PET Assay of Acetylcholine Beta2* Nicotinic Receptor Density in Smoking and Non-Smoking Schizophrenics

Background:

• Previous studies have suggested that smoking cigarettes affects the number of receptors in the brain for nicotine, a chemical present in cigarette smoke. The receptors play a role in an individual's ability to think and concentrate. Many people with schizophrenia and similar disorders smoke, and research suggests that smoking may temporarily improve concentration and focus in individuals with schizophrenia. Researchers are interested in studying both current smokers and nonsmokers with schizophrenia to determine whether smoking affects the number of nicotine receptors in the brains of people with schizophrenia.

Objectives:

• To study the distribution and volume of nicotine receptors in the brains of individuals with schizophrenia who are either nonsmokers or current smokers.

Eligibility:

• Individuals between 18 and 50 years of age who have been diagnosed with schizophrenia and are either nonsmokers or current smokers (at least 10 cigarettes per day for the past year).
• Current smokers must be able to give up smoking for 48 hours.

Design:

• This study involves an initial screening visit and up to five study visits.
• After the screening visit, participants will have two sessions in which they will complete questionnaires about thoughts, memory, and smoking habits. Smokers will also have nicotine blood and carbon monoxide breath levels taken during these sessions, before and after smoking a cigarette.
• Participants will have sessions with imaging studies (e.g., magnetic resonance imaging) to provide baseline measurements for later tests, and will also have tests to measure brain electrical activity.
• Participants will have a positron emission tomography (PET) scanning session to examine the nicotine receptors in the brain. Participants will need to stay overnight (nonsmokers) or for 2 nights (smokers) as an inpatient before the session. The PET scan session will take up to 6 hours, although participants will only be in the scanner for up to 3 hours.
• Participants will have a follow-up phone call with study researchers 1 week after the PET scanning session.