Disorders of compulsivity: a common bias towards learning habits.

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Derbyshire, K 
Rück, C 
Irvine, MA 
Worbe, Y 

Why do we repeat choices that we know are bad for us? Decision making is characterized by the parallel engagement of two distinct systems, goal-directed and habitual, thought to arise from two computational learning mechanisms, model-based and model-free. The habitual system is a candidate source of pathological fixedness. Using a decision task that measures the contribution to learning of either mechanism, we show a bias towards model-free (habit) acquisition in disorders involving both natural (binge eating) and artificial (methamphetamine) rewards, and obsessive-compulsive disorder. This favoring of model-free learning may underlie the repetitive behaviors that ultimately dominate in these disorders. Further, we show that the habit formation bias is associated with lower gray matter volumes in caudate and medial orbitofrontal cortex. Our findings suggest that the dysfunction in a common neurocomputational mechanism may underlie diverse disorders involving compulsion.

Adult, Algorithms, Bias, Brain, Case-Control Studies, Choice Behavior, Computer Simulation, Female, Habits, Humans, Image Processing, Computer-Assisted, Learning, Magnetic Resonance Imaging, Male, Middle Aged, Obesity, Obsessive-Compulsive Disorder, Regression Analysis, Reward, Substance-Related Disorders, Surveys and Questionnaires, Young Adult
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Mol Psychiatry
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Springer Science and Business Media LLC
Wellcome Trust (093705/Z/10/Z)
Medical Research Council (G0001354)
Wellcome Trust (089589/Z/09/Z)
Wellcome Trust (095844/Z/11/Z)
Medical Research Council (G1000183)
This study was funded by the WT fellowship grant for VV (093705/Z/ 10/Z) and Cambridge NIHR Biomedical Research Centre. VV and NAH are Wellcome Trust (WT) intermediate Clinical Fellows. YW is supported by the Fyssen Fondation and MRC Studentships. PD is supported by the Gatsby Charitable Foundation. JEG has received grants from the National Institute of Drug Abuse and the National Center for Responsible Gaming. TWR and BJS are supported on a WT Programme Grant (089589/Z/09/Z). The BCNI is supported by a WT and MRC grant.