Common and unique alterations of functional connectivity in major depressive disorder and bipolar disorder

Abstract

Objective Major depressive disorder (MDD) and bipolar disorder (BD) are considered whole‐brain disorders with some common clinical and neurobiological features. It is important to investigate neural mechanisms to distinguish between the two disorders. However, few studies have explored the functional dysconnectivity between the two disorders from the whole brain level. Methods In this study, 117 patients with MDD, 65 patients with BD, and 116 healthy controls completed resting‐state functional magnetic resonance imaging (R‐fMRI) scans. Both edge‐based network construction and large‐scale network analyses were applied. Results Results found that both the BD and MDD groups showed decreased FC in the whole brain network. The shared aberrant network across patients involves the visual network (VN), sensorimotor network (SMN), dorsal attention network (DAN), and ventral attention network (VAN), which is related to the processing of external stimuli. The default mode network (DMN) and the limbic network (LN) abnormalities were only found in patients with MDD. Furthermore, results showed the highest decrease in edges of patients with MDD in between‐network FC in SMN–VN, whereas in VAN–VN of patients with BD. Conclusions Our findings indicated that both MDD and BD are extensive abnormal brain network diseases, mainly aberrant in those brain networks correlated to the processing of external stimuli, especially the attention network. Specific altered functional connectivity also was found in MDD and BD groups, respectively. These results may provide possible trait markers to distinguish the two disorders.

Shared and unique alterations of large-scale network connectivity in drug-free adolescent-onset and adult-onset major depressive disorder

“…NBS analysis revealed interaction effects within the LN network. In contrast, previous studies reported decreased connectivity within LN networks in adults with MDD [ 25 ]. This disparity could be due to uncontrolled factors such as AOO and medication in previous studies, where adult MDD patients might include both adolescent-onset and adult-onset cases.…”

“…DPABISurf, an extension of DPABI/DPARSF [ 24 ], was developed by the Institute of Psychology of the Chinese Academy of Sciences and interfaces with the FMRIPprep docker, integrating FreeSurfer, ANTs, FSL, and AFNI for MRI data preprocessing. Further details on MRI data processing are available in our previous research [ 25 ]. Initially, EPI and T1 DICOM data were converted to BIDS format, with the first 10 time points of the EPI data being discarded to eliminate magnetic field instability effects.…”