This study will investigate how the brain generates tics in patients with Tourette's
syndrome and which areas of the brain are primarily affected. Tourette's syndrome is a
neuropsychiatric disorder characterized by motor and vocal tics, and is associated with
behavioral and emotional disturbances, including symptoms of attention deficit hyperactivity
disorder and obsessive-compulsive disorder. This study will examine whether tic generation
is related to changes in brain cell receptors for a chemical messenger called
gamma-aminobutyric acid (GABA).
Healthy normal volunteers and patients with Tourette's syndrome between 21 and 65 years of
age may be eligible for this study. Candidates will be screened with a medical history and
physical and neurological examinations.
Participants will undergo positron emission tomography (PET) scanning to measure brain blood
flow. For this procedure, the subject receives an injection of H215O, a radioactive
substance similar to water. A special camera detects the radiation emitted by the H215O,
allowing measurement of the blood flow. Subjects will receive up to five injections of H215O
during the scanning. They will also be injected with another radioactive chemical, (11C)
flumazenil, which binds to GABA receptors, to measure the density and distribution of these
receptors. This will reveal which areas of the brain in patients with Tourette's syndrome
have abnormal binding of flumazenil compared with the brains of healthy control subjects.
During the PET procedure, the subject lies on a table in the PET scanner. A small catheter
(plastic tube) is placed in an arm vein for injecting the radioactive tracers, and a mask is
placed on the face to help keep the head still during scanning. The mask has large openings
for eyes, nose and mouth, so that it does not interfere with talking or breathing. The
entire test takes about 3 hours.
On a separate day, participants will also undergo magnetic resonance imaging (MRI), a
diagnostic test that uses a magnetic field and radio waves to produce images of the brain.
For this procedure, the subject lies still on a stretcher that is moved into the scanner (a
narrow cylinder containing the magnet). Earplugs are worn to muffle loud noises caused by
electrical switching of radio frequency circuits used in the scanning process. The scan
lasts about 45 to 60 minutes.
The purpose of this study is to determine if symptoms of Tourette's syndrome are due to
dysfunction of GABA-ergic neurons causing disinhibition originating in basal ganglia, and
involving thalamus, frontal and prefrontal cortices and contributing to tic generation.
The major inhibitory neurotransmitter in central nervous system is gamma-aminobutyric acid
(GABA), which acts mainly through the GABA A receptors. Pathological processes involving
GABA-ergic neurons cause alterations in the density of GABA A receptors of the targeted
neurons. These changes can be visualized and measured with Positron Emission Tomography
using as a radioactive ligand [11C] flumazenil. We will examine changes in the density and
distribution of GABA A receptors in 17 adult patients with a DSM-IV-TR (American Psychiatric
Association 2000) diagnosis of a tic disorder and 17 control subjects. This study should
provide new information concerning localization and degree of dysfunction of GABA-ergic
neurons in areas involved in Tourette's syndrome, which, in turn, might open new
possibilities in pharmacological treatment of this disorder.
- INCLUSION CRITERIA:
A. Patients will have clinically documented TS as defined by DSM-IV and evaluation of tics
severity using Yale Tic Scale. This criterion will be established by the preliminary
screening in the NINDS Movement Disorders Outpatient Clinic.
B. Patients (either male or female) will range in age from 18 to 65 years. Female patients
of child-bearing potential will have a pregnancy test prior to each PET and MRI scan and
specific interview prior to the study to ensure that pregnant patients will not
participate in the study. Patients will be asked to stop for two weeks prior to the exam
any medication that can influence the CNS. Fluoxetine will be stopped for four weeks. They
will be asked to abstain from alcohol for one week before the study.
C. Seventeen normal controls will be included; controls will be screened in the NINDS
Movement Disorders Outpatient Clinic, and will have neurological and physical
examinations. Controls with chronic illnesses, taking any medication that affects the CNS
will be excluded. They will be asked to abstain from alcohol for one week before the
A. Patients younger than 18 years old and older than 65 will be excluded from the study.
B. Patients with MRI findings consistent with brain tumors, strokes, trauma or AVMs will
C. Patients with progressive neurological disorders other than TS will be excluded.
D. Patients with a history of significant medical disorders, or requiring chronic
treatment with other drugs, which, cannot be stopped, will be excluded.
E. Patients with cancer will be excluded.
F. Patients incapable of giving an informed consent will be excluded.
G. Patients who are pregnant or nursing.