M1 Schizophrenia PET Study

Converging lines of evidence from postmortem studies provide strong evidence that brain muscarinic M1 receptor deficit is present in a subset of schizophrenia (SZ) patients. M1 receptors are an important target for cognitive deficits in SZ. However, until now, it has not been possible to examine the heterogeneity of SZ with respect to M1 receptor availability in vivo. The development of a novel positron emission tomography (PET) ligand, [11C]EMO, at Yale PET Center provides a unique opportunity to, for the first time, examine in vivo brain muscarinic M1 receptor availability in SZ and, concurrently, elucidate the relationship of M1 receptors to cognitive deficits in SZ.

The investigators will compare M1 receptor availability in SZ patients and age-, gender-matched healthy controls using [11C]EMO and the High Resolution Research Tomograph (HRRT), a PET scanner with high sensitivity and resolution available for human brain imaging. This study will explore the relationship between: hippocampal [11C]EMO binding (as a measure of hippocampal M1 AChR availability), encoding-related γ power during a verbal memory task, verbal memory, gender, and serum acetylcholine level. This exploratory study will provide the necessary pilot data to conduct a larger study to fully investigate the heterogeneity of SZ with respect to M1 receptor availability.

Inclusion Criteria:

• Men and women aged 18- 55 years that are physically and mentally healthy with the exception of DSM-5 schizophrenia or schizoaffective disorder diagnosis
• Subjects with no metal in the body that may pose a risk during MRI scanning
• No significant medical history, including head trauma and bleeding disorders

Exclusion Criteria:

• Men and women with a history or presence of clinically significant medical conditions
• Smokers who are unable to abstain from cigarette use for 5 days
• People who suffer from claustrophobia, have MRI incompatible implants, or other contraindications for MRI and PET scans