title: Major depressive disorder: Findings of reduced homotopic connectivity and investigation of underlying structural mechanisms.
abstract: Depression has been associated with various alterations in magnetic resonance imaging (MRI) derived resting-state functional connectivity. Recently, homotopic connectivity, defined as functional connectivity between homotopic regions across hemispheres, has been reported to be reduced in patients with major depressive disorder (MDD). However, little is known about structural factors underlying alterations of homotopic connectivity, which would contribute to the understanding of the altered neurophysiological architecture in patients with MDD. We compared 368 patients with MDD and 461 never-depressed controls regarding voxel-mirrored homotopic connectivity (VMHC) and potential underlying mechanisms such as the structural connectivity of the corpus callosum, measured by DTI-derived fractional anisotropy (FA), and left-right symmetries in homotopic gray matter volumes. Compared to controls, patients with MDD exhibited reduced VMHC in the cuneus, putamen, superior temporal gyrus, insula, and precuneus. Within these regions, no differences in left-right symmetries in homotopic gray matter volumes were evident across cohorts. FA of the corpus callosum correlated with VMHC in the entire sample. However, patients with MDD and controls did not differ with regard to callosal FA. The findings indicate that MDD is associated with a loss of interhemispheric synchrony in regions known to be implicated in self-referential and reward processing. They also suggest that additional mechanisms are implicated in altered homotopic connectivity of patients with MDD, other than direct callosal fiber pathways or asymmetries in homotopic gray matter volumes.
authors.affiliation: Institute of Epidemiology and Social Medicine, University of Münster, Münster, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Hermesdorf
authors.affiliation: Department of Clinical Radiology, University Hospital Münster, Münster, Germany.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Sundermann
authors.affiliation: Department of Clinical Radiology, University Hospital Münster, Münster, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Feder
authors.affiliation: Department of Clinical Radiology, University Hospital Münster, Münster, Germany.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Schwindt
authors.affiliation: Department of Neurology, University Hospital Münster, Münster, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Minnerup
authors.affiliation: Department of Psychiatry, University Hospital Münster, Münster, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Arolt
authors.affiliation: Institute of Epidemiology and Social Medicine, University of Münster, Münster, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Berger
authors.affiliation: Department of Clinical Radiology, University Hospital Münster, Münster, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Pfleiderer
authors.affiliation: Institute of Epidemiology and Social Medicine, University of Münster, Münster, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Wersching
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000473:pathology*; D003865:Major Depressive Disorder / Q000473:pathology*; D005260:Female; D066128:Gray Matter / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000473:pathology; D009929:Organ Size; D066127:White Matter / Q000473:pathology
keywords: fMRI; functional connectivity; interhemispheric connectivity; resting-state; structural connectivity