Risky Decision Making in Methamphetamine Users: The Role of Opioid Blockade

Not Applicable

Completed

• Conditions: Methamphetamine Abuse; HIV
• Interventions: Drug: Placebo; Drug: Extended release naltrexone

• Registration Number: NCT01822132
• Lead Sponsor: Oregon Health and Science University

Brief Summary

The purpose of this protocol is to learn more about impulsive decision making in people who use methamphetamines. The investigators would like to know if a medication called naltrexone changes how people make decisions. The investigators would also like to know whether changes in decision making can be observed by MRI (magnetic resonance imaging).

The research is conducted in Portland, OR.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2013-03-21
• Study First Submitted QC: 2013-03-27
• Study First Posted: 2013-04-02
• Study Start: 2013-05
• Primary Completion: 2015-03
• Study Completion: 2015-03
• Results First Submitted: 2017-09-20
• Results First Submitted QC: 2019-01-16
• Status Verified: 2019-02
• Results First Posted: 2019-02-06
• Last Update Submitted: 2019-02-12
• Last Update Posted: 2019-03-05

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 76

Inclusion Criteria

• Diagnostic and Statistical Manual (DSM)-IV Methamphetamine Dependence
• Deemed healthy enough to participate by study physician
• Age 18-55
• Right handed
• English-speaking

Summary

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Exclusion Criteria

• Current opioid use in the last 30 days; opioid abuse or dependence within past 5 years
• Pregnancy
• MRI contraindications (e.g. metal in head).

The research is conducted in Portland, OR.

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Placebo	Placebo	One dose of intramuscular injection of placebo.
Extended release naltrexone	Extended release naltrexone	One dose of intramuscular injection of 380mg extended-release naltrexone.

Primary Outcome Measures

Name	Time	Method
Discounting Tasks: Sexual Probability Discounting (SexPD)	28 days post drug intervention	In the SexPD task, subjects are asked to choose between having sex with a more appealing partner with a varying chance of having a sexually transmitted infection (STI) or a less appealing partner with no STI.; A hyperbolic decay model was used to calculate h, a free parameter that indexes the rate of probabilistic discounting. Smaller h values indicate a preference for probabilistic (i.e., riskier) outcomes. To normalize the data, the natural log of h values were calculated and reported here.
Discounting Tasks: Standard Delay Discounting (DD)	28 days post drug intervention	Monetary delay discounting task consisted of choosing between a larger, delayed and a smaller, immediate reward. A hyperbolic decay model was used to calculate k, a free parameter that indexes the rate of delay discounting. As k values are typically skewed across subjects, the distribution of k was normalized by using a natural log transformation. The normalized values are reported here. If k typically ranges between 0.5 and 10\^-5, then the natural log of k will range between -0.69 and -11.5. Larger normalized k values indicate a preference for smaller sooner outcomes (i.e., more impulsive decision-making).
Barrat Impulsiveness Scale (BIS)	28 days post drug intervention	The Barrat Impulsiveness Scale (BIS) is a 30 item questionnaire to measure a persons impulsiveness. Items are answered on a 4-point scale and scored 1-4 then summed across responses. Total scores range from 30-120 with a higher summed score indicating higher impulsivity.
Risk Assessment Battery (RAB)	28 days post drug intervention	The Risk Assessment Battery (RAB) is a 26 question self-administered assessment focusing on drug use, injection and sexual risk during the past 30 days.; Three composite HIV risk scores (drug, sex, and total score) are calculated. The questions have different numbers of items, and scores for a single question can range from 0 to 7, with higher values reflecting more instances of risk behavior. The drug risk score has a range of 0 to 22 and is calculated from 8 questions that address recent substance use, including frequency, needle sharing, and cleaning of the "works." 9 questions are used to calculate a sex risk score that has a range of 0 to 18, and these questions address the frequency and types of sexual behavior, HIV status of sexual partners, and type of protection that was used (if any). Total score is calculated by adding drug and sex scores and dividing by 40, the maximum score possible, and ranges from 0 to 40 where higher scores indicate greater risk behavior.

Secondary Outcome Measures

Name	Time	Method
Methamphetamine Use	28 days post drug intervention	Participants were asked "How many days in the past 30 days did you use methamphetamine?". This is a self-report measure.

Trial Locations

Locations (2)

Oregon Health & Science University; 🇺🇸 Portland, Oregon, United States

Portland VA Medical Center; 🇺🇸 Portland, Oregon, United States