title: Stress and reward processing in bipolar disorder: a functional magnetic resonance imaging study.
abstract: A link between negative life stress and the onset of mood episodes in bipolar disorder (BD) has been established, but processes underlying such a link remain unclear. Growing evidence suggests that stress can negatively affect reward processing and related neurobiological substrates, indicating that a dysregulated reward system may provide a partial explanation. The aim of this study was to test the impact of stress on reward-related neural functioning in BD.
  
  
  
  Thirteen euthymic or mildly depressed individuals with BD and 15 controls performed a Monetary Incentive Delay (MID) task while undergoing functional magnetic resonance imaging during no-stress and stress (negative psychosocial stressor involving poor performance feedback and threat of monetary deductions) conditions.
  
  
  
  In hypothesis-driven region-of-interest analyses, a significant group-by-condition interaction emerged in the amygdala during reward anticipation. Relative to controls, while anticipating a potential reward, subjects with BD were characterized by amygdalar hyperactivation in the no-stress condition but hypoactivation during stress. Moreover, relative to controls, subjects with BD had significantly larger amygdala volumes. After controlling for structural differences, the effects of stress on amygdalar function remained, whereas groups no longer differed during the no-stress condition. During reward consumption, a group-by-condition interaction emerged in the putamen due to increased putamen activation in response to rewards in participants with BD during stress, but an opposite pattern in controls.
  
  
  
  Overall, findings highlight possible impairments in using reward-predicting cues to adaptively engage in goal-directed actions in BD, combined with stress-induced hypersensitivity to reward consumption. Potential clinical implications are discussed.
authors.affiliation: Department of Psychology, Harvard University, Cambridge, MA, USA.
authors.forename: Lisa H
authors.initials: LH
authors.lastname: Berghorst
authors.affiliation: Center for Depression, Anxiety and Stress Research, McLean Hospital, Belmont, MA, USA.|Department of Psychiatry, Harvard Medical School, Boston, MA, USA.
authors.forename: Poornima
authors.initials: P
authors.lastname: Kumar
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA.
authors.forename: Doug N
authors.initials: DN
authors.lastname: Greve
authors.affiliation: Department of Psychiatry, Harvard Medical School, Boston, MA, USA.|Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Thilo
authors.initials: T
authors.lastname: Deckersbach
authors.affiliation: Department of Psychiatry, Harvard Medical School, Boston, MA, USA.|Schizophrenia and Bipolar Disorder Research Program, McLean Hospital, Belmont, MA, USA.
authors.forename: Dost
authors.initials: D
authors.lastname: Ongur
authors.affiliation: Department of Psychology, Yale University, New Haven, CT, USA.
authors.forename: Sunny J
authors.initials: SJ
authors.lastname: Dutra
authors.affiliation: Center for Depression, Anxiety and Stress Research, McLean Hospital, Belmont, MA, USA.|Department of Psychiatry, Harvard Medical School, Boston, MA, USA.|McLean Imaging Center, McLean Hospital, Belmont, MA, USA.
authors.forename: Diego A
authors.initials: DA
authors.lastname: Pizzagalli
mesh_terms: D000223:Adaptation, Psychological / Q000502:physiology*; D000328:Adult; D000679:Amygdala / Q000000981:diagnostic imaging / Q000503:physiopathology; D001714:Bipolar Disorder / Q000175:diagnosis / Q000523:psychology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009042:Motivation / Q000502:physiology; D009929:Organ Size; D012201:Reward; D013223:Statistics as Topic; D013315:Stress, Psychological / Q000473:pathology / Q000503:physiopathology / Q000523:psychology
keywords: 
  Monetary Incentive Delay (MID)
  ; 
  functional magnetic resonance imaging (fMRI)
  ; amygdala; bipolar disorder; putamen; reward; stress