Project 8F: Methamphetamine Use, Delay Discounting, Opioid Maintenance Treatment

Methamphetamine use and delay discounting among individuals in opioid maintenance treatment

Dennis McCarty, Ph.D., Principal Investigator

Oregon reports the nation's highest per capita rate of treatment admissions for methamphetamine use: 314 per 100,000 persons aged 12 years and older. Individuals admitted to a methadone maintenance program in Portland have relatively high rates of methamphetamine-positive urine tests at admission. Thus, there are opportunities to examine methamphetamine use during maintenance treatment for opiate dependence.

The Clinical Trial Network is conducting a randomized trial comparing six months of buprenorphine with six months of methadone among opiate-dependent individuals. Participants in the trial frequently use methamphetamine, amphetamine, and cocaine.

A retrospective review of 120 clinical charts will assess influence of the study medications on continued use of stimulants. Qualitative interviews with a small sample of study participants (n = 20) will provide detail on the subjective response to the study medications and perceived influences on stimulant use and impulsive behavior.

To explore linkages with impulsivity, 64 methadone patients will be recruited to complete a delay-discounting task within three weeks of admission and again 12 weeks later. Variations in impulsivity may be associated with differential use of stimulants and with greater risks for relapse and continued use.

The pilot study has two specific aims: 1) review clinical charts and conduct qualitative interviews with patients to assess patterns of methamphetamine and cocaine use and compare the influence of buprenorphine and methadone on use of stimulants, and 2) assess delay discounting among 64 methadone patients (half positive for stimulant use at admission) at admission and 12 weeks post-initial-test to examine the association of impulsivity on relapse and continued use of methamphetamine and other stimulants.