Parkinson's Disease, slowly progressive
disabling ailment, marked by tremor and increasing stiffness of the muscles. The
disease, which occurs in all parts of the world, affects more men than women and
is most likely to develop after the age of 35. The disease results from
degeneration of the basal ganglia, an area of nerve cells at the base of the
brain. The chief carrier of nerve signals in this area is the chemical dopamine,
which is grossly deficient in Parkinsonian patients. The cause of this
deficiency is not known, but the discovery in 1983 that the chemical MPTP (a
byproduct of a synthetic form of heroin) could cause similar damage suggests
that Parkinson's disease may have an environmental origin. Symptoms of the
disease include excessive salivation, poor coordination, faulty body balance,
tremors, and muscle rigidity. Shortening of the muscles along the front of the
neck tends to bend the head and spine forwards.
Introduction of the drug L-dopa in the mid-1960s led to
symptomatic relief in many patients. L-dopa is converted to dopamine
in the basal ganglia and takes the place of the missing nerve signal.
After a variable period of years, however,
L-dopa becomes less effective in relieving symptoms, at
which point a substitute drug such as amantadine or bromocriptine may be taken.
Anticholinergic drugs have proven useful in relieving tremors. In 1987,
transplantation of dopamine-producing cells from the adrenal medulla into the
brains of patients with severe Parkinson's disease was performed to reduce
symptoms.
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