Parkinson's disease is a neurological disorder that attacks the motor system. The disease has four primary symptoms: tremors in the arms and hands, head and face and legs; stiffness in limbs and torso; slow movements, also known as bradykinesia; and impaired balance and coordination. The disease is degenerative in nature, and the symptoms become worse over time. Secondary Parkinson's symptoms include emotional changes and sleep disturbances, speech problems and urinary and intestinal problems. Parkinson's is directly linked to a chemical called dopamine.
What is Dopamine?
The chemical dopamine is known as neurotransmitter -- a class of chemicals that transmit messages to and from the neurons in the brain. The dopamine molecules sit in pockets called receptors on the ends of the nerve cells. Dopamine controls movement and emotional response and also contributes to the brain's reward system and is closely tied to addictive behavior. Dopamine is made in a section of the midbrain called the substantia nigra.
Parkinsons and Dopamine
With Parkinson's disease, this part of the brain becomes damaged. As the cells die, the substantia nigra produces less and less until there is no dopamine at all. The disease progresses at different rates in different people, and the symptoms usually manifest after age 50 years. Because dopamine controls movement, it is the absence of this neurotransmitter that causes the primary and some of the secondary symptoms of Parkinson's.
Causes
Doctors are not certain what causes the damage to the substantia nigra or how the disease progresses the way it does. The National Institute of Neurological Disorders and Stroke, NINDS, and the National Institutes of Health, NIH, have funded research programs to study environmental and genetic factors that may trigger the disease.
Parkinson's Treatments
The primary treatment for Parkinson's is the drug levodopa, or L-dopa, a synthetic drug that turns into dopamine in the body. Doctors also prescribe a drug called carbidopa, which prevents levodopa from converting into dopamine until it reaches the brain. L-dopa treats the stiffness and bradykinesia but is not as effective against the tremors. Drugs that mimic dopamine, such as bromocriptine and pramipexole, are also effective against Parkinson's. The NINDS and NIH are also researching more effective therapies to prevent and treat the disease.
