Parkinson disease involves the nervous system, specifically, movement
and control of muscles. Parkinson disease affects more than 1 million individuals
in the United States. Because it is more common in older persons, the incidence (number of new cases) of Parkinson disease is
increasing as the population grows older. Parkinson disease was first described
in 1817 and was originally called "shaking palsy." Medical researchers later
discovered that parkinsonian symptoms were due to degeneration of nerve cells
in an area of the brain called the substantia nigra.
These cells supply dopamine, a chemical that modulates
movement, to other areas of the brain called the basal ganglia. Parkinson disease is progressive and leads to severe limitations
in activity and quality of life if the disorder is not treated. Neurologists (doctors who specialize in treating diseases of the nervous
system) and neurosurgeons (doctors who specialize
in surgery of the nervous system) individualize each person's treatment to
manage the symptoms and slow the progress of Parkinson disease. The January
21, 2004, issue of JAMA includes an article about
treatment of Parkinson disease.