Working Memory Training Improves Alcohol Users' Episodic Future Thinking: A Rate-Dependent Analysis

Abstract

Background: Episodic thinking, whether past or future, uses similar neural machinery, and individuals with alcohol dependence have clear challenges with both. Moreover, alcohol-dependent individuals' narrowed temporal window likely gives rise to greater valuation of immediate rewards. We aimed to strengthen working memory (WM) in alcohol-dependent individuals and measure performance on near-transfer (novel WM) and far-transfer delay discounting (DD) tasks, including episodic future thinking (EFT) performance. Importantly, heterogeneous intervention responses could obscure a treatment effect due to individuals' baseline differences. Therefore, we considered WM, DD, and EFT DD scores using rate-dependent analyses.

Methods: A total of 50 alcohol-dependent individuals received either 20 active (Trained) or sham (Control) WM training sessions using the Cogmed adaptive WM training program. Participants completed a near-transfer novel WM task and far-transfer DD and EFT DD tasks before and after training.

Results: Active WM training improved performance on the near-transfer task. As determined by Oldham's correlation [rmean(x,y),y-x], initially low near-transfer task scores improved more than initially high scores (i.e., rate dependence) in the Trained group only. Moreover, Trained group individuals with the highest rates of EFT DD at baseline rate-dependently decreased following training, whereas WM training had no effect on DD alone.

Conclusions: These data support the notion that WM training improves near-transfer task performance and may enhance the effects of EFT DD in a subset of alcohol-dependent individuals trapped within the narrowest temporal window. Rate-dependent changes highlight that we should attend to baseline performance to better identify individuals who would most benefit from an intervention.

Keywords: Alcohol; Delay discounting; Episodic future thinking; Near-transfer; Rate dependence; Working memory training.

Copyright © 2017 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

Consolidated Standards of Reporting Trials (CONSORT) chart represents the flow of participant allocation and completion, including the number of participants and reasons for non-completion. Delay Discounting is abbreviated “DD” within the chart.

Figure 2

Working memory training effects on near-transfer task performance. Panel A: Proportion of change in near-transfer task scores from baseline between Trained and Control groups. Horizon lines indicate group means ±SEM. Panel B: Depicts the traditional method for representing proportion of change from baseline plotted as a function of baseline near-transfer task scores. Note: the presence of rate dependence was determined using Oldham’s correlation (see text). *p

Figure 3

Working memory training effects on Episodic Future Thinking (EFT) delay discounting. Panel A: Change in EFT delay discounting from baseline EFT delay discounting between the Trained and Control groups. Horizon lines indicate group means ±SEM. Panel B: Depicts the traditional method for representing change from baseline plotted as a function of baseline EFT delay discounting lnk. Note: the presence of rate dependence was determined using Oldham’s correlation. *p<0.05.