Altered functional activity in bipolar disorder: A comprehensive review from a large-scale network perspective

Area of Science:

• Neuroscience
• Psychiatry
• Brain Imaging

Background:

• Bipolar disorder is associated with altered brain function, but network-level changes remain unclear.
• Previous research shows inconsistent findings regarding specific functional network correlates.
• A large-scale network perspective is needed to understand bipolar disorder's neuropathology.

Purpose of the Study:

• To critically review neuroimaging research on bipolar disorder from a network-based perspective.
• To identify consistent functional network alterations in bipolar disorder.
• To elucidate the neuropathology of bipolar disorder through network analysis.

Main Methods:

• Systematic literature search of PubMed and Google Scholar (2009-2019).
• Selection of functional magnetic resonance imaging (fMRI) studies examining large-scale brain networks in bipolar disorder.
• Review of 49 selected studies.

Main Results:

• Hypoconnectivity within default mode, salience, and central executive networks at rest.
• Hyperconnectivity within the central executive network during cognitive tasks.
• Altered internetwork connectivity: increased between salience and default mode networks, decreased between salience and central executive networks at rest.

Conclusions:

• Bipolar disorder exhibits disrupted functional activity in large-scale brain networks, both at rest and during tasks.
• Altered intra- and internetwork functional connectivity are associated with clinical symptoms.
• Disrupted network connectivity plays a significant role in the pathophysiology of bipolar disorder.