Training and transfer effects of working memory training in male abstinent long-term heroin users

OBJECTIVE: Heroin abuse is associated with cognitive deficits. These might play a role in relapse after abstinence, which could be reduced by cognitive trainings. A previous study assessed effects of working memory (WM) training on executive functioning (EF) in heroin addicts undergoing methadone treatment, potentially limiting training effects. The present study assessed WM training effects in abstinent heroin addicts currently no longer receiving pharmacological treatment. METHOD: Inpatients were randomly assigned to a WM training or active control condition and performed EF tasks before and after training. RESULTS: Trained participants improved their performance on the trained task. Using the control group as reference, they showed short-lived beneficial near- but no far-transfer effects to non-trained cognitive tasks. Participants with a strong baseline WM showed stronger training but smaller transfer effects than participants with a weak baseline WM. CONCLUSION: The combined results suggest limited cognitive transfer effects of WM training in heroin addicts irrespective of current methadone treatment status. They also suggest individual differences in training and transfer benefits dependent on baseline EF.