Caffeine and Cocaine

Experiment 1: Adenosine Receptor A2A Antagonists and Cocaine Dependence

This study is being done to find out if medicines that affect a neurotransmitter (chemical messenger) in the brain called adenosine improve behavioral problems that are related to drug abuse. Another purpose of the study is to find out how genes related to adenosine change how people respond to these medicines. More information about how these medicines change behaviors may be helpful to come up with new treatments for drug abuse.

Specific Aims:

Aim 1. To characterize the behavioral and subjective effects of acute caffeine administration in cocaine-dependent subjects, using laboratory measures of impulse control, drug discrimination (with d-amphetamine as the training dose), and subjective effects.

Hypotheses related to Aim 1:

1. Subjects will show decreases in impulsivity (delay to reward and response inhibition) after acute oral doses of caffeine compared to placebo.
2. Subjects will show some stimulant-like subjective effects following acute oral doses of caffeine, but not the euphoric effects that would predict abuse potential.

Inclusion Criteria:

• Subjects who currently meet DSM-IV criteria for cocaine dependence and healthy controls
• At least one cocaine positive urine during screening.
• Current regular consumption of caffeine.
• Female subjects: a negative pregnancy test.

Exclusion Criteria:

• Current or past DSM-IV Axis I disorder other than substance abuse/ dependence
• Any significant non-psychiatric medical illness requiring ongoing medical treatment or which would preclude treatment with d-amphetamine or caffeine
• Substance dependence other than cocaine within the last 3 months.
• Positive breath alcohol.
• Positive urine drug screen for drugs other than cocaine or THC at the time of behavioral testing
• For female subjects: known pregnancy or a positive pregnancy test or current breast feeding.
• Diagnosis of Adult Attention Deficit Disorder as determined by: a) meeting DSM-IV criteria for childhood ADHD, b) currently has impairing ADHD symptoms, c) ADHD symptoms can not have remitted at any period since childhood.
• HIV positive.
• I.Q. below 70.