Effects of N-acetylcysteine on Brain Chemistry and Behavior in Cocaine Abusers (NAC)
Condition: Cocaine Abuse or Dependence; Cocaine Related Disorders
MeSH terms: Cocaine-Related Disorders
Study type: Observational

Summary: 
      N-acetylcysteine (NAC) is a medication that the Food and Drug Administration (FDA) has
      approved for several medical uses, such as dissolving mucus in patients with breathing
      problems, treating overdose from acetaminophen (Tylenol), and protecting the kidneys from
      toxic substances.

      Some recent studies suggest that NAC could be useful in the treatment of other disorders
      including addictions. One purpose of this study is to determine whether NAC alters the level
      of brain glutamate (a chemical that excites brain cells). The other main purpose is to
      determine whether NAC affects how much cocaine people use.
    

Detailed description: 
      Inpatient Phase: Participants will live on an inpatient research unit at least 2 consecutive
      nights and possibly up to 20 consecutive nights. Participants cannot have visitors and will
      not be allowed to leave the inpatient unit (except with a staff escort) unless they drop out
      of the study. We will collect daily urine samples to make sure participants are not using any
      drugs except those in the study. In addition, each morning, afternoon and evening
      participants will receive a capsule containing placebo (a blank) or different doses of
      N-acetylcysteine.

      Participants will take part in multiple trials (up to 9 sessions) where they will be given a
      standard amount of powder (identified as Drug A or Drug B) to inhale through a straw into
      their nose. The powder will contain placebo (a powder containing no drug) or different doses
      of cocaine. We will measure how participants are feeling using questionnaires and we will
      record vital signs-including breathing rate, blood oxygen level, heart rate, and blood
      pressure.

      Participants will also be asked to perform a 3-hour computer task that allows them to work
      for Drug A, Drug B, or money. At the end of the computer task participants will receive the
      amount of drug they earned and a receipt for the amount of money they earned.

      On each Monday of the inpatient stay, participants will be escorted to Harper Hospital for a
      special type of magnetic resonance imaging (MRI) scan, known as magnetic resonance
      spectroscopy (MRS). This is a non-invasive way to study brain chemistry. Participants will
      take part in a total of two (2) MRI scans. The total length of each brain scan will be about
      2 hours.

      Additionally on each Monday of the inpatient stay we will test the sensitivity of the
      participants brain to magnetic stimulation. A small magnet will be placed on top of the head
      so that a small electrical current is generated inside the brain. This procedure is called
      transcranial magnetic stimulation (TMS). We will stimulate the part of the brain that
      controls finger movement. Three recording electrodes (metal sensors like those used for EKG)
      will be placed on the right thumb and index fingers. We will measure the effects of different
      amounts of magnetic stimulation on the muscle activity of the thumb and index fingers (as
      seen on a computer screen). We will also ask participants to push a lever with their finger
      during parts of the procedure. These tasks will last about 2 hours.

      To complete the study, a minimum stay of 16 inpatient nights is required. The maximum stay is
      20 inpatient nights.
    

Observational model: Case-Only
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Cocaine abusing or dependent research volunteers
      
Keywords: Contingency Management; Drug Self-Administration