Altered dynamic functional connectivity across mood states in bipolar disorder

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Bipolar disorder (BD) is characterized by distinct mood states (depressed and euthymic).
• Understanding large-scale brain dynamic functional connectivity (dFC) differences is crucial for BD.
• Resting-state functional magnetic resonance imaging (rsfMRI) is a key tool for assessing brain connectivity.

Purpose of the Study:

• To investigate differences in large-scale brain dFC between depressed and euthymic mood states in bipolar disorder (BD).
• To compare dFC patterns in BD patients with healthy controls (HCs).
• To identify potential neural markers for distinguishing mood states in BD.

Main Methods:

• Recruited subjects with BD in depressed and euthymic states, and matched HCs.
• Acquired rsfMRI data for all participants.
• Analyzed whole-brain dFC using a parcellation approach to identify network connection patterns.

Main Results:

• Depressed BD showed greater dFC between the somatomotor network (SMN) and default mode network (DMN) compared to euthymic BD.
• No significant dFC differences were found between euthymic BD and HCs in these specific SMN/DMN regions.
• Euthymic BD patients exhibited abnormal connectivity within the frontal-striatal-thalamic (FST) circuit compared to HCs.

Conclusions:

• dFC differences within and between DMN and SMN can distinguish depressed from euthymic states in BD.
• Hyperconnectivity within and between DMN and SMN may be a state-dependent feature of depressed BD.
• Abnormal FST circuit connectivity can help differentiate euthymic BD from HCs.