Brain network analysis reveals affected connectome structure in bipolar I disorder

Area of Science:

• Neuroscience
• Psychiatry
• Network Science

Background:

• Healthy brain function relies on coordinated neural activity within the brain's anatomical network (connectome).
• Alterations in connectome architecture are implicated in brain disorders like schizophrenia, showing reduced efficiency and hub disruptions.
• The impact of connectome alterations on bipolar disorder remains largely unexplored.

Purpose of the Study:

• To investigate structural connectome topology in bipolar I disorder.
• To compare brain network organization in bipolar I disorder patients versus healthy controls.
• To specifically examine alterations in central brain hubs and key network connections.

Main Methods:

• Structural connectome analysis was performed on 216 patients with bipolar I disorder and 144 healthy controls.
• Focus was placed on evaluating global efficiency, brain hub connectivity, and 'rich club' connections.
• Interhemispheric connections were also assessed for topological differences.

Main Results:

• Bipolar I disorder patients exhibited significantly reduced global network efficiency (-4.4%, P=0.002).
• This reduced efficiency correlated with decreased strength of interhemispheric connections (-13.0%, P=0.001).
• No significant alterations were found in the strength of connections involving brain hubs or in 'rich club' connections.

Conclusions:

• Aberrant brain network architecture, characterized by reduced global efficiency and disrupted interhemispheric connectivity, is associated with bipolar I disorder.
• The 'rich club' system, a central network organization, does not appear to be a primary site of disruption in bipolar I disorder.
• Findings suggest specific network deficits in bipolar I disorder, distinct from those observed in schizophrenia.