title: Investigating the Impact of a Genome-Wide Supported Bipolar Risk Variant of MAD1L1 on the Human Reward System.
abstract: Recent genome-wide association studies have identified MAD1L1 (mitotic arrest deficient-like 1) as a susceptibility gene for bipolar disorder and schizophrenia. The minor allele of the single-nucleotide polymorphism (SNP) rs11764590 in MAD1L1 was associated with bipolar disorder. Both diseases, bipolar disorder and schizophrenia, are linked to functional alterations in the reward system. We aimed at investigating possible effects of the MAD1L1 rs11764590 risk allele on reward systems functioning in healthy adults. A large homogenous sample of 224 young (aged 18-31 years) participants was genotyped and underwent functional magnetic resonance imaging (fMRI). All participants performed the 'Desire-Reason Dilemma' paradigm investigating the neural correlates that underlie reward processing and active reward dismissal in favor of a long-term goal. We found significant hypoactivations of the ventral tegmental area (VTA), the bilateral striatum and bilateral frontal and parietal cortices in response to conditioned reward stimuli in the risk allele carriers compared with major allele carriers. In the dilemma situation, functional connectivity between prefrontal brain regions and the ventral striatum was significantly diminished in the risk allele carriers. Healthy risk allele carriers showed a significant deficit of their bottom-up response to conditioned reward stimuli in the bilateral VTA and striatum. Furthermore, functional connectivity between the ventral striatum and prefrontal areas exerting top-down control on the mesolimbic reward system was reduced in this group. Similar alterations in reward processing and disturbances of prefrontal control mechanisms on mesolimbic brain circuits have also been reported in bipolar disorder and schizophrenia. Together, these findings suggest the existence of an intermediate phenotype associated with MAD1L1.
authors.affiliation: Department of Psychiatry and Psychotherapy, Center for Translational Research in Systems Neuroscience and Clinical Psychiatry, Georg August University Goettingen, Goettingen, Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Trost
authors.affiliation: Department of Psychiatry and Psychotherapy, Center for Translational Research in Systems Neuroscience and Clinical Psychiatry, Georg August University Goettingen, Goettingen, Germany.|Biocenter Grindel and Zoological Institute, Department of Human Biology, Hamburg University, Hamburg, Germany.
authors.forename: Esther K
authors.initials: EK
authors.lastname: Diekhof
authors.affiliation: Department of Psychiatry and Psychotherapy, Center for Translational Research in Systems Neuroscience and Clinical Psychiatry, Georg August University Goettingen, Goettingen, Germany.|Department of Psychology, Neuroimaging Center and Institute of General Psychology, Biopsychology, and Methods of Psychology, Technische Universitaet Dresden, Dresden, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Mohr
authors.affiliation: Department of Psychiatry and Psychotherapy, Center for Translational Research in Systems Neuroscience and Clinical Psychiatry, Georg August University Goettingen, Goettingen, Germany.|Department of Psychiatry and Psychotherapy, University Medical Center, Eppendorf, Hamburg, Germany.
authors.forename: Henning
authors.initials: H
authors.lastname: Vieker
authors.affiliation: Department of Psychiatry and Psychotherapy, Center for Translational Research in Systems Neuroscience and Clinical Psychiatry, Georg August University Goettingen, Goettingen, Germany.|Section for Experimental Psychopathology and Neuroimaging, Department of General Psychiatry, Heidelberg University Hospital, Ruprecht Karls University, Heidelberg, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Krämer
authors.affiliation: Department of Psychiatry and Psychotherapy, Center for Translational Research in Systems Neuroscience and Clinical Psychiatry, Georg August University Goettingen, Goettingen, Germany.|Laboratory of Behavioral Neuroscience, Biomedical Research Center, National Institute on Aging, Baltimore, MD, USA.
authors.forename: Claudia
authors.initials: C
authors.lastname: Wolf
authors.affiliation: Department of Psychiatry and Psychotherapy, Center for Translational Research in Systems Neuroscience and Clinical Psychiatry, Georg August University Goettingen, Goettingen, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Keil
authors.affiliation: Department of Cognitive Neurology, Georg August University, Goettingen, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Dechent
authors.affiliation: Department of Translational Psychiatry, Max Planck Institute of Psychiatry, Munich, Germany.
authors.forename: Elisabeth B
authors.initials: EB
authors.lastname: Binder
authors.affiliation: Department of Psychiatry and Psychotherapy, Center for Translational Research in Systems Neuroscience and Clinical Psychiatry, Georg August University Goettingen, Goettingen, Germany.|Section for Experimental Psychopathology and Neuroimaging, Department of General Psychiatry, Heidelberg University Hospital, Ruprecht Karls University, Heidelberg, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Gruber
mesh_terms: D000293:Adolescent; D000328:Adult; D001714:Bipolar Disorder / Q000000981:diagnostic imaging / Q000235:genetics*; D001921:Brain / Q000000981:diagnostic imaging*; D001931:Brain Mapping; D018797:Cell Cycle Proteins / Q000235:genetics*; D003216:Conditioning, Operant; D005260:Female; D055106:Genome-Wide Association Study; D005838:Genotype; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000000981:diagnostic imaging; D009687:Nuclear Proteins / Q000235:genetics*; D010100:Oxygen / Q000097:blood; D010555:Personality Inventory; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012201:Reward; D012559:Schizophrenia / Q000000981:diagnostic imaging / Q000235:genetics; D055815:Young Adult
chemical_list: D018797:Cell Cycle Proteins; C501384:MAD1L1 protein, human; D009687:Nuclear Proteins; D010100:Oxygen