Resting state networks activity in euthymic bipolar disorder.

Area of Science:

• Neuroscience
• Psychiatry
• Neuroimaging

Background:

• Bipolar disorder (BD) significantly impacts patients' quality of life, even during euthymic phases.
• The underlying neurobiological mechanisms of BD in the euthymic state remain poorly understood.
• Characterizing brain activity during euthymia is crucial for developing effective neurobiological models.

Purpose of the Study:

• To investigate resting-state functional connectivity in euthymic bipolar disorder patients.
• To identify specific alterations in brain networks associated with BD during periods of mood stability.
• To contribute to a better understanding of BD pathogenesis and inform future research.

Main Methods:

• Functional MRI (fMRI) was used to scan 15 euthymic BD patients and 27 healthy controls (HC) at rest.
• Independent Component Analysis (ICA) was employed to extract 22 resting-state networks (RSNs).
• Within-network and between-network connectivity analyses were performed.

Main Results:

• Decreased connectivity was observed within visual, temporal, motor, and cerebellar RSNs in BD patients compared to HC.
• Increased connectivity between the motor network and the default mode network (DMN), overlapping with the fronto-parietal network (FPN), was found in BD patients.
• These alterations were identified in the euthymic state, suggesting persistent neurobiological changes.

Conclusions:

• Within-network findings confirm prior evidence of altered cerebellar, temporal, motor, and visual networks in BD.
• Increased DMN-motor network connectivity indicates alterations in fronto-parietal regions, precuneus, and cingulate cortex in euthymic BD.
• Connectivity changes persist in the euthymic state, highlighting the importance of examining both within- and between-network connectivity for a comprehensive understanding of BD.