This research study will evaluate functions of memory, thinking, eye movements and walking
and how these relate to the measurement of certain chemicals (acetylcholine and dopamine) in
the brain using an imaging procedure called positron emission tomography (PET). You may know
that the brain chemical dopamine, a "neurotransmitter" substance (a chemical messenger that
nerve cells need to communicate with each other), is important for the brain to control
movements and that the brain chemical acetylcholine may have functions related to mental
concentration and attention. At the present time, the investigators have no clear
information how these two chemicals in the brain of patients with Parkinson's disease are
related to the risk of falling.
Minimum age: 50 Years.
Maximum age: 85 Years.
Gender(s): Both.
Inclusion Criteria:
- Subjects considered for inclusion will be female or male subjects either currently
enrolled or eligible for care at the VA aged 50-85 years, or community volunteers.
- The racial, gender and ethnic characteristics of the proposed subjects population
reflect the demographics of the patient population of the VA. However, extra efforts
will be made to recruit women and minorities (see table 5).
- Children will be excluded from the study.
- No exclusion criteria shall be based on race, ethnicity, gender, or asymptomatic HIV
status.
Exclusion Criteria:
- Inability to stand or walk independently (i. e., patients in Hoehn and Yahr stage IV
and V).
- Vertiginous disorder.
- Orthostatic hypotension or unstable cardiovascular disease at risk of syncope (drop
in systolic blood pressure of > 20 mm Hg upon standing).
- History of stroke with focal cortical lesions.
- Cerebellar, myelopathic or significant radiculopathy syndrome.
- Diminished light perception in both eyes (< 20/40 corrected OU).
- Intracranial surgery.
- Subjects who have participated in other research protocols such that their cumulative
radiation absorbed dose to whole body, gonads, bone marrow or lens of the eye would
exceed 5 Rem, or dose to other body organs is more than 15 Rem in preceding 12
months.
- Pregnancy (beta-HCG test within 48 hours of PET study) or breastfeeding.
- Contra-indications to MRI.