorder of the brain that causes a variety of movement problems, including:

• shaking (tremor)
• difficulty walking
• muscle stiffness or aching
• slowness of movement
• small handwriting
• decreased facial expression

Movement and coordination in your body are controlled in part by a chemical in your brain called dopamine. In Parkinson's disease, dopamine-producing nerve cells are damaged, gradually reducing dopamine levels in the parts of the brain thought to control movement. Without dopamine, the brain doesn't send signals to the muscles so that they can function properly.

The cause of Parkinson's disease is still unknown. Many researchers believe Parkinson's disease may be caused by a combination of genetic factors and environmental factors, such as exposure to certain toxins.

Do I Have Parkinson's Disease?

Not all movement difficulties are related to Parkinson's disease. If you are experiencing signs and symptoms associated with Parkinson's disease, or have other reasons to believe you may have Parkinson's disease, take action and contact your physician. Early testing and diagnosis will help you manage your symptoms, or identify other conditions that may be causing the symptoms. If you would like to get information from a doctor online, the National Parkinson Foundation offers an  "Ask the Doctor" Forum.  You can also find additional information on Parkinson's disease at Parkinsonshealth.com.