A D2 Receptor Occupancy and fMRI Study in Schizophrenic Subjects Treated With Lurasidone

The purpose of this research study is to measure how many of the dopamine receptors lurasidone occupies throughout the brain of patients with schizophrenia or schizoaffective disorder and over what time period the occupancy occurs. This is research because lurasidone is an investigational medication that has not yet been approved by the Food and Drug Administration (FDA). Dopamine receptors have key roles in many processes, including the control of motivation, learning, and fine motor movement. The degree of occupancy and the transience of occupancy D2 receptor occupancy for optimal clinical response and to prevent relapses is a controversial area that this study will address. In this study Positron Emission Tomography (PET) scanning will be performed with D2/D3 ligand 18F-fallypride (a radioactive, injectable substance) to help the researchers measure the use of these receptors. Researchers hope that quantifying the amount of receptors being occupied by the medication will help them to determine the best dose of study medication in terms of improvement and least side effects related to body size and gender as well as in preventing relapse that may be related to hypersensitivity. Magnetic Resonance Imaging (fMRI) will also be performed. MRI is a scanning method which makes pictures of parts of the brain using a large magnetic field. This study will use a particular kind of MRI called fMRI, or functional MRI. fMRI takes pictures of the brain while the person is thinking or doing a simple task. fMRI will allow the researchers to investigate patients regional brain activation during cognitive (mental) and emotional tasks.