Alternations of White Matter Structural Networks in First Episode Untreated Major Depressive Disorder with Short Duration

Abstract

It is crucial to explore the pathogenesis of major depressive disorder (MDD) at the early stage for the better diagnostic and treatment strategies. It was suggested that MDD might be involving in functional or structural alternations at the brain network level. However, at the onset of MDD, whether the whole brain white matter (WM) alterations at network level are already evident still remains unclear. In the present study, diffusion MRI scanning was adopt to depict the unique WM structural network topology across the entire brain at the early stage of MDD. Twenty-one first episode, short duration (<1 year) and drug-naïve depression patients, and 25 healthy control (HC) subjects were recruited. To construct the WM structural network, atlas-based brain regions were used for nodes, and the value of multiplying fiber number by the mean fractional anisotropy along the fiber bundles connected a pair of brain regions were used for edges. The structural network was analyzed by graph theoretic and network-based statistic methods. Pearson partial correlation analysis was also performed to evaluate their correlation with the clinical variables. Compared with HCs, the MDD patients had a significant decrease in the small-worldness (σ). Meanwhile, the MDD patients presented a significantly decreased subnetwork, which mainly involved in the frontal–subcortical and limbic regions. Our results suggested that the abnormal structural network of the orbitofrontal cortex and thalamus, involving the imbalance with the limbic system, might be a key pathology in early stage drug-naive depression. And the structural network analysis might be potential in early detection and diagnosis of MDD.

Connectome analysis of functional and structural hemispheric brain networks in major depressive disorder

“…No significant alterations were observed in the network efficiency for structural hemispheric networks in the patients. This finding is in line with our structural connectivity results and previous structural network studies demonstrating preserved global network configurations in MDD 41,46–48 . Notably, altered global organization of structural brain networks was also reported in MDD 2,49 .…”

Decreased Connection Between Reward Systems and Paralimbic Cortex in Depressive Patients

“…Depressive patients also exhibit hypoactivation of medial OFC in the neural coding for reward prediction ( Rothkirch et al, 2017 ), as well as the decreased activity in NAcc ( Ubl et al, 2015 ). In addition, the aberrancy of OFC and NAcc in depression is also supported by evidence from structural findings ( Kempton et al, 2011 ; Lu et al, 2017 ).…”

Accelerated intermittent theta burst stimulation in major depression induces decreases in modularity: A connectome analysis

“…Twenty-nine MDD participants showed changes (mainly in cognitive-emotional circuitry and fronto-parietal circuitry) in eigenvector centrality, local clustering coefficient, and nodal efficiency in the study by Qin et al (2014) using white matter networks. In early stage MDD patients, a significant decrease in small-worldness and a significantly decreased strength in the frontal-subcortical and limbic regions was found by Lu et al (2017). Korgaonkar et al (2014) found no significant group differences for the graph theory measures, despite the fact that their network-based statistics revealed lowered structural connectivity in two subnetworks in a cohort of 95 MDD outpatients.…”