Effects of methadone plus alcohol on cognitive performance in methadone-maintained volunteers

Abstract

Background: Methadone maintenance patients (MMP) often abuse other drugs, including alcohol. The combined use of methadone and alcohol could impair performance and daily functioning. Objective: To examine the effects of methadone in combination with alcohol, as well as acute increases in methadone, on performance outcomes. Methods: This double-blind, double-dummy, crossover study included eight opioid-dependent participants stabilized on methadone. Participants completed six inpatient sessions corresponding to methadone (100% or 150% of daily dose) and beverage (placebo, 0.25 or 0.50 g/kg alcohol). Performance tasks were completed before and after drug administration. Area under the time-course values were analyzed by a 2 (methadone dose) by 3 (alcohol dose) repeated measures analysis of variance. Results: Main effects of methadone were observed for two attention outcomes, suggesting reduced accuracy and slowed responding at an elevated methadone dose. In addition, main effects of alcohol were observed for episodic memory (false alarms and response bias) suggesting more impulsive responding as alcohol dose increased. No robust interactions of methadone and alcohol were observed for any outcome. Conclusions: Study findings indicate that an acute increase in methadone (150%) and a moderate dose of alcohol (2–3 drinks) can impair distinct aspects of performance, although no significant interactive effect between methadone and alcohol was found. Future studies with larger sample sizes, larger doses, and more clinically informative tasks could expand on the present findings and further explore the cognitive consequences of concurrent opioid and alcohol use.

• Alcohol
• attention
• cognition
• methadone
• performance

Acknowledgements

We thank Julie Garson, Maggie Klinedinst, Erica Smearman, Crystal Barnhouser, and the BPRU nursing staff for protocol management and technical assistance, John Yingling for computer programming assistance and technical support, and Paul Nuzzo for assistance with the data analysis. Portions of these data were presented as an oral presentation at the 2010 annual meeting of the College on Problems of Drug Dependence, and as an invited oral presentation during the Division 28 Presidential Address and a Division 28 poster presentation at the 2010 annual meeting of the American Psychological Association.

Funding

This project was supported by National Institute on Drug Abuse Research Grants R01 DA17688, K24 DA023186, and T32 DA07209. The funding source had no other role than financial support.

Authors’ contributions

All authors contributed in a significant way to the manuscript and have read and approved the final manuscript. Drs. Mintzer, Bigelow, and Strain designed the study. Dr. Vandrey and Dr. Mintzer wrote the protocol. Dr. Kleykamp and Dr. Mintzer managed the final data analysis, literature searches, and summaries of previous related work. Dr. Kleykamp wrote the first draft of the manuscript. All authors contributed to editing the manuscript. Dr. Bethea Kleykamp completed the data collection associated with this publication while a Postdoctoral Fellow at the Behavioral Pharmacology Research Unit and she is now a Scientist at PinneyAssociates.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this paper.