Abnormal Large-Scale Network Activation Present in Bipolar Mania and Bipolar Depression Under Resting State.

Can Zeng,Xiaojun Huang,Brendan Ross,Zhimin Xue,Haojuan Tao,Weidan Pu,Zhening Liu,Guowei Wu

doi:10.3389/fpsyt.2021.634299

Abstract

Introduction: Previous studies have primarily focused on the neuropathological mechanisms of the emotional circuit present in bipolar mania and bipolar depression. Recent studies applying resting-state functional magnetic resonance imaging (fMRI) have raise the possibility of examining brain-wide networks abnormality between the two oppositional emotion states, thus this study aimed to characterize the different functional architecture represented in mania and depression by employing group-independent component analysis (gICA).Materials and Methods: Forty-one bipolar depressive patients, 20 bipolar manic patients, and 40 healthy controls (HCs) were recruited and received resting-state fMRI scans. Group-independent component analysis was applied to the brain network functional connectivity analysis. Then, we calculated the correlation between the value of between-group differences and clinical variables.Results: Group-independent component analysis identified 15 components in all subjects, and ANOVA showed that functional connectivity (FC) differed significantly in the default mode network, central executive network, and frontoparietal network across the three groups. Further post-hoc t-tests showed a gradient descent of activity—depression > HC > mania—in all three networks, with the differences between depression and HCs, as well as between depression and mania, surviving after family wise error (FWE) correction. Moreover, central executive network and frontoparietal network activities were positively correlated with Hamilton depression rating scale (HAMD) scores and negatively correlated with Young manic rating scale (YMRS) scores.Conclusions: Three brain networks heighten activity in depression, but not mania; and the discrepancy regions mainly located in prefrontal, which may imply that the differences in cognition and emotion between the two states is associated with top–down regulation in task-independent networks.

Highlights

Previous studies have primarily focused on the neuropathological mechanisms of the emotional circuit present in bipolar mania and bipolar depression
There is no significant difference in age, sex, age at illness onset, or illness duration across the three groups
Further post-hoc testing found that the activity of these four regions showed a decline in activity trending across the three groups

Summary

Introduction

Previous studies have primarily focused on the neuropathological mechanisms of the emotional circuit present in bipolar mania and bipolar depression. Previous studies have often performed emotional facerecognition tasks to examine the neuropathological mechanisms driving mania and depression [6,7,8,9,10,11,12,13], which have involved a so-called “emotional circuit” that comprised the limbic structures (such as the amygdala, insula, anterior cingulate cortex) and prefrontal cortex including the medial prefrontal cortex (mPFC) and orbital frontal cortex (OFC) [14,15,16,17,18]. Research has suggested that the highs and lows of amygdala activity may be a state-dependent phenomenon caused by trait-like hypoactivation of regulatory frontal regions in BDs [9], but others have proposed that the amygdala fluctuations were affected by medication use or different emotional recognition tasks (e.g., sad, happy, fear face) [11]

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