Parkinson's disease may go far beyond the brain in its damage to nerve cells, researchers have discovered. While it has long been known that the disease involves a loss of nerve endings in part of the brain, new research shows that it also damages related nerves in the heart. This discovery could lead to new ways of predicting or even preventing Parkinson's, according to investigators at the National Institute of Neurological Disorders and Stroke (NINDS). In a study of 29 Parkinson's patients, Dr. David S. Goldstein and his colleagues found that most had lost heart nerve endings that produce the chemical norepinephrine. Norepinephrine is related to dopamine, the chemical that declines in the brains of Parkinson's patients. This suggests, according to Goldstein's team, that whatever triggers the loss of dopamine-producing nerve endings in the brain also depletes nerve endings in the heart. Their findings were published in the September 5 issue of the Annals of Internal Medicine. Parkinson's is a chronic, progressive disease that strikes the motor system, gradually robbing patients of muscle control, balance and coordination. Many patients also experience a drop in blood pressure when they stand--a condition called orthostatic hypotension. Doctors had believed the Parkinson's drug levodopa was behind this blood pressure abnormality. But according to the NINDS researchers, the explanation may instead lie in nerve damage to the heart. Among their study patients, nine had orthostatic hypotension. All nine, as well as 11 without the blood pressure condition, showed a loss of nerve endings in the heart. When the researchers looked at a group of patients with a disorder similar to Parkinson's--multiple system atrophy--they found normal heart nerve endings. Goldstein's team is currently studying whether other organs show similar nerve-ending loss in Parkinson's. According to Goldstein, damage to the hearts of Parkinson's patients may involve a toxin in the blood that prematurely wears out nerve endings. Because this hypothesis may also apply to the brain, according to NINDS, the new findings could "point to a way of predicting and ultimately preventing the disorder." About 500,000 Americans have Parkinson's. The disease usually appears when people are in their 50s and 60s, but it can also strike young adults. SOURCE: Annals of Internal Medicine 2000;133:338-347, 382-384. Reuters Health Copyright: Copyright © 1999 Reuters Limited. All rights reserved. Republication or redistribution of Reuters Limited content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters Limited. Reuters Limited shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon.