Uncovering Shared and Distinct Brain Connectome Dynamics in Working Memory Tasks Between Bipolar and Unipolar...

Area of Science:

• Neuroscience
• Psychiatry
• Graph Theory

Background:

• Working memory (WM) deficits may differentiate bipolar disorder depression (BDD) from major depressive disorder (MDD).
• Dynamic functional connectivity (dFC) alterations are implicated in mood disorders.
• Graph theory metrics, such as degree centrality (DC), offer insights into brain network organization.

Purpose of the Study:

• To investigate whole-brain dynamic functional connectivity (dFC) alterations related to working memory (WM) in BDD and MDD using degree centrality (DC).
• To explore potential genetic mechanisms underlying observed dFC differences between BDD and MDD.

Main Methods:

• Calculated coefficient variation of dynamic DC (CVDC) and employed clustering analysis to identify meta-stable states of DC configuration in BDD, MDD, and healthy controls (HC) during n-back tasks.
• Tested associations between altered DC and clinical symptoms.
• Utilized imaging transcriptomic analysis to explore genetic underpinnings of DC differences.

Main Results:

• No significant differences in CVDC were found among the three groups.
• A 'ladder-like' pattern in DC was observed across BDD, MDD, and HC in several brain regions during a 2-back task compared to a 0-back task.
• Significant DC differences between BDD and MDD were noted in the right superior frontal gyrus and right middle temporal gyrus, linked to pathways like chemical synaptic transmission and neurodegeneration.

Conclusions:

• BDD and MDD display highly similar aberrant dynamic functional connectivity characteristics under increased cognitive demand.
• BDD exhibits a greater magnitude of these dynamic connectivity alterations than MDD.