• Serge Sevy, Youssef Hassoun, Antoine Bechara, Eldad Yechiam, Barbara Napolitano, Katherine Burdick, Howard Delman, and Anil Malhotra.
• Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Yeshiva University, Bronx, and Psychiatry Research Department , The Zucker Hillside Hospital, Glen Oaks, NY, USA. sevy@lij.edu
• Psychopharmacology (Berl.). 2006 Oct 1;188(2):228-35.

IntroductionConverging evidences from animal and human studies suggest that addiction is associated with dopaminergic dysfunction in brain reward circuits. So far, it is unclear what aspects of addictive behaviors are related to a dopaminergic dysfunction.DiscussionWe hypothesize that a decrease in dopaminergic activity impairs emotion-based decision-making. To demonstrate this hypothesis, we investigated the effects of a decrease in dopaminergic activity on the performance of an emotion-based decision-making task, the Iowa gambling task (IGT), in 11 healthy human subjects.Materials And MethodsWe used a double-blind, placebo-controlled, within-subject design to examine the effect of a mixture containing the branched-chain amino acids (BCAA) valine, isoleucine and leucine on prolactin, IGT performance, perceptual competency and visual aspects of visuospatial working memory, visual attention and working memory, and verbal memory. The expectancy-valence model was used to determine the relative contributions of distinct IGT components (attention to past outcomes, relative weight of wins and losses, and choice strategies) in the decision-making process.Observations And ResultsCompared to placebo, the BCAA mixture increased prolactin levels and impaired IGT performance. BCAA administration interfered with a particular component process of decision-making related to attention to more recent events as compared to more distant events. There were no differences between placebo and BCAA conditions for other aspects of cognition. Our results suggest a direct link between a reduced dopaminergic activity and poor emotion-based decision-making characterized by shortsightedness, and thus difficulties resisting short-term reward, despite long-term negative consequences. These findings have implications for behavioral and pharmacological interventions targeting impaired emotion-based decision-making in addictive disorders.

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