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

April 15, 2014 updated by: New York Institute of Technology

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.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

40

Phase

  • Phase 2
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • New York
      • Old Westbury, New York, United States, 11568-8000
        • New York Institue of Technology

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

46 years to 76 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Diagnosis of PD according to the UK Brain Bank Diagnostic criteria
  • Diagnosis of orthostatic hypotension according to EFNS guidelines
  • Able to walk on a treadmill comfortably for 6-10 minutes
  • Currently taking levodopa
  • Subjects between the age of 50-80 years old

Exclusion Criteria:

  • Currently taking an amino acid supplement
  • Currently taking medication that affects BP
  • Normal BP response to testing

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Tyrosine
Tyrosine supplementation (500 mg 2x daily) for 7 days
Dietary supplement: Tyrosine
Tyrosine supplementation (500 mg 2 x daily) for 7 days
Placebo Comparator: Sugar pill
Placebo sugar pills (2x daily) for 7 days
Other: Placebo Comparator:Sugar Pill
Placebo sugar pills (2x daily

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Determine the effects of tyrosine supplementation on orthostatic hypotension in people with PD
Time Frame: 7 days

Orthostatic Blood Pressure Testing:

Subjects will sit and rest for 10 minutes. Blood pressure will be taken in this resting position after the 10 minutes. Subjects will then stand upright for 3 minutes. Blood pressure will be taken every minute for those 3 minutes. A drop in systolic BP of 20 mmHg and a 10 mmHg in diastolic drop within these 3 minutes indicates orthostatic hypotension according to the American Academy of Neurology.

Blood Samples:

Norepinephrine and tyrosine will all be examined via blood samples drawn by a medical assistant or physician from the forearm vein in vacutainer tubes. Two vacutainers of three cc's of blood will be collected and frozen until analyzed.
7 days

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
To determine the effects of tyrosine supplementation in people with PD with autonomic insufficiency on heart rate, blood pressure, and norepinephrine responses during acute exercise stress.
Time Frame: 7 days

An exercise stress test using a Modified Bruce Protocol, which consists of five 3-minute stages on a treadmill, will be used to implement acute stress. During the test, heart rate, oxygen consumption (VO2), Respiratory Exchange Ratio (RER), and 12 lead EKG tracings will be recorded at 1-minute intervals and BP and a rate of perceived exertion (RPE) will be recorded. The treadmill test will conclude when subjects attain peak exercise. Peak exercise will be determined when a subject attains any one of the following: 1) 85% of target heart rate; 2) an RPE of 8; 3) inability to maintain the pace of the treadmill; 4) an RER of over 1.3. Additionally, the American College of Sports Medicine (ACSM) guidelines for terminating exercise testing will be followed.

Subjects will be tested on the first visit and then receive supplementation or placebo for 2x daily for 7 days. Subjects will then repeat all the tests they performed on the first visit.
7 days

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

New York Institute of Technology

Collaborators

Michael J. Fox Foundation for Parkinson's Research

Investigators

  • Principal Investigator: Joanne DiFrancisco-Donoghue, PhD, New York Institute of Technology

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

September 1, 2012

Primary Completion (Actual)

November 1, 2013

Study Completion (Actual)

November 1, 2013

Study Registration Dates

First Submitted

August 28, 2012

First Submitted That Met QC Criteria

August 28, 2012

First Posted (Estimate)

August 30, 2012

Study Record Updates

Last Update Posted (Estimate)

April 16, 2014

Last Update Submitted That Met QC Criteria

April 15, 2014

Last Verified

April 1, 2014

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • BHS-797

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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