Obst E Schad DJ Huys QJ Sebold M Nebe S Sommer C Smolka MN Zimmermann US 2018 BACKGROUND Studies in humans and animals suggest a shift from goal-directed to habitual decision-making in addiction. We therefore tested whether acute alcohol administration reduces goal-directed and promotes habitual decision-making, and whether these effects are moderated by self-reported drinking problems. METHODS Fifty-three socially drinking males completed the two-step task in a randomised crossover design while receiving an intravenous infusion of ethanol (blood alcohol level=80 mg%), or placebo. To minimise potential bias by long-standing heavy drinking and subsequent neuropsychological impairment, we tested 18- to 19-year-old adolescents. RESULTS Alcohol administration consistently reduced habitual, model-free decisions, while its effects on goal-directed, model-based behaviour varied as a function of drinking problems measured with the Alcohol Use Disorders Identification Test. While adolescents with low risk for drinking problems (scoring <8) exhibited an alcohol-induced numerical reduction in goal-directed choices, intermediate-risk drinkers showed a shift away from habitual towards goal-directed decision-making, such that alcohol possibly even improved their performance. CONCLUSIONS We assume that alcohol disrupted basic cognitive functions underlying habitual and goal-directed decisions in low-risk drinkers, thereby enhancing hasty choices. Further, we speculate that intermediate-risk drinkers benefited from alcohol as a negative reinforcer that reduced unpleasant emotional states, possibly displaying a novel risk factor for drinking in adolescence. https://sonar.ch/global/documents/30990 eng info:eu-repo/semantics/altIdentifier/doi/10.1177/0269881118772454 info:eu-repo/semantics/altIdentifier/pmid/29764270 Journal of psychopharmacology (Oxford, England). - 2018 Computer-assisted Alcohol Infusion System drinking problems habitual learning model-free and model-based decision-making real-life drinking behaviour subjective response to ethanol two-stage Markov decision task Adolescent Alcohol Drinking Alcoholic Intoxication Alcoholism Animals Behavior, Addictive Child Cross-Over Studies Decision Making Ethanol Goals Humans Male Motivation Underage Drinking Drunk decisions: Alcohol shifts choice from habitual towards goal-directed control in adolescent intermediate-risk drinkers. http://purl.org/coar/resource_type/c_6501