Clinical Neurobiology of Serotonin and Addiction

Inclusion Criteria: * Non-Drug Abusing Control Subjects: Male and female subjects age 18 to 55 who do not meet current or past DSM-IV criteria for any Axis I disorder including substance abuse or dependence. * Cocaine Dependent Subjects: Male and female subjects age 18 to 55 who meet current DSM-IV criteria for cocaine dependence. * Female subjects: a negative pregnancy test. Exclusion Criteria: * Non-Drug Abusing Control Subjects: 1. Current or past DSM-IV Axis I disorder 2. Any serious non-psychiatric medical illness requiring ongoing medical treatment or which could affect the central nervous system. 3. Positive HIV test. 4. For female subjects: a positive pregnancy test or breast feeding. 5. Concomitant use of prescription medications that could affect the central nervous system. 6. Active suicidal ideation. 7. Hamilton Depression or Anxiety Scale score greater than 15 * Cocaine Dependent Subjects: 1. Current DSM-IV Axis I disorder other than substance abuse/dependence 2. Current diagnosis of other substance dependence besides cocaine. 3. Any serious non-psychiatric medical illness requiring ongoing medical treatment or which could affect the central nervous system. 4. Positive HIV test. 5. For female subjects: a positive pregnancy test or breast feeding. 6. Concomitant use of prescription medications that could affect the central nervous system. 7. Active suicidal ideation. 8. Subjects within 14 days of discontinuing a monoamine oxidase inhibitor. 9. Subjects with cardiac arrythmias. 10. Subjects with known hypersensitivity to escitalopram or citalopram, or mirtazapine 11. Hamilton Depression or Anxiety Scale score greater than 15. 12. Current alcohol abuse or dependence.