Clinical Study Of Schizophrenia in Both Men and Women

Inclusion criteria: * If female, must not be pregnant, or must be incapable of conceiving or be taking steps to prevent conception. * Diagnosis of Schizophrenia * Patients must be taking clozapine monotherapy or other atypical antipsychotic at least 3 months prior to this study. Exclusion criteria: * Patients who are currently taking or have taken antidepressant medication in the last month prior. * Patients who are or have been suicidal or homicidal in the last 6 months. * Patients with a history of autistic disorder or another pervasive developmental disorder * Patients whose condition is due to the direct physiological effects of a substance (e.g. a drug of abuse, a medication) or a general medical condition