Rebalancing the Serotonergic System in Cocaine Dependence

Inclusion Criteria:

- - Participants will be male and female volunteers between the ages of 18-55

- Participants will report having used cocaine on at least four occasions within the
month prior to screening; the urine sample obtained during the screening visit must be
positive for the cocaine metabolite benzoylecgonine (>300 ng/ml). They can meet DSM-IV
criteria for cocaine abuse and dependence.

- Participants cannot meet DSM-IV criteria for current psychotic disorders (e.g.,
bipolar disorder, schizophrenia, schizoaffective disorder)

- Participants cannot meet DSM-IV criteria for a current major depressive episode

- Participants cannot meet DSM-IV criteria for current drug dependence (except nicotine,
cocaine, and marihuana)

- Participants can report current dependence of alcohol

- Participants can report current abuse of marihuana, tobacco and alcohol but must test
negative for alcohol on the day of the scan. Participants cannot have used marihuana
within twelve hours of their study visits.

- Participants cannot be regular opiate users including prescription opiate analgesics

- Participants cannot have a history of major head trauma resulting in cognitive
impairment, seizure, or other neurological disorders.

- Participants cannot have any conditions that are contraindicated for MRI (see next
section)

- Participants cannot be pregnant (pregnancy test will be performed before each scanning
session)

- Participants must be able to read screening materials including consent form and give
informed consent

- Participants cannot be taking any medications with a 5-HT mechanism including
serotonin-norepinephrine reuptake inhibitors (SNRIs), selective serotonin reuptake
inhibitors (SSRIs), tricyclic antidepressants (TCAs), monoamine oxidase inhibitors
(MAOIs) and St. John's Wort and tryptophan.

- Participants cannot be currently taking any medications that might affect the central
nervous system including prescription analgesics, anxiolytics, antipsychotics, and
antidepressants. A complete review of medications will be evaluated by study staff.

- Cannot have any history of a medical condition that might affect the central nervous
system at the time of scanning including: Abnormal structural MRI, or a history of
head trauma or injury causing loss of consciousness lasting longer than 3 minutes or
associated with skull fracture or intracranial bleeding or who had irremovable
magnetically active objects on or within their body, or history of epilepsy.

Exclusion Criteria:

- - Weight greater than 350 pounds (cannot easily fit inside the magnet bore)

- Cardiac pacemakers

- Aneurysm clips and other vascular stents, filters, clips or other devices

- Prosthetic heart valves

- Other prostheses

- Neuro-stimulator devices

- Implanted infusion pumps

- Cochlear implants

- Ocular implants or known metal fragments in eyes

- Exposure to shrapnel or metal filings (sheet metal workers, welders, and others)

- Other metallic surgical hardware in vital areas

- History of major head trauma resulting in cognitive impairment

- Certain tattoos (e.g. older dye with metallic pigment)

- Certain medication patches (if they cannot be removed)

- Metal containing IUDs

- Claustrophobia

- Pregnancy

- Metallic implants except fillings and crowns

- Tattoos containing metallic ink on the neck, shoulders, upper arm, and head (these
could become heated during scanning, potentially causing burns

- Medication patches that cannot be removed during scanning

- Claustrophobia