What is Parkinson's Disease?
Parkinson's disease is a slowly progressive, neurodegenerative
disease generally associated with tremor or trembling
of the arms and legs, stiffness and rigidity of the muscles, and slowness
of movement. The cause is still unknown, although medical
experts believe the symptoms are related to a chemical imbalance
in the brain. This chemical imbalance is caused by brain cell
An estimated 1 million people in the United States have
Parkinson's disease. It affects both men and women,
generally 40 years of age or older.
Symptoms vary from patient to patient. Symptoms appear
slowly and in no particular order. Many years may pass
before early symptoms progress to the point where they interfere with normal
activities. The four major hallmark symptoms of Parkinson's
Rigidity -- stiffness when the arm, leg or neck is moved
back and forth
Resting Tremor -- tremor most prominent at rest, when sitting
Bradykinesia -- slowness in initiating movement
Loss of postural reflexes -- patients have poor balance
and may fall
A small area in the brain called the substantia nigra produces
a chemical called dopamine. Dopamine, once it is produced,
travels through the cell to its end terminal in another portion of the brain
called the striatum.
In Parkinson's disease, the cells in the substantia nigra
begin to die. As they die, less dopamine is made so that
less is transported to the striatum. Since the striatum is a coordination
center for the various chemicals, when there is not
enough dopamine, there is a chemical imbalance. This chemical imbalance
leads to the symptoms of Parkinson's disease. Later
in the disease, cells in other portions of the brain and nervous
system also degenerate.
Current therapy consists primarily of dopamine replacement.
This is accomplished by using levodopa and other dopamine-enhancing
agents. These drugs are helpful for the majority of Parkinson's patients
in both improving disability and reducing mortality.
Pallidotomy and Thalamotomy are treatments in which a surgical
lesion is made in a portion of the brain called the
pallidum (globus pallidus) or the thalamus. This treatment has been shown
to reduce symptoms in some patients.
PD is characterized by specific brain
lesions found in substantia nigra and other subcortical nuclei, namely Lewy
bodies, made up of aggregates of alpha-synuclein.
Deep brain stimulation is an experimental method of treating
Parkinson's disease. In this treatment, electrodes
are placed in a part of the brain called the thalamus and a pacemaker is
used to stimulate the thalamus.
There is also significant research showing that fetal tissue
transplants survive and replace the brain cells that
have died as a result of Parkinson's disease.
There are a multitude of exciting new drugs expected to
be on the market soon for the treatment of Parkinson'
s disease. These include dopamine agonists, COMT inhibitors and growth factors.