Altered functional connectivity density in major depressive disorder at rest

Abstract

Major depressive disorder is characterized by abnormal brain connectivity at rest. Currently, most studies investigating resting-state activity rely on a priori restrictions on specific networks or seed regions, which may bias observations. We hence sought to elicit functional alterations in a hypothesis-free approach. We applied functional connectivity density (FCD) to identify abnormal connectivity for each voxel in the whole brain separately. Comparing resting-state fMRI in 21 MDD patients and 23 matched healthy controls, we identified atypical connections for regions exhibiting abnormal FCD and compared our results to those of an independent component analysis (ICA) on networks previously investigated in MDD. Patients showed reduced FCD in mid-cingulate cortex (MCC) and increased FCD in occipital cortex (OCC). These changes in global FCD were driven by abnormal local connectivity changes and reduced functional connectivity (FC) toward the left amygdala for MCC, and increased FC toward the right supplementary motor area for OCC. The altered connectivity was not reflected in ICA comparison of the salience and visual networks. Abnormal FC in MDD is present in cingulate and OCC in terms of global FCD. This converges with previous structural and metabolic findings; however, these particular changes in connectivity would not have been identified using canonical seed regions or networks. This implies the importance of FC measures in the investigation of brain pathophysiology in depression.

Novelty seeking and reward dependence‐related large‐scale brain networks functional connectivity variation during salience expectancy

“…Indeed, decreased FC was recently observed between the bilateral insula and the DMN in cocaine‐dependent individuals during rest, and the organizational disruptions within the SN in these individuals have been associated with greater alexithymia [Liang et al, ]. RSFC in depressive patients has also been found to alter to other target networks [Zhang et al, ]. Furthermore, the FC between dorsomedial prefrontal cortex (dACC) and posterior DMN showed an abnormal disconnection when depressive patients were expecting positive stimuli [Zhang et al, ].…”

Depression Disorder Classification of fMRI Data Using Sparse Low-Rank Functional Brain Network and Graph-Based Features

“…Functional magnetic resonance imaging (fMRI) can contribute to the diagnosis and a better understanding of the pathogenesis of depression disorder [4, 5]. This brain imaging technique provides an effective tool to explore functional abnormalities of depression disorder [6]. …”

Decreased Subcortical and Increased Cortical Degree Centrality in a Nonclinical College Student Sample with Subclinical Depressive Symptoms: A Resting-State fMRI Study

“…Therefore, DC is a better network metric than other measurements because it counts the number of direct connections for a given voxel in a network and reflects its FC within the brain network without requiring a priori selection. The DC approach has recently been used in mental disorders including MDD (Zhang et al, 2016), hepatic encephalopathy (Qi et al, 2015), schizophrenia (Zhuo et al, 2014), multiple sclerosis (Zhuang et al, 2015), and autism and attention-deficit (Di Martino et al, 2013). However, no study so far has investigated DC alterations in subclinical depression.…”