title: Cortico-cortical white matter motor pathway microstructure is related to psychomotor retardation in major depressive disorder.
abstract: Alterations of brain structure and function have been associated with psychomotor retardation in major depressive disorder (MDD). However, the association of motor behaviour and white matter integrity of motor pathways in MDD is unclear. The aim of the present study was to first investigate structural connectivity of white matter motor pathways in MDD. Second, we explore the relation of objectively measured motor activity and white matter integrity of motor pathways in MDD. Therefore, 21 patients with MDD and 21 healthy controls matched for age, gender, education and body mass index underwent diffusion tensor imaging and 24 hour actigraphy (measure of the activity level) the same day. Applying a probabilistic fibre tracking approach we extracted connection pathways between the dorsolateral prefrontal cortex (dlPFC), the rostral anterior cingulate cortex (rACC), the pre-supplementary motor area (pre-SMA), the SMA-proper, the primary motor cortex (M1), the caudate nucleus, the putamen, the pallidum and the thalamus. Patients had lower activity levels and demonstrated increased mean diffusivity (MD) in pathways linking left pre-SMA and SMA-proper, and right SMA-proper and M1. Exploratory analyses point to a positive association of activity level and mean-fractional anisotropy in the right rACC-pre-SMA connection in MDD. Only MDD patients with low activity levels had a negative linear association of activity level and mean-MD in the left dlPFC-pre-SMA connection. Our results point to structural alterations of cortico-cortical white matter motor pathways in MDD. Altered white matter organisation of rACC-pre-SMA and dlPFC-pre-SMA pathways may contribute to movement initiation in MDD.
authors.affiliation: University Hospital of Psychiatry, University of Bern, Bern, Switzerland. bracht@puk.unibe.ch
authors.forename: Tobias
authors.initials: T
authors.lastname: Bracht
authors.forename: Andrea
authors.initials: A
authors.lastname: Federspiel
authors.forename: Susanne
authors.initials: S
authors.lastname: Schnell
authors.forename: Helge
authors.initials: H
authors.lastname: Horn
authors.forename: Oliver
authors.initials: O
authors.lastname: Höfle
authors.forename: Roland
authors.initials: R
authors.lastname: Wiest
authors.forename: Thomas
authors.initials: T
authors.lastname: Dierks
authors.forename: Werner
authors.initials: W
authors.lastname: Strik
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Müller
authors.forename: Sebastian
authors.initials: S
authors.lastname: Walther
mesh_terms: D056044:Actigraphy; D000328:Adult; D001931:Brain Mapping; D003865:Major Depressive Disorder / Q000503:physiopathology*; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D017397:Prefrontal Cortex / Q000502:physiology