A long‐term fatty fish intervention improved executive function in inpatients with antisocial traits and a history of alcohol and drug abuse

The aim of the present study was to investigate the effects of fatty fish consumption on cognitive functioning in a group of inpatients characterized by antisocial behavior. Eighty‐three male forensic inpatients participated in this study. Participants were randomly assigned into a Fish or a Control group (e.g., meat, chicken, pork). One decision‐making task, the Iowa Gambling Task (IGT), and one planning task, the Tower of Hanoi (ToH), were administered before (pre‐test) and at the end of the intervention period (post‐test). For the IGT the Fish group showed improved performance from pre‐ to post‐ test. Moreover, the Fish group showed significantly better performance than the Control group on the IGT at post‐test. The Fish group also demonstrated improved performance from pre‐ to post‐test on the ToH; however, this was limited to participants with a history of substance abuse. Further, the improvement was only significant for tasks with high working memory load (5–7 move problems), and not for tasks with low working memory load (1–4 move problems). The Control group showed no improvement on any of the tasks regardless of alcohol or drug abuse history. The present study suggests that regular fatty fish consumption may improve executive functions in forensic inpatients with antisocial traits and a history of substance abuse. Thus, the current results may have important implications with regard to health care interventions.