X-Message-Number: 11187
Date: Wed, 27 Jan 1999 17:42:00 -0500
From: Jan Coetzee <>
Subject: Parkinson's disease is environmental in origin

Environment Causes Most Parkinson's Cases -Study

SUNNYVALE, Calif. (Reuters) - Environment, and not heredity, is the
likely cause of
Parkinson's disease in most patients over the age of 50, according to a
new study announced

Researchers at the Parkinson's Institute in Sunnyvale, Calif., reached
the landmark conclusion
after studying almost 20,000 twins who were veterans of the Second World

``The results appear to be fairly clear-cut,'' said Dr. J. William
Langston, institute president and
lead author of the study appearing in Wednesday's Journal of the
American Medical

``They tell us that in typical Parkinson's disease, occurring over the
age of 50, there does not
appear to be a genetic component. There was no evidence of a hereditary
factor,'' he said.

Scientists have argued for decades about the potential causes of
Parkinson's disease, a
progressive, degenerative brain disease which slowly reduces the ability
of the nerves to
control the muscles.

Famous Parkinson's patients include Attorney General Janet Reno, Pope
John Paul II, boxer
Muhammad Ali and actor Michael J. Fox.

In recent years, research has turned up evidence of specific genetic
defects which can cause
Parkinson's, leading some to speculate that heredity was a principal
cause for a condition
suffered by an estimated one million Americans. But Langston said the
California study
indicated the main factor in most typical cases of Parkinson's was
environmental, turning the
focus of research onto such potential external factors as herbicides,
pesticides, and other

``If it's not inherited, that really points very strongly to something
in the environment,'' Langston
said in an interview. ''From a scientific angle, we really know where to
invest our money in

The study examined both identical and fraternal sets of twins. Identical
twins share the exact
same genetic profile, while fraternal twins are no closer genetically
than any other siblings --
giving researchers a clear view of how closely the disease is tied to
genetic factors.

It found that, in the rare instances of ``early onset'' Parkinson's
striking before the age of 50, both
members of each of the identical twin sets in the study came down with
the disease, meaning the
cause was almost certainly genetic.

But in the ``typical'' cases of Parkinson's, diagnosed after the age of
50, the study found no
statistical difference between identical and fraternal twins sets. In
each case, only about 10
percent of the twins came down with Parkinson's -- meaning environmental
factors were almost
certainly to blame.

Langston said the results of the study pointed to such a major
difference between ``early-onset''
Parkinson's and the typical form the disease that the two could be
entirely separate conditions.

``Our suspicion is that typical Parkinson's disease is environmental in
origin, but that
'young-onset' cases belong to a group of genetic disorders,'' Langston
said. ``I think they are
actually going to turn out to be different diseases, albeit


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