Physical activity is associated with left corticospinal tract microstructure in bipolar depression

Abstract

Psychomotor retardation and reduced daily activities are core features of the depressive syndrome including bipolar disorder (BD). It was the aim of this study to investigate white matter microstructure of the motor system in BD during depression and its association with motor activity. We hypothesized reduced physical activity, microstructural alterations of motor tracts and different associations between activity levels and motor tract microstructure in BD. Nineteen bipolar patients with a current depressive episode (BD) and 19 healthy controls (HC) underwent diffusion weighted magnetic resonance imaging (DW-MRI)-scans. Quantitative motor activity was assessed with 24 h actigraphy recordings. Bilateral corticospinal tracts (CST), interhemispheric connections between the primary motor cortices (M1) and between the pre-supplementary motor areas (pre-SMA) were reconstructed individually based on anatomical landmarks using Diffusion Tensor Imaging (DTI) based tractography. Mean fractional anisotropy (FA) was sampled along the tracts. To enhance specificity of putative findings a segment of the optic radiation was reconstructed as comparison tract. Analyses were complemented with Tract Based Spatial Statistics (TBSS) analyses. BD had lower activity levels (AL). There was a sole increase of fractional anisotropy (FA) in BD in the left CST. Further, there was a significant group x AL interaction for FA of the left CST pointing to a selective positive association between FA and AL in BD. The comparison tract and TBSS analyses did not detect significant group differences. Our results point to white matter microstructure alterations of the left CST in BD. The positive association between motor activity and white matter microstructure suggests a compensatory role of the left CST for psychomotor retardation in BD.

Microstructural Alterations in Bipolar and Major Depressive Disorders: A Diffusion Kurtosis Imaging Study

“…A change in RK instead of AK is thought to indicate that a more pronounced alteration occurs in the direction perpendicular to the principal axis of white matter axons. An increase in oligodendrocyte density or cell clustering of astrocytes may be responsible . Antidepressant medication may be implicated in BD patients .…”

Actigraphically measured psychomotor slowing in depression: systematic review and meta-analysis

“…Few studies have examined neural correlates of psychomotor retardation in MDD and BD and found brain alterations in functional and structural networks, mainly including the motor circuitry (Bracht et al, 2018;Buyukdura et al, 2011;Koo et al, 2019;Martino et al, 2020;Walther et al, 2012aWalther et al, , 2012b. There is some evidence suggesting distinct neural differences between unipolar and bipolar depression (Diler et al, 2014;Han, De Berardis, Fornaro, & Kim, 2019).…”

“…However, it remains unclear whether this difference pertains to psychomotor retardation, as very few studies have directly compared its correlates between the two diagnoses (Cantisani et al, 2016). Also in neuroimaging studies, actigraphy has proven to be an informative measure of psychomotor disturbance when exploring brain-behavior associations (Bracht et al, 2012(Bracht et al, , 2018Cantisani et al, 2016;Walther et al, 2012aWalther et al, , 2012b.…”

The role of the orbitofrontal cortex and the nucleus accumbens for craving in alcohol use disorder

“…Diffusion-weighted MRI (DW-MRI) data were analyzed using ExploreDTI 4.8.6 58 . Data were pre-processed as described in previous publications 59 , 60 . In short, a subjection motion and distortion correction and an EPI-correction was performed 61 .…”