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 Tuesday. 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 War. ``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 Association.'' ``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 chemicals. ``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 research.'' 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 look-alikes.'' J.C. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=11187