Study finds widespread sympathetic nerve damage in Parkinson...( orepinephrine levels in their blood tha...),Health

For years, neurologists have believed that OH in PD was due to treatment with the drug levodopa. However, several of the patients in this study who had OH had never taken levodopa, and blood levels of levodopa were the same in patients with and without OH. This shows that the development of OH is unrelated to treatment with levodopa, although it is possible that the levodopa may cause the blood vessel walls to dilate, making the OH worse, Dr. Goldstein says. Since significant loss of sympathetic nerve endings in the heart was found in all the patients with OH, the study suggests that OH in PD is due to the loss of these nerve endings.

"One implication of this finding is that if we can understand what causes the sympathetic nerve loss, we may be able to identify the cause of the entire disease," says Dr. Goldstein. Since norepinephrine and dopamine are part of the same family of chemicals, called catecholamines, the findings suggest that whatever causes the loss of dopamine-producing nerve fibers in the brain also causes the loss of sympathetic nerve endings in other parts of the body. The pattern of sympathetic nerve fiber loss in the heart suggests that these fibers gradually die back over time, Dr. Goldstein notes. However, more study is needed to determine what causes the fibers to die.

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Contact: Paul Girolami or Natalie Frazin
301-496-5751
NIH/National Institute of Neurological Disorders and Stroke
22-Apr-2002