Clinical Neurobiology of Serotonin and Addiction

Study Overview
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Brief Summary
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The purpose of this study is to examine the relationship between 5-HT2R function, impulsivity and cue reactivity in cocaine dependent subjects and healthy controls and examine specific effects of escitalopram and mirtazapine on impulsivity and cue reactivity in human cocaine users.

Detailed Description
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Specific Aim 1: We will test the hypothesis that cocaine-dependent subjects will exhibit greater impulsivity than controls as determined by a battery of impulsivity measures and that impulsivity will be associated with specific profiles of 5-HT2AR and/or 5-HT2CR expression in platelets. We predict that treatment of cocaine-dependent subjects with escitalopram and/or mirtazapine will reduce impulsivity and cocaine-positive urines, in concert with a normalized balance of platelet 5-HT2AR and/or 5-HT2CR expression. Specific Aim 2: We will test the hypothesis that cocaine-dependent subjects will exhibit greater cue reactivity than controls as determined by a modified Stroop task, and that cue reactivity will be associated with specific profiles of 5-HT2AR and/or 5-HT2CR expression in platelets. We predict that treatment of cocaine-dependent subjects with escitalopram and/or mirtazapine will reduce cue reactivity and cocaine-positive urines, in concert with a normalized balance of platelet 5-HT2AR and/or 5-HT2CR expression. Specific Aim 3: We will test the hypothesis that specific polymorphisms in the 5-HT2AR and/or 5-HT2CR will predict baseline impulsivity and/or cue reactivity as well as treatment response to serotonergic medications in cocaine-dependent subjects.

Official Title
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Project 1: Clinical Neurobiology of Serotonin and Addiction

Conditions
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Cocaine Dependence

Intervention / Treatment
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* Drug: Escitalopram
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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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: Current or past DSM-IV Axis I disorder Any serious non-psychiatric medical illness requiring ongoing medical treatment or which could affect the central nervous system. Positive HIV test. For female subjects: a positive pregnancy test or breast feeding. Concomitant use of prescription medications that could affect the central nervous system. Active suicidal ideation. Hamilton Depression or Anxiety Scale score greater than 15 Cocaine Dependent Subjects: Current DSM-IV Axis I disorder other than substance abuse/dependence Current diagnosis of other substance dependence besides cocaine. Any serious non-psychiatric medical illness requiring ongoing medical treatment or which could affect the central nervous system. Positive HIV test. For female subjects: a positive pregnancy test or breast feeding. Concomitant use of prescription medications that could affect the central nervous system. Active suicidal ideation. Subjects within 14 days of discontinuing a monoamine oxidase inhibitor. Subjects with cardiac arrythmias. Subjects with known hypersensitivity to escitalopram or citalopram, or mirtazapine Hamilton Depression or Anxiety Scale score greater than 15. Current alcohol abuse or dependence.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 55 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: A (escitalopram)<br>Escitalopram | Drug: Escitalopram<br>* Escitalopram: once daily 10 mg on days 1-3, 20 mg on days 4-24 and 10 mg on days 25-28<br>* Other names: Lexapro;|
| Experimental: B (placebo)<br>Placebo | Drug: Placebo<br>* Once daily days 1-28<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Immediate Memory Task | The IMT was used to measure impulsivity. The IMT is a continuous performance test. Subjects were instructed to respond on the computer's left mouse button when a five-digit number the target stimulus appeared that was exactly like the preceding stimulus. A catch stimulus was a number that differed only slightly from the preceding number. Only one of the five digits was changed its position and value was determined randomly. Responses errors made to catch stimuli were considered commission errors or 'false alarms'. Immediate Memory Task Commission Errors to catch stimuli were the primary measure of impulsivity in this study. Scale is percentage of overall responses to a catch stimulus that were commission errors, ranging from 0 to 100. Zero would equate to no impulsivity and 100 would equate to 100% impulsive responses. | after acute dose and after chronic administration | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Attentional Bias as Measured by the Cocaine Stroop Task. | Attentional bias is the difference in reaction time to cocaine related words and neutral words. A slower reaction time indicates greater attentional bias. | 5 weeks of treatment | 
| Cocaine Positive Urines | Number of urine drug screens positive for cocaine metabolite benzoylecgonine. | 5 weeks of treatment | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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substance abuse, cocaine, impulsivity, serotonin, Remeron, Mirtzapine, Lexapro, Escatilopram