Major depressive disorder (MDD) is known to be characterized by altered brain functional connectivity (FC) patterns. However, whether and how the features of dynamic FC would change in patients with MDD are unclear. In this study, we aimed to characterize dynamic FC in MDD using a large multi-site sample and a novel dynamic network-based approach. Resting-state functional magnetic resonance imaging (fMRI) data were acquired from a total of 460 MDD patients and 473 healthy controls, as a part of the REST-meta-MDD consortium. Resting-state dynamic functional brain networks were constructed for each subject by a sliding-window approach. Multiple spatio-temporal features of dynamic brain networks, including temporal variability, temporal clustering and temporal efficiency, were then compared between patients and healthy subjects at both global and local levels. The group of MDD patients showed significantly higher temporal variability, lower temporal correlation coefficient (indicating decreased temporal clustering) and shorter characteristic temporal path length (indicating increased temporal efficiency) compared with healthy controls (corrected p < 3.14×10-3). Corresponding local changes in MDD were mainly found in the default-mode, sensorimotor and subcortical areas. Measures of temporal variability and characteristic temporal path length were significantly correlated with depression severity in patients (corrected p < 0.05). Moreover, the observed between-group differences were robustly present in both first-episode, drug-naïve (FEDN) and non-FEDN patients. Our findings suggest that excessive temporal variations of brain FC, reflecting abnormal communications between large-scale bran networks over time, may underlie the neuropathology of MDD.

Background: The high synchrony of spontaneous neural activity in the homotopic region of the resting hemisphere is considered to be an important functional structural feature of normal human brain, while a series of studies of mental disorders such as depression, schizophrenia, dementia, and sleep disorders, the feature was found to be broken. Until now, the synchrony of spontaneous neural activity of the resting hemisphere in obsessive-compulsive disorder (OCD) remain unclear. Present study aimed to detect the abnormal synchrony of spontaneous neural activity in OCD. Methods: Forty-six patients with OCD and 46 -gender, -age and education matched healthy subjects (HC) received MRI scans. The voxel-mirrored homotopic connectivity (VMHC) method was used to evaluate the resting state functional connections between the both hemispheres of each subject. The two sample T-test was used to compare VMHC between OCD and HC. A partial correlation analysis was used to investigate the relationship between VMHC and clinical features in patients with OCD. Results: Compared to HC, the VMHC values were found decreased widely in many brain regions, such as bilateral fusiform gyrus/inferior occipital gyrus, bilateral lingual gyrus, bilateral postcentral gyrus/precentral gyrus, bilateral putamen and bilateral orbital frontal gyrus in patients with OCD. The values of VMHC in the bilateral angular gyrus/middle occipital gyrus were significantly correlated with illness duration. Conclusions: Interhemispheric functional coordination abnormalities may be one of the important pathophysiological mechanisms of OCD.

Objective: To study changes in blood brain barrier (BBB) permeability in systemic lupus erythematosus (SLE) patients, and explore the association between the alterations in BBB permeability and depression/anxiety in SLE.Methods: Brain dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) images were collected from 42 SLE patients and 23 healthy controls (HCs). Based on the Patlak pharmacokinetic model, the K^trans value of each voxel in the whole brain of each subject was calculated. BBB permeability indicator (the K^trans value) between SLE patients and healthy control group was compared. Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA) were used to assess the mental health of SLE patients. The difference in BBB permeability was compared on SLE patients with depression/anxiety, SLE patients without depression/anxiety and HCs by ANOVA analysis.Results: The K^trans value of the right insular region of the SLE group was significantly higher than that of the healthy control group. And the K^trans value of the right insular region in SLE patients with depression/anxiety was significantly increased compared with SLE patients without depression/anxiety and HCs.Conclusions: SLE patients have increased BBB permeability, mainly in the right insular area. The increased BBB permeability in the right insular region is associated with the depression/anxiety in SLE patients.