Reward Processing in Cocaine Addiction
Condition: Drug Abuse; Cocaine Dependence
MeSH terms: Cocaine-Related Disorders; Substance-Related Disorders
Study type: Observational

Summary: 
      Background:

      - Cocaine affects the brain's ability to process information. However, different people
      respond to cocaine in different ways, and differences in brain structure and function may
      affect how cocaine alters brain activity. By using functional magnetic resonance imaging
      (fMRI) to monitor brain activity during tasks that provide simple rewards, researchers hope
      to better understand how the brain responds to rewards and how this response is affected by
      drugs like cocaine.

      Objectives:

        -  To determine the effect of cocaine administration on the reward experience in
           cocaine-dependent individuals.

        -  To study genetic and personality factors that may contribute to cocaine dependence.

      Eligibility:

      - Individuals between 18 and 45 years of age who either are cocaine-dependent and not seeking
      treatment or are healthy volunteers.

      Design:

        -  Participants will be asked to avoid consuming alcohol and restrict consumption of
           caffeine prior to the study. Participants provide urine and breath samples to be tested
           for chemicals that may interfere with the study.

        -  All participants will complete a training session and at least one fMRI scanning
           session. During the training session, participants will be introduced to the reward
           tasks and MRI equipment.

        -  Healthy volunteers will have a single fMRI session that will involve reward tasks to be
           completed during the scanning. Rewards will include small amounts of fruit juice and the
           opportunity to win money.

        -  Cocaine-dependent participants will have a training session and three experimental
           sessions including 1) a mock MRI scan to test cocaine tolerance, 2) one fMRI scan with
           reward tasks after administration of IV cocaine, and 3) one fMRI scan with reward tasks
           after administration of IV placebo (saline solution). Rewards will include small amounts
           of fruit juice and the opportunity to win money.

        -  In addition to the scans, participants will provide a blood sample for further study and
           will answer questionnaires provided by the researchers.
    

Detailed description: 
      Objective:

      The overall objective of this study is to determine the effect that cocaine administration
      has upon the experience of reward in dependent individuals and the contribution of reward
      processing (or dysfunction) to the reinforcing effects of cocaine and the recidivism rates
      noted in cocaine-dependent individuals. The primary goal is to employ functional magnetic
      resonance imaging (fMRI) to ascertain the function of neural systems that respond to cocaine
      in human participants and to determine the role that they play in the processing of different
      types of rewarding stimuli during episodes where individuals are drug-free and those where
      they are under the acute influence of cocaine.

      Study Population:

      The experimental population for this investigation will be non-treatment seeking,
      cocaine-dependent adults (i.e. 18 45 years old). A cohort of healthy, drug-free, individuals,
      matched for age, gender, ethnicity and IQ, will serve as a control group.

      Design:

      This experiment employs a mixed-measures, counter-balanced design. Participants will complete
      two measures of reward processing (i.e. the revised monetary incentive delay (MID) task and a
      temporal difference error task (TDE/juice) task) while undergoing BOLD EPI fMRI. The scanning
      procedure will be repeated for all subjects, such that each participant undertakes 2
      sessions. Cocaine-dependent individuals will receive either two injections of cocaine (30
      mg/70 kg body weight; intravenous (IV) administration) or two injections of saline during
      scanning. Within each session, each IV injection will be given approximately 10 minute prior
      to the start of one of the reward measures. The order of cocaine and saline scans will be
      randomized and participants will be blind to the experimental condition prior to
      participation.

      Outcome Measures:

      The primary outcome measures will be the neural substrates of reward processing and how these
      differ between cocaine-dependent individuals and controls, and the impact of acute cocaine
      administration upon brain function associated with reward function.
    

Keywords: Drug Abuse; Cocaine; Cocaine Dependence; Functional MRI; Pharmalogical MRI; Conditioning