Default mode network subsystem alterations in bipolar disorder during major depressive episode

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• The default mode network (DMN) is implicated in bipolar disorder during depressive episodes.
• Emerging research suggests the DMN is a network of distinct functional subsystems, not a unitary system.
• Previous studies indicate altered DMN function in bipolar disorder with depression (BDD).

Purpose of the Study:

• To investigate abnormal functional connectivity (FC) patterns within DMN subsystems in individuals with BDD.
• To explore the relationship between DMN subsystem connectivity and clinical features of BDD.

Main Methods:

• Utilized a seed-based FC method on resting-state fMRI data.
• Analyzed data from 40 patients with BDD and 63 healthy controls.
• Extracted 11 DMN components for detailed analysis.

Main Results:

• Patients with BDD exhibited reduced FC between the precuneus and all three DMN subsystems.
• Increased FC was observed between the posterior cingulate cortex (PCC) seed and lateral orbitofrontal cortex in the midline core.
• BDD patients showed increased FC between DMN subsystems and sensorimotor, visual, and salience networks.
• Abnormal FC between PCC and precuneus correlated with higher levels of pessimism.

Conclusions:

• The study identified distinct abnormal FC patterns in DMN subdivision circuits in BDD.
• These abnormalities are associated with the underlying pathological mechanisms of bipolar disorder.
• Findings underscore the importance of considering DMN subsystems in understanding BDD.