The Effects of Supplementing Tyrosine on Blood Pressure in Parkinson's Disease

The objective of this experiment is: Primary: To determine the effects of tyrosine supplementation on orthostatic hypotension in people with PD. Secondary: To determine the effects of tyrosine supplementation in people with PD with autonomic insufficiency on HR, BP, and norepinephrine responses during acute exercise stress. Orthostatic hypotension and autonomic abnormalities are a common problem for individuals who suffer from PD, especially as it leads to lightheadedness and falling. For those affected, it can drastically reduce quality of life. It has been hypothesized that tyrosine may impact upon individuals suffering from PD. There is ample evidence in animal models that supports our theory; however there is no clinical evidence of the impact tyrosine supplementation may have in PD patients who suffer from orthostatic hypotension and blunted BP and HR responses. Positive findings that supplemental tyrosine increases BP and HR in people with PD during daily activities such as standing up from a chair and walking can lead to new therapies to improve Parkinsonian orthostatic hypotension. Hypothesis We will test the hypothesis that symptomatic individuals with PD on dopamine therapy who suffer from orthostatic hypotension and blunted HR and BP responses will improve after tyrosine supplementation.