A randomized controlled trial of the effects of working memory training in methadone maintenance patients

Abstract

Objective: Working memory impairment in individuals with chronic opioid dependence can play a major role in cognitive and treatment outcomes. Cognitive training targeting working memory shows promise for improved function in substance use disorders. To date, cognitive training has not been incorporated as an adjunctive treatment for opioid dependence.

Methods: Methadone maintenance patients were randomly assigned to experimental (n=28) or active control (n=28) 25-session computerized training and run in parallel. Cognitive and drug use outcomes were assessed before and after training.

Results: Participants in the experimental condition showed performance improvements on two of four working memory measures, and both groups improved on a third measure of working memory performance. Less frequent drug use was found in the experimental group than in the control group post-training. In contrast to previous findings with stimulant users, no significant effect of working memory training on delay discounting was found using either hypothetical or real rewards. There were no group differences on working memory outcome measures that were dissimilar from the training tasks, suggesting that another mechanism (e.g., increased distress tolerance) may have driven drug use results.

Conclusions: Working memory training improves performance on some measures of working memory in methadone maintenance patients, and may impact drug use outcomes. Working memory training shows promise in patients with substance use disorders; however, further research is needed to understand the mechanisms through which performance is improved and drug use outcomes are impacted.

Trial registration: ClinicalTrials.gov NCT01271413.

Keywords: Cognitive impairment; Delay discounting; Memory training; Methadone maintenance; Working memory.

Conflict of interest statement

Conflict of interest

The authors have no conflicts of interest relevant to the present work to disclose.

Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Figures

Fig. 1

CONSORT flow diagram. Experimental group participants who did not complete the study attended an average of 9.3 sessions (SD = 6.1, range = 3–19). Control group participants who did not complete the study attended an average of 9.1 sessions (SD = 5.5, range = 0–15).

Fig. 2

Visuo-spatial working memory performance as a function of group for pre-training assessment and post-training assessment. Data represent fitted (model-based) means ±1 standard error of the mean. Analysis showed a group × session interaction and a main effect of condition (ps < .05).

Fig. 3

GEE model of the percent of positive urine rates across visits for any drug (left) and THC (right) for Experimental and Control groups.