Imaging of Brain Receptors in Healthy Volunteers and in Patients With Schizophrenia
Status:
Completed
Trial end date:
2004-08-01
Target enrollment:
Participant gender:
Summary
This study will use single photon emission computed tomography (SPECT) to study brain
nicotine receptors (proteins on the surface of brain cells) in healthy subjects and in
patients with schizophrenia. Autopsy findings in patients with schizophrenia show changes in
their nicotine receptors. This study will use SPECT to look at these receptors in living
schizophrenia patients and compare them with those in healthy subjects.
The following individuals between 21 and 50 years of age (or between 21 and 80 years of age
for Group 1 only) are eligible for this study: healthy non-smokers (Group 1); schizophrenia
patients who smoke (Group 2); schizophrenia patients who do not smoke (Group 3); healthy
smokers (Group 4); healthy non-smokers (Group 5). Patients with schizophrenia must be taking
olanzapine (Zyprexa) or risperidone (Risperdal) for at least 6 months. All candidates will be
screened at the first visit. Group 1 participants will have three more visits; Groups 2
through 5 will have two more visits.
Visit 1
All participants will be screened with physical and neurological examinations; blood and
urine tests; and neuropsychological tests to assess their ability to learn and remember words
and numbers, to pay attention, and to quickly perform motor tasks, such as putting pegs into
a piece of wood. In addition, they will have an eye movement test and event-related potential
testing. For the eye test, the subject sits in a chair and leans forward with the chin on a
chin rest. A band is tied around the head and very small amounts of invisible (infrared)
light are shined into the eyes. The light is reflected back and measured. Wire electrodes are
placed around the area of the eye and cheek to monitor eye blinks and eye movements. Subjects
are asked to follow a light with their eyes and to look away from a light. For event- related
potential testing, electrodes are placed on the scalp, forehead and cheeks, and brain
activity is recorded while the subject identifies particular pictures and sounds.
Visit 2 (and Visit 3 for Group 1)
Participants will have a SPECT scan. On the night before the scan, the day of the scan, and
for 4 days after the scan, subject take an oral dose of potassium iodide to protect the
thyroid gland from the radioactive tracer used in the SPECT procedure. (Individuals allergic
to potassium iodide will take potassium perchlorate instead.) For the SPECT scan, small
radioactive markers containing 99mTc are glued to the subject's head. Two catheters (thin,
flexible tubes) are placed in veins in the arms to inject the radioactive tracer
[123I]5-I-A-85380 and to draw blood samples. During the scan, the subject lies on a bed with
his or her head held still with a headholder. The scans are taken over a 9-hour period after
injection of the tracer injection. An electrocardiogram, respiration, and blood pressure
measures are taken before injection of [123I]5-I-A-85380, then 5 minutes after the injection,
and again 30 to 60 minutes after the injection. Breath samples are collected every 60
minutes. Blood and urine samples are collected 5 to 6 hours after starting the scan. Group 1
subjects will have a second SPECT scan within 4 weeks of the first.
Visit 3 (Visit 4 for Group 1)
Participants will have a magnetic resonance imaging (MRI) scan. For this procedure, the
subject lies on a table that slides into a narrow metal cylinder with a strong magnetic field
for the scan. The scanner uses a magnetic field and radio waves to produce images that show
structural and chemical changes in tissues. The test lasts up to 1 hour.