title: Reward Processing in Unipolar and Bipolar Depression: A Functional MRI Study.
abstract: Differentiating bipolar disorders (BD) from unipolar depression (UD) remains a major clinical challenge. The identification of neurobiological markers may help to differentiate these disorders, particularly during depressive episodes. This cross-sectional study, including 33 patients with UD, 33 patients with BD, and 34 healthy controls, is one of the first to directly compare UD and BD with respect to reward processing. A card-guessing paradigm was employed and brain activity associated with reward processing was investigated by means of fMRI. A 3 (group) × 2 (condition: reward>control, loss>control) ANOVA was conducted using the nucleus accumbens (NAcc) as ROI. Furthermore, a whole-brain approach was applied. A functional connectivity analysis was performed to characterize diagnosis-related alterations in the functional coupling between the NAcc and other brain areas. The ANOVA revealed higher activity for healthy controls (HCs) than for BD and UD in the NAcc during reward processing. Moreover, UD showed a higher functional connectivity between the NAcc and the VTA than HC. The patients groups could be differentiated in that BD showed a decreased activation, in the reward condition, of the NAcc, caudate nucleus, thalamus, putamen, insula, and prefrontal areas compared with UD. These results may help to refine the understanding of neural correlates of reward processing in both disorders, and to understand the neural underpinnings of anhedonia, a core symptom of depressive episodes.
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.
authors.forename: Ronny
authors.initials: R
authors.lastname: Redlich
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Dohm
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Grotegerd
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Opel
authors.affiliation: Department of Psychology, University of Münster, Münster, Germany.
authors.forename: Pienie
authors.initials: P
authors.lastname: Zwitserlood
authors.affiliation: Department of Clinical Radiology, University of Münster, Münster, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Heindel
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Arolt
authors.affiliation: Department of Clinical Radiology, University of Münster, Münster, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Kugel
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.|Department of Psychiatry, University of Marburg, Marburg, Germany.
authors.forename: Udo
authors.initials: U
authors.lastname: Dannlowski
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001714:Bipolar Disorder / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008606:Mental Processes / Q000502:physiology*; D009434:Neural Pathways / Q000503:physiopathology; D009483:Neuropsychological Tests; D012201:Reward; D012815:Signal Processing, Computer-Assisted