title: A voxel-based diffusion tensor imaging study in unipolar and bipolar depression.
abstract: The absence of neurobiological diagnostic markers of bipolar disorder (BD) leads to its frequent misdiagnosis as unipolar depression (UD). We investigated if changes in fractional anisotropy (FA) could help to differentiate BD from UD in the state of depression.
  
  
  
  Using diffusion tensor imaging (DTI) we employed a voxel-based analysis approach to examine fractional anisotropy (FA) in 86 patients experiencing an acute major depressive episode according to DSM-IV (N=39 BD, mean age 39.2 years; N=43 UD, mean age 39.0 years), and 42 healthy controls (HC, mean age 36.1 years). The groups did not differ in sex, age or total education time. FA was investigated in white matter (FA >.2) and hypothesis-driven anatomically defined tracts (region-of-interest [ROI] analysis). Additionally, an exploratory gray matter FA analysis was performed.
  
  
  
  White matter analysis showed decreased FA in the right corticospinal tract in UD vs HC and in the right corticospinal tract/superior longitudinal fascicle in BD vs HC and also in BD vs UD. ROI analysis revealed decreased FA in BD vs UD in the corpus callosum and in the cingulum. Gray matter exploratory analysis revealed decreased FA in the left middle frontal gyrus and in the right inferior frontal gyrus in UD vs HC, and in the left superior medial gyrus in BD vs HC.
  
  
  
  This is one of very few studies directly showing differences in FA between BD and UD. Gray matter FA changes in prefrontal areas might be precursors for future prefrontal gray matter abnormalities in these disorders.
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.
authors.forename: Jonathan
authors.identifier: 0000-0003-1379-9491
authors.initials: J
authors.lastname: Repple
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Meinert
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Grotegerd
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.
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: Dario
authors.initials: D
authors.lastname: Zaremba
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Opel
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Buerger
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Förster
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.
authors.forename: Theresa
authors.initials: T
authors.lastname: Nick
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: Walter
authors.initials: W
authors.lastname: Heindel
authors.affiliation: Department of Neurology, University of Münster, Münster, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Deppe
authors.affiliation: Department of Psychiatry, University of Münster, Münster, Germany.
authors.forename: Udo
authors.initials: U
authors.lastname: Dannlowski
mesh_terms: D000328:Adult; D016880:Anisotropy; D001714:Bipolar Disorder / Q000175:diagnosis / Q000503:physiopathology; D003866:Depressive Disorder / Q000175:diagnosis / Q000503:physiopathology; D003937:Diagnosis, Differential; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D066128:Gray Matter / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D013223:Statistics as Topic; D066127:White Matter / Q000000981:diagnostic imaging / Q000503:physiopathology
keywords: bipolar disorder; connectivity; diffusion tensor imaging (DTI); magnetic resonance imaging (MRI); major depressive disorder; white matter