Screening: Screening will include demographics, medical and psychiatric histories and a clinical interview to determine psychiatric diagnosis. Screening will also include a physical examination and laboratory assessments (CBC, electrolytes, kidney function, liver function, TSH) to rule out concurrent medical illness that could be a contraindication to amantadine treatment. Blood will also be drawn for fasting lipid profile, glucose, insulin, C reactive protein, adiponectin, and leptin. Subjects will also have the option of allowing us to draw 2 additional tubes for as yet to be determined studies, not to include HIV or genetic testing. Subjects will also have the option of allowing us to draw 1 additional tube for platelet-specific protein assay, termed SEPT5. The rationale for measuring SEPT5 levels is to test a hypothesis that individuals with clinically-defined mental disorders have altered levels of this protein in their circulating blood platelets. A urine drug screen will be performed.