This study has two purposes: 1) to understand the effect of a decline of dopamine in the
brain during normal aging and in patients with Parkinson's disease, and 2) to investigate
how medicines used to treat Parkinson's disease improve movement performance in patients.
Patients with Parkinson's disease have difficulty performing precise finger movements,
mainly because of a dramatic decrease of a substance called dopamine in parts of the brain.
Medicines such as levodopa, which help restore dopamine levels, can greatly improve
function; however, little is known about how these drugs work. In normal aging, dopamine
decreases slightly in certain parts of the brain, but the importance of this decline is
poorly understood. This study may provide new information about Parkinson's disease and
normal aging that might lead to better treatment strategies.
Patients with mild to moderate Parkinson's disease and healthy volunteers 21 years of age
and older may be eligible for this study. All participants must be right-handed. All
candidates will be screened with a medical history and physical and neurological
examinations, including memory tests and mood examination.
Brain function will be studied using functional magnetic resonance imaging (fMRI) study and
positron emission tomography (PET). Participants may be asked to stop using medications that
can affect the central nervous system, such as sleeping pills or drugs for depression or
anxiety, for 1 week before each study visit. Patients with Parkinson's disease may also be
asked to stop using antiparkinsonian medications at least 12 hours before each visit. In
addition, all participants will be asked to abstain from alcoholic beverages at least 24
hours before the fMRI and PET scans, and from nicotine and caffeine for at least 12 hours
before the scans.
Participants will have fMRI, which uses a strong magnetic field and radio waves to create
images of the brain. The subject lies on a table in a tunnel-like cylinder (the scanner) for
1 to 2 hours, lying still for 5 to 15 minutes at a time. He or she can communicate with the
technician or researcher at all times during the test through an intercom system. Scans will
be done while the subject is at rest and while he or she is performing finger movements. The
movements involve pushing five buttons on a box-each button every 3 seconds on average in a
specific order. Patients with Parkinson's disease will be studied off- and then on-
medications that restore the levels of levodopa in the brain.
Some participants may be asked to undergo a PET scan on a separate visit. A PET scanner is a
doughnut-shaped machine similar in appearance to a CT (computed tomography) scanner. PET
scans detect radioactivity used to provide information on brain activity. Before the test
begins, subjects are given a dose of carbidopa-a medicine that increases the amount of
levodopa in the brain. A catheter (thin, plastic tube) is then inserted into an arm or wrist
vein, and a radioactive form of levodopa called 18Fluorodopa is injected through the
catheter. A moldable plastic mask with large openings for eyes, nose, and mouth is placed on
the face to help keep the head still during scanning. The total scan time is 2 hours or
Objective: In the central nervous system, short-term plasticity can be defined as a change
in connection strength that is induced by receiving presynaptic inputs. Dopamine (DA), a
neuromodulatory neurotransmitter, is believed to play a role in short-term plasticity.
[18F]dopa positron emission tomography (PET) studies have shown progressive impairment of
presynaptic dopaminergic (DAergic) function in both healthy elderly subjects (HES) and
patients with Parkinson's disease (PD). Both PD and HES are characterized by a progressive
decline in performance on some motor tasks and changes in activity in brain areas involved
in motor control (including motor control by cognitive functions) as shown by functional
imaging studies. However, little is known about the exact neurobiological mechanisms linking
DAergic function, brain activity and motor (and cognitive) performances in PD and HES. In
the present study, we hypothesize that impaired performance on some motor tasks in those
subject groups is related to a dysfunction of task-specific functional connections between
areas participating in motor control. In addition, the brain activation with fMRI across
sessions and across subjects in the healthy group will be examined to investigate the
reliability of the fMRI techniques.
Study population: We will study two groups of participants: one group of patients with
mild-to-moderate PD and one group of healthy subjects.
Design: We will measure cerebral activity in baseline condition and during the execution of
sequential finger movements using perfusion functional magnetic resonance imaging (fMRI) in
the three subject groups. The reliability of fMRI data across sessions and across subjects
in the healthy young group and brain activity in patients with PD will be studied "off" and
then "on" medication.
Outcome measures: Imaging data will be compared in terms of both regional activity and
effective connectivity using the statistical parametric mapping (SPM) software.
These experiments should lead to better understanding the pathophysiology of the
mesencephalic DAergic system in human motor control and may lead to better treatment
strategies in PD.
- INCLUSION CRITERIA:
We will only include PD patients with a stable clinical response to L-DOPA and DAergic
We will only recruit patients with early or mild-to-moderate PD (score on Hoehn & Yahr
scale 148 less than 3).
To obtain a homogeneous group, the PD cohort will comprise only non-demented,
non-depressed, with parkinsonian symptoms and signs primarily akineto-rigid.
If resting tremor is present, only patients with mild or moderate tremor (UPDRS tremor
ratings 1 or 2 in the right upper limb) will be included in the study.
Our group of healthy volunteers will include the following age range: 21-30 years, 31-40
years, 41-50 years, 51-60 years, 61-70 years, and 70 years and over.
Research subjects may be male or female and they must be right-handed.
Pregnant women will not participate in the study.
Research subjects will be asked to refrain from caffeine and nicotine for at least 12
hours and to abstain from alcohol at least 24 hours before the fMRI.
Subjects belonging to one of the following groups will be excluded from the study:
Subjects with a familial history of PD.
Patients with a marked resting tremor (score at the UPDRS scale above 3 in the right upper
Patients with a score at Hoehn & Yahr scale equal or above 3.
Patients with progressive neurological disorders other than PD.
Subjects with cognitive impairment (i.e., score on Mattis scale below 123/144).
Subjects with significant mood disturbances (i.e., score on BDI scale above 10).
Subjects with abnormal MRI findings at visual inspection (prominent normal variants such
as mega cisterna or cavum septum pellucidum, signs of severe cortical or subcortical
atrophy, brain tumors, vascular diseases, trauma or AVMs).
Subjects with a history of significant medical disorders, or requiring chronic treatment
with other drugs that cannot be stopped.
Subjects with prior exposure to neuroleptic agents or drug use.
Subjects with significant past and present history of hypertension, cardiovascular disease
and diabetes mellitus.
Subjects with severe orthopedic or rheumatologic pathology of the right upper limb.
Subjects with past or present neuropsychiatric illness, head trauma with loss of
consciousness, epilepsy, cerebro-vascular disease, past and present history of alcohol or
substance abuse, including cigarettes, medical conditions that may alter cerebral
Subjects with cancer.
Subjects who have pacemakers, aneurysm clips (metal clips on the wall of a large artery),
metallic prostheses (including heart valves and cochlear implants) or shrapnel fragments.
Subjects incapable of giving an informed consent.
Subjects with a positive pregnancy test.
Subjects with pre-existing eyes condition.
Subjects who are unable to tolerate being off of antiparkinsonian medications for 12
Children will be excluded from the study because PD is infrequent before age 30.